A medical device uses UWB units to infer a position of an adjunct positioned in proximity to an exterior portion of a patient's body. The position information can be used to provide CPR feedback to a rescuer. In other applications, the position information can be used to provide prompts to a user to change the position of the adjunct.

A motion assistance apparatus including a fixing module attached to a user, a driving module fixed to the fixing module to generate rotation power, a supporting module configured to support a portion of a body of the user and driven by the driving module, a sensor configured to measure a width of the fixing module, and a controller configured to adjust the rotation power of the driving module based on the measured width.

A motion assistance apparatus including a fixing module attached to a user, a driving module fixed to the fixing module to generate rotation power, a supporting module configured to support a portion of a body of the user and driven by the driving module, a sensor configured to measure a width of the fixing module, and a controller configured to adjust the rotation power of the driving module based on the measured width.