Research on the Impedance Control of Human-robot Cooperative Manipulator Based on Human-friendly Technology

Abstract

The paper had studied the human-robot cooperation with moving an object based on a three DOF (Degree of Freedom) manipulator. Firstly,the impedance control based on impedance model for the manipulator had been designed, and confirmed through the Simulink simulation. And then, the impedance parameters of the manipulator were obtained by using the least square method. For the human-friendly, the paper had proposed a new method. That is to compare the impedance characteristics of the manipulator with the impedance model of the human-human cooperation. The paper analyzed the human-friendly in quantitative by calculating the percentage error of the impedance parameters. Finally, the paper verified the human-friendly of the manipulator using the method. And it found that the designed impedance control can make the manipulator be human-friendly Introduction Robots have been widely used in various fields of industrial production. But most of them have been programmed and just do something simple and repeatable. With the development of robotics, robots are expected to be work in agriculture, domestic service and medicine. Usually, it is difficult for the robots to complete the task alone. Human-robot cooperation that combines the advantages of human and robot, will be more and more important. In the papers [1-3], human-robot cooperation has been studied. They present the methods to analysis the human-friendly. Ikeura [1] let the human give marks about the feelings for viscosity, stability and maneuverability, and the feelings for the operation of the cooperation task was evaluated subjectively. Ben-Lamine [2] thought that to reach a friendly human perception during cooperation with robots, the robot has to develop the same mechanical trajectories that would be developed by some selected mass-damper-spring systems which could receive the same human force applied over the actual robot. Those selected mechanical impedances are considered friendly if they can provide a simultaneous human perception of touching something reassuring, flexible, pleasant and human-alike. All of them analysis the human-friendly by recording the feeling of the human. That is too subjectively. So they cannot analysis it in quantitative and objective. Silva[3], however, analysis the human-friendly in quantitative. He thought that the friendly perception effectiveness can be proved from the error between the speed of the friendly emulated mechanical impedance and the speed of actual vehicle when both receives the same human force. There we can see that, only the speed had been compared. It is not comprehensive in the impedance control when the force is ignored. This paper has proposed a method to analysis the human-friendly during the human-robot cooperation. Which is to compare the impedance characteristics of the manipulator with the impedance model of the human-human cooperation. The percentage error of the impedance parameters shows the human-friendly more objective and more imprehensive. Equations on Manipulators The paper established the coordinate system on the manipulator through the D-H method [4], 3rd International Conference on Machinery, Materials and Information Technology Applications (ICMMITA 2015) © 2015. The authors Published by Atlantis Press 1110 which is show in Fig.1. The manipulator has three rotating joints, and the joint axes of each articulation are perpendicular to the paper. So the manipulator is a planar motion mechanism. Joint angle 1 2 3 , ,    seen in Fig.1. Links length 1 2 3 , , l l l , where 1 2 l l  . And the mass of link are 1 2 3 , , m m m .