Vibrotactile Haptic and Gesture Feedback in a Smartwatch for Controlling a Multi-Activity Powered Knee-Ankle Prosthesis.

For powered lower-limb prostheses to be translated from research environments to real-world use, they must be able to perform a variety of daily activities, such as walking on level or ramped surfaces, stair climbing, sitting, and standing. The device must quickly and predictably switch between the modes corresponding to these activities. Multiple methods exist to trigger activity mode transitions, but they can overlook user agency, be slow and cumbersome to enact, lack discretion, or have limited predictability. This work presents a smartwatch application that allows the user to wirelessly control the activity mode of the prosthesis. The user can perform a swipe gesture on the smartwatch to transition to the desired mode, while the smartwatch provides vibrotactile haptic and visual feedback to the user to indicate the activity mode of the device. An experiment with one transfemoral amputee participant showed that the smartwatch application is viable for providing user control of the activity mode to traverse a multi-activity circuit using a powered knee-ankle prosthesis.