Olivier Toupet
NASA Jet Propulsion Laboratory, USA
Title: Traction Control for the Curiosity Rover: A New Capability to Minimize Slip and Wheel Wear on Mars
Biography
Biography: Olivier Toupet
Abstract
The Mars Science Laboratory (MSL) rover has accumulated substantial damage on its wheels over the 15 km travelled so far
on Mars. One reason for the wheel wear is that the rover is commanded to drive as if the terrain was fl at. For example, a
straight drive is achieved by commanding all wheels at the same speed. However, when one of the wheels needs to drive over a
rock, that wheel needs to go faster since it needs to travel a longer distance over the same time period. Failure to do so results
in that wheel going slower than it should and getting pushed into the rock by the other wheels, which can cause damage such
as wheel skin puncture or cracking. In order to minimize wheel wear, a new capability was developed that adapts the speed of
each wheel to minimize slip. Modulating wheel speed to match the terrain topography is a very challenging problem, especially
when that topography is unknown. While the Curiosity rover can image the terrain and generate a height map, it rarely does so
during a drive, as this is a time-consuming process. Moreover, the noise in the mesh and accumulated errors in the rover’s pose
would make it unpractical to rely on terrain topography to optimize wheel speeds. Instead, a novel approach was developed
which relies only on the rover’s measured attitude rates and suspension angles (from the onboard gyroscopes and rocker/
bogies encoders) and leverages rigid-body kinematics to calculate the optimal wheel speeds..