Journal of South China University of Technology(Natural Science Edition) ›› 2022, Vol. 50 ›› Issue (9): 126-137.doi: 10.12141/j.issn.1000-565X.210769

Special Issue: 2022年机械工程

• Mechanical Engineering • Previous Articles     Next Articles

A Robot Grasping Policy Based on Viewpoint Selection Experience Enhancement Algorithm

WANG Gao1,2 CHEN Xiaohong1,2 LIU Ning2,3 LI Deping2,3   

  1. 1.College of Information Science and Technology,Jinan University,Guangzhou 510632,Guangdong,China
    2.Robotics Intelligence Technology Research Institute,Jinan University,Guangzhou 510632,Guangdong,China
    3.School of Intelligent Systems Science and Engineering,Jinan University,Zhuhai 519070,Guangdong,China
  • Received:2021-12-06 Online:2022-09-25 Published:2022-02-11
  • Contact: 李德平(1987-),男,博士,讲师,主要从事物体三维位姿估计、机器人抓取、移动机器人研究。 E-mail:lideping@jnu.edu.cn
  • About author:王高(1978-),男,博士,副研究员,主要从事数控与机器视觉、机器人技术研究。E-mail:twangg@jnu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(62172188)

Abstract:

To solve the problem of the low success rate of robot vision grasping using fixed environment camera in the scene of cluttered and stacked objects, an eye-hand follow-up camera viewpoint selection policy based on deep reinforcement learning is proposed to improve the accuracy and speed of vision-based grasping. Firstly, a Markov decision process model is constructed for robot active vision-based grasping task, then the problem of viewpoint selection is transformed into a problem of solving the viewpoint value function. A deconvolution network with encoder-decoder structure is used to approximate the viewpoint action value function, and the reinforcement learning is carried out based on the deep Q-network framework. Then, to resolve the problem of sparse reward existing in reinforcement learning, a novel viewpoint experience enhancement algorithm is proposed. The different enhancement methods between the successful and failed grasping process are designed respectively. And the reward region can be expanded from a single point to a circular region for improving the convergence speed of the approximation network. The preliminary experiment is deployed on the simulation platform, and the robot model and the grasping environment are simultaneously built in the simulation platform to implement the offline reinforcement learning. In the process, the proposed viewpoint experience enhancement algorithm can effectively improve the sample utilization rate and speed up the convergence of training. Based on the proposed viewpoint experience enhancement algorithm, the viewpoint action value function approximation network can converge within 2 h. To obtain the results from the verification with application, the proposed viewpoint selection policy is applied to the real-world scenes with robot for grasping experiments. The result shows that the viewpoint optimization based on this policy can effectively promote the accuracy and speed of robot grasping. Compared with the general grasping methods, the proposed viewpoint selection policy needs only one viewpoint selection in real-world robot grasping to find the focus region with high grasping success rate. And the method can also promote the processing efficiency of the best viewpoint selection. The grasping success rate in cluttered scenes is increased by 22.8% against the single-view method, and the mean picks per hour can reach 294 units. As whole, it shows that the proposed policy has the capacity of industrial application.

Key words: robot grasping, reinforcement learning, robot vision, viewpoint selection, best viewpoint prediction, active perception approach, experience enhancement

CLC Number: