Application of Grey predictor in controlling 5 DOF power assistant robot

Abstract

Due to their high power output and reliability, robots can replace humans in most modern industrial tasks associated with heavy loads. However, there are some jobs that require both human flexibility and robot power. Consequently, there is a demand to combine the high power of a robot arm with the dexterity of a human. In this work, a robot system called the power assistant robot (PAR) is proposed to satisfy this demand. The system can be applied not only in heavy industrial tasks, but also in various fields such as rehabilitation, the military, and security. This research focuses on applying a new type of actuator, called an electro-hydraulic system (EHA), in a power assistant robot. The EHA-PAR includes 5 degrees of freedom (1 passive joint and 4 active joints) and interacts with the user through a 4-dimensional intelligent joystick. By analyzing commands from a human, the human-robot interface distributes reference angles for all active joints. However, in some positions, robot operation is suffered from singularity phenomenon; thus it affect to the control quality. This paper proposes a strategy for this problem by combining the Grey predictor and the conventional kinematic solving method. It can be realized that the performance of the system is ameliorated by applying the proposed method.