Study On Structure Design And Control Of Light Compliant Robotic Arm For Human-robot Collaboration

Traditional robots are mostly made of rigid structures,it needs to be isolated from the external environment when working.With the development of science and technology,industrial robots and service robots need more interaction with the external environment.This makes the interaction between the robot and the external environment becomes a major concern.In order to ensure the safe interaction between human and robot for human-robot collaboration,developing lightweight and compliant robots becomes an important trend.Robotic arm is an important part of frequent contacting with the external environment,therefore,designing lightweight and compliant robotic arms is an important way to realize the safety of human-robot interaction.In this paper,a lightweight compliant robotic arm with 3DOF is designed,to achieve lightweight trough using light materials and structure optimization,and achieve compliance by introducing elastic element in its mechanical structure.Compliant interaction between the robotic arm and external environment is realized by employing a compliant control scheme.The main contents of this paper are as follows:Imitating the structure and size of the human arm,a humanoid arm of 3DOF is designed.The series elastic actuator(SEA)based on linear spring is designed to achieve the compliance of the joint;lightweight is achieved by using light materials and structure optimization.The elastic element is designed.The characteristics of the humanoid robot arm is analyzed.The kinematic model of the robotic arm is established,deriving the forward and inverse kinematic solution,the Jacobian matrix and the work space.The dynamic model of the robotic arm is built and the equivalent momenta of each joint are calculated.The robotic arm control system is designed and the hardware of the control system is selected.The position PI and speed PI of the motors are set up via the upper computer interface.The pressure sensor and MTI position sensor are corrected and a method of MTI position correction is presented.We Imitated Taiji pushing-hand motion to plan a circular trajectory for the robotic arm.The position tracking experiments in the free workspace are conducted.The results show that the system has good stability and position following performance in free workspace.An active obstacle avoidance algorithm based on contact force is designed.The results show that the robotic arm can avoid curved surface obstacles,and then go back to the planning trajectory.It proves the compliance and security of the robotic arm.The study implies that the compliant robotic arm has the potential of compliance and adaptability for its use.