Robot actuator utilizing a differential pulley transmission

A differential pulley actuator comprising:

• a first input drive gear for coupling to a motor, wherein the first input drive gear couples rotation of the motor to rotation of an output pulley;
• a first timing belt pulley pair coupled to the first input drive gear, wherein rotation of the first input drive gear causes rotation of the first timing belt pulley pair;
• a first idler pulley element suspended between the first timing belt pulley pair and the output pulley and held in tension to the first timing belt pulley pair via a first tension-bearing element and to the output pulley via a second tension-bearing element;
• a second input drive gear for coupling to the motor, wherein the second input drive gear couples rotation of the motor to rotation of the output pulley;
• a second timing belt pulley pair coupled to the second input drive gear, wherein rotation of the second input drive gear causes rotation of the second timing belt pulley pair;
• a second idler pulley element suspended between the second timing belt pulley pair and the output pulley and held in tension to the second timing belt pulley pair via a third tension-bearing element and to the output pulley via the second tension-bearing element;
• and
• the output pulley for coupling to a load, wherein the output pulley couples to the first idler pulley element and the second idler pulley element via the second tension-bearing element looping around the output pulley and is configured to apply motion of the first idler pulley element and the second idler pulley element to the load.