Analysis of the singularity of spatial parallel manipulator with terminal constraints

Abstract Reducing consumed power of a robotic machine has an essential role in enhancing its energy efficiency and must be considered during its design process. This paper deals with dynamic modeling and power optimization of a four-degrees-of-freedom flight simulator machine. Simulator cabin of the machine has yaw, pitch, roll and heave motions produced by a 4RPSP+PS parallel manipulator (PM). Using the Euler–Lagrange method, a closed-form dynamic equation is derived for the 4RPSP+PS PM, and its power consumption is computed on the entire workspace. Then, a newly introduced optimization algorithm called multiobjective golden eagle optimizer is utilized to establish a Pareto front of optimal designs of the manipulator having a relatively larger workspace and lower power consumption. The results are verified through numerical examples.

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Performance evaluation of a special 6-PUS type parallel manipulator

Robotica ◽

10.1017/s0263574721000655 ◽

2021 ◽

pp. 1-15

Author(s):

Xiaochu Liu ◽

Yunfei Cai ◽

Weitian Liu ◽

Linlong Zhang ◽

Chengxin Hu

Keyword(s):

Performance Evaluation ◽

Natural Frequency ◽

Parallel Manipulator ◽

Screw Theory ◽

Shaking Table ◽

Axial Stiffness ◽

Neutral Position ◽

Dynamics Model ◽

Force Transmissibility ◽

Kane Method

Abstract In this paper, a special 6-PUS parallel manipulator (PM) is utilized as a shaking table. Unlike the existing results about 6-PUS PMs, we make the actuator direction collinear with the linkage direction at neutral position. With respect to the application background, a further analysis of the special PM is carried out from the perspective of motion/force transmissibility, natural frequency and acceleration capability. Specially, the complete dynamics model is established based on the Kane method. Then, generalized transmission indices based on the screw theory are utilized to reflect its motion ability, and a model of natural frequency is proposed with the axial stiffness of linkages considered. Finally, the effect of the angle between the actuator direction and the linkage direction α on various performances is analyzed, and other results are included to illustrate its feasibility and usability.

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Stiffness analysis of a planar parallel manipulator with variable platforms

Mechanics Based Design of Structures and Machines ◽

10.1080/15397734.2021.1875333 ◽

2021 ◽

pp. 1-18

Author(s):

Xiaoyong Wu ◽

Yujin Wang ◽

Zhaowei Xiang ◽

Ran Yan ◽

Rulong Tan ◽

...

Keyword(s):

Parallel Manipulator ◽

Stiffness Analysis ◽

Planar Parallel Manipulator

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Trajectory shaping guidance law design using constraint-combining multiplier

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410020986371 ◽

2021 ◽

pp. 095441002098637

Author(s):

Min-Guk Seo ◽

Chang-Hun Lee ◽

Tae-Hun Kim

Keyword(s):

Design Method ◽

Impact Angle ◽

State Variables ◽

Flight Trajectory ◽

Potential Significance ◽

Guidance Law ◽

Terminal Constraints ◽

The Impact ◽

Guidance Laws ◽

Impact Angle Constraint

A new design method for trajectory shaping guidance laws with the impact angle constraint is proposed in this study. The basic idea is that the multiplier introduced to combine the equations for the terminal constraints is used to shape a flight trajectory as desired. To this end, the general form of impact angle control guidance (IACG) is first derived as a function of an arbitrary constraint-combining multiplier using the optimal control. We reveal that the constraint-combining multiplier satisfying the kinematics can be expressed as a function of state variables. From this result, the constraint-combining multiplier to achieve a desired trajectory can be obtained. Accordingly, when the desired trajectory is designed to satisfy the terminal constraints, the proposed method directly can provide a closed form of IACG laws that can achieve the desired trajectory. The potential significance of the proposed result is that various trajectory shaping IACG laws that can cope with various guidance goals can be readily determined compared to existing approaches. In this study, several examples are shown to validate the proposed method. The results also indicate that previous IACG laws belong to the subset of the proposed result. Finally, the characteristics of the proposed guidance laws are analyzed through numerical simulations.

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Task-based torque minimization of a 3-PṞR spherical parallel manipulator

Robotica ◽

10.1017/s026357472100062x ◽

2021 ◽

pp. 1-30

Author(s):

Soheil Zarkandi

Keyword(s):

Closed Form ◽

Dynamic Modeling ◽

Dynamic Equation ◽

Parallel Manipulator ◽

Optimization Problem ◽

Dynamic Constraints ◽

Part C ◽

Euler Approach ◽

Three Degree Of Freedom ◽

Spherical Parallel Manipulator

Abstract A comprehensive dynamic modeling and actuator torque minimization of a new symmetrical three-degree-of-freedom (3-DOF) 3-PṞR spherical parallel manipulator (SPM) is presented. Three actuating systems, each of which composed of an electromotor, a gearbox and a double Rzeppa-type driveshaft, produce input torques of the manipulator. Kinematics of the 3-PṞR SPM was recently studied by the author (Zarkandi, Proc. Inst. Mech. Eng. Part C J. Mech. Eng. Sci. 2020, https://doi.org/10.1177%2F0954406220938806). In this paper, a closed-form dynamic equation of the manipulator is derived with the Newton–Euler approach. Then, an optimization problem with kinematic and dynamic constraints is presented to minimize torques of the actuators for implementing a given task. The results are also verified by the SimMechanics model of the manipulator.

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