Shadow Control of a fully modular prosthetic arm with 3-DoF Shoulder.

Shoulder amputation is a complex condition that significantly challenges prosthetic design and control. Here we propose a master-slave control paradigm to operate a modular whole-arm prosthesis (HANNES Arm). Our solution uses Inertial Measurement Units (IMUs) to estimate the movements of the intact arm, which are then replicated in the prosthetic arm. The use of quaternion representations for the kinematics of both human and prosthetic arm kinematics ensures computationally efficient and singularity-free motion tracking and control. The algorithm was validated through simulations, integrating a virtual model of the prosthesis with a personalized human arm model. The human arm configuration was then used to compute the joint rotations of the prosthetic device, which served as reference signals for its control. Despite minor alignment errors, the results demonstrated satisfactory performance, aligning closely with qualitative assessments conducted using an optical motion tracking system (Vicon). Beyond technical innovation, this research contributes to the study of human arm movement synergies, offering new directions for future investigations. The algorithm's adaptability to individual variations highlights its potential for personalized prosthetic applications, ultimately enhancing the quality of life for individuals with upper limb amputations.Clinical relevance This research not only contributes to technical advancements in the prosthesis control field, but also fosters a deeper understanding of the relationship between humans and prosthetic devices, paving the way for a future where prosthetics seamlessly integrate into daily life.