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Experimental Evaluation of Kinematic Compatibility in Three Upper Limb Exoskeleton Configurations Using Interface
Hui Zeng1, Hao Liu1, Longfei Fu2
1School of Bailie Mechanical Engineering, Lanzhou City University, No. 572, Anning East Road, Anning District, Lanzhou 730070, China.
Biomimetics (Basel, Switzerland)
|February 26, 2026
Summary
This study compared upper limb rehabilitation exoskeleton designs. Releasing passive joints reduced interaction forces, with Category 2 showing the best compatibility and lowest forces during movement.
Area of Science:
- Rehabilitation robotics
- Biomechanics
- Human-robot interaction
Background:
- Upper limb exoskeletons create kinematic chains with the human arm.
- Misalignment causes unwanted interaction forces and torques.
- Passive degrees of freedom (DOF) enhance kinematic compatibility.
Purpose of the Study:
- To experimentally compare three compatible four-DOF exoskeleton configurations.
- To evaluate the impact of passive joint release versus locking.
- To determine the most compatible exoskeleton configuration for rehabilitation.
Main Methods:
- Used a reconfigurable rehabilitation robot to test three exoskeleton configurations.
- Instrumented with six-axis force-torque sensors at arm interfaces.
- Measured interaction forces/torques during eating and combing tasks in passive mode.
Main Results:
- Releasing passive joints consistently reduced interaction forces and torques.
- Exoskeleton Category 2 demonstrated the lowest forces and torques.
- Category 2 exhibited the strongest peak force/torque suppression.
Conclusions:
- Passive joint release is crucial for reducing interaction loading in exoskeletons.
- Exoskeleton configuration Category 2 offers superior kinematic compatibility.
- Findings guide the design of more effective upper limb rehabilitation robots.
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