Single-Leg Integrated Test Bench Designed For Legged Robots

Compared with the traditional wheel-tracked robots,legged robots have become the hotspots of research due to the advantages of high passability and flexibility.At the same time,it also faces more complex constraints on the walking mechanism and motion control.For legged robots to build electromechanical systems and research motion control strategy,it is difficult to set and evaluate robot motion performance accurately due to the lack of necessary test conditions and basic experimental data,which increases unnecessary costs in the iteration process of the whole machine platform design.This topic focuses on the research on the single-leg bench test of the legged robot.For medium and light legged robot’s single-leg system test requirements,demonstrate and determine the configuration design,effective stroke and load capacity index of the test platform,design a high real-time electronic control servo system based on the EtherCAT bus,and establish the forward and inverse kinematics of the mechanism model,design and deploy a nonlinear variable stiffness variable damping admittance control law,details as follows:(1)For the problem of the six-degree-of-freedom dynamic loading problem on the single-leg bench test,design a "3+3" kinematic mechanism with a gantry structure and a three-joint spherical wrist.The gantry structure maintains good positioning accuracy within the stroke,and the three-joint spherical wrist has solved the force loading test requirements of simulating the fuselage of different postures.(2)For the requirements that the test platform deployed by the electronic control system requires real-time and scalability of the motion control algorithm,design and build a high-bandwidth bus motion control system based on EtherCAT,and demonstrate the selection and data calibration of each sensor,motion controller,servo drive assembly,etc.The overall electronic control system scheme is designed according to safety standards,verifying its feasibility by experiments.(3)For the problem of simulating the motion of a single robot rigid body based on six-dimensional force.Using the D-H method to establish the "3+3" mechanism kinematics model,calculating the forward and inverse kinematics solutions,achieving multi-axis linkage of the kinematic mechanism,and the accessible operation space at the end of the kinematic mechanism is analyzed by the Monte-Carlo method.Furthermore,a nonlinear variable stiffness variable damping admittance control strategy based on position loop is proposed,and the stiffness and damping of admittance control are adjusted adaptively according to the expected force.The proposed algorithm is evaluated by single-dimensional force loading and multi-dimensional force following experiments.The experiments show that this test bench has good following performance and multidimensional force simulation ability.