HADAR Hand: 13-DoF Hybrid Actuation-Based Dextrous Anthropomorphic Robotic Hand

Dextrous robotic hand designs are pivotal in advancing the field of hand prosthetics, enabling users to perform robust grasping tasks essential for daily activities and improved quality of life. However, the widespread adoption of such dextrous hand prosthetics remains hindered by prohibitive costs that arise from the high number of actuators used to replicate natural human hand movements. This research seeks to address this challenge by critically evaluating the necessity of replicating many human hand DoFs and instead proposing a design that achieves 95% of human grasp configurations with a significantly reduced actuator count compared to conventional biomimetic robotic hands. We present the Hybrid-Actuated dextrous Anthropomorphic Robotic (HADAR) Hand, a novel 13-DoF robotic hand optimised for dextrous object grasping with a high degree of visual anthropomorphism. The HADAR Hand employs a hybrid actuation strategy, combining linkagedriven mechanisms for robust proximal joint control and tendon-based actuation for compliant distal joint movement, which is essential for delicate object handling. Utilizing insights from long-term occupational studies and Functional Range of Motion (FROM) data, rigid and elastomeric couplings were developed to bring down the actuator count to less than half the number of major tendons present in the human hand without compromising on the ability to perform human-like grasp configurations. Comprehensive performance evaluations validate the HADAR Hand's capabilities, with results demonstrating success in replicating hand grasps as per Cutkosky's taxonomy (14/15), Feix's GRASP taxonomy (31/33), and the Kapandji thumb opposability test (6/10). To promote accessibility and reproducibility, the HADAR Hand leverages cost-effective, widely available actuators, additive manufacturing techniques, and a compact, two-layer PCB capable of concurrently driving all 13 N20 DC motors that drive the HADAR Hand. This work represents a significant step in developing affordable, highperformance prosthetics and robotic hands.