Real-Time 3D Lunar Excavation Simulation using the Digital

Spaces Open-Source PlatformFINAL PROJECT PRESENTATION

Bruce Damer, CEO, Digitalspace Corp

Dave Rasmussen, Merryn Nelson, Peter Newman, DM3D Studios

Brad Blair, Engineering Consultant

May 31, 2007

Precursor Simulations

• Digitalspace (DS) generated prior driveable simulations of mobile lunar exploration and ISRU systems

• Relevant NASA SBIR-funded work included– CSM Bucket Wheel Excavator– NASA Robotic Lunar Exploration Rover– Physics models for these sims were limited to vehicle

mobility and arm articulation only

• A “Clean Room” simulation of a grabber arm and blocks was also created by DS for experimental purposes

CSM Bucket Wheel Excavator Simulation

RLEP 2 Mobility trade studyUse of Plow as Trenching Tool in Sampling Area

RLEP 2 Mobility trade studyDeployment of Drill Assembly-Lower Pose

RLEP 2 Mobility trade studyCut Away of Drill Action

RLEP 2 Mobility trade studyEngage Plow for Braking

DS “Clean Room” sim of grabber arm with blocks

DS “Clean Room” sim of grabber arm with blocks

Lunar Excavation Simulation

• A real-time, driveable, physics-based simulation was then proposed to NASA-SOMD as a tool to examine lunar excavation operations

• The physics model would be expanded to include soil mechanics

• An output file would be generated containing engineering data

• Partners for the project included National Securities Technology LLC and Los Alamos National Laboratories

Sketch of “Jell-O Block” concept

Sim #1: Backhoe in “Clean-Room” Environment

• Backhoe style excavator was created and rigged using physics model

• Jell-O blocks introduced into ‘clean room’ environment

• Volumetric friction (viscosity) used to provide ‘drag forces’ while bucket is inside block

Sim #2: Excavators and Balovnev Soil Mechanics Model

• No mobility in Sim #2• Concentrated on implementing proof-of-concept

for Balovnev soil mechanics model for excavator blade resistance

• Three excavators were modeled: Bucket Wheel, Front-end loader and Clamshell

• Lack of constraints caused tipping of mobility platforms (validating force increase with depth of penetration)

Sim #3: Lunar Excavators at Polar Lunar Base Site

• Three lunar excavation systems were then rigged, constrained to dig into the uppermost regolith layer, and placed in a simulated lunar polar base site

• Waypoints were added to automatically guide each excavator through a mining sequence

• Output files were generated for torques and forces for each excavator

• Sophisticated user interaction with physics model (including Balovnev soil resistance) was enabled through input windows

Sim #3 Cut-Away Views of Excavation Box

• An ‘Excavation Test Box’ was rigged with the Balovnev soil mechanics model in order to collect force and torque data

• The following views show the excavators penetrating the surface plane into the test box

• Three excavators automatically repeat the mining cycle by loading regolith then driving to the dump zone and unloading using waypoints

• Notice suspended rock hazards

Sim #4: Bucket Ladder Excavator

• A fourth simulation was built for the fourth excavator – a bucket ladder

• The system was placed in an ‘improved’ version of the lunar polar base site

• Physics modeling and user input windows were derived from simulation #3

• Minor improvements were made to ‘debug’ the DSS software platform and improve sim performance