Evaluation of Computer-Based Target Achievement Tests for Myoelectric Control.

Area of Science:

• Prosthetics and Artificial Limbs
• Human-Computer Interaction
• Rehabilitation Engineering

Background:

• Real-time evaluation of prosthetic control schemes is vital for advancing artificial limb technology.
• Two tools, the target achievement control (TAC) test and the Fitts' law test (FLT), have been proposed for assessing real-time controllability.
• TAC offers anthropomorphic feedback but can be visually confusing, while FLT uses simplified representations for clearer feedback.

Purpose of the Study:

• To compare the performance metrics obtained using the TAC test and the FLT.
• To quantify differences in controllability assessment based on visual feedback methods.
• To determine the impact of visual feedback clarity on prosthetic control evaluation.

Main Methods:

• Ten able-bodied and one amputee subject performed target achievement tasks using both FLT and TAC protocols.
• Tasks were designed with equivalent indices of difficulty to ensure fair comparison.
• Key performance metrics including completion rate, path efficiency, overshoot, and throughput were recorded.

Main Results:

• Able-bodied subjects showed significantly better completion rate, path efficiency, and overshoot with FLT (p <0.05).
• The amputee subject demonstrated significantly better overshoot with FLT.
• FLT revealed a strong linear relationship (R²=0.96) between movement time and index of difficulty, unlike TAC (R²=0.19).

Conclusions:

• The simplified visual feedback of the Fitts' law test (FLT) leads to superior performance and more reliable data compared to the TAC test.
• The confusing visual limb representation in the TAC test appears to negatively impact user performance.
• Understanding evaluation protocol biases is crucial for translating prosthetic research into clinical practice.