A Cognitive Joint Angle Compensation System Based on Self-Feedback Fuzzy Neural Network With Incremental Learning

Abstract

Joint angle error of robotic arm has great impacts on the accuracy of the end-effector, which is critical in industrial applications. Therefore, in this article, an online cognitive joint angle error compensation method based on incremental learning is proposed to reduce joint angle error. The proposed method consists of a joint angle error solver and a compensation module, which ensure that the robot can obtain effective joint angle compensation in various situations. The joint angle error solver is used to solve joint angle error online. It uses the redundant constraint method for multilink position measurement so as to calculate the position error of the robot accurately later. The compensation module uses the self-feedback incremental fuzzy neural network (SFIFN) to predict and update the compensation in real time. SFIFN is a variant of the fuzzy neural network (FNN), which uses long short-term memory to introduce a feedback mechanism based on FNN. The incremental learning capability of SFIFN reduces the time for solving error and makes the module runs in real time. Specifically, two inertial measurement units mounted at the ends of links are used to measure pose changes of the ends of corresponding links. Both the simulated and the real experiments show that the proposed method yields good compensations to joint angle error and its potentials for smart manipulation.