Robotic Deployment of Extraterrestrial Seismic Networks Daniel Leidner , Selma Musić, and Armin Wedler German Aerospace Center (DLR), Institute of Robotics and Mechatronics Noordwijk, 12.05.2015
Robotic Deployment ofExtraterrestrial Seismic Networks
Daniel Leidner, Selma Musić, and Armin Wedler
German Aerospace Center (DLR), Institute of Robotics and Mechatronics
Noordwijk, 12.05.2015
DLR.de • Chart 2 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Motivation
Manual deployment of extraterrestrial seismic networks
● Expensive
● Dangerous
● And error-prone
DLR.de • Chart 3 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Motivation
Manual deployment of extraterrestrial seismic networks
● Expensive
● Dangerous
● And error-prone
Recent LRO Images of the ALSEP network on Moon revealed signi-ficant misalignment up to 40 m (Czeluschke et. al. 2015)
A. Czeluschke, M. Knapmeyer, J. Oberst, and I. Haase,“New Lunar Depth Profiles Derived From LROC-based
Coordinates of Apollo 17 Seismic Equipment”, In Proc. of the European Lunar Symposium, May 2015
DLR.de • Chart 4 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
The ROBEX Field Mission (scheduled for 2017)
The ROBEX Alliance Field Mission
● Simulate extraterrestrial soil conditions
● in a volcanic environment
● to deploy a seismic network
DLR.de • Chart 5 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
The ROBEX Field Mission (scheduled for 2017)
Isola di Vulcano
DLR.de • Chart 6 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Robotic geophone deployment
Considering geological aspects
● analytically,
● numerically.
● and empirically,.
w.r.t. robotic control strategies
● Cartesian impedance control
● with feed-forward force term.
Experimental validation under laboratory conditions
DLR.de • Chart 7 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Geophones in Seismic Networks
Requirements:
● Full spike insertion
● minimized reaction force
● Tilting angle < 7°
DLR.de • Chart 8 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Robot Control for Contact Situations
Cartesian Impedance
● Suitable for compliant environment interaction
– unknown environment
– e.g. soil or regolith
● Cartesian Impedance control action for the regulation task (quasi static):
C. Ott, “Cartesian impedance control of redundant and flexible-joint robots”, Vol. 49. Springer Science & Business Media, 2008
DLR.de • Chart 9 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Robot Control for Contact Situations (cont.)
Soil Insertion Depth with Cartesian Impedance Control
DLR.de • Chart 10 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Robot Control for Contact Situations (cont.)
Soil Insertion Depth with Cartesian Impedance Control
inappropriate
DLR.de • Chart 11 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Robot Control for Contact Situations (cont.)
Feed-Forward Force Term is required
● Dynamical equation of the impedance control action
DLR.de • Chart 12 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Robot Control for Contact Situations (cont.)
Feed-Forward Force Term is required
● Dynamical equation of the impedance control action
Force exerted by the imp. controller
External forces of the environment
Desired feed-forward force
DLR.de • Chart 13 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
The Fundamental Earth Moving Equation (FEME)
● Analytical approach
● 2D model of a blade cutting into soil
Tool-Soil Interaction: Estimating Soil Resistance Force 1
Soil Weight
CohesionSurcharge
Adhesion
Reece, A. R. "The Fundamental Equation of Earth-Moving Mechanics." Proceedings of the Institution of Mechanical Engineers, Conference Proceedings. Vol. 179. No. 6. SAGE Publications, 1964.
DLR.de • Chart 14 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
The Fundamental Earth Moving Equation (FEME)
Tool-Soil Interaction: Estimating Soil Resistance Force 1
DLR.de • Chart 15 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Tool-Soil Interaction: Estimating Soil Resistance Force 2
Discrete Element Method (DEM)
● Numerical Approach
● Time Discrete Simulation
● Open source Yade-DEM
Kozicki, J., and F. V. Donzé. "Yade-open DEM: An open-source software using a discrete element method to simulate granular material." Engineering Computations pp. 786-805, 2009
DLR.de • Chart 16 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Tool-Soil Interaction: Estimating Soil Resistance Force 2
Discrete Element Method (DEM)
DLR.de • Chart 17 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Tool-Soil Interaction: Estimating Soil Resistance Force 3
Empirical Approach
● Inserting the geophone with a stiff position controller
● Measuring the force, and estimating the soil model
DLR.de • Chart 18 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Tool-Soil Interaction: Estimating Soil Resistance Force 3
● Relating the FEME Approach to the modeled soil stiffness
● Estimation of C1 and C2 with the least squares method
DLR.de • Chart 19 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Experimental Evaluation
● Insertion of a geophone dummy
● Three different soil samples:
– Basalt Rocks (22 – 8 mm)
– Clay Particles (8 – 2 mm)
– Martian Soil Simulant (< 2 mm)
● Three different control strategies:
– State Space
– Cart. Impedance Ctrl.
– Cart. Impedance Ctrl. w/ fd
DLR.de • Chart 20 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Experimental Evaluation
Depth deviation plots
DLR.de • Chart 21 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Experimental Evaluation
Soil reaction force plots
DLR.de • Chart 22 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Toward Isola di Volcano (Future Work)
● Development of a docking interface for more robust sensor deployment
● Executing the procedure with the LRU rover
● The mission:
– Automated deployment of a full seismic network consisting of
– geophones, seismometers and a seismic source
– Validating the deployment with real geologic experiments
DLR.de • Chart 23 > Robotic Deployment of Extraterrestrial Seismic Networks > Daniel Leidner • Noordwijk > May 12, 2015
Conclusion
Autonomous deployment of a geophone
● Utilizing a Cart. Imp. controller w/ fd
Estimation of the feed-forward force
● Analytically (FEME method)
● Numerically (Yade-DEM simulation)
● Empirically with the robot
Laboratory validation
● Three different soil samples