robotic deployment of extraterrestrial seismic networksrobotics.estec.esa.int/astra/astra2015... ·...

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


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


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


The ROBEX Field Mission (scheduled for 2017)

Isola di Vulcano


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


Geophones in Seismic Networks

Requirements:

● Full spike insertion

● minimized reaction force

● Tilting angle < 7°


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


Robot Control for Contact Situations (cont.)

Soil Insertion Depth with Cartesian Impedance Control



Soil Insertion Depth with Cartesian Impedance Control

inappropriate



Feed-Forward Force Term is required

● Dynamical equation of the impedance control action



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


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.


The Fundamental Earth Moving Equation (FEME)




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



Discrete Element Method (DEM)



Empirical Approach

● Inserting the geophone with a stiff position controller

● Measuring the force, and estimating the soil model



● Relating the FEME Approach to the modeled soil stiffness

● Estimation of C1 and C2 with the least squares method


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



Depth deviation plots



Soil reaction force plots


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


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

robotic deployment of extraterrestrial seismic networksrobotics.estec.esa.int/astra/astra2015... ·...

Documents