Development Of Cable-driven Manipulator On The Base Of Wheelchair

The aging population is a thorny problem obsessing many countries in the world. In the following 30 years, the population over 60 years old will keep increasing continuously, while the lack of nursing workers and endowment facilities make the family pension be the main form of pension in our country. To help the old and the handicapped live with self-reliance is rather important to guarantee the family pension. In this research topic, a cable-driven manipulator mounted on wheelchair is proposed, aimed at assisting the old and the handicapped who lose their basic living abilities to accomplish the necessary operations in their daily life, so as to raise their quality of life. The research in this paper has important practical significance.Based on the summary the development of the typical wheelchair manipulators domestic and abroad, the overall optimized mechanical design of manipulator was completed. A multi-functional end-effecter was designed which has wide-ranged grasping abilities; underactuation fingers was adopted to improve the grasping efficiency. Apart from completing general grasping actions, the end-effecter could also implement picking actions on small things such as paper and tablets.Next, the kinematics of wheelchair manipulator system was analyzed, and the manipulability of manipulator was discussed. A motion planning method for robot based on task decomposition and speed distribution was proposed. In this algorithm, the control task is divided into several sub-tasks according to their priorities, and each sub-task is controlled independently. The velocity component of each sub-task is determined according to the driving capability of joint motors and the priority of each sub-task, which helps implement the coordinated movement of robot even in the condition of low flexibility when the robot moves near the singularities or stays in the singularities, thus achieving the control objective and avoiding the excessive end-effecter error and system instability caused by the sudden change of joint relative velocity. This method provide an effective technical approach to overcome the motion difficulty for robot near singularities. On the basis of the above-mentioned research work, the hardware circuit of manipulator was set up and the embedded code was programmed for the control system based on DSP+FPGA, and the connecting interface of circuit was expanded. According to the controlling requirements of manipulator, a wireless gamepad was used as the controller to realize the telecontrol of manipulator, and the holistic debugging for the control platform was accomplished.At last, experiments were carried out to demonstrate the rationality of mechanical structure, the reliability of control system and the validity of motion planning algorithm.