Abstract. This study proposes a haptic interactive robot (HIR) configuration and a control strategy based on a cable-driven parallel mechanism. The ball screw drives the cable to improve the motion control accuracy. The robot system control strategy improves the accuracy and stability of haptic interaction. Through configuration optimization design and analysis, eight cables are used to ensure that the robot end effector exerts force and enables motion. Moreover, a forward and inverse kinematics model of the robot is developed. According to the configuration of the HIR, an improved cable tension distribution algorithm can facilely determine the cable tension. Hence, each cable is consistently in a tight state, and the change in tension is not sudden. Drive unit and robot system control strategies are proposed to render the haptic interaction accurate and stable. A simulation experiment of a complex space motion track is implemented through the robot end effector, thus verifying the accuracy of the established forward and inverse kinematics model. The accuracy of the tension distribution algorithm, control strategy, and robot stability are verified through simulation experiments, considering different forces and motion tracks of robot end effectors.

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This work presents the effect of ultrasonic surface rolling process (USRP) on fretting friction and wear properties of Ti-6Al-4V alloy that was prepared by hot isostatic pressing (HIP) before and after heat treatment. The results suggest that the heat-treated HIPed Ti-6Al-4V alloy exhibits higher microhardness and surface roughness values along with a grain size of 200 nm under the same USRP treatment. The thickness of the strengthening surface layer of the heat-treated sample was reduced by 20% compared to the unheat-treated sample on the identical USRP treatments. Meanwhile, it has higher coefficient of friction (CoF) and more severe fretting wear scar. Moreover, the wear debris was contained some large blocks. Additionally, the wear mechanism was mainly abrasive and accompanied by a bonding behavior. The sliding regimes were analyzed by the changes in CoFs and fretting wear scars. In addition, the friction temperature and viscoplasticity were also very important for the fretting friction and wear performance under identical slip conditions. Finally, the heat-treated material after USRP showed a higher wear rate because of the change in microstructure and mechanical properties. This would intensify the friction and wear response between the counter grinding sample and target sample.

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