Journal articles: 'Actuator Orientation'

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Wetherhold, Robert, Markus Messer, and Abani Patra. "Optimization of Directionally Attached Piezoelectric Actuators." Journal of Engineering Materials and Technology 125, no. 2 (April 1, 2003): 148–52. http://dx.doi.org/10.1115/1.1555653.

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A directionally attached piezoelectric (DAP) actuator is one method to control the twisting vibration of a plate with high authority. Although insuring proper performance for DAP actuators has been discussed in terms of the control law used, the optimization of the mechanical details of the actuator itself has received little attention. There is an interaction between the actuator and the controlled structure because more actuator material on the structure adds actuation power but also stiffens the structure. The effects of DAP actuator geometric parameters and material properties are explored in a systematic way for the case of a cantilever beam and it is shown that significant improvements in performance are possible. The material property study indicates that an optimum point exists whereby the weight and thus cost can be lowered while improving structure response by using a composite actuator. The actuator thickness, width, orientation angle, and offset from the clamped end have significant effects on structure response. In order of importance, the geometric parameters are: actuator thickness, orientation angle, width and offset. A study of the modal distribution for the structure shows that if the input disturbance that is to be suppressed is modally well characterized, the structure can be efficiently controlled by using more than one independent actuation voltage.

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Wang, Jinsong, Jun Wu, Tiemin Li, and Xinjun Liu. "Workspace and singularity analysis of a 3-DOF planar parallel manipulator with actuation redundancy." Robotica 27, no. 1 (January 2009): 51–57. http://dx.doi.org/10.1017/s0263574708004517.

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SUMMARYThis paper deals with the position workspace, orientation workspace, and singularity of a 3-degree-of-freedom (DOF) planar parallel manipulator with actuation redundancy, which is created by introducing a redundant link with active actuator to a 3-DOF nonredundant parallel manipulator. Based on the kinematic analysis, the position workspace and orientation workspace of the redundantly actuated parallel manipulator and its corresponding nonredundant parallel manipulator are analyzed, respectively. In the singularity analysis phase, the relationship between the generalized input velocity and the generalized output velocity is researched on the basis of the theory of singular value decomposition. Then a method to investigate the singularity of parallel manipulators is presented, which is used to determine the singularity of the redundantly actuated parallel manipulator. In contrast to the corresponding nonredundant parallel manipulator, the redundant one has larger orientation workspace and less singular configurations. The redundantly actuated parallel manipulator is incorporated into a 4-DOF hybrid machine tool which also includes a feed worktable to demonstrate its applicability.

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Kittinanthapanya, Rasheed, Yusuke Sugahara, Daisuke Matsuura, and Yukio Takeda. "Development of a Novel SMA-Driven Compliant Rotary Actuator Based on a Double Helical Structure." Robotics 8, no. 1 (February 18, 2019): 12. http://dx.doi.org/10.3390/robotics8010012.

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This paper proposes a new shape memory alloy (SMA)-driven compliant rotary actuator that can perform both passive and self-actuated motions. This SMA actuator is suitable as a redundant actuation part in a parallel robot joint to assist with singularity postures where the robot might lose the ability to maintain the position and orientation of the end effector. The double helical compliant joint (DHCJ) was chosen as a candidate mechanism; it can act in soft compliance with linear characteristics and a wide range of motion. The experimental results validated that the proposed model can be used to simulate the DHCJ behavior. The use of this mechanism exhibits advantages such as one-axis rotational motion, linear behavior even for a compliant mechanism, stiffness in the other axes of motion, and compact size. SMA leaves (strips) were used as actuation parts, and a single SMA leaf was tested before combining with the double helical frame as an SMA actuator. The prototype was fabricated, and necessary parameters such as deflection angle, temperature, torque, and stress–strain were collected to define the model for a controller. This actuator is controlled by a feedforward controller and provides rotational motion for both forward and reverse sides with a maximal range of 40 degrees.

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Kino, Hitoshi, Akihiro Kiyota, Nobuyoshi Miyamoto, Takumi Inadomi, Tomonori Kato, and Hiroyuki Fujioka. "Basic Study of Heating Response Measurement for Nanosheet Particle/Polymer Composite Gel Actuator with Anisotropic Contraction." Key Engineering Materials 804 (May 2019): 17–21. http://dx.doi.org/10.4028/www.scientific.net/kem.804.17.

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A soft actuator is expected to be applied in the next generation of robotics. This study focuses on soft gel actuators hybridized with nanosheet liquid crystals. The resulting soft actuator has a highly hydrophilic property, and is suitable for underwater use. When the gel in water is heated to more than the transition temperature, the gel contracts; conversely, it swells when it is cooled. This gel actuator remarkably has an anisotropic contraction characteristic because the orientation of the nanosheets is uniformly arranged. However, little is known about its dynamic characteristics of the thermal contraction. As a basic analysis, this paper investigates the heating step response through experiments, and reveals the variation of the time constant against the dimensions.

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Kang, Tey Wei, Lim Thol Yong, Yeong Che Fai, and Eileen Su Lee Ming. "Design and Development of an Omnidirectional Mobile Robot." Applied Mechanics and Materials 432 (September 2013): 494–99. http://dx.doi.org/10.4028/www.scientific.net/amm.432.494.

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Most mobile robots use differential-drive concept, where they are equipped with two actuators that permit only single-direction rotation at a time. This concept limits the robots navigation because its orientation must always change according to the direction of movement. This paper presents the development of an omnidirectional mobile robot that uses three actuators, aligned in 120 degrees separation and each attached to an omniwheel. By manipulating actuator speed, the robot can navigate to any direction without changing its orientation. UsingNIsbRIO9632xtas the main controller, navigation algorithm is implemented in LabVIEW, integrated with PID controller to fine-tune robot movements.

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Chen, Wei Hai, Liang Zhang, Fang Hong Guo, and Jing Meng Liu. "Design and Modeling of a Spherical Actuator with Three Dimensional Orientation Measurement System." Advanced Materials Research 317-319 (August 2011): 1088–97. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.1088.

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This paper presents the design and modeling of a permanent magnet spherical actuator which consists of a rotor with eight cylindrical permanent magnet (PM) poles and a stator with twenty-four air-core coils. Torque and dynamic model of this PM spherical actuator are formulated analytically. An optimal design procedure is proposed to achieve a high torque output, and significant design parameters of the actuator are discussed. As there is no effective method for three dimensional orientation measurement of the spherical actuator currently, a novel orientation measurement system is proposed. Finally, experimental works are carried out, and the experiment results demonstrate the effectiveness of the proposed orientation measurement system.

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Ericson Rajagukguk. "Perbaikan Sistem Pelacakan Panel Surya Menggunakan Penyesuaian Posisi Massa Tambahan." JURNAL TEKNIK MESIN, INDUSTRI, ELEKTRO DAN INFORMATIKA 1, no. 1 (March 12, 2022): 07–15. http://dx.doi.org/10.55606/jtmei.v1i1.463.

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This study aims to obtain an effective solar panel tracking mechanism using energy-efficient electric actuators. Furthermore, we designed and implemented a semi-active solar tracking system. A tracking system is proposed to control solar panel orientation using a moving mass, a spring system, and an actuator. The weight of the moving mass and the spring constant are optimized to reduce actuator size. A stepper motor was used for this case. This electric drive is not the prime mover of the solar tracker; hence, it works against mass elements lighter than solar panel weight as used in the active solar tracker. Experimental results suggest that the average power required by the stepper motor is 0.21% of the energy generated by the solar tracking system. The results indicate that the proposed solar panel tracker works satisfactorily to control solar panel orientation.

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Firmani, Flavio, Alp Zibil, Scott B. Nokleby, and Ron P. Podhorodeski. "FORCE-MOMENT CAPABILITIES OF REVOLUTE-JOINTED PLANAR PARALLEL MANIPULATORS WITH ADDITIONAL ACTUATED BRANCHES." Transactions of the Canadian Society for Mechanical Engineering 31, no. 4 (December 2007): 469–81. http://dx.doi.org/10.1139/tcsme-2007-0034.

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The force-moment capabilities of revolute-jointed planar parallel manipulators (PPMs) are presented. A previously developed analysis that determines explicitly the force-moment capabilities of parallel manipulators is considered and the formulation is improved. This analysis is based upon properly adjusting the actuator outputs to their maximum capabilities. The force-moment capabilities of two actuation layouts are investigated: the non-redundant 3-RRR PPM and the redundantly actuated 4-RRR PPM, where the underline indicates the actuated joint. Four studies of force-moment capabilities are presented: maximum force with a prescribed moment, maximum applicable force, maximum moment with a prescribed force, and maximum applicable moment. These studies are performed for constant payload orientation of the mobile platform throughout the manipulator’s workspace. It is concluded that the manipulator with the additional actuated branch shows an improvement of the force-moment capabilities at the expense of reducing its workspace.

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Firmani, Flavio, Alp Zibil, Scott B. Nokleby, and Ron P. Podhorodeski. "Wrench capabilities of planar parallel manipulators. Part II: Redundancy and wrench workspace analysis." Robotica 26, no. 6 (November 2008): 803–15. http://dx.doi.org/10.1017/s0263574708004396.

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SUMMARYThis part of the paper investigates the wrench capabilities of redundantly actuated planar parallel manipulators (PPMs). The wrench capabilities of PPMs are determined by mapping a hypercube from the torque space into a polytope in the wrench space. For redundant PPMs, one actuator output capability constrains the wrench space with a smaller polytope that is contained inside the overall polytope. Performance indices are derived from six study cases. These indices are employed to analyze the wrench workspace for constant orientation of the mobile platform of the non-redundant 3-RRR PPM, and actuation redundant 4-RRR and 3-RRR PPMs, where the underline indicates the actuated joints. A comparison of the results shows that both of the redundantly-actuated PPMs give better wrench capabilities than the non-redundant PPM. However, it is shown that scaled for the operational cost (wrench capabilities divided by total actuation output) the non-redundant 3-RRR PPM provides the highest maximum reachable force, the 3-RRR PPM produces the highest isotropic force, and the 4-RRR yields the highest reachable moment.

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Sokhanvar, S., A. Zabihollah, and R. Sedaghati. "INVESTIGATING THE EFFECT OF THE ORTHOTROPIC PROPERTY OF PIEZOELECTRIC PVDF." Transactions of the Canadian Society for Mechanical Engineering 31, no. 1 (March 2007): 111–25. http://dx.doi.org/10.1139/tcsme-2007-0007.

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The applications of the piezoelectric Polyvinylidene Fluoride, PVDF, integrated with the beams, plates, and membranes, performing as sensor, actuator or combination have been received considerable attention in the recent years. However, not much work has been reported on the influence of the PVDF’s orthotropic behavior, particularly the effect of the orientation of the PVDF film in the host structure, on the performance of the system. In the present study, the effect of the piezoelectric PVDF film orientation on the output voltage, the actuation force, and the dynamic response of the integrated structures has been studied using the finite element method. In the sensory mode, the difference between the output voltages obtained from the biaxial piezoelectric PVDF film and uniaxial one, when the orientation of the film varies from 0 to 90 degree, is investigated. In each case the proportion contributions of the involved piezoelectric coefficients including d31, d32 and are studied. Alternatively, in the actuation mode, the effect of orthotropic behavior of the actuator on the nodal displacements has been taken into consideration. The influence of the material orthotropic property of the transducer on the free undamped response of the system is also investigated. Moreover an effective Young’s modulus and effective Poisson ratio for the uniaxial PVDF film has been introduced using an optimization procedure to minimize the error caused by isotropic assumption of uniaxial PVDF film.

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Kino, Hitoshi, Akihiro Kiyota, Takumi Inadomi, Tomonori Kato, Hiroyuki Fujioka, and Nobuyoshi Miyamoto. "Step Response Characteristics of Anisotropic Gel Actuator Hybridized with Nanosheet Liquid Crystal." Journal of Robotics and Mechatronics 31, no. 5 (October 20, 2019): 647–56. http://dx.doi.org/10.20965/jrm.2019.p0647.

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In this study, we focus on a soft anisotropic gel actuator hybridized with nanosheet liquid crystal. This gel actuator is highly hydrophilic and can be operated underwater. Gel actuators can contract when heated and expand back to their original size when cooled down. It is anisotropic in the contraction direction, aligned with the orientation of the nanosheet liquid crystal. However, details of this step response property against the actuator undergoing thermal change have not been clarified. In this paper, we introduce a method to measure the step response using a square test sheet with a side length of 2–10 mm and thickness of 0.1–1.0 mm. This measurement was used to measure the heating and cooling step response. The obtained result was approximated using a first-order lag system to determine a steady-state value and time constant. In addition, the characteristics of steady-state value and time constant were clarified from the viewpoint of shapes such as specific surface area and thickness.

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Ciobanu, Daniela, Codruta Jaliu, and Radu Saulescu. "Chain Tracking System for Solar Thermal Collector." Applied Mechanics and Materials 658 (October 2014): 35–40. http://dx.doi.org/10.4028/www.scientific.net/amm.658.35.

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The use of renewable energy sources represents a continuous concern for the researchers around the world. The main source of renewable energy, the sun can be used for producing hot water / heating or electric energy, by means of solar collectors. The concentrating solar collectors contain tracking systems for orientation on one or two axes. The tracking system for the elevation motion has to ensure a reduced angular stroke. The mechanism that is usually included in the system structure is of linkage type, being driven by a linear actuator. The mechanism has the advantages of low complexity and reduced cost. In the case of diurnal motion, the angular stroke is larger, being usually obtained with gears or chain drives. The actuation is achieved by motor-reducers with high transmission ratios and costs. In order to reduce the costs, mechanisms containing linkages driven by linear actuators are proposed in literature. These tracking systems have the disadvantage of large overall dimensions. To reduce this disadvantage, the paper proposes a new variant of chain tracking system driven by a linear actuator. Then the proposed tracking system is structurally optimized, process that generates 6 new variants of mechanisms. These solutions eliminate the problems created by the hyperstatical constraints and avoid blocking in case of assembling errors.

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Neagoe, Mircea, Radu Saulescu, Olimpiu Munteanu, and Bogdan Burduhos. "Low Speed Linear Actuator for Accurate Orientation of Concentrated Solar Convertors." Applied Mechanics and Materials 658 (October 2014): 99–104. http://dx.doi.org/10.4028/www.scientific.net/amm.658.99.

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The accurate orientation of concentrated solar converters (e.g. solar parabolic dish, concentrated photovoltaic) requires small stepwise angular displacements at short intervals of time aiming to track accurately the sun. These tracking systems are usually operated, especially the elevation movement, by low speed linear actuators (LSLA) with special configuration. The main drawbacks of the known LSLA solutions refers to the high constructive complexity of the intermediate gear reducer and its relative low efficiency due to the high value of the kinematic ratio, required to harmonize high speed motors and low speed outputs. The paper presents a geometrical synthesis algorithm and kinematic simulations of a new LSLA variant, proposed by the authors, consisting of a classical electrical motor (AC or DC), a linkage reducer transmitting intermittently the motion to a final irreversible screw-nut transmission through backstopping clutches. Compared to the known solutions, the proposed actuator has the advantage of decreasing the structural, constructive and technological complexity of the intermediate gear reducer (between the motor and the irreversible screw-nut transmission) by replacing it with a linkage type speed reducer and backstopping clutches, achieving a fixed or adjustable high kinematic ratio.

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Neagoe, Mircea, Ion Visa, Nadia Cretescu, and Macedon Moldovan. "On a New Parallel Tracking System for Accurate Orientation of Concentrated Solar Convertors." Applied Mechanics and Materials 658 (October 2014): 105–10. http://dx.doi.org/10.4028/www.scientific.net/amm.658.105.

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The concentrated solar energy convertors (e.g. solar-thermal dish, concentrated photovoltaic) require high tracking accuracy to maintain low incidence angles of the solar ray in relation with the concentrator optical axis (e.g. tracking accuracy of 0.05°...0.1°). This functional requirement is currently ensured by the high performance dual-axis solar tracking systems, able to reach the imposed accuracy, including expensive rotary actuator solutions. This paper proposes a new high accuracy tracking system for diurnal orientation, integrating a 2 DOF parallel linkage driven by linear actuators, as a simple, accurate, and cost-effective solution. A kinematic and static approach used for optimisation of the driving programs of the two linear actuators is presented, following the requirements: a) ensure the imposed tracking accuracy and b) achieve advantageous transmitting angles and hence lowest driving forces. The performances of the system are analysed on large orientation strokes (over 130°); the results obtained confirm the viability of the new tracking system concept, with higher performances compared to other similar known solutions.

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Jiang, Shulan, and Li Xia. "Bioinspired High-Performance Bilayer, pH-Responsive Hydrogel with Superior Adhesive Property." Polymers 14, no. 20 (October 19, 2022): 4425. http://dx.doi.org/10.3390/polym14204425.

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Soft actuators have attracted extensive attention for promising applications in drug delivery, microfluidic switches, artificial muscles and flexible sensors. However, the performance of pH-responsive hydrogel actuators, such as regarding reversible bending property and adhesive property, remains to be improved. In this study, inspired by drosera leaves, we have fabricated high-performance bilayer, pH-responsive poly(acrylamide-acrylic acid-3-acrylamidophenylboronic acid)(P(AAm-AAc-3-AAPBA)) based on the copolymers of AAm, AAc and 3-AAPBA. The pH-sensitive actuators were fabricated by ultraviolet polymerization of the P(AAm-AAc-3-AAPBA) layer as the active actuating layer and the PAAm layer as the auxiliary actuating layer. The effects of pH, glucose concentration and content of 3-AAPBA on bending behavior of P(AAm-AAc-3-AAPBA)/PAAm bilayer actuators were discussed. By tuning the pH of media, the soft actuator could achieve fast and large-amplitude bidirectional bending behaviors. The bending orientation and bending degree can be reversibly and precisely adjusted. More importantly, P(AAm-AAc-3-AAPBA) hydrogel shows good adhesive property in polyvinyl alcohol (PVA) solution; thus, complex structures have been fabricated. In addition, the bilayer hydrogel structures have been demonstrated as soft actuators, bionic flowers and bionic manipulators. The proposed pH-responsive bilayer actuator shows great potential for drug delivery and other medical systems.

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Balk, M., M. Behl, and A. Lendlein. "Hydrolytic Degradation of Actuators Based on Copolymer Networks From Oligo(ε-caprolactone) Dimethacrylate and n-Butyl Acrylate." MRS Advances 4, no. 21 (2019): 1193–205. http://dx.doi.org/10.1557/adv.2019.202.

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ABSTRACTShape-memory polymer actuators often contain crystallizable polyester segments. Here, the influence of accelerated hydrolytic degradation on the actuation performance in copolymer networks based on oligo(ε-caprolactone) dimethacrylate (OCL) and n-butyl acrylate is studied. The semi-crystalline OCL was utilized as crosslinker with molecular weights of 2.3 and 15.2 kg∙mol−1 (ratio: 1:1 wt%) and n-butyl acrylate (25 wt% relative to OCL content) acted as softening agent creating the polymer main chain segments within the network architecture. The copolymer networks were programmed by 50% elongation and were degraded by means of alkaline hydrolysis utilizing sodium hydroxide solution (pH = 13). Experiments were performed in the range of the broad melting range of the actuators at 40 °C. The degradation of test specimen was monitored by the sample mass, which was reduced by 25 wt% within 105 d. As degradation products, fragments of OCL with molecular masses ranging from 400 to 50.000 g·mol-1 could be detected by NMR spectroscopy and GPC measurements. The cleavage of ester groups included in OCL segments resulted in a decrease of the melting temperature (Tm) related to the actuator domains (amorphous at the temperature of degradation) and simultaneously, the Tm associated to the skeleton domain was increased (semi-crystalline at the temperature of degradation).The alkaline hydrolysis decreased the polymer chain orientation of OCL domains until a random alignment of crystalline domains was obtained. This result was confirmed by cyclic thermomechanical actuation tests. The performance of directed movements decreased almost linearly as function of degradation time resulting in the loss of functionality when the orientation of polymer chains disappeared. Here, actuators were able to provide reversible movements until 91 d when the accelerated bulk degradation procedure using alkaline hydrolysis (pH = 13) was applied. Accordingly, a lifetime of more than one year can be guaranteed under physiological conditions (pH = 7.4) when, e.g., artificial muscles for biomimetic robots as potential application for these kind of shape-memory polymer actuators will be addressed.

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Karssies, H. J., and C. De Wagter. "Extended incremental non-linear control allocation (XINCA) for quadplanes." International Journal of Micro Air Vehicles 14 (January 2022): 175682932110708. http://dx.doi.org/10.1177/17568293211070825.

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Hybrid UAVs have gained a lot of interest for their combined vertical take-off & landing (VTOL) and efficient forward flight capabilities. But their control is facing challenges in over-actuation and conflicting requirements depending on the flight phase which can easily lead to actuator saturation. Incremental Non-linear Control Allocation (INCA) has been proposed to solve the platform’s control allocation problem in the case of saturation or over-actuation by minimizing a set of objective functions. This work demonstrates INCA on quadplanes, an in-plane combination between a quadrotor and a conventional fixed-wing, and proposes an extension to control the outer loop. The novel controller is called Extended INCA (XINCA) and adds the wing orientation as a force-generating actuator in the outerloop control optimization. This leads to a single controller for all flight phases that avoids placing the wing at negative angles of attack and minimizes the load on hover motors. XINCA has low dependence on accurate vehicle models and requires only several optimization parameters. Flight simulations and experimental flights are performed to demonstrate the performance.

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Kostenko, V. V., and A. Yu Tolstonogov. "On Propulsion-based Estimation of Incoming Flow Velocity." IOP Conference Series: Earth and Environmental Science 988, no. 3 (February 1, 2022): 032070. http://dx.doi.org/10.1088/1755-1315/988/3/032070.

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Abstract AUV’s actuators systems are highly affected by external conditions such as incoming flow velocity. The paper aims to estimation of incoming flow velocity based on quasi-steady model of thruster. The work motivation is compensation of incoming flow effect on AUV’s actuators dynamic model for improving actuator control or a velocity estimation in case of velocity sensors absence. The equation for incoming flow velocity estimation is presented. It accounts orientation of thrusters relative to the longitudinal vehicle axis. Thruster parameters identification procedure based on bollard pull tests and marine trials are presented. Comparative results of propulsion-based velocity estimation with DVL data are discussed. Velocity estimation error between methods is less than 0.1 m/s in steady motion and less than 0.2 m/s in transition process.

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Wu, Weixin, Yujie Dong, and Adam Hoover. "Measuring Digital System Latency from Sensing to Actuation at Continuous 1-ms Resolution." Presence: Teleoperators and Virtual Environments 22, no. 1 (February 2013): 20–35. http://dx.doi.org/10.1162/pres_a_00131.

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This paper describes a new method for measuring the end-to-end latency between sensing and actuation in a digital computing system. Compared to previous works, which generally measured the latency at 10–33-ms intervals or at discrete events separated by hundreds of ms, our new method measures the latency continuously at 1-ms resolution. This allows for the observation of variations in latency over sub 1-s periods, instead of relying upon averages of measurements. We have applied our method to two systems, the first using a camera for sensing and an LCD monitor for actuation, and the second using an orientation sensor for sensing and a motor for actuation. Our results show two interesting findings. First, a cyclical variation in latency can be seen based upon the relative rates of the sensor and actuator clocks and buffer times; for the components we tested, the variation was in the range of 15–50 Hz with a magnitude of 10–20 ms. Second, orientation sensor error can look like a variation in latency; for the sensor we tested, the variation was in the range of 0.5–1.0 Hz with a magnitude of 20–100 ms. Both of these findings have implications for robotics and virtual reality systems. In particular, it is possible that the variation in apparent latency caused by orientation sensor error may have some relation to simulator sickness.

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Qiang, Hongbin, Lihang Wang, Jisong Ding, and Lijie Zhang. "Multiobjective Optimization of 6-DOF Parallel Manipulator for Desired Total Orientation Workspace." Mathematical Problems in Engineering 2019 (April 22, 2019): 1–10. http://dx.doi.org/10.1155/2019/5353825.

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A desired total orientation workspace for a parallel manipulator is usually an essential requirement in a practical application. At present, for the multiobjective optimization method of 6-DOF parallel manipulator for desired total orientation workspace, it is needed to predefine maximal and minimal lengths of the legs to serve as the constraint, and then the numerical method is used to solve the length of the legs and judge whether the solved maximal and minimal leg lengths meet the constraint. Predefining maximal and minimal length of the legs limits of the optimal range, the numerical method has heavy calculation burden and low calculating accuracy. In this paper, a hybrid method for solving the maximal and minimal lengths of the legs of 6-DOF parallel manipulator with desired total orientation workspace is proposed, and the actuator stroke length is calculated according to the maximal and minimal leg lengths. By judging whether the actuator stroke length can be solved to serve as the constraint, without the predefined maximal and minimal leg lengths to serve as the constraint, the optimal range is enlarged. Aiming at the physical size of the parallel manipulator and the proposed desired workspace condition index (DWCI), the optimization of the geometric parameters of the parallel manipulator is conducted based on the multiobjective optimization algorithm (NSGA-II), which is subject to the actuator stroke length. Stewart platform is set as the example; the geometric parameters of the platform whose workspace contains the desired total orientation workspace are optimized and the hybrid method is proved to be more accurate and efficient compared to the traditional numerical method. This method provides the optimization guidance for engineering designers to design the parallel manipulator for desired total orientation workspace.

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Ciambella, Jacopo, Antonino Favata, and Giuseppe Tomassetti. "A nonlinear theory for fibre-reinforced magneto-elastic rods." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, no. 2209 (January 2018): 20170703. http://dx.doi.org/10.1098/rspa.2017.0703.

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We derive a model for the finite motion of a fibre-reinforced magneto-elastic rod. The reinforcing particles are assumed weakly and uniformly magnetized, rigid and firmly embedded into the elastomeric matrix. We deduce closed-form expressions of the quasi-static motion of the rod in terms of the external magnetic field and of the body forces. The dependences of the motion on the shape of the inclusions, their orientation, their anisotropic magnetic properties and the Young modulus of the matrix are analysed and discussed. Two case studies are presented, in which the rod is used as an actuator suspended in a cantilever configuration. This work can foster new applications in the field of soft-actuators.

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Shaari, M. F., S. K. Saw, and Z. Samad. "Fabrication and Characterization of IPMC Actuator for Underwater Micro Robot Propulsor." Applied Mechanics and Materials 575 (June 2014): 716–20. http://dx.doi.org/10.4028/www.scientific.net/amm.575.716.

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The usage of Ionic Polymer-Metal Composite (IPMC) actuator as the propulsor for underwater robot has been worked out by many scientists and researchers. IPMC actuator had been selected due to its advantages such as low energy consumption, low operation noise and ability to work underwater. This paper presents the fabrication and characterization of the IPMC actuator. The IPMC actuator samples had been fabricated using electroless plating for three different thickness and lengths. The characterization was conducted to determine the influence of the thickness, length, input frequency, drive voltage and orientation angle on the tip force and output frequency. The results show that IPMC thickness has significant influence on the tip force generation and lower input frequency would results wider displacement. The recorded results are essential as future reference in developing the propulsor for the underwater robot.

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Mai, S. P., and N. A. Fleck. "Reticulated tubes: effective elastic properties and actuation response." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 465, no. 2103 (November 18, 2008): 685–708. http://dx.doi.org/10.1098/rspa.2008.0328.

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The structural performance is explored for a reticulated circular tube made from a periodic lattice: triangulated; hexagonal; Kagome; and square lattices. The finite-element (FE) method is used to determine the macroscopic bending, torsional and axial rigidities of each tube. Additional insight is obtained by examining the structural mechanics of the pin-jointed version of each topology. For all pin-jointed lattices considered, no states of self-stress exist. However, collapse mechanisms do exist for all reticulated tubes, and for the Kagome and hexagonal lattices some of these mechanisms produce macroscopic generalized strain. These strain-producing collapse modes are additional to those observed in the planar version of these lattices. Consequently, the structural rigidities of tubes with walls made from the rigid-jointed Kagome lattice or hexagonal lattice are less than those predicted from the in-plane effective properties of these two lattices. The morphing capacity of reticulated tubes is also explored by replacing a single bar with an actuator in the FE simulations. The actuation stiffness of the structure is defined by the stiffness of the reticulated tube in resisting extension by the actuated bar. The actuation stiffness is explored as a function of the type of lattice, number of unit cells around the circumference, orientation of the actuated bar and of the bar stockiness. In all cases, the macroscopic shape change of the tube can be idealized as a combination of a local rotation, axial extension, axial twist and shear displacement of the cross-section.

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Grujicic, M., C. L. Zhao, and E. M. Austin. "Optimization of a piezoelectric bimorph grasper for use in minimally invasive surgical applications." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 219, no. 9 (September 1, 2005): 673–83. http://dx.doi.org/10.1243/095440505x32607.

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The potential use of piezoelectric bimorph actuators in minimally invasive surgery suture-needle grasper/holder applications is explored computationally. Upon defining the design/functional requirements for such surgical tools, a finite element analysis of the underlying piezoelectric boundary value problem is combined with the genetic algorithm optimization routine to arrive at an optimal morphology of the suture-needle grasper/holder. The results obtained show that, if the actuator is based on several constant-thickness segments, a proper combination of thicknesses of such segments can substantially improve the performance of such surgical tools. Specifically, a good combination of the relatively large grasper-jaws opening and the required level of the holding force when the grasper is closed on a 0.5 mm diameter suture-needle is obtained. The effect of orientation of the poling direction in the piezoelectric layers on the performance of the bimorph actuator is also examined. It is found that, at the same level of the required grasping force, a change in the poling direction by about 2.3° from the through-the-thickness direction can increase the maximum grasper-jaws opening by about 10 per cent.

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Chee, C., L. Tong, and G. P. Steven. "Piezoelectric actuator orientation optimization for static shape control of composite plates." Composite Structures 55, no. 2 (February 2002): 169–84. http://dx.doi.org/10.1016/s0263-8223(01)00144-1.

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Gong, Xiaoxiang, Weiguo Ge, Juan Yan, Yiwei Zhang, and Xiangyu Gongye. "Review on the Development, Control Method and Application Prospect of Brake-by-Wire Actuator." Actuators 9, no. 1 (March 5, 2020): 15. http://dx.doi.org/10.3390/act9010015.

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This paper reviews and summarizes the development, key technologies, and application of brake-by-wire (BBW) actuators. BBW is the technology orientation of future vehicle brake system. The main feature of BBW is to replace some of the mechanical and hydraulic components of traditional brake system with electronic control components, and use cables and wires to transmit energy and signals. BBW actuators have outstanding advantages, such as fast response, accurate control, and compact structure. They are easy to integrate with active safety functions and they are easily matched with the regenerative braking systems of electric vehicle. First, this paper summarizes the classification, characteristics, performance, and architecture of BBW actuators. Subsequently, the braking process regulation of vehicle is considered to be the main target, which is summarized from two aspects of actuator regulation and braking force distribution. The state estimation algorithm and control algorithm applied to these actuators are summarized and analyzed, and the development trend, challenges, and schemes of the braking force distribution are proposed. The development and research trend of braking force match strategies between the regenerative brake system and BBW system are also analyzed and summarized. The further electrification and intelligence of vehicle demand BBW’s braking force control method and distribution method must have higher control accuracy, stronger robustness, and wider adaptability, and the effects on braking comfort and handling stability must be further discussed.

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KERUR, S. B., and ANUP GHOSH. "ACTIVE VIBRATION CONTROL OF COMPOSITE PLATE USING AFC ACTUATOR AND PVDF SENSOR." International Journal of Structural Stability and Dynamics 11, no. 02 (April 2011): 237–55. http://dx.doi.org/10.1142/s0219455411004075.

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A finite element formulation for active vibration control of laminated composite plate integrated with active fiber composite (AFC) layer acting as distributed actuator and PVDF layer as sensor is presented in this paper. An eight noded quadratic isoparametric element with five mechanical degrees of freedom and one electrical degree of freedom per node of the element is considered. Newmark time integration method is used to calculate the dynamic response and negative velocity feedback control algorithm is used to control the dynamic response of the laminated composite plate. The effect of piezoelectric fiber orientation in actuator layer on the control of vibration is studied.

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Wang, Songlai, Wanrong Wu, Yiping Shen, Yi Liu, and Shuai Jiang. "Influence of the PZT Sensor Array Configuration on Lamb Wave Tomography Imaging with the RAPID Algorithm for Hole and Crack Detection." Sensors 20, no. 3 (February 6, 2020): 860. http://dx.doi.org/10.3390/s20030860.

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The tomography technique is an effective way to quantitatively evaluate damage from reconstruction imaging in structure health monitoring (SHM). The reconstruction algorithm for the probabilistic inspection of damage (RAPID) algorithm based on the signal difference coefficient (SDC) feature is a promising approach due to its superior performance. This paper focuses on the influence of different patterns of PZT (Lead Zirconate Titanate) sensor array configurations, i.e., the circular, square, and parallel array, on reconstruction image qualities for evaluating hole and crack damage. Variable shape parameters are applied to account for the unequal damage distances of different actuator-sensor pairs. Considering the directionality scattering fields of cracks, the angular scattering pattern of the SDC values are studied by simulation. The SDC variations for different groups of sensing paths at the same actuator are applied to predict the crack orientation. An improved RAPID algorithm is proposed by defining an additional SDC value of 1 in the path along the predicted crack orientation, which is determined by the point of the actuator causing the minimal SDC variation and the center point of the initial reconstruction image of the crack. The results show that the improved RAPID algorithm is effective for the evaluation of crack damage. Reconstruction image qualities with three PZT sensor array configurations for both holes and cracks are compared. The research is significant for selecting the PZT sensor array configuration in SHM.

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Aziz Muslim, Muhammad, Goegoes Dwi Nusantoro, Rini Nur Hasanah, and Mokhammad Hasyim Asy’ari. "Control of Pole-Climbing Robot Orientation using Self-Tuning Method." International Journal of Power Electronics and Drive Systems (IJPEDS) 9, no. 3 (September 1, 2018): 1029. http://dx.doi.org/10.11591/ijpeds.v9.i3.pp1029-1037.

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This paper describes the method to control a hybrid robot whose main task is to climb a pole to place an object on the top of the pole. The hybrid pole-climbing robot considered in this paper uses 2 Planetary PG36 DC-motors as actuators and an external rotary encoder sensor to provide a feedback on the change in robot orientation during the climbing movement. The orientation control of the pole-climbing robot using self-tuning method has been realized by identifying the transfer function of the actuator system under consideration, being followed with the calculation of control parameters using the self-tuning pole-placement method, and furthermore being implemented on the external rotary encoder sensor. Self-tuning pole-placement method has been explored to control the parameters q0, q1, q2, and p1 of the controller. The experiments were done on a movement path in a form of a cylindrical pole. The first experiment was done based one the change in rotation angle of the rotary sensor with the angle values greater than 50˚ in the positive direction, whereas the second experiment was done with the angle values greater than -50˚ in the negative direction. The experiment results show that the control of the robot under consideration could maintain its original position at the time of angle change disturbance and that the robot could climb in a straight direction within the specified tolerance of orientation angle change.

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Han, Liang, Li Yu Wang, and Guo Ping Hu. "A Study on the Machine Vision Assisted Vibratory Feeding System." Applied Mechanics and Materials 220-223 (November 2012): 1377–80. http://dx.doi.org/10.4028/www.scientific.net/amm.220-223.1377.

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Vibratory feeding is the most significant approach for parts orientation and feeding in production; the process of production automation has been seriously hindered due to the problems with low feeding efficiency, high jamming rate. This project combines machine vision and vibratory feeding technology in substitute for the currently used mechanical orientation mechanism, in order to automatically recognize work pieces of different size, shape and color. The special vibratory feeder and frame are designed. According to the system work requirement, in the thesis, the adjustable light source and illumination system are designed, and the CCD camera and optical lens are chosen. The pneumatic actuator is also designed with the microcomputer as the controller. The area, perimeter, dispersion and invariant moment parameters are used in parts type identification. The image centroid is used to confirm parts position. By using the Hough transform, the image edge can be extracted to get the deflection angle. By using Matlab, the image can be captured, processed, analyzed and judged, meanwhile, communicate with actuator and control it.

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Warzocha, Krzysztof, Jerzy Szura, Piotr Bąk, Paweł Rzucidło, and Tomasz Rogalski. "Transformative Use of Additive Technology in Design and Manufacture of Hydraulic Actuator for Fly-by-Wire System." Applied Sciences 11, no. 11 (May 22, 2021): 4772. http://dx.doi.org/10.3390/app11114772.

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In this paper, the results of research on additively manufactured aerospace parts made of maraging steel are presented. This state-of-the-art technology seems to have the highest potential for practical use in the field of ultra-light and high-performance aerospace hydraulic parts. The strength properties of representative specimens made with steel 1.2709 were investigated. The researchers conducted static tensile testing, fatigue tensile testing, and pressure impulse testing. A Goodman diagram was plotted to visualize the impact of the building orientation vs. load character on the fatigue strength of the additive manufacturing (AM) specimens. Based on the research carried out on the strength of the AM samples, an aircraft flight control actuator was designed to achieve the highest level of safety integrity along with the greatest simplicity and lowest weight relative to hydraulic actuators manufactured using classical methods. The entire design process was integrated with the manufacturing process to achieve this target.

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Flores-Campos, Juan Alejandro, J. A. Perrusquía Guzmán, Juan Alfonso Beltrán-Fernández, and Luis Héctor Hernández-Gómez. "Sliding Mode Control of a Water-Displacement Based Mechanism Applied to the Orientation of a Parabolic-Trough Solar Concentrator." Defect and Diffusion Forum 370 (January 2017): 90–97. http://dx.doi.org/10.4028/www.scientific.net/ddf.370.90.

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In this paper the problem of guiding a parabolic trough solar concentrator through a system based on a water displacement mechanism is addressed. The actuator mechanism consists of a set of four on/off electrovalves in ”H-bridge” configuration, a small water pump, a sun sensor and two containers half-filled with water, installed on the side ends of the concentrator. To guide and balance the concentrator, a sliding mode controller (SMC) to enable / disable the opening and closing of the valves that control the direction and flow of water between the two containers is proposed. The validity of the implementation of the proposed law of control applied to the actuator mechanism is verified with stability analysis and simulation results.

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Shevtsov, Sergey, Valery Chebanenko, Maria Shevtsova, Shun-Hsyung Chang, Evgenia Kirillova, and Evgeny Rozhkov. "On the Directivity of Lamb Waves Generated by Wedge PZT Actuator in Thin CFRP Panel." Materials 13, no. 4 (February 18, 2020): 907. http://dx.doi.org/10.3390/ma13040907.

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This paper addresses investigation of guided-wave excitation by angle-beam wedge piezoelectric (PZT) transducers in multilayered composite plate structure with orthotropic symmetry of the material. The aim of the present study is to determine the capability of such actuators to provide the controlled generation of an acoustic wave of a desirable type with the necessary wavelength, propagation distance and directivity. The studied CFRP (Carbon Fiber Reinforced Plastic) panel is considered to be homogenous, with effective elastic moduli and anisotropic structural damping, whose parameters were determined experimentally. According to the results of dispersion analysis and taking into account the data of wave attenuation in a highly damping CFRP composite, the two types of propagating waves A0 and S0 were considered theoretically and experimentally in the frequency range of 10–100 kHz. Using the results of a previous study, we reconstructed the structure of the wedge actuator, to develop its finite-element (FE) model, and a modal analysis was carried out that revealed the most intense natural vibration modes and their eigenfrequencies within the frequency range used. Both experimental and numerical studies of the generation, propagation, directivity and attenuation of waves in the orthotropic composite panel under study revealed the influence of the angular orientation of the actuator on the formation of wave patterns and allowed to determine the capabilities of the wave’s directivity control.

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Yan, Liang, I. Ming Chen, Zhongwei Guo, Yan Lang, and Yunhua Li. "A Three Degree-of-Freedom Optical Orientation Measurement Method for Spherical Actuator Applications." IEEE Transactions on Automation Science and Engineering 8, no. 2 (April 2011): 319–26. http://dx.doi.org/10.1109/tase.2010.2089981.

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Zhu, Yan, Shi Shun Zhu, Guo Jun Wang, and Xu Gang Liu. "Kinematics Analysis of 6-DOF Transportation Vibration Platform." Advanced Materials Research 199-200 (February 2011): 1419–22. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.1419.

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Based on the principle of Space Mechanism, the kinematics model of 6-DOF transportation vibration platform is described, and system kinematics analysis and calculation are finished. With an example, the displacement of actuator is solved according to the position and orientation of moving platform. The kinematics analysis is the basis of deciding system motion parameters, motion trajectory planning and system dynamics analysis.

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Kim, J., W. Jung, C. H. Jo, J. Shelton, and W. Craft. "Mechanical properties of cellulose-based electro-active paper." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 4 (April 1, 2008): 577–83. http://dx.doi.org/10.1243/09544062jmes652.

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Mechanical properties of cellulose-based electro-active paper (EAPap) are characterized in this work. Cellulose-based EAPap has been studied as a potential actuator concept, as a result of its low actuation voltage, lightweight, low power consumption, biodegradability and low cost. EAPap is made from cellulose paper, coated with thin electrically conducting electrodes. This EAPap shows a reversible and reproducible bending movement as well as a longitudinal displacement under electric field excitation. However, the EAPap is a complex anisotropic material, which has not been extensively characterized. It is important to have extended property data for EAPap so that the actuator performance can be optimized, and this requires additional material testing. Our material test results show that EAPap has two distinct elastic constants. The initial Young's modulus of EAPap is in the range of 4–9 GPa, which is higher than other polymer materials. This modulus is also orientation dependent, which may be associated with the piezoelectricity of the EAPap materials. Another important property is that the dynamically induced mechanical strains of these materials exhibit linear creep behaviour as confirmed by constant stress and low frequency cyclic loading tests. From scanning electron microscope investigations, cellulose EAPap exhibits a layered, anisotropic cellulose macromolecular structure that exhibits both elastic and plastic deformations, as well as substantial temperature and humidity dependence.

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Karginov, L. A., E. I. Vorobyov, and A. K. Kovalchuk. "Coordination of Movements of Two-Handed 12-DOF Robot Manipulators at Their Joint Manipulation." Proceedings of Higher Educational Institutions. Маchine Building, no. 12 (741) (December 2021): 11–18. http://dx.doi.org/10.18698/0536-1044-2021-12-11-18.

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The study focuses on a two-handed robot with twelve degrees of freedom, six for each arm, and gives an example of calculating generalized coordinates for the two-armed robot limbs at their joint manipulation. The initial data for obtaining generalized coordinates are represented by the location of the work object, which is a cube. When solving the problem, the last arm links reach the faces of the work object with a given orientation. To obtain generalized coordinates, we used a hierarchical approach, which is based on an algorithm for solving the inverse problem of kinematics, and developed a control flow chart. The values ??of generalized robot coordinates were obtained for each location of the object of work, taking into account the kinematic constraints in the joints of the robot actuator. Findings of research show that it is possible to obtain generalized coordinates for the coordinated movement of the robot actuators with tree-like kinematic scheme.

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Zhang, Wu Jun. "Using Genetic Algorithm for the PID Control of Voice Coil Actuator in A Precision Locating System and Simulation." Applied Mechanics and Materials 376 (August 2013): 257–61. http://dx.doi.org/10.4028/www.scientific.net/amm.376.257.

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Precision manufacturing is very important in the modern industrial manufacturing. Voice coil actuator (VCA) is the actuator, which directly change the signal of electricity to movement. We devised a form of precision locating system driven directly by VCA and apply gas static pressure bracing to substitute rigid bracing by mechanical contact. PID Control is widely used to control the system, but the parameters of PID control hard to be get out. Genetic algorithm is imitate living creature environment in of a kind of orientation overall situation of the genetic, can be professional at solving complicated system or the huge problem and it acquired a success application in many industrial engineering realms and had already got extensive concern. Thus, we use genetic algorithm to find the right parameters of PID control. As a whole, in this paper we introduce the genetic algorithm, analyze the control model of precision locating System, discuss using the Genetic algorithm to find the right parameter to control the precision locating System of voice coil actuator, the simulation is give out.

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39

Piñan Basualdo, Franco N., A. Bolopion, M. Gauthier, and P. Lambert. "A microrobotic platform actuated by thermocapillary flows for manipulation at the air-water interface." Science Robotics 6, no. 52 (March 31, 2021): eabd3557. http://dx.doi.org/10.1126/scirobotics.abd3557.

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Future developments in micromanufacturing will require advances in micromanipulation tools. Several robotic micromanipulation methods have been developed to position micro-objects mostly in air and in liquids. The air-water interface is a third medium where objects can be manipulated, offering a good compromise between the two previously mentioned ones. Objects at the interface are not subjected to stick-slip due to dry friction in air and profit from a reduced drag compared with those in water. Here, we present the ThermoBot, a microrobotic platform dedicated to the manipulation of objects placed at the air-water interface. For actuation, ThermoBot uses a laser-induced thermocapillary flow, which arises from the surface stress caused by the temperature gradient at the fluid interface. The actuated objects can reach velocities up to 10 times their body length per second without any on-board actuator. Moreover, the localized nature of the thermocapillary flow enables the simultaneous and independent control of multiple objects, thus paving the way for microassembly operations at the air-water interface. We demonstrate that our setup can be used to direct capillary-based self-assemblies at this interface. We illustrate the ThermoBot’s capabilities through three examples: simultaneous control of up to four spheres, control of complex objects in both position and orientation, and directed self-assembly of multiple pieces.

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Tohluebaji, Nikruesong, Chatchai Putson, and Nantakan Muensit. "High Electromechanical Deformation Based on Structural Beta-Phase Content and Electrostrictive Properties of Electrospun Poly(vinylidene fluoride- hexafluoropropylene) Nanofibers." Polymers 11, no. 11 (November 5, 2019): 1817. http://dx.doi.org/10.3390/polym11111817.

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The poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) polymer based on electrostrictive polymers is essential in smart materials applications such as actuators, transducers, microelectromechanical systems, storage memory devices, energy harvesting, and biomedical sensors. The key factors for increasing the capability of electrostrictive materials are stronger dielectric properties and an increased electroactive β-phase and crystallinity of the material. In this work, the dielectric properties and microstructural β-phase in the P(VDF-HFP) polymer were improved by electrospinning conditions and thermal compression. The P(VDF-HFP) fibers from the single-step electrospinning process had a self-induced orientation and electrical poling which increased both the electroactive β-crystal phase and the spontaneous dipolar orientation simultaneously. Moreover, the P(VDF-HFP) fibers from the combined electrospinning and thermal compression achieved significantly enhanced dielectric properties and microstructural β-phase. Thermal compression clearly induced interfacial polarization by the accumulation of interfacial surface charges among two β-phase regions in the P(VDF-HFP) fibers. The grain boundaries of nanofibers frequently have high interfacial polarization, as they can trap charges migrating in an applied field. This work showed that the combination of electrospinning and thermal compression for electrostrictive P(VDF-HFP) polymers can potentially offer improved electrostriction behavior based on the dielectric permittivity and interfacial surface charge distributions for application in actuator devices, textile sensors, and nanogenerators.

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Robyns, B., H. Buyse, and F. Labrique. "Fuzzy logic based field orientation in an indirect FOC strategy of an induction actuator." Mathematics and Computers in Simulation 46, no. 3-4 (May 1998): 265–74. http://dx.doi.org/10.1016/s0378-4754(97)00140-7.

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Li, Yang-Rui, and Chao-Chung Peng. "Super-Twisting Sliding Mode Control Law Design for Attitude Tracking Task of a Spacecraft via Reaction Wheels." Mathematical Problems in Engineering 2021 (March 15, 2021): 1–13. http://dx.doi.org/10.1155/2021/6644033.

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The attitude control has been recognized as one of the most important research topics for spacecraft. If the desired attitude trajectory cannot be tracked precisely, it may cause mission failures. In the real space mission environment, the unknown external perturbations, for example, atmospheric drag and solar radiation, should be taken into consideration. Such external perturbations could deviate the precision of the spacecraft orientation and thereby lead to a mission failure. Therefore, in this paper, a quaternion-based super-twisting sliding mode robust control law for the spacecraft attitude tracking is developed. The finite time stability based on the formulation of the linear matrix inequality (LMI) is also provided. To avoid losing the control degree of freedom due to the certain actuator fault, a redundant reaction wheels configuration is adopted. The actuators distribution associated force distribution matrix (FDM) is analyzed in detail. Finally, the reference tangent-normal-binormal (TNB) command generation strategy is implemented for simulating the scenario of the space mission. Finally, the simulation results reveal that the spacecraft can achieve the desired attitude trajectory tracking demands in the presence of the time-varying external disturbances.

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Jūrėnas, Vytautas, Gražvydas Kazokaitis, and Dalius Mažeika. "3DOF Ultrasonic Motor with Two Piezoelectric Rings." Sensors 20, no. 3 (February 4, 2020): 834. http://dx.doi.org/10.3390/s20030834.

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A novel design of a multiple degrees of freedom (multi-DOF) piezoelectric ultrasonic motor (USM) is presented in the paper. The main idea of the motor design is to combine the magnetic sphere type rotor and two oppositely placed ring-shaped piezoelectric actuators into one mechanism. Such a structure increases impact force and allows rotation of the sphere with higher torque. The main purpose of USM development was to design a motor for attitude control systems used in small satellites. A permanent magnetic sphere with a magnetic dipole is used for orientation and positioning when the sphere is rotated to the desired position and the magnetic field synchronizes with the Earth’s magnetic dipole. Also, the proposed motor can be installed and used for robotic systems, laser beam manipulation, etc. The system has a minimal number of components, small weight, and high reliability. Numerical simulation and experimental studies were used to verify the operating principles of the USM. Numerical simulation of a piezoelectric actuator was used to perform modal frequency and harmonic response analysis. Experimental studies were performed to measure both mechanical and electrical characteristics of the piezoelectric motor.

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LI, Zheng. "NEURAL NETWORK BASED MULTISENSOR FUSION IN A NOVEL PERMANENT MAGNET MULTI-DOF ACTUATOR ORIENTATION DETECTION SYSTEM." International Journal on Smart Sensing and Intelligent Systems 5, no. 4 (2012): 911–27. http://dx.doi.org/10.21307/ijssis-2017-514.

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Buryy, Oleh, Ihor I. Syvorotka, Yuriy Suhak, Uliana Yakhnevych, Dmytro Sugak, Sergii Ubizskii, and Holger Fritze. "Determination of optimal crystallographic orientations for LiNbO3 and LiTaO3 bimorph actuators." Journal of Sensors and Sensor Systems 10, no. 1 (May 3, 2021): 121–26. http://dx.doi.org/10.5194/jsss-10-121-2021.

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Abstract. The actuators for precise positioning based on bimorph structures of piezoelectric LiNbO3 and LiTaO3 crystals are considered. The optimal orientations of the actuator plates ensuring the highest possible displacements are determined by the extreme surfaces technique and the finite-element method. The simulated displacements for optimal orientations of LiNbO3 and LiTaO3 plates are compared with those obtained experimentally for manufactured LiNbO3 and LiTaO3 actuators, whose orientations are not optimal. As is shown, the optimal configuration of the actuator allows us to significantly increase its displacement for both LiNbO3 and LiTaO3 specimens.

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Guo, Jin, Jin-Huat Low, Jun Liu, Yangfan Li, Zhuangjian Liu, and Chen-Hua Yeow. "Three-Dimensional Printable Ball Joints with Variable Stiffness for Robotic Applications Based on Soft Pneumatic Elastomer Actuators." Polymers 14, no. 17 (August 29, 2022): 3542. http://dx.doi.org/10.3390/polym14173542.

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This paper contributes to a new design of the three-dimensional printable robotic ball joints capable of creating the controllable stiffness linkage between two robot links through pneumatic actuation. The variable stiffness ball joint consists of a soft pneumatic elastomer actuator, a support platform, an inner ball and a socket. The ball joint structure, including the inner ball and the socket, is three-dimensionally printed using polyamide−12 (PA12) by selective laser sintering (SLS) technology as an integral mechanism without the requirement of assembly. The SLS technology can make the ball joint have the advantages of low weight, simple structure, easy to miniaturize and good MRI compatibility. The support platform is designed as a friction-based braking component to increase the stiffness of the ball joint while withstanding the external loads. The soft pneumatic elastomer actuator is responsible for providing the pushing force for the support platform, thereby modulating the frictional force between the inner ball, the socket and the support platform. The most remarkable feature of the proposed variable stiffness design is that the ball joint has ‘zero’ stiffness when no pressurized air is supplied. In the natural state, the inner ball can be freely rotated and twist inside the socket. The proposed ball joint can be quickly stiffened to lock the current position and orientation of the inner ball relative to the socket when the pressurized air is supplied to the soft pneumatic elastomer actuator. The relationship between the stiffness of the ball joint and the input air pressure is investigated in both rotating and twisting directions. The finite element analysis is conducted to optimize the design of the support platform. The stiffness tests are conducted, demonstrating that a significant stiffness enhancement, up to approximately 508.11 N·mm reaction torque in the rotational direction and 571.93 N·mm reaction torque in the twisting direction at the pressure of 400 kPa, can be obtained. Multiple ball joints can be easily assembled to form a variable stiffness structure, in which each ball joint has a relative position and an independent stiffness. Additionally, the degrees of freedom (DOF) of the ball joint can be readily restricted to build the single-DOF or two-DOFs variable stiffness joints for different robotic applications.

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Mouhat, Ouadia, Abdelmajid Bybi, Ahmed El Bouhmidi, Hasnae Boubel, Omaima Elmrabet, and Mohamed Rougui. "The Effect of Ply Orientation and Damage Detection in Composite Stiffened Panel Using Lamb Waves." Solid State Phenomena 298 (October 2019): 161–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.298.161.

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The present work proposes a vibration study with different surface and layers orientations at 0°, 15°, 30°, 45°, 60°, 75° and 90°using the Abaqus finite element code, the frequencies Stratified laminate composite panels were studied and the comparison between damaged structures and perfect structures we used stiffened panels based on T-shaped reinforced fibers. Lamb waves (LW) were widely proposed for the long-range inspection of Structural Structural Health Monitoring (SHM) oriented composite structures, the obtained results show the angle effects on the natural frequency increase at a peak then decrease in the form of a sinusoidal half-curve and the numerical results found in this work can be compared to those of other authors in the same area of research, A piezoelectric actuator is used to design acoustic waves and a sensor is used for signal acquisition.

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Prusak, Daniel, Konrad Kobus, and Grzegorz Karpiel. "Kinematics Analysis of a Novel Five-Degree-of-Freedom Spatial Parallel Micromanipulator." Journal of Robotics 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/806294.

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A study of the inverse kinematics for a five-degree-of-freedom (DOF) spatial parallel micromanipulator is presented here below. The objective of this paper is the introduction of a structural and geometrical model of a novel five-degree-of-freedom spatial parallel micromanipulator, analysis of the effective and useful workspace of the micromechanism, presentation of the obtained analytical solutions of the microrobot’s inverse kinematics tasks, and verification of its correctness using selected computer programs and computation environments. The mathematical model presented in this paper describes the behaviour of individual elements for the applied 2-DOF novel piezoelectric actuator, resulting from the position and orientation of the microrobot’s moving platform.

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Xu, Wei, Yaoyao Wang, Surong Jiang, Jiafeng Yao, and Bai Chen. "Kinematic analysis of a newly designed cable-driven manipulator." Transactions of the Canadian Society for Mechanical Engineering 42, no. 2 (June 1, 2018): 125–35. http://dx.doi.org/10.1139/tcsme-2017-0019.

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In this paper, the cable routing configurations for a cable-driven manipulator are introduced, and the impact of motion coupling caused by cable transmission routing of a 2n type cable-driven manipulator is analyzed in detail. Based on different configurations of cable routings, the relationship between variation of joint angles and the geometrical sizes of guide pulleys is established, represented by a matrix for coupled motion. Moreover, based on the effects of the motion coupling of a cable-driven manipulator, we propose the condition for the invariance of orientation, which can be achieved constraining of the geometrical sizes of guide pulleys and driven wheels. In addition, to identify the correctness of analysis for coupled motion, a 3-DOFs planer cable-driven manipulator prototyping model is constructed, and the kinematics and trajectory planning has been solved. Finally, the relationship among actuator space, joint space, and Cartesian space, including the mapping of the motion coupling, is experimentally validated. The property of invariance of orientation is also validated by an experiment.

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Allenspach, Mike, Karen Bodie, Maximilian Brunner, Luca Rinsoz, Zachary Taylor, Mina Kamel, Roland Siegwart, and Juan Nieto. "Design and optimal control of a tiltrotor micro-aerial vehicle for efficient omnidirectional flight." International Journal of Robotics Research 39, no. 10-11 (August 6, 2020): 1305–25. http://dx.doi.org/10.1177/0278364920943654.

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Abstract:

Omnidirectional micro-aerial vehicles (MAVs) are a growing field of research, with demonstrated advantages for aerial interaction and uninhibited observation. While systems with complete pose omnidirectionality and high hover efficiency have been developed independently, a robust system that combines the two has not been demonstrated to date. This paper presents the design and optimal control of a novel omnidirectional vehicle that can exert a wrench in any orientation while maintaining efficient flight configurations. The system design is motivated by the result of a morphology design optimization. A six-degree-of-freedom optimal controller is derived, with an actuator allocation approach that implements task prioritization, and is robust to singularities. Flight experiments demonstrate and verify the system’s capabilities.

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Journal articles on the topic 'Actuator Orientation'

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