Papers by Keyword: Flexible Manipulator

Abstract: The positioning accuracy and work efficiency of flexible manipulator is seriously affected by its vibration. Therefore, vibration control of single joint flexible manipulator is studied by using an improved PPF algorithm based on LabVIEW and piezoelectric technology. Firstly, the improved PPF algorithm principle is introduced. Then, the experiment process is discussed in detail. Experimental result shows that the improved PPF algorithm can effectively control the first two modal vibration of flexible manipulator. The control effect is close to 14 dB and improved nearly 4.5 dB compared with PPF algorithm.

Abstract: In recent years, modeling and control of flexible space robots are extensively researched. Compared with traditional rigid robots, flexible robots have low energy consumption, wide operating space, high carrying capacity and other characteristics. However, due to its special structure, the robot arm will get deformation and vibration in motion, which brings a lot of problems to the positioning and tracking control of flexible space robots. Therefore, directing at the dynamics modeling and control issues of the free-floating flexible dual-arm space robots, this article carries out in-depth study. This paper first studies the elastic deformation and vibration of the flexible space manipulator and the robust control problem of the system trajectory tracking for free-floating flexible dual-arm space robots.

Abstract: An idea is proposed to use the controllable local degree of freedom to reduce vibration of the flexible manipulator performing the periodic task. The controllable local degree of freedom is incorporated into the flexible manipulator and used as an effective way to alleviate vibration through dynamic coupling. The feature of the periodic motion is utilized and a simple method is suggested to control vibration by constructing the appropriate modal control force via the controllable local degree of freedom, thereby counteracting the effects of the periodic exciting force. The numerical and experimental results preliminarily prove its effectiveness and feasibility in practical applications.

Abstract: This paper presents a novel trajectory planning for a multilink rigid-flexible manipulator. An original trajectory is given according to the site condition and requirement of motion, and desired trajectory is determined by using an optimization. To satisfy the requirement of motion with restrictions, the desired trajectory cannot significantly deviate from the original trajectory. Consequently, the lower distortion in trajectory planning should be considered in optimization algorithm. Two different formulations of trajectory are introduced in two optimization algorithms to compare the distortion degree. Finally, the calculation samples are addressed by using specific site conditions and requirements of motion to verify the validity of proposal.

Abstract: The applications of flexible manipulators are increasing and due to the high demand on fuel consumption there is a need to optimize the energy consumption for stable and durable operation of the flexible manipulators. In the present work the Genetic Algorithm (GA) is employed to optimize the total torque and the torque of the first link of a two-link flexible manipulator with a fourth order polynomial trajectory. The mathematical model of the manipulator is obtained using the extended Hamilton's Principle where the flexible links are treated as Euler- Bernoulli's beam theory. A fifth order polynomial trajectory undergoes a rest-to rest maneuvering is proposed as a bench mark for validation.

Abstract: Worse than common vibration, resonance is a form of severe vibration. It is very important and useful to know what factors and conditions can result in resonance of flexible manipulators, when both link flexibility and joint flexibility are taken into account. In this paper, resonance analysis of the flexible manipulator with both link flexibility and joint flexibility is studied. Based on the flexible dynamic equations, main factors resulting in resonance of the flexible manipulator are analyzed. Furthermore, several conditions exciting resonance are derived and verified with numerical simulations. These conclusions are helpful to predict resonance and useful to the structure design and motion planning for a flexible manipulator to evade resonance

Abstract: This paper concerns the dynamic modeling and vibration control of a space two-link flexible manipulator. Two types of PZT actuators, PZT shear actuator and torsional actuator, are used to suppress the bending-torsional-coupled vibration of the space manipulator. Using extended Hamilton’s principle and the finite element method, equations of motion of the space flexible manipulator with PZT actuators and tip mass are obtained. Based on modal analyze theory, the state space model of the system is then used to design the control system. A linear quadratic regulator (LQR) controller is designed to achieve vibration suppression of the space manipulator system. From the numerical results, we can get that the proposed controller has a suitable and efficient performance suppressing the bending-torsional-coupled vibration of the space two-link flexible manipulator.

Abstract: The dynamic analysis and control of flexible robot manipulators have been the main concerns of many recent studies in aeronautics and robotics. Moreover, the complexity of this problem increases when a flexible manipulator carries a payload. In this paper, we proposed a space two-link flexible manipulator with tip payload featuring surface-bonded piezoelectric torsional actuator and shear actuator. The equations of motion for the system are obtained using Hamilton’s principle. A Lyapunov-based controller is proposed to suppress the vibration of the system. Stability of the system is also investigated. The simulation results demonstrate the proposed control strategy is well suited for active control of vibration suppression on flexible manipulators.

Abstract: In order to investigate dynamic performance of flexible multi-link manipulators more exactly, establishing the dynamic model with accounting for link foreshortening and link material damping is needed. In this paper, a new dynamic model for planar flexible multi-link manipulators is established by using Lagrange approach. Both link foreshortening and link material damping are accounted for in this model. As a case simulation, this model is applied to a planar flexible two-link manipulator with a tip mass, and the motion responses of the manipulator are obtained using Gear method.

Abstract: For flexible manipulator, the analysis of the joint characteristics and the stability become very important for controller design. The boundary conditions of the flexible manipulator with noncollocated P controller and collocated P controller are developed in this paper. And the stability of the flexible manipulator is also discussed.