Scientists at the Italian Institute of Technology in Genoa have developed a rotary actuator which is very compact, small, with an active control mechanism. It is suitable in particular for robotic applications, where size, weight and complexity are critical parameters.
The device’s compact structure is down to an input drive unit on the shaft of an electric motor-reduction gearbox, which is coupled to a three-spoke drive output, via six helical springs. Differential rotation between input and output provides a first, fixed degree of compliance for the drive, determined by the springs’ elastic constant. Moreover, the addition of rotary encoders in both the input and the output sections of the actuator give information on absolute position, rotation speed and applied torque (via relative rotation), which allows an active control unit to provide effective control, regulated over a wide range.
The small size and effective control over a wide range would allow this actuator to be integrated in robotic systems with various degrees of complexity. Despite its small size, the actuator still retains high levels of performance and it is a potential actuation solution for robotic systems when compliance is also desired. The passive compliance of this unit is also combined with active compliance control, based on velocity regulation, allowing the compliance adjustment within a wide range. Industrial applications are in the field of industrial automation and robotics.