Nine Degree-of-Freedom Kinematic Modeling of the Upper-Limb Complex for Constrained Workspace Evaluation

Area of Science:

• Biomechanics
• Robotics
• Rehabilitation Engineering

Background:

• Musculoskeletal disorders (MSDs) significantly impact upper-limb function, necessitating specialized rehabilitation devices.
• Designing effective and safe robotic rehabilitation tools requires accurate patient-specific kinematic models.
• Assessing a patient's functional workspace is crucial for tailoring rehabilitative treatments.

Purpose of the Study:

• To develop a comprehensive 9 degree-of-freedom (DOF) kinematic model of the upper limb.
• To guide the design of robotic rehabilitation devices for patients with MSDs, prioritizing safety and efficacy.
• To determine patient workspace limitations and identify areas where assistive devices are needed.

Main Methods:

• Derived a 9-DOF kinematic model of the upper limb complex.
• Developed a novel differential inverse kinematic method incorporating joint constraints via saturation functions.
• Re-evaluated the model Jacobian to handle redundancy and ensure feasible inverse kinematic solutions.
• Validated the model through three scenarios with varying elbow and palm orientation constraints.

Main Results:

• The model accurately determines patient workspace, distinguishing between functional and limited ranges due to MSDs.
• Constraint mapping effectively compensates for joint limitations, ensuring realistic kinematic solutions.
• Comparison of pre-injury and MSD-affected workspaces quantifies functional loss.
• Identified specific regions where rehabilitation devices must provide assistance.

Conclusions:

• The developed kinematic model provides a robust framework for designing patient-specific upper-limb rehabilitation devices.
• This approach enhances the safety and effectiveness of robotic-assisted rehabilitation for MSDs.
• The method accurately quantifies functional limitations and guides targeted therapeutic interventions.