A Study On The Cable-driven And Hyper Redundant Manipulator For The Narrow Space Operations

It is unsuitable for the human beings and large equipment to work for the special occasions, such as the disaster relief, the maintenance of equipment in the nuclear and radiation environment, the toxic waste sampling, pipeline monitoring and so on, due to the narrow space and its greater risk. Therefore, the hyper redundant manipulator with a slender body and flexible movement has aroused the interest among scholars. The mechanical and electrical components of traditional articulated robot are installed in the link connection of the arm, leading to its several disadvantages, including the large quality, big exterior dimensions as well as small load ratio, which are difficult to meet the requirements of narrow space operations. In this paper, a cable-driven and hyper-redundant manipulator with a continuous curved surface is developed and it has the characteristics of good flexibility and flexible movement.According to the application requirement of the narrow space operations, the function and performance index of the robot arm are analyzed, and a cable-driven hyper-redundant manipulator with super movement ability is designed. The manipulator is composed of 10 modular joints with two degrees of freedom, the cable device, transmission mechanism and drive controller, which has the movement ability of 20 degrees of freedom. The drive motors, the transmission mechanism and the control box(mechanical and electrical) are integrated in the roots and are packaged in a box, while the operating segment(known as the operating arm) contains only a link and a universal joint, which can minimize the load and improves the transmission efficiency. In order to realize the cooperative control of the multiple degrees of freedom, a three layer architecture of the control system is developed, namely the remote control and monitoring layer, the planning and control layer and the movement execution layer, with CAN bus, UART to USB and NRF wireless communication module. Taking the visual inspection as a practical application case, the manipulator carries a wireless camera in the end so as to transmit the video to the user interface through the wireless link.Based on the development of the manipulator, the kinematics equations are derived and the typical trajectory of the manipulator is planned. The mapping relationship between the manipulator joint space and operational space is establish with the traditional D-H method while the decoupling equations between the drive space and joint space of the manipulator are derived by the geometric analysis method; The trajectory of the manipulator is planned according to a typical task and its kinematics and trajectory planning algorithm accuracy has been verified by the co-simulation of Matlab and Adams.According to the manipulator system designed above, a prototype system is developed and several experiments are carried out for some verifications. The results show that the algorithm of decoupling kinematics can work effectively for the analysis about the motion of cable-driven hyper redundant manipulator and the manipulator has a good bending characteristic as well as dexterous movement so as to meet the requirement of the narrow and complex environment operations.