Haptics ME7960, Sect. 007 Lect. 6: Device Design I

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1 Haptics ME7960, Sect. 007 Lect. 6: Device Design I Spring 2009 Prof. William Provancher Prof. Jake Abbott University of Utah Salt Lake City, UT USA Today s Class Haptic Device Review (be sure to review kinematics and Jacobians from Lect. 3 if you are rusty) (We will discuss tactile devices in the next device design lecture) Impedance Device Design Case Study: Cheap haptics Haptic Paddle Falcon device design Readings: No readings start on your lab We would like to acknowledge the many colleagues whose course materials were borrowed and adapted in putting together this course, namely: Drs. Allison Okamura (JHU), Katherine Kuchenbecker (U Penn), Francois Conti, Federico Barbagli, and Kenneth Salisbury (Stanford), Ed Colgate (Northwestern), Hong Tan (Purdue), Blake Hannaford and Ganesh Sankaranarayanan (U. Washington), and Karon MacLean (UBC). 2 Physical Haptic Systems Physical Device Basic Elements of a haptic system Physical device (the plant of a control system) Actuators and transmission Sensors High power (current) amplifier + power supply Controller Computer Controller Control (DAQ) Card Servo control loop (typically at 1kHz) Discussed today (and answer questions from lect. 3) Illustration from K. J. Kuchenbecker and G. Niemeyer, Induced Master Motion in Force-Reflecting Teleoperation. ASME Journal of Dynamic Systems, Measurement, and Control. Volume 128(4): , December Illustration from K. J. Kuchenbecker and G. Niemeyer, Induced Master Motion in Force-Reflecting Teleoperation. ASME Journal of Dynamic Systems, Measurement, and Control. Volume 128(4): , December

2 Haptic System Diagram Mechanisms Common mechanism for 2&3 dof: five-bar SensAble Omni SensAble s Phantoms Novint Falcon Immersion IE2000 & 3GM K. Kuchenbecker A. Okamura Immersion 3GM Kinematics Stringed Devices From Burdea, p. 92 L. Y. Pao, and S. Aphanuphong. "Bow Spring/Tendon Actuation for Low Cost Haptic Interfaces," Proc. 1st Joint EuroHaptics Conf. and Symp. on Haptic Interfaces for Virtual Environments and Teleoperator Systems, Pisa, Italy, pp , Mar A. Okamura A. Okamura W. Provancher

3 Grounded kinesthetic devices Admittance Type Platform Devices Stewart Platform (parallel actuator robot) (Uncommon haptic interface, but used in vehicle simulators and telesurgery) Cobot Hand Controller [Faulring/Colgate] l Haptic Master (Moog Inc.) From Burdea, p. 83 Wikipedia.org J. Edward Colgate A. Okamura W. Provancher Arm-based devices Body-Based B d Devices Displays unilateral constraints, inertial forces, and slope Percro L-Exos Arm From Burdea, color plate 2 FREFLEX device Sarcos Dexterous Master & Arm 11 Sarcos Treadport (Hollerbach, Univ. of Utah) A. Okamura

4 Design Principles for impedance devices Low inertia (should appear mass-less) Note, transmissions can increase the reflected inertia of the motor (see below) Low friction/drag Smooth mechanisms Smooth bearings (typically ABEC-5 ball bearings or better, roller bearings tend to not be as smooth) Smooth actuator (e.g. Maxon motors) and transmission (e.g. Capstan) No cogging (e.g., torque ripple or gear meshing) Some friction/damping can improve stability [Colgate, et al. 1994] This can be partially cancelled using control (cogging or configuration dependent friction is usually undesirable) 13 Most common Impedance device design DC Motors with capstan drives for rotary motion Pros Cog-less gear- ratio transmission Cons Issues with friction transmission of cable on capstan pulley High cable tension high drag Possibly high reflected N 2 inertia SensAble (Premium) Phantom Motor Capstan Pulley Sector Pulley Motor Capstan Pulley T Motor 14 Low Cost impedance Device The Haptic Paddle Its humble beginnings g Stanford University used to teach system dynamics $27 in parts, using a surplus motor, bronze bushings, laser cut acrylic and a hall-effect sensor magnet Hall-effect Sensor From Stanford Haptic Paddle See C. Richard, A.M. Okamura, M.R. Cutkosky, "Getting a Feel for Dynamics: using haptic interface kits for teaching dynamics and controls", 1997 ASME IMECE 6th Annual Symposium on Haptic Interfaces, Dallas, TX, Nov θ 15 Low Cost impedance Device The Haptic Paddle Adopted and revised Johns Hopkins University used to teach system dynamics and haptics Uses motor, bronze bushings, laser cut acrylic and a hall-effect sensor Added PCB for parallel communication and amplifier magnet Hall-effect Sensor From Stanford Haptic Paddle D. I. Grow, L. N. Verner, and A. M. Okamura. "Educational Haptics", AAAI 2007 Spring Symposia - Robots and Robot Venues: Resources for AI Education, θ 16

5 Low Cost impedance Device The Haptic Paddle Adopted and revised Rice University used to teach system dynamics and haptics Uses motor, ball bearings, laser cut acrylic and a hall-effect sensor Added higher end amp and Labview control interface. Inverted capstan drive to be opposite the handle and lower the motor Added grooved capstan pulley and shoulder bolt paddle axle magnet From Stanford Haptic Paddle θ Hall-effect Sensor Kevin Bowen, Marcia K. O?Malley, "Adaptation of Haptic Interfaces for a LabVIEW- based System Dynamics Course, " Haptic Interfaces for Virtual Environment and Teleoperator Systems, International Symposium on, vol. 0, no. 0, pp. 23, 2006 International Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (HAPTICS'06), Low Cost impedance Device The Haptic Paddle Adopted and revised University of Utah used to teach robot control and haptics Follows the inverted capstan drive, shoulder bolt paddle axle, and grooved capstan pulley motor drive from Rice University design Uses high quality surplus Maxon motor, ball bearings, waterjet cut parts, and optical encoder Adds paddle stops to prevent cable from unstringing Adds alignment pin for calibration Restores inline cantilever spring to accommodate cable stretch and improved cable tensioning with lower drag Motor Capstan Pulley T Motor EduHaptics.org Tension Sector Pulley For further info see: EduHaptics.org (to be posted spring 2009) Tension 18 Design Principles for impedance devices Reviewed Low inertia (should appear mass-less) Developing a Mass Market Haptic Interface Slides Courtesy of Francois Conti (Stanford University, CS277) Note, transmissions can increase the reflected inertia of the motor (see below) Low friction/drag Smooth mechanisms Smooth bearings (typically ABEC-5 ball bearings or better, roller bearings tend to not be as smooth) Smooth actuator (e.g. Maxon motors) and transmission (e.g. Capstan) No cogging (e.g., torque ripple or gear meshing) Some friction/damping can improve stability [Colgate, et al. 1994] This can be partially cancelled using control (cogging or configuration dependent friction is usually undesirable) $20,000 $

6 Product Requirements Overview $10,000 $100 to convert a ROLEX into a SWATCH divide the costs by Low Cost Actuators t Low Cost Position Sensors $100 $1 going from high precision actuators to motors which are found in hair dryers Can anything bad happen when you do this? usdigital.com $40 ~$2? 23 + W. Provancher

7 Ati Articulated t dstructures t Prototyping t Prototyping t Design 27 28

8 Design Manufacturing Final Release The Falcon available through Novint and slightly cheaper through major distributors such as Amazon and Walmart 31