Dynamics and Control of a Flexible-Link Flexible-Joint Space Robot with Joint Friction

The problem of dynamics and control using a space robot to capture a noncooperative satellite is an important issue for on-orbit services. Inertia parameters of the satellite should be identified before capturing such that the robot can design an active controller to finish the capturing task. In this paper, a new identification scheme is proposed for parameter identification of a noncooperative satellite. In this scheme, the space robot is controlled to contact softly and then maintain contact with the noncooperative target firstly, then the variation of momentum of the target during the contact-maintaining phase is calculated using the control force and torque acting on the base of the space robot and the kinematic information of the space robot, and finally, the momentum-conservation-based identification method is used to estimate inertia parameters of the target. To realize soft contact and then maintain contact, a damping contact controller is designed in this paper, in which a mass-damping system is designed to control the contact between the robot and the target. Soft contact and then contact maintenance can be realized by utilizing the buffering characteristics of the mass-damping system. The effectiveness of the proposed identification scheme is verified through numerical simulations at the end of this paper. Simulation results indicate that the proposed scheme can achieve high-precision identification results.

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Experimental results for the flexible joint cable-suspended manipulator of ICaSbot

Robotica ◽

10.1017/s026357471300009x ◽

2013 ◽

Vol 31 (6) ◽

pp. 887-904 ◽

Cited By ~ 2

Author(s):

M. H. Korayem ◽

M. Bamdad ◽

H. Tourajizadeh ◽

A. H. Korayem ◽

R. M. Zehtab ◽

...

Keyword(s):

Degrees Of Freedom ◽

Experimental Tests ◽

Parallel Robot ◽

Joint Space ◽

End Effector ◽

Flexible Joint ◽

Cable Robot ◽

Six Dof ◽

And Control ◽

Computed Torque

SUMMARYIn this paper, design, dynamic, and control of the motors of a spatial cable robot are presented considering flexibility of the joints. End-effector control in order to control all six spatial degrees of freedom (DOFs) of the system and motor control in order to control the joints flexibility are proposed here. Corresponding programing of its operation is done by formulating the kinematics and dynamics and also control of the robot. Considering the existence of gearboxes, flexibility of the joints is modeled in the feed-forward term of its controller to achieve better accuracy. A two sequential closed-loop strategy consisting of proportional derivative (PD) for linear actuators in joint space and computed torque method for nonlinear end-effector in Cartesian space is presented for further accuracy. Flexibility is estimated using modeling and simulation by MATLAB and SimDesigner. A prototype has been built and experimental tests have been done to verify the efficiency of the proposed modeling and controller as well as the effect of flexibility of the joints. The ICaSbot (IUST Cable-Suspended robot) is an under-constrained six-DOF parallel robot actuated by the aid of six suspended cables. An experimental test is conducted for the manufactured flexible joint cable robot of ICaSbot and the outputs of sensors are compared with simulation. The efficiency of the proposed schemes is demonstrated.

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Dynamics and control of a 6-DOF space robot with flexible panels

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

10.1177/0954410016646616 ◽

2016 ◽

Vol 231 (6) ◽

pp. 1022-1034 ◽

Cited By ~ 1

Author(s):

Yu Zhang-Wei ◽

Liu Xiao-Feng ◽

Li Hai-Quan ◽

Cai Guo-Ping

Keyword(s):

Dynamic Model ◽

Control Method ◽

Torque Control ◽

Space Robot ◽

Velocity Variation ◽

Variation Principle ◽

Dynamics Modeling ◽

Dynamics And Control ◽

Flexible Panels ◽

And Control

With the development of space exploration, researches on space robot will cause more attentions. However, most existing researches about dynamics and control of space robot concern planar problem, and the effect of flexible panel on dynamics of the system is not considered. In this article, dynamics modeling and active control of a 6-DOF space robot with flexible panels are investigated. Dynamic model of the system is established based on the Jourdain's velocity variation principle and the single direction recursive construction method. The computed torque control method is used to design point-to-point active controller of the space robot. The validity of the dynamic model is verified through the comparison with ADAMS software; the effects of panel flexibility on the system performance and the active controller design are studied in detail. Simulation results indicate that the proposed model is effective to describe the dynamics of space robot; panel flexibility has large influence on the dynamic behavior of space robot; the designed controller can effectively make the robot reach a specified position and the elastic vibration of the panels may be suppressed simultaneously.

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