A Mechatronic Thumb for Grasping and In-Hand Manipulation Tasks

We present the design, kinematic modeling, and control of a wearable mechatronic thumb device, which is intended to seamlessly integrate with the human hand. The device exhibits lightweight construction, portability, robustness, and safety during use. Initially, we describe the mechanical design of the thumb and an accompanying custom-made data glove that is utilized as a user interface. The kinematic analysis of the mechatronic thumb in conjunction with the human hand is then derived. We subsequently propose intuitive control methods to effectively oppose and coordinate the mechatronic thumb with the remaining fingers, so as to facilitate tasks such as envelope or precision tip grasping, as well as in-hand object manipulation. The potential of the proposed mechatronic thumb to compensate for thumb loss or disability is demonstrated through a series of experiments involving stable grasp and in-hand manipulation tasks of various objects. Grasp quality measures are utilized to assess the experimental results, focusing on the cooperative grasp of the designed mechatronic thumb and the other fingers, in comparison to a non-impaired human hand.