Proportional myoelectric control

There are four purposes that robotic lower limb exoskeletons can accomplish:[1] Robotic lower-limb exoskeletons can be controlled by several methods, including a footswitch (a pressure sensor attached to the bottom of the foot), gait-phase estimation (using joint angles to determine the current phase of walking), and myoelectric control (using electromyography).

The controller filters out noise from the EMG signals and then normalizes them so as to better analyze the muscle activation pattern.

An alternative method to normalization is to proportionally match the actuator power to the EMG signal between a minimum activation threshold and an upper saturation level.

[10] To correct for this unwanted co-activation, a rule can be added to the control scheme so that artificial dorsiflexor activation is inhibited when soleus EMG is above a set threshold.

Many full-body robotic exoskeletons currently in development use controllers based on joint torques and angles instead of electromyography.

One application of a robot lower limb exoskeleton is to assist in the movement of a disabled individual in order to walk.

Individuals with spinal cord injury, weakened leg muscles, poor neuromuscular control, or who have suffered a stroke could benefit from wearing such a device.

For example, high EMG signals in the vastus medialis (a quadriceps muscle) and low EMG signals in the biceps femoris (a hamstring muscle) would indicate that the user is extending his/her leg, therefore the exoskeleton would provide torque on the knee to help straighten the leg.