A Novel Bidirectional Controlled Prosthetic Hand With Rigid-Flexible Coupled Structure and Skin Stretch Feedback

A bionic prosthetic hand is critical for individuals with upper limb disabilities to gain the ability to live independently. However, practical applications are often limited by low adaptability in grasping, complex control, and feedback difficulties. To address these challenges, this work designs a prosthetic hand with a rigid-flexible coupling structure, demonstrating promising adaptability in grasping. It can successfully grasp objects with common shapes, materials, and stiffness. To realize intuitive feedback, the prosthetic hand utilizes a skin-stretching actuator array to simulate the tactile feedback experienced when a normal human hand grasps a heavy object with the palm oriented downward. The fuzzy control encodes the actuator array to provide the user with information such as grasping location, stability, and force level, thus allowing the user to control the motion of the prosthetic hand more intuitively. The array of actuators enables the user to perceive the grasping state of all fingers and lowers the user's threshold of understanding based on fuzzy control, facilitating quicker and easier understanding of the grasping situation. Additionally, for bidirectional control, this prosthetic hand enables neural control using electromyographic (EMG) signals obtained from the proximal surface of the forearm. The EMG sensor's acquisition sites are optimized, and real-time bidirectional demonstration is achieved. This study paves the way for high-performance bionic prosthetics and proposes a novel tactile feedback system with easier understood cascaded spatiotemporal type-2 fuzzy tactile control mapping.