Research On Supern Umerary Robotic Muti-Limbs Modeling And Compliance Control Method

Wearable Supernumerary Robotic Limbs(SRL)provides auxiliary functions such as load support for the wearer by installing additional independent mechanical limbs on the human body,so as to improve the single-person operation ability and scope of operation.The supernumerary robot with four external limbs has better stability than single limb and double limbs,which can realize more task modes,and greatly improves the working ability and working efficiency.It can be widely used in industry,construction,medical,military,aerospace and other fields,and has extremely broad development prospects.Research and analysis on the modeling and motion control methods of limbs and backplanes can promote the practical application of supernumerary robotic muti-limbs,which has important theoretical value and practical significance.This dissertation mainly includes the following aspects:Establish the forward and inverse kinematics models of the supernumerary robotic muti-limbs' limb based on the mechanical structure of the supernumerary robotic muti-limbs,and realize the conversion between the robot limb joint coordinate system and the Cartesian coordinate system.The work space is solved and analyzed based on the kinematics equations of limbs.The limb dynamics equation is derived based on the Lagrange's mechanics law,and the limb dynamics model is verified and analyzed through the three-dimensional simulation platform of supernumerary robotic muti-limbs built by Recurdyn software.According to the position of the end of the support phase of the supernumerary robotic muti-limbs in the world coordinate system and the homogeneous transformation matrix from the backplane to the end of the limbs,the forward and inverse kinematics models of the backplane are deduced recursively,and the work space is expressed by simulation experiments.Based on the kinematics model,the position control of the supernumerary robotic muti-limbs in the suspended support posture is realized to realize the stable movement of the robot while supporting the human body,and the posture of the robot is adjusted to adapt to the uneven support surface.Model Predictive Control(MPC)method is used to control the trajectory of the non-linear,strongly coupled,multi-input and multi-output limb model.The prediction model of the supernumerary robotic muti-limbs is established,and the mathematical description and solution steps of the optimization strategy are given.The joint torque control of the limbs is realized by optimizing and correcting the deviation between the end position of the limb and the expected position,and finally the end trajectory tracking control is realized.Considering the problem of excessive contact force generated when the rigid supernumerary robotic muti-limbs interacts with the environment,a compliant control strategy is designed for the limbs of the swing phase and the backplane of the supporting phase.By analyzing the principle and characteristics of the impedance control method of the robotic arm,a method of limb compliance control based on the limb dynamics model is proposed.Establish the virtual force model acting on the center of mass of the backplane,derive the relationship between the virtual force acting on the backplane and the force on the end of the supporting limbs in the suspended state.Control the joint torque of each supporting limb to adjust the virtual force of the center of mass of the backplane.Adjust the size of the virtual force of the backplane to control the position and posture of the backplane,as well as the speed of movement and the angular speed of the backplane,so as to realize the compliant control of the backplane movement.