Compliant control of a humanoid robot helping a person stand up from a seated position

Supporting somebody while standing up from a seated position is one of the most frequent tasks envisaged for a humanoid assistant used in order to help somebody with reduced mobility around the house. The safest way to do this for a human carer has been clearly defined in patient handling guides for hospitals where a policy of never lifting the patient is strongly recommended. Based on these guidelines, this paper proposes a stable initial posture for a humanoid robot supporting a person from sitting to standing, as well as a control law to make the robot keep a contact force and follow the motion of the person compliantly. This initial position and compliant control of the robot was implemented and tested on the humanoid HRP-4 interacting with a healthy subject.