Simulating Mars Science Laboratory Curiosity Rover Traverses Using Artemis

Introduction: Curiosity has been traversing across the northern plains of Gale Crater since August 2012 and on 1/6/17 (Sol 1571) has traveled over ~15 km (based on wheel odometry). The rover is approaching a prominent hematite-bearing ridge, which it will ascend to make measurements, thereafter continuing south up the slopes of Mount Sharp. Curiosity has already encountered multiple mobility issues, including generation of punctures and cracks in the thin aluminum wheel skins when crossing sharp sandstone outcrops [1] and high wheel sinkage and slip when crossing megaripple deposits [2]. To better understand these conditions and to support future path planning, a software package called Artemis (Adams-based Rover Terramechanics and Mobility Interaction Simulator) has been used to simulate Curiosity’s existing or potential drives [1, 2]. This abstract summarizes simulations of Curiosity’s expected performance while crossing the hematite ridge and also megaripples found within a canyon cut into Mount Sharp strata. Background: Artemis is a software tool used to simulate the motion of rovers over realistic terrains [3]. Artemis contains multiple components: a mechanical model of the rover, a wheel-terrain module that models wheel-terrain interactions on deformable and non-deformable surfaces, and terrain topographic models. The mechanical model includes a 6-wheel drive, 4-wheel steered vehicle model, with a rocker-bogie suspension system, as well as rover motion controls to simulate actual drive commands. Artemis employs a classical Coulomb friction contact model for wheel-bedrock interactions and a classic terramechanics-based model for wheel-soil interactions. Soil and rock properties are based on the best estimate from in-situ observations as well as relevant laboratory tests. Terrain surfaces are modeled using digital elevation models derived from orbital and rover-based images. Surface roughness can be modeled as a fractal surface using Perlin noise to approximate natural terrains. Artemis has been validated using single-wheel laboratory-based, JPL Mars yard tests, and field tests on bedrock and dunes in the Mojave Desert. More details about Artemis and validation approaches can be found in [2, 3]. Hematite-Bearing Ridge: The ridge is about 200 meters wide and extends about 6.5 kilometers from northeast to southwest, approximately parallel with Mount. Sharp [4]. The potential path to reach the hematite exposures on the ridge top will necessarily include traversing up steep slopes with bedrock partially covered by rubble and soil. Driving uphill will be problematic because the trailing wheels (the downhill wheels) will bear more weight and the other wheels might not provide sufficient traction to keep from reaching high rover-based slip values.