Innovative Test-beds for Validation of Motion Recognition Systems Intended for Orbital Capture Manoeuvres

Transcription

1 Innovative Test-beds for Validation of Motion Recognition Systems Intended for Orbital Capture Manoeuvres Tomasz Rybus 1, Karol Seweryn 1, Janusz Grzybowski 1, Janusz Nicolau-Kukliński 1, Rafał Przybyła 1, Tomasz Szewczyk 1, Konrad Bojar 2, Mateusz Maciaś 2, Mateusz Wolski 2 (1) Space Research Centre of the Polish Academy of Sciences (CBK PAN) (2) Industrial Research Institute for Automation & Measurements (PIAP) 1 3 th S y m p o s i u m o n A d v a n c e d S p a c e Te c h n o l o g i e s i n R o b o t i c s a n d A u t o m a t i o n A S T R A

2 1. Introduction. 2. Motion recognition system for orbital rendezvous. 3. Validation of motion recognition system: requirements for the test-bed. 4. Virtual test-bed. 5. Test-bed based on a dedicated 3 DOF manipulator. 6. Summary. Outline

3 Role of motion recognition systems Servicing spacecraft performing Active Debris Removal or On-Orbit Servicing mission requires information on target object motion. If target object is uncooperative its motion parameters must be estimated basing on the measurements performed by sensors on-board the servicing spacecraft. Accurate evaluation of object motion is especially important in case of capture performed with the use of a manipulator. Servicing spacecraft observing tumbling target object before the capture maneuver

4 Motion recognition system 1/2 Motion recognition system developed in frame of the ESA PECS project Robust, unsupervised visual motion recognition of noncooperative satellite for on-orbit capture by PIAP and CBK PAN. Determination of target object motion parameters (relative position, orientation, linear and angular velocity) during rendezvous on LEO basing on: - visual observations of known structure of the target performed by a single camera, - rangefinder measurements of relative distance between the satellites, - knowledge of the approximate inertia parameters of the object. Hardware of the new motion recognition system for orbital rendezvous

5 Motion recognition system 2/2 Approach used in the new motion recognition system: - input image is matched to 2D images depicting various poses of the target, - transformations from model images to the acquired image are obtained by means of a method assuring global optimality. Assumptions about target object: - is at a distance below 20 m (final phase of the orbital rendezvous), - is uncooperative and without any markers that can assist pose estimation, - is uncontrolled and could be tumbling with angular velocity of up to 10 deg/s.

6 Body orientation [deg] Angular velocity (body frame) [deg/s] Motion of the target object Target rotational motion is described by Euler's rotation equation: Iω + ω Iω = Angle X Angle Y Angle Z Time [s] Orientation of the target object described by Euler angles (in ZYX convention) -6 X -8 Y -10 Z Time [s] Angular velocity (in body reference frame) of the target object

7 Test-bed requirements Test-bed shall allow simulation of view of the target object mock-up in range from 3 m to 20 m. Test-bed shall allow motion of the target object mock-up with maximal angular velocity of at least 10 deg/s (no motion with linear velocity is required). Time of experiment shall allow more than one full rotation of target object mock-up. Lighting conditions of LEO shall be simulated. Target object shall resembles LEO communication satellite.

8 Virtual test-bed 1/2 Preliminary tests of the motion recognition algorithms on an early stage of the project. CATIA V5 R18 is used to create artificial video images that simulate view from the motion recognition system camera. Model of the satellite is connected to a mechanism created in CATIA environment. This mechanism gives the satellite all 6 DOF. Rapid assessment of algorithm performance in various environmental conditions and with different motion parameters of the target object CATIA rendering of the target object

9 Virtual test-bed 2/2

10 Test-bed based on a dedicated 3 DOF manipulator Conceptual illustration of a new test-bed based on a dedicated 3 DOF manipulator

11 Usual approach vs new test-bed Usual approach: use of industrial manipulators for rotating the target object. - Adventages: possibility to simulate linear motion of the target object and approach of the servicing satellite. - Disadventages: rotational motion of the mock-up is limited and in some configurations large parts of the mock-up can be obscured by the manipulator links. New test-bed designed and manufactured at CBK PAN. - Adventages: unlimited rotations of the manipulator allowing simulation of tumbling motion of target object for a prolonged period of time (with high maximal rotational velocity: 10 deg/s). - Disadventages: linear motion cannot be simulated, for some configurations maximal velocity is less than 10 deg/s.

12 Dedicated 3 DOF manipulator 1/2

13 Dedicated 3 DOF manipulator 2/2

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15 Joint angular velocity [deg/s] Angular velocity (body frame) [deg/s] Maximal velocities of manipulator joints X Y Z Time [s] Angular velocity (in body reference frame) of the target object Joint 1 Joint 2 Joint 3 Max. rotational velocity: 10 deg/s. Some trajectories require infinite velocity of joints (singularities). Max. joint velocity: 50 deg/s Time [s] Velocities of manipulator joints

16 Mock-up obstruction by test-bed elements Plot showing what percentage of the target object mock-up is obscured by elements of the test-bed Target object mock-up is sometimes obscured by elements of the test-bed such situations are unavoidable. There exist configurations in which even more than 50% of the mock-up is obstructed. It is necessary to select such trajectories of the tumbling motion, that will not result in significant obstructions of the mock-up during the time of the experiment.

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18 Test on planar air-bearing microgravity simulator Mock-up of the target object could be used on a planar microgravity simulator available at CBK PAN. This simulator uses planar air-bearing to provide frictionless motion in one plane (free-floating motion can be simulated). Mock-up of the target object on planar air-bearing microgravity simulator

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20 Summary We presented two test-beds developed at CBK PAN in the frame of ESA PECS project Robust, unsupervised visual motion recognition of non-cooperative satellite for on-orbit capture for validation of the motion recognition system. On the virtual test-bed algorithm of the motion recognition system is tested on an artificially visualized motion of the target object. On the second test-bed dedicated 3 DOF manipulator is used to simulate rotational motion of a free-floating target object. Results of tests will be used for two purposes: - to evaluate performance of the motion recognition algorithm in various conditions, - to validate breadboard of the motion recognition system. motion recognition systems.

21 Thank you for your attention! ACKNOWLEDGMENTS This study was supported by the ESA PECS project no /13/NL/KML Robust, unsupervised visual motion recognition of noncooperative satellite for on-orbit capture. This project is led by Industrial Research Institute for Automation and Measurements (PIAP).