Systems and control methodologies for improving stability in powered lower limb devices

A method of controlling a prosthetic lower limb device comprising a powered knee joint, the method comprising:

• detecting a stumble event based on one or more sensor signals associated with at least an overall motion of the prosthetic lower limb device;
• classifying a likely response strategy for the stumble event as a lowering strategy or an elevating strategy based on the sensor signals after the stumble event, the classifying comprising:
• estimating at least one measure of a motion of a residual limb associated with the prosthetic lower limb device based on the sensor signals,
• comparing the at least one measure to a threshold amount, and
• choosing one of the lowering strategy or the elevating strategy as the likely response strategy based on the comparing;
• and
• configuring the powered knee joint of the prosthetic lower limb device to operate according to one of a lowering response corresponding to the lowering strategy or an elevating response corresponding to the elevating strategy based on the classifying,
• wherein the lowering response comprises extension of the prosthetic lower limb device relative to the powered knee joint, and wherein the elevating response comprises an initial flexion of the prosthetic lower limb device relative to the powered knee joint and a subsequent extension of the prosthetic lower limb device relative to the powered knee joint.