A greedy assist-as-needed controller for end-effect upper limb rehabilitation robot based on 3-DOF potential field constraints - Lu, Yue; Lin, Zixuan; Li, Yahui; Lv, Jinwang; Zhang, Jiaji; Xiao, Cong; Liang, Ye; Chen, Xujiao; Song, Tao; Chai, Guohong; Zuo, Guokun (Frontiers in Robotics and AI, 2024)