NOV. 1 2019

A REACTIVE JOGGER FOR
TELEOPERATION AND CONTACTTASKSANDY ZELENAK1, ROBERT G REID2, MITCH PRYOR11
The University of Texas at Austin, 2Woodside Energy

Presentation Outline••••

Problem Statement
Current Practice
Solution: Reactive Jogger (jog_arm package)
Technical Challenges– Deterministic Control– Robust Singularity Handling– Robust to Input Signal Noise– Reduce Actuator Jerk
– Support Multiple Manipulators– Safe Operation• Package Links and Demonstrations
SLIDE 2

Presentation Outline••••

Problem Statement
Current Practice
Solution: Reactive Jogger (jog_arm package)
Technical Challenges– Deterministic Control– Robustly handle singularities– Robust to input signal noise– Minimize Actuator Jerk
– Support Multiple Manipulators– Safe Operation• Package Links and Demonstrations
SLIDE 3

Problem: End-effector pose regulation to avoid
damaging forces during contact tasks•••

Efficient teleoperation with contact tasks
or collision risks
Support contact tasks during basemotions
Robust to uncertainties/errors in contact
task descriptors such as Affordance
Templates

Example contact tasks:•••

Opening a sprung door
Valve turning (double-block-and-bleed)
Manipulating high voltage switches, circuit testing

commons.wikimedia.org/wiki/File:Oil_platform_P-51_(Brazil).jpg

High-frequency EEF pose regulation is necessary for:

Presentation Outline••••Problem Statement
Current Practice (example)
Solution: Reactive Jogger (jog_arm package)
Technical Challenges– Deterministic Control– Robustly handle singularities– Robust to input signal noise– Minimize Actuator Jerk
– Support Multiple Manipulators– Safe Operation• Package Links and Demonstrations
SLIDE 5

TRACLabs, 2015, https://www.youtube.com/watch?v=MXyy3AV9Mmk

Presentation Outline••••Problem Statement
Current Practice (example)
Solution: Reactive Jogger (jog_arm package)
Technical Challenges– Deterministic Control– Robustly handle singularities– Robust to input signal noise– Minimize Actuator Jerk
– Support Multiple Manipulators– Safe Operation• Package Links and Demonstrations
SLIDE 7

The jog_arm package• A Jacobian-based jogger• Utilizes ros-control to support robotagnosticism

UR3
U. Texas, 2019
Simulated Motoman SIA5
U. Texas, 2019

HEBI Robot
Adam Pettinger, U. Texas, 2019

Presentation Outline••••Problem Statement
Current Practice (example)
Solution: Reactive Jogger (jog_arm package)
Technical Challenges– Deterministic Control– Robustly handle singularities– Robust to input signal noise– Minimize Actuator Jerk
– Support Multiple Manipulators– Safe Operation• Package Links and Demonstrations
SLIDE 9Deterministic Control Rate
• Multi-threaded architecture• Timeout for safety
Cartesiancommands(uncertain rate)

ROS Interface(master thread)

Collision checking(slave thread)Jog calculations(slave thread)

jog_arm node

Joint commands(steady 250 Hz ormore)Singularity Handling• “Look ahead” toward singularities with singular vectors• Slow down if singularity is closer than a threshold

Universal Robots software does not handle singularities

jog_arm singularity handling is configurable via yamlparameters

Signal Filtering••

Configurable low-pass filter– Computationally efficient, does not overshootReduces noise and jerk to actuators
Thanks @SansoneG and several other contributors
Command Magnitude

•

Time

Jog multiple manipulators simultaneously• Any number of arms can be jogged
simultaneously with namespacing• Average CPU load is ~20% per arm

A limitation for large industrial robots• Large industrial robots often require jerklimited commands• Options:– Reflexxes (Google)– TrackPose (PickNik Robotics)

KUKA Roboter GmbH,https://commons.wikimedia.org/wiki/File:Factory_Automation_Robotics_Palettizing_B
read.jpg

Presentation Outline••••

Problem Statement
Current Practice (example)
Solution: Reactive Jogger (jog_arm package)
Technical Challenges– Deterministic Control– Robustly handle singularities– Robust to input signal noise– Minimize Actuator Jerk
– Support Multiple Manipulators– Safe Operation• Package Links and Demonstrations (non-contact/contact)
SLIDE 15

Package availability (part of MoveIt)
https://github.com/ros-planning/moveit/tree/master/moveit_experimental/moveit_jog_arm

Tutorial

https://ros-planning.github.io/moveit_tutorials/doc/arm_jogging/arm_jogging_tutorial.html

P. Fan, A. Pettinger, and A. Zelenak, U. Texas, 2019

Writing with a haptic pen with virtual fixtures
Y. Su
U. Canterbury, 2019

Controlling a UR5 intuitively with a tracker
Y. Su, E. Sevestre
U. Canterbury, 2019