Mechatronics of David

Mechanics

Anthropomorphic light weight robot

Overview

  • Variable passive compliance in each joint
  • Human like strength
  • Human like range of motion
  • Robust to impacts
  • Potential energy storage in joints
  • Three different Variable Stiffness Actuator (VIA) concepts
  • No torque sensors
  • Fully integrated electronics
  • Modular design

Variable Stiffness Actuators (VSA)

The Hand Arm System is equipped with 3 types of Variable Stiffness Actuators:

  • Antagonism (20 DoF Hand):

    • Two equivalent motors adjusting joint stiffness and position in-tendon progressive spring mechanism

  • BAVS - Bidirectional Antagonism with Variable Stiffness Actuation (2 DoF wrist,1 DoF forearm-rotation):

    • Two equivalent motors adjusting joint stiffness and position
    • Asymmetric cam disc shape
    • Redundant joint actuation

  • FSJ - Floating Spring Joint (4 DoF upper arm joints):

    • One big motor for joint positioning
    • One small motor to change the stiffness
    • One single spring

Electronics

Very high integration and power density

Units integrated in the forearm

  • 42 intelligent motor modules with integrated power inverters and 180 W peak power each
  • Two FPGA based control units
  • 12 V and 5 V power supplies and distribution
  • Spring deflection sensors

Units integrated in the upper arm / shoulder

  • Eight motors with up to 1 kW peak power
  • Modular power inverters
  • Spring deflection sensors
  • Control units

Customized power supply (IGOR)

  • Five independent 24 V and 48 V outputs with soft start and fast electronic fuse to power the complete Hand Arm System
  • 4 kW peak source and sink capability
  • Energy storage using supercapacitors allows operation from standard wall outlet
  • Control via touch screen display or USB/RS232

Selected Publications

Friedl, W., Chalon, M., Reinecke, J. and Grebenstein, M., FAS A flexible antagonistic spring element for a high performance over, Intelligent Robots and Systems (IROS), 2011 IEEE/RSJ International Conference on, 2011, pp. 1366-1372. [elib]

Friedl, W., Hoppner, H., Petit, F. and Hirzinger, G., Wrist and forearm rotation of the DLR Hand Arm System: Mechanical design, shape analysis and experimental validation, Intelligent Robots and Systems (IROS), 2011 IEEE/RSJ International Conference on, IEEE/RSJ, 2011, pp. 1836-1842. [elib]

Wolf, S., Eiberger, O. and Hirzinger, G., The DLR FSJ: Energy based design of variable stiffness joints, Robotics and Automation (ICRA), 2011 IEEE International Conference on, IEEE, 2011, pp. 5082 - 5089. [elib]

Wolf, S. & Hirzinger, G., A New Variable Stiffness Design: Matching Requirements of the Next Robot Generation, Robotics and Automation (ICRA), IEEE International Conference on, 2008, 1741-1746. [elib]

Grebenstein, M. & van der Smagt, P., Antagonism for a highly anthropomorphic hand-arm system, Advanced Robotics, 2008, 22, 39-55. [elib]