Distributed Macro-Mini Actuation

  • The REACH lab is investigating the extension of the Distributed Macro-Mini actuation approach to high-force haptic interfaces and hybrid high-power and high-force manipulation.  This work was originally funded by the National Science Foundation as part of Prof. Zinn’s Ph.D. work. 
  • Faculty:
  • Michael Zinn – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Students:   
  • Chembian Parthiban  – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Patrick Dills  – Department of Mechanical Engineering, University of Wisconsin-Madison
  • Funding:
  • Oculus Research (current)
  • National Science Foundation (NSF) MRI Program (2000 – 2005)
  • Human-centered robotics involves the close interaction between robotic systems and human beings, including direct human-manipulator contact. In such applications, we must consider the requirements of safety in addition to traditional performance metrics. While there has been significant progress in manipulator and actuator design, there has yet to be a successful manipulator design that possesses the characteristics of both safety and performance. To address this need, a new actuation method, referred to as Distributed Macro-Mini actuation (DM2), has been developed. Recognizing that manipulator torque requirements, as a function of frequency, fall-off sharply at higher frequencies, the DM2 approach partitions the actuation into separate macro- and mini-actuators that provide the low- and high-frequency torques, respectively. Locating the actuators at arm locations where they are most effective, referred to as distributed actuation, is an essential feature of this new approach. Large, macro actuators provide the low frequency torque required to compensate gravity and provide acceleration torques. Locating the macro actuators at the base of a manipulator reduces the size and weight of the manipulator substantially. The use of a compliant element between the macro actuator and drive-train decouples the reflected inertia of the macro actuator from the manipulator, further reducing the effective inertia. To recover high-frequency torque capability, the mini actuators are collocated at the joints, providing the high mechanical bandwidth necessary for high performance tasks. Because the required high-frequency torque magnitude is small, the mini motors can be kept small enough so that they contribute only a minor increase in manipulator size and weight.

Recent Work

  • IEEE Haptics Symposium 2008: Large Workspace Haptic Devices – A New Actuation Approach Large workspace haptic devices have unique requirements, requiring increased power capabilities along with increased safety considerations. While there are numerous haptic devices available, large workspace systems are hampered by the limitations of current actuation technology. To address this, the Distributed Macro-Mini (DM2 ) actuation method has been applied to the design of a large workspace ...
  • International Journal of Robotics Research (IJRR) 2004: A New Actuation Approach for Human-friendly Robot Design In recent years, many successful robotic manipulator designs have been introduced. However, there remains the challenge of designing a manipulator that possesses the inherent safety characteristics necessary for human-centered robotics. In this paper, we present a new actuation approach that has the requisite characteristics for inherent safety while maintaining the performance expected of modern designs. ...