Comparison of Drivetrain Topologies: An Ankle Gait Cycle

Electric actuation is used in a wide variety of applications and fields. One of the fields is prosthesis actuation where energy efficiency and mass are important characteristics. A lot of applications within this field (e.g. knee prosthesis, ankle prosthesis,...) require a high torque at low speed and a low torque at high speed. These motion requirements are difficult to effectively combine into a single electric motor. A possibility is to use an oversized direct–drive motor that can deliver the peak torque. However, this results in a heavy actuation system and low overall efficiency. A common practice is combining a smaller electric motor with a gear reduction system. In literature, novel redundant electric actuation systems were presented with or without locking mechanisms. In this work, multiple electrical actuation systems composed of electric motors, gear reduction systems and locking mechanisms are compared to each other. This is done using the gait cycle of a human ankle as a case study