Figure 2.

(A) The participant was shown his unattached prosthesis with the inertial measurement unit (IMU) modules attached proximally and distally of the knee joint. For each segment of the prosthesis, the orientation of the IMU module was calibrated as described in Section 2.1. The participant was informed that movement of the prosthesis, as detected by the wireless modules, was responsible for triggering the vibratory actuator. (B) The participant was unaware, however, that the robotic arm was used instead to provide motion measurements, triggering the vibration motor. The calibrated local coordinate frames and the global coordinate frame are shown within and below the figure, respectively.