An experimental comparison of energy efficiency between a directly driven elbow and an indirectly driven elbow

This paper presents an experimental result to compare energy efficiency between two elbow driven mechanisms. A directly driven mechanism is to drive the elbow by a motor with a gearbox which is installed at the joint axis. An indirectly driven mechanism uses a 4-bar linkage mechanism which is driven by a linear actuator installed in the upper arm. Experimental elbows are made to implement each mechanism and both of elbows use a same motor. The electrical energy consumption by the motors is measured while both the elbows are doing the same physical work.