Kinematic and Static Analysis of a Prosthetic Hand Incorporating Inter-phalangeal Constraints and Dimensional Ratios

The ability of a prosthetic hand to mimic the biomechanics of a human hand is one of the approaches to assess its effectiveness. Despite significant advancements, replicating the dexterity and natural motion of a human hand remains a challenge. One critical yet often overlooked factor in prosthetic hand development is incorporating interphalangeal constraints and dimensional ratios, which play a key role in achieving natural finger articulation. To address these limitations, this study presents the kinematic and static analyses of ENRICH (EMG coNtrolled pRosthetIC Hand), a prosthetic hand designed with a biomimetic approach. The kinematic analysis evaluates joint variable relationships with actuation parameters, fingertip trajectories, and workspace analysis. The static analysis investigates the relationship between joint variables and actuator torque. Results indicate a linear correlation between joint variables and actuation parameters, while the estimated work-volume of ENRICH closely resembles $\mathbf{9 1. 6 7 \%}$ of a human hand’s work-volume. Additionally, the static analysis reveals that actuator torque follows a periodic function of joint variables. Due to the incorporation of inter-phalangeal constraints and dimensions, ENRICH demonstrates the ability to perform natural grasping.