Papers by Author: Li Xun Zhang

Abstract: During rehabilitative training, a 3-DOF wire-driven parallel robot driven was designed to coordinate and control the trainer pelvis movement. Based on the force balance equation of the end-effector, the stiffness problem about the robot system was analyzed and one kind of force/position parallel control strategy was proposed that the position loop would realize the end-effector motion trajectory, and the force loop would control the wire tension. The experimental results have shown that the robot systematic stiffness is related with the wire tension and can be changed to realize the compliance control of the robot system by adjusting the wire tension.

Abstract: A mobile grinding robot is present here for the wind turbine blade grinding work. The robot is a mobile manipulator equipped with a grinding wheel. A mobile manipulator robot is built up with a mobile platform and a robotic arm mounted on it. The dynamic model of the robot is built, and the dynamic model of the two subsystems is derived from it, so the dynamic coupling items can be deduced. In order to discover how the coupling force influence the robotic manipulator, the SimMechanics model of the robot is built up and the simulation research is carried out by the built model. The results show the influence of coupling force on the manipulator.

Abstract: A robot system is present for the wind turbine blade grinding work. The robot is a mobile manipulator equipped with a grinding tool. In order to realize the compliant control of the operation force, a robust impedance controller is present in the presence of coupling factors between the mobile platform and manipulator, modeling uncertainties and existing bounded disturbances. The proposed control strategies guarantee that the system motion converges to the desired manifold and the desired constraint force. Simulation experiment has been done and the experiment results show that, the presented control method can realize the robust control of mobile manipulator, and thus show the effectiveness and correctness of the designed controller.

Abstract: An Ocean Casing Pipes Centering Equipment is designed and implemented. Utilizing the equipment, two casing pipes can be fastened together by means of welding. The equipment can automatically carry out clamping and centering two casing pipes, and then the butt welding is conducted at their adjacent ends. In the development of this equipment, some advanced means, such as digital modelling and FEA (Finite Element Analysis), are taken full advantage of. First, all the parts’ 3D models are built with Pro/Engineer. Then, those digital parts is assembled in Pro/E assembly environments. Meanwhile, assembly interference detection is executed. Furthermore, by means of universal finite-element software，the finite element model is constructed. The strength and stiffness of the structure is calculated and analyzed so that the faults of the equipment can be found out in design stage. Through repeating this designing and verifying course, the structure of the equipment can be improved.

Abstract: In this paper, multi-legged walking machine is simplified as one leg, which the whole machine is constructed by the modularization configuration of the legs in an axisymmetric way. Consequently, the control of one leg and its trajectory planning is the significant part for multi-legged walking machine. This paper, according to the structure of the walking machine's leg with 3-DOF open chains, calculates the terminal track of the leg using the principle of kinematics and presents a foot's controller based on dSPACE. In order to obtain the optimization of the foot's track, the three-cubic spline algorithm is considered. Depending on the model of the control system in Matlab, the paper provides a semi-physical simulation for a real leg using dSPACE. The feasibility of the planned track is demonstrated and the PID parameters have been adjusted.

Abstract: A new kind of walking assistance mechanism in aided-walking wheelchair is proposed to help stroke and cord injury patients on gait rehabilitation training and aided-walking indoor and outdoor. Each side of the walking assistance mechanism, which is a double-crank linkage mechanism actuated by one driver, assists the motion of thigh and shank synchronously. The mechanism can control the walking gait of both legs to assist the patients in walking and gait rehabilitation training. The mechanism is analyzed, and the optimal proportion of the structure dimension suitable for different person is obtained according to the clinical gait analysis data. The simulation results show that the walking assistance mechanism can simulate the nature gait during human walking and realize the walking assistance and gait rehabilitation training function.