Mock-up of the Exhaust Shaft Inspection by Dexterous Hexrotor at the DOE WIPP Site

Transcription

1 Mock-up of the Exhaust Shaft Inspection by Dexterous Hexrotor at the DOE WIPP Site Prof. Richard Voyles Guangying Jiang Purdue University Collaborative Robotics Lab Purdue Robotics Accelerator

2 U.S. DOE WIPP Site Nuclear waste storage facility in Carlsbad, New Mexico, USA, Deep geological repository licensed to permanently dispose of transuranic radioactive waste Radioactive waste packed in individual storage containers. Inside the WIPP storage facility at the transitional dressing area prior to the boundary between "clean" and "unclean" areas. Energetic incident occurred on Feb. 14, 2014.

3 WIPP: Structure Sub-surface storage facility in deep salt deposits approximately 660 meters (2150 feet) below the surface. Radioactive waste is packed in individual storage containers and lowered by elevator to "panels An improperly loaded container that caused one container to burst, spewing radioactive smoke through a large portion of the WIPP Spatial layout of the U.S. DOE WIPP site indicating surface buildings with four shafts connecting the main work surface 660 meters below ground. (reprinted from

4 Radiological Rollback 4

5 WIPP: Ventilation System Nearly all of the 200 mg of material has been recovered in the HEPA filters Possible trace amounts of americium left in the exhaust shaft The shaft is circular in cross section, 14 feet in diameter, and about 2150 feet long, with 60,000 cubic foot air per minute (CFM) flowing through it. WIPP ventilation system. (reprinted from

6 Challenge Challenge in the inspection and cleaning of the exhaust shaft: constrained environment Very high aspect ration (660 m x 4 m) Partially lined column Water intrusion sensing of americium Low energy Small quantities Requires physical sampling UAV solution of using fully-actuated Dexterous Hexrotor : precision flight in close proximity to the structure walls ability to maintain contact forces at swabbing sites

7 Quick Proof-of-Concept Ideas We settled on two basic approaches, based on existing capabilities: Rapelling CRAWLER robot Tethered robot for core-bored search and rescue Two-limb crawler, supported by environment Lower robot from top of shaft Dexterous Hexrotor UAV Fully-Actuated Aerial Mobile Manipulator Platform Force controllable in 6 DoF Lower half from bottom, Upper half from top

8 CRAWLER Concept Rapelling Robot to Sampling: Use Existing CRAWLER tethered robot Lower from top of Shaft Suction approach to stick to surface (Jizhong Xiao City Climber wall climbing technology) Use limbs for crawling and sampling discrete points

9 Phase I Discrete Sampling Method Semi-autonomous control Localized by laser and optical flow Sampling by a swab stick Phase I Dexterous Hexrotor Prototype Mock-up flight test in a grain silo Collaboration with CyPhy Works

10 Phase II description

11 Phase II Continuous Sampling Method fully-autonomous control Force control during contact Sampling by a reel to reel platform force measure reel reel to reel sampling Dexterous Hextotor reel sampling material A compression spring pushes sampling material against the shaft surface Measurement of the reaction force

12 Phase II Sampling End Effector Design Slide track hing e reel A front plate holding sampling material against the shaft surface A compression spring pushes the front plate Two slide tracks constraint the movement of front plate One reel driven by a low speed dc motor A hinge allows some tilt reel compression spring Front plate Force Measurement To measure the contact force, a load cell or a potentiometer is used. a a: load cell behind the spring b: potentiometer changed by the front plate b

13 Phase II Autonomy Through Visual SLAM Definition of Frames Pilot gives targets coordinates in earth frame Transform targets coordinates to Cartesian coordinates in body frame * * * * * x * y * UAV always keeps its heading along shaft radius, toward shaft surface Simplified fit of LIDAR points to a circle on sample of data points Pressure fused with small number of vidual data points for altitude Earth Frame: Cylindrical coordinates Body Frame: Cartesian coordinates ( x, y ) Exhaust shaft

14 Experiment 2: Position Keeping with Wind Disturbance Flight Test Setup Recorded Position of Dexterous Hexrotor Standard deviation of position error and increased error under wind disturbances Thruster Type Parallel Nonparallel Free Hover 16.2 mm 14.3 mm Under Disturbance 32.1 mm 24.2 mm Increased Error 98.1 % 69.2 % A Nonparallel Hexrotor UAV with Faster Response to Disturbances for Precision Position Keeping SSRR 2014

15 Experiment 3: Low-Altitude Hover Precision Dexterous Hexrotor vs. Quadrotor Makes use of navigation controller Standard deviation of the UAV position Quadrotor Dexterous Hexrotor Normal Flight Low Altitude Flight Increased Errors 7.13 x 2.49 x 50 cm 5 cm A Nonparallel Hexrotor UAV with Faster Response to Disturbances for Precision Position Keeping SSRR 2014

16 Optimization w.r.t. Application Collaborative Robotics Lab 94% Efficient 85% Efficient

17 Static Peg-in-Hole Test Peg-in-hole setup Collaborative Robotics Lab, Purdue University

18 Static Peg-in-Hole Response Time <100 ms Dexterous Hexrotor Quadrotor 300 ms Collaborative Robotics Lab, Purdue University

19 Phase I Autonomous Flight Test in Grain Silo Localization Data from take off to fly out of the silo Climb Speed Flight Performance Standard Deviation from Desired 0.5 (m/s) 3.72 (cm) Localization Data in 3D with silo shape indicated

20 Workshop on Robotic Handling of High- Consequence Materials What are High-Consequence Materials? Materials that require complex processing/investigation Materials that pose significant risk to human handlers and the general public Examples: Military and civilian nuclear waste Infectious biological pathogens with no known cure (BSL-4) Extra-planetary return mission samples (asteroid, comet, moon, planet, etc) What are common implications for a Science of Safety?

21 USAMRIID and Hanford with NASA

22 DOE Sites Dec 7-10, 2015 WIPP, Carlsbad, NM Savannah River, SC Hanford, WA