Double actuator unit with planetary gear train for a safe manipulator

Byeong Sang Kim, Jung Jun Park, Jae Bok Song

Research output: Chapter in Book/Report/Conference proceedingConference contribution

47 Citations (Scopus)


Control of a robot manipulator in contact with the environment is usually conducted by the direct feedback control system using a force-torque sensor or the indirect impedance control scheme. Although these methods have been successfully applied to many applications, simultaneous control of force and position cannot be achieved. Furthermore, collision safety has been of primary concern in recent years with emergence of service robots in direct contact with humans. To cope with such problems, redundant actuation has been used to enhance the performance of a position/force controller. In this paper, the novel design of a double actuator unit (DAU) composed of double actuators and a planetary gear train is proposed to provide the capability of simultaneous control of position and force as well as the improved collision safety. Since one actuator controls position and the other actuator modulates stiffness, DAU can control the position and stiffness simultaneously at the same joint. The torque exerted on the joint can be estimated without an expensive torque/force sensor. DAU is capable of detecting dynamic collision by monitoring the speed of the stiffness modulator. Upon detection of dynamic collision, DAU immediately reduces its joint stiffness according to the collision magnitude, thus providing the optimum collision safety. It is shown from various experiments that DAU can provide good performance of position tracking, force estimation and collision safety.

Original languageEnglish
Title of host publication2007 IEEE International Conference on Robotics and Automation, ICRA'07
Number of pages6
Publication statusPublished - 2007
Event2007 IEEE International Conference on Robotics and Automation, ICRA'07 - Rome, Italy
Duration: 2007 Apr 102007 Apr 14

Publication series

NameProceedings - IEEE International Conference on Robotics and Automation
ISSN (Print)1050-4729


Other2007 IEEE International Conference on Robotics and Automation, ICRA'07

ASJC Scopus subject areas

  • Software
  • Control and Systems Engineering
  • Artificial Intelligence
  • Electrical and Electronic Engineering


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