over the arm positions and the subjects. When the EMG data from all five arm positions were involved in thetraining set, the average classification error reached a value of around 10.8% for amputated arms. Using a two-stagecascade classifier, the average classification error was around 9.0% over all five arm positions. Reducing ACC-MMG channels from 8 to 2 only increased the average position classification error across all five arm positions from 0.7%to 1.0% in amputated arms.