Research On The Chain Reconfigurable Manipulator For Space On Orbit Operation

With the rapid development of space engineering,the application of multi-purpose space manipulator is increasing in the face of complex space environment.However,due to the special environment in space and the requirement of unmanned complex mission in vacuum,the traditional mechanical arm scheme,if applied to the space mission in orbit,will face the disadvantages of single configuration,limited types of executive functions,lack of autonomous motion ability and so on.At the same time,in the space task,all the functional structures will face the limitation of device weight and space volume.It is necessary to realize the various task requirements of the space manipulator in the minimum weight.In order to solve the problem of weight and multi-functional application of on orbit manipulator,this paper studies a kind of chain modular manipulator which can realize rapid reconfiguration.The manipulator consists of different types of reconfigurable minimum joint units and active and passive two kinds of rapid reconfiguration pairs.It can change its configuration according to the task requirements.The smallest unit of each manipulator consists of a pair of interface systems,modular motion systems,and electrical systems.In this paper,the chain type multi degree of freedom modular manipulator is designed.A single closing motion joint is composed of a pitch drive joint and a rotation drive joint by a motor and a harmonic reducer in the form of direct connection.The sensor system of each joint includes a temperature sensor,a joint rotation angle sensor,a drive current detection and a travel switch.The active butt joint is the main joint in the docking process of the manipulator.The memory alloy bidirectional rotary driver is used to drive the docking,and the cam mechanism and four rotating claws are used as the actuators.The passive interface consists of a passive connection circuit board and a fixed claw.Using ANSYS Workbench to analyze the strength of the mechanical arm's active and passive components in the joint,to ensure that the strength of the multi-level chain manipulator can work stably at all levels in the process of docking and stable work.In the control and communication of the multi-stage manipulator,the chain manipulator control system based on CAN bus communication is adopted in the chain reconstruction scheme.Two amplifying circuits are designed to drive the shape memory metal(SMA)in the opposite winding direction,which is used to drive the active locking process in the docking of the actuator.After locking,the communication between the chain manipulators is completed through contact Letter.Thirdly,the most commonly used multi branch configuration scheme in the practical work of modular manipulator is proposed,and the chain configuration scheme and the motion control scheme of different configuration schemes are discussed.The kinematic model of single arm reconstruction is established,and the kinematic analysis and solution of the most representative three branch chain configuration are proposed.The D-H parameters of each branch chain manipulator are used to get the pose information,and the inverse kinematics of the three branch chain manipulator is solved.How to realize inchworm gait and rotation gait of the three branch chain manipulator is emphasized.In this paper,the trajectory of the multi branch manipulator is planned.The rationality of the on orbit working scheme of the reconfigurable manipulator is verified.