1 / 18

A Method of Robotic Actuation using Control Moment Gyros

A Method of Robotic Actuation using Control Moment Gyros. Presenter: Ian Livingston AIAA YPSE ‘08 November, 21 st 2008. Overview. Introduction What is a CMG Reactionless Actuation Joint Torques vs. Body Torques Planar Robot Design Simulation Results

ismet
Download Presentation

A Method of Robotic Actuation using Control Moment Gyros

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A Method of Robotic Actuation using Control Moment Gyros Presenter: Ian Livingston AIAA YPSE ‘08 November, 21st 2008

  2. Overview • Introduction • What is a CMG • Reactionless Actuation • Joint Torques vs. Body Torques • Planar Robot Design • Simulation Results • Experimental Design (Functional Flow) • Hardware and GUI • Controller Design • Closed Loop Gimbal Control • Feed Forward Joint Angle Control • Video • Future Plans • Acknowledgements • Questions Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions

  3. Control Moment Gyros (CMGs) • Components: • Constant speed reaction wheel • Gimbal motor (positioned along g axis) • Applications: • Momentum Storage • Propellant-less Attitude Control • Advantages: • Low Power (100x)1 • Spaceflight heritage Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions Equation for torque output Equation for reaction wheel momentum hr = Irw·wrw 1. Carpenter, Peck 2008

  4. Reactionless Actuation • Reaction Forces from Mechanism • Actuator Reaction Forces • Caused by direct-drive motors. To rotate an object the motor rotates the base object in the opposite direction. • Inertial Reaction Forces • Caused by a spinning object not at the center of mass. • Advantages to Reaction- • Less Actuation: • Isolate subsystems • Reduce dumped • momentum to the base • structure. Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions CMG Arm from previous project team on the “Vomit Comet”

  5. Joint Torques Versus Body Torques Joint Torques Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions Body Torques • CMGs create body torques • The motion of the arm remains the same • Only the torque caused by the off center reaction force needs to be absorbed using body torques. tcmg tmotor R2 T2 R2 q1 R2 t2 R q1 R2 t2

  6. Planar Robot Arm Design • Purpose: • To create a CMG robot arm to demonstrate the advantages of body torques on space applications. • Design: • Two or more link free floating CMG arms • Air bearings to provide frictionless surface • Use Scissored Pair CMGs to remove • Gyroscopic effects and off axis torques • Previous work and Motivation: • Past teams built the reaction wheels for a CMG arm test • Only open-loop results were obtained from zero-g tests • This experiment was created to perform tests anytime Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions Photo: A. Soto

  7. Scissored Pair CMGs • Advantages: • Eliminate off-axis torques • Direction of torque is fixed • No internal singularities • Cancelation of unwanted gyroscopic effects Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions Video: M. Peck

  8. Simulation Analysis and Hypothesis1 • Simulation to determine power properties of CMG arm • Utilized several set ups for links and properties • Main focus on one link and two link robot arms both in parallel axis and perpendicular joint axes. • Simulation assumes 0 initial and final velocities and accelerations. Joint torque advantage Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions CMG advantage • From power simulation results: • CMGs are better for reaching tasks • Joint torques better for panning tasks D. Brown, 2008

  9. Experimental Design (Functional Flow) Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions

  10. Hardware and MATLAB GUI Design Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions

  11. Controller Design Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions • Gimbal Angle is controlled by a PID closed loop control • Joint Angle is controlled using a Simulink model with feed forward control

  12. CL Gimbal Angle Control Analysis Equations of motion for gimbal motor: Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions Transfer function for gimbal motor: Root locus, Bode Plots and gains: Gains: Kp= 3 Ki = 1 Kd = .1

  13. CL Gimbal Angle Control Results Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions

  14. Feed-forward Control Design • System is non-linear • Small angle approximation was not assumed since f can rotate up to 70° Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions Relationship between Joint angle and gimbal angle: • Current issues with Feed-Forward: • The runtime of the feed forward Simulink block is approximately .11 seconds. • This would limit the control system by 10 data points • At maximum voltage this is equivalent to 30 degree rotation

  15. Video of CMG robot arm Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions

  16. Future task, test, and Goals • Current Issues: • Joint angle control is not fully functional • No support for multi-links • Air canisters are currently leaking • Planned Tests: • Full systems test using feed forward control • Evaluation of power consumption versus joint angle control • Identified Improvements: • Characterize noise in potentiometer and build LQG control • Replace existing reaction wheels with smaller and faster COTS wheels • Reduce the size of the supporting arm and structure • Remove chain and replace with gears Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions

  17. Acknowledgements • Daniel Brown, PhD. Candidate, Aerospace • Dr. Mason Peck • Space Systems Design Studio • Cornell CMG team Outline: -Introduction -What is a CMG -Reactionless Actuation -Joint Torques vs. Body Torques -Planar Robot Design -Simulation Results -Experimental Design -Hardware and GUI -Controller Design -CL Gimbal Control -Feed Forward Control -Video -Future Plans -Acknowledgements -Questions 1. DARPA SUMO spacecraft with CMG arms

  18. Questions?

More Related