Forced liquid impregnation technique as validation approach of two cooling geometries tested in air and oil conditions for a humanoid robot joint actuator

When a humanoid robot lifts a heavy object this demands maximum load capacity of each joint. The amount of power of these joints determines the maximum object's weight the robot is able to carry. Humanoid robots must be lightweight, small and have a load capacity similar to humans. To achieve that, first of all, each joint must be as strong as possible to lift the sum of weights of the following joints plus the weight of the object. There have been some efforts in order to extract more power from an electric motor, the most effective have integrated an external jacket to pump liquid inside it to reduce the external heat of the motor, however, this don't represent an adequate integration of the liquid in the electric motor designing process. In this work, we propose to test and validate a cooling solution for high power applications in a prototype-hollow humanoid robot joint that uses a fractional-slot concentrated-winding brushless direct current motor as an actuator. The geometry of the proposed cooling solution was built and implemented to be tested under high current conditions.