Abstract: Focusing on massage state drive and the influence of the action component on the end massage head force, a safe and effective back massage actuator integrating multiple massage techniques is designed. Based on traditional Chinese massage points and manipulative techniques, and guided by established design indices for the back massage actuator, the movement characteristics of massage manipulations are analyzed, resulting in a synergistic back massage actuator combining multiple manipulation modules. The actuator employs a design that closely mimics human touch sensation and includes safety features for contact force threshold protection. For the cam mechanism module used in the finger-kneading and finger-vibrating techniques, analyses are conducted on driving force to determine optimal working torque and push rod parameters, ensuring optimal performance. Furthermore, based on human skin friction theory, adjustments are made to the kneading radius of the actuator to address relative slip between the massage head and human skin during the finger-kneading technique. By solving for adhesion friction, deformation friction, and transverse stiffness, key parameters are optimized. For the finger-vibrating technique, particle swarm optimization is applied to enhance structural parameters, such as push rod mass and spring pre-compression, thereby ensuring that the cam’s critical angular velocity remains higher than the maximum working angular velocity. A prototype of the massage actuator is constructed, and the actuator’s force and technique are evaluated experimentally by comparing human and machine massage effects. Results demonstrate that the massage actuator achieves a compact, streamlined structural design, with strength errors fluctuating within ±1 N. This consistency verifies that the massage force, technique, and frequency processes meet the technical specifications required for back massage applications, affirming the design’s efficacy and rationality.

Key words: Chinese medicine massage robot, contact force, critical slip, particle swarm algorithms, optimization of structural parameters