FMG Versus EMG: A Comparison of Usability for Real-Time Pattern Recognition Based Control

Objective: Force myography (FMG), which measures the surface pressure profile exerted by contracting muscles, has been proposed as an alternative to electromyography (EMG) for human-machine interfaces. Although FMG pattern recognition-based control systems have yielded higher offline classification accuracy, comparatively few works have examined the usability of FMG for real-time control. In this work, we conduct a comprehensive comparison of EMG- and FMG-based schemes using both classification and regression controllers. Methods: A total of 20 participants performed a two-degree-of-freedom Fitts' Law-style virtual target acquisition task using both FMG- and EMG-based classification and regression control schemes. Performance was evaluated based on the standard Fitts' law testing metrics throughput, path efficiency, average speed, number of timeouts, overshoot, stopping distance, and simultaneity. Results: The FMG-based classification system significantly outperformed the EMG-based classification system in both throughput (0.902 +/- 0.270) versus (0.751 +/- 0.309), (rho < 0.001) and path efficiency (87.2 +/- 8.7) versus (83.2 +/- 7.8), (rho < 0.001). Similarly, FMG-based regression significantly outperformed EMG-based regression in throughput (0.871 +/- 0.2) versus (0.69 +/- 0.3), (rho < 0.001) and path efficiency (64.8 +/- 5.3) versus (58.8 +/- 7.1), (rho < 0.001). Conclusions: The FMG-based schemes outperformed the EMG-based schemes regardless of which controller was used. This provides further evidence for FMG as a viable alternative to EMG for human-machine interfaces. Significance: This work describes a comprehensive evaluation of the online usability of FMG- and EMG-based control using both sequential classification and simultaneous regression control.