Detumbling and Capturing Strategies with Eddy Current Brake System on Orbital Space Robot

Transcription

1 Detumbling and Capturing Strategies with Eddy Current Brake System on Orbital Space Robot The Next Generation of Space Robotic Servicing Technologies IEEE International Conference on Robotics and Automation May 26, 2015 Satoko Abiko Dept. of Electrical Engineering, Shibaura Institute of Technology, Japan since April 2015

2 Outline of the Talk 1. Background of the Research 2. Detumbling Strategies with Eddy Current Brake 3. Performance Evaluation of Eddy Current Brake System 4. Detumbling Experiments with Dual-arm System 5. Conclusions

3 Introduction Active Debris Removal (ADR) 1. To avoid collisional cascading (Kessler Syndrome) 2. To sustainably use space in future Recovery mission of WESTAR VI (STS 41 B) (NASA). Recovery mission of INTELSAT6 (NASA). Robotic technology is required to achieve it.

4 Past Activities for Grasping a Target ETS VII Mission in Japan, Rendezvous Docking Active Discussion in Japan for Debris Removal Orbital Express in USA, Rendezvous Docking 2009 International workshop for Active Debris Removal Many researches have been executed for ADR ETS VII (JAXA) DEOS (DLR) Space Infrastructure Servicing (MDA) Orbital Express (Boeing) Various concepts have been proposed for grasping non cooperative target. But

5 Scope of This Study Contactless Detumlbing System Eddy Current Brake on the EE

6 Free Rotational Motion of Space Debris e.g. Second stage of Zenit rocket Spin velocity 8.8[ /s] Nutation angle30 [ ] Nutation velocity 0.2 [ /s] ADEOS-earth observing satellite Rotational speed around base body :0.1[ /s] Rotational speed around a boom:0.4[ /s] Observation data of ADEOS [2] [1] A. Nakajima, et. al Space debris observation by ground based optical telescopes, [2] D. Mehrholz, et. al Detecting, tracking and imaging space debris, 2002.

7 Nutational Motion of a Target Spin axis rotates around H with maintaining a certain angle: nutational angle θ Nutational motion.

8 Grasping a Target by a Robot Arm

9 The Problem Before grasping a non coorprative target, How to detumble a large attitude change of the target The approach only with robot manipulator system, Joint limitation of the robot arm Singularity Workspace constraints of the robot arm The serial link manipulators have a limited capability to follow large attitude change of the tumbling target.

10 The Approach of the Study Distinguish translational motion and rotational motion of the end effector Robot manipulator system Mainly used to keep a distance between the EE and the target Eddy Current Brake (ECB) Attached on the EE Used to brake rotational motion

11 What is Eddy Current Brake (ECB) System? When the rotating conductive object exposed to a magnetic field, Eddy current is applied to disturb changing of magnetic field. Force is applied to rotating object to brake a spinning motion. Detumbling method without physical contact Principle of an eddy current brake.

12 Detumbling Operation with ECB Detumbling nutational motion by changing H direction Eddy current brake exerts f to the target Nutation angle changes with Precession by an eddy current brake.

13 Detumbling Strategy with ECB 1. Space robot detumbles the target with ECBs on the EE of the robotic arms. 2. The ECB reduces a spinning rate. 3. Space robot captures the target by two arms.

14 Detumbling Simulation Simulating detumbling operation for more realistic targets. Simulation model: Himawari 5(GMS-5) Initial condition Spinning rate: 10 /3[rad/s] Nutational angle: 30 [ ] Angular momentum: along Z axis GMS 5 (JAXA). Diameter: 2.15 [m] Height: 3.54 [m] Mass: 345 [kg]

15 Detumbling Simulation

16 Detumbling Strategy: One ECB case Trajectory of spin axis and angular momentum (using one coil).

17 Detumbling Strategy: One ECB case Due to the reaction of the braking force, the space robot move away. To keep relative position with the target, the space robot consumes propellent. Position.

18 Detumbling Strategy with ECB Problem: reaction force Use two ECB and place them opposite to each other Reaction forces are canceled Only getting reaction torque Angular momentum changes around initial direction in X axis Two ECBs have to move in order to keep the distance Trajectory of spin axis and angular momentum (using two coils).

19 Detumbling Strategy Position Change: O(10-7 ) [m] Impulse:O(10-2 ) [Ns] 速度は O(10-5 )[m/s] Compared to the case with one ECB, the case with two ECB systems could cancel out the effect of the reaction force. Position. Impulse.

20 Design and Development of ECB 1st developed ECB 2nd Developed ECB 1. approx. 1.02[N] 2. Distributed Winding 3. Magnetic saturation happened in the yoke 4. Eddy current loss happened 1. approx [N] 2. Concentrated Winding 3. Design the size of yoke with the consideration of magnetic saturation 4. Layered structure of yoke to avoid eddy current loss

21 Field Oriented Control of ECB ECB was developed based on Linear Inductance Motor. With Relative Angular Velocity Constant Braking Force (CBF) Total braking force is constant. CBF

22 Field Oriented Control of ECB ECB was developed based on Linear Inductance Motor. W/o Target Angular Velocity Maximized Braking Force (MBF) Maximum velocity of the magnetic field is used. MBF

23 Performance Evaluation of ECB 1st developed ECB 2nd Developed ECB

24 Performance Evaluation of ECB CBF: Constant Braking Force Maintain constant braking force despite changing angular velocity of the target MBF: Maximized Braking Force Braking force becomes larger when angular velocity becomes larger In general, MBF approach generates larger braking force than that in the CBF approach 2 nd developed ECB

25 Slowing down with ECB

26 Mock of the Target Mechanism Material Diameter Mass Moment of Inertia Ratio Maximum angle 3axis gimbal mechanism Aluminum column 296 [mm] 18 [kg] 1 ±20 [deg.]

27 Detumbling Experiments with Robot Arms

28 Experimental Results Detumbling operation was achieved. Nutation angle converges to zero. Nutation angle. Spin axis trajectory. Spin angular velocity.

29 Conclusions Active debris removal mission is required for sustainable space missions. Space robotic technology is one approach for the active debris removal. Grasping and detumbling operation is a key to achieve the above mission. Eddy current brake system is one promising technology to detumble the target.