The Effect of an Automatically Levelling Wrist Control System

Area of Science:

• Biomedical Engineering
• Rehabilitation Robotics
• Human-Machine Interaction

Background:

• Upper limb loss significantly impacts quality of life, with current prostheses offering limited functionality, particularly lacking wrist movement.
• Absence of prosthetic wrist articulation necessitates compensatory movements in the shoulder and back, leading to potential strain and overuse injuries.

Purpose of the Study:

• To introduce and evaluate a novel self-regulating prosthetic wrist control scheme designed to maintain terminal device orientation.
• To assess the impact of this automatic levelling (AL) control on compensatory movements, objective performance, and user-reported experience compared to fixed-wrist (FW) and sequential switching (SS) schemes.

Main Methods:

• Twelve able-bodied participants controlled a robotic arm with three distinct wrist control schemes (FW, SS, AL) during simulated tasks.
• 3D motion capture technology was used to record movement strategies and quantify compensatory actions.

Main Results:

• Both SS and AL schemes reduced compensatory movements compared to FW for horizontal tasks.
• The AL scheme decreased shoulder flexion during vertical tasks compared to FW and SS.
• Users perceived AL as less intuitive and reliable than FW, requiring more conscious effort.

Conclusions:

• Advanced prosthetic wrist control systems can mitigate detrimental compensatory movements.
• System simplicity and reliability are critical factors for user acceptance, even when more complex systems offer functional benefits.