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  • Introduction Hardware Research Packages Conclusion

    Intern Presentation: Gripper Stereo and Assisted Teleoperation

    Adam Leeper Stanford University

    December 13, 2010

  • Introduction Hardware Research Packages Conclusion

    Outline

    1. Introduction

    2. Hardware

    3. Research

    4. Packages

    5. Conclusion

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Motivation (1/2) Why use a gripper stereo sensor?

    It is easy to obtain good viewpoints.

    Object modeling I Data from multiple

    perspectives. I Potentially less noise from

    distance.

    Exploration I See in and around

    occluding objects. I Low cost to exploration;

    base does not move. Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Motivation (2/2) Why use a gripper stereo sensor?

    There is no kinematic chain between sensor and end-effector.

    I Uncalibrated URDF I Head stereo and gripper

    stereo differ by >3cm

    I Grasping based on gripper stereo works fine

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Outline

    1. Introduction

    2. Hardware

    3. Research

    4. Packages

    5. Conclusion

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Small-Baseline Stereo (1/3) The off-the-shelf approach

    Custom mounting of Logitech C905 webcams.

    I Rolling shutter, not synchronized

    I Baseline = 25mm

    I FOV 65◦

    I Minimum distance 8cm

    I 640x480 resoution

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Small-Baseline Stereo (2/3) The custom camera approach

    Custom stereo camera made from WGE100 cameras - functionally identical to PR2 head stereo.

    I Synchronized, global (instantaneous) shutter.

    I Baseline = 30mm

    I Wide-angle, FOV 90◦

    I Minimum distance 10cm

    I 640x480 resoution

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Small-Baseline Stereo (3/3) How do they compare?

    I Trade off between FOV and depth noise. I Rolling shutter is fine for static scenes only. I Narrower angle for autonomy, wider angle for teleop.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Hardware Calibration

    I Stereo camera calibration is natively supported in ROS. I pr2_calibration was modified to calibrate the gripper stereo

    frame location on the PR2 model.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Outline

    1. Introduction

    2. Hardware

    3. Research

    4. Packages

    5. Conclusion

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Grasp Adjustment - Overview

    Developed novel grasp adjustment for cluttered environments. I Versatile, feature-based local point cloud grasp planner. I Ideal for co-oriented sensor and gripper. I Published in ISER 2010.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Grasp Adjustment - Evaluation

    Grasp quality is computed from features of local points. I Distance to Centroid - Pulls gripper into object. I Points in Collision - Penalizes collisions! I Symmetry - Even distribution of points in vicinity of gripper. I Normals - Point normals aligned with gripper frame axes.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Grasp Adjustment - Search

    I Seed poses chosen from a grid centered at the input pose. I Brief gradient search corrects unlucky seed poses. I All poses are ranked according to cost. I The best poses are selected for full optimization.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Assisted Teleoperation "So... am I helping the robot, or is it helping me?

    Developed joystick teleop of PR2 arms with grasp assistance. I Multiple control perspectives aid maneuvering. I Preset shortcuts for gripper orientations aid positioning. I Grasp adjustment is used to suggest grasp poses. I Rviz is used for viewing cameras and the virtual scene.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Outline

    1. Introduction

    2. Hardware

    3. Research

    4. Packages

    5. Conclusion

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    pr2_gripper_stereo

    Package for managing and using gripper cameras. I Launch files for calibration, stereo processing. I URDF and meshes for modified hardware. I Proof-of-concept nodes for point-cloud concatenation.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    pr2_gripper_grasp_adjust

    Package for running grasp adjust server. I Service uses GripperGraspAdjust service message. I Could be expanded to general grasp planner. I NOT dependent on gripper stereo.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    pr2_remote_teleop

    Package enables full teleoperation of PR2. I Head and base control is similar to pr2_teleop package. I Grippers controlled using Cartesian J-inverse controller. I Spacenav and ps3 controller supported by default. I Config file supports button remapping on any joystick. I Useful as local pr2_teleop replacement, or for remote

    operation.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    What’s Next?

    I Object modeling using gripper stereo. I Multiple cloud registration, surface smoothing. I Integration with octomap framework.

    I Human-in-the-loop robotics. I Find strategies for human-robot multi-tasking. I Robot: Grasp assist, collision avoidance, object tracking. I Human: Object identification, edge-case recovery.

    –> Teleoperation would greatly benefit from RVE / Rviz2.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    Conclusion

    I Gripper stereo provides valuable new viewpoint. I Grasp adjustment works well on cluttered scenes. I Remote operation is ready for added levels of autonomy.

    Intern PresentationAdam Leeper

  • Introduction Hardware Research Packages Conclusion

    The Final Slide

    Acknowledgments: I Kaijen Hsiao, WG mentor I Blaise Gassend, much camera help I Kenneth Salisbury, PhD advisor

    Questions?

    Intern PresentationAdam Leeper

    Introduction Hardware Research Packages Conclusion