Research On Structural Design And Motion Control Of Cable-driven Robot

Due to the advantages of high precision,speed and efficiency,the traditional industrial robots have been widely used in field of manufacture,assembly,logistics and healthcare.However,there are some deficiencies also exist as follows: large mass and volume,high moment of inertia,small load-to-weight ratio,and the lack of compliance,which make robots restricted in the places requiring high safety in man-machine interaction,such as service and medical treatment.Therefore,a novel 4-DOF cable-driven robot with higher load-weight ratio and better interactive safety is designed in this paper.First of all,a 4-DOF serial cable-driven robot was designed.The actuators on the joints are mounted on the base.the movement and force are transmitted through the cables to reduce the selfweight of the arm and the inertia of the joints,and improve the load-to-weight ratio.The mode and mechanism of cable transmission,the cable tensioner,and the electrical system of servo were designed and constructed.the experimental prototype was built completely and worked properly.Secondly,the cable coupling relationship of the multi-joint planer robot was analyzed and derived when considering the geometrical parameters of structure.The motion mapping relationship among the actuator,joint,and Cartesian space was established.The constraint of orientation invariant was proposed.Based on the structure and movement characteristics,the kinematics of two types cabledriven robots with different degrees of freedom was modeling.The kinematic performance was evaluated from the aspects of workspace,Jacobian and global condition index.Thirdly,aiming at the problem of the inaccurate structural parameters and the complexity transmission model of cable-driven robot,a nonlinear controller based on time-delay estimation was established.A PD and a fuzzy PD controller with parameter self-tuning both based on time-delay estimation were proposed.By using Simulink SimMechanics,the simulation was established.The results show that the control schemes based on time-delay estimation is not sensitive to system model and have strong robustness.The effectiveness and reliability of time-delay estimation are verified.Finally,based on Qt5 / C ++,the software of upper monitor system was designed with good interactive interface,composed of trajectory planning,data acquisition and analysis,servo controller communication,system status monitoring,and other functions.Based on Simulink Real-Time,control experimental platform was established.the comparative analysis of the control algorithms was carried out.The effectiveness of the control strategies based on the time-delay estimation is further proved.In the last chapter,the main contents and conclusions were summarized briefly,and the future research developments of cable-driven robot was prospected.