Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Towards An Adaptive Locomotion Strategy For Quadruped Rovers: Quantifying When To Slide Or Walk On Planetary Slopes

Alberto Sanchez-Delgado, João Carlos Virgolino Soares, David Omar Al Tawil, Alessia Li Noce, Matteo Villa, Victor Barasuol, Paolo Arena, Claudio Semini

TL;DR

This work tackles the challenge of energy-efficient locomotion for quadruped rovers on inclined planetary terrains by comparing walking and torso-based sliding through Cost of Transport (CoT). It combines a multi-modal locomotion framework with a dual-simulator workflow (Isaac Sim for closed-loop rigid-surface testing and ANSYS Rocky for granular DEM validation) to derive CoT curves across slope, friction, and speed, and identifies preliminary transition thresholds where CoT_walk and CoT_slide intersect. The findings show complementary trends: walking is favorable on gentle slopes at low speeds, while sliding becomes advantageous on steeper inclines, though granular terrain elevates costs relative to rigid models. These insights lay groundwork for energy-aware, multi-modal locomotion policies, with future work extending to varied morphologies, controllers, gravity levels, and experimental granular validations to support robust planetary exploration missions.

Abstract

Legged rovers provide enhanced mobility compared to wheeled platforms, enabling navigation on steep and irregular planetary terrains. However, traditional legged locomotion might be energetically inefficient and potentially dangerous to the rover on loose and inclined surfaces, such as crater walls and cave slopes. This paper introduces a preliminary study that compares the Cost of Transport (CoT) of walking and torso-based sliding locomotion for quadruped robots across different slopes, friction conditions and speed levels. By identifying intersections between walking and sliding CoT curves, we aim to define threshold conditions that may trigger transitions between the two strategies. The methodology combines physics-based simulations in Isaac Sim with particle interaction validation in ANSYS-Rocky. Our results represent an initial step towards adaptive locomotion strategies for planetary legged rovers.

Towards An Adaptive Locomotion Strategy For Quadruped Rovers: Quantifying When To Slide Or Walk On Planetary Slopes

TL;DR

This work tackles the challenge of energy-efficient locomotion for quadruped rovers on inclined planetary terrains by comparing walking and torso-based sliding through Cost of Transport (CoT). It combines a multi-modal locomotion framework with a dual-simulator workflow (Isaac Sim for closed-loop rigid-surface testing and ANSYS Rocky for granular DEM validation) to derive CoT curves across slope, friction, and speed, and identifies preliminary transition thresholds where CoT_walk and CoT_slide intersect. The findings show complementary trends: walking is favorable on gentle slopes at low speeds, while sliding becomes advantageous on steeper inclines, though granular terrain elevates costs relative to rigid models. These insights lay groundwork for energy-aware, multi-modal locomotion policies, with future work extending to varied morphologies, controllers, gravity levels, and experimental granular validations to support robust planetary exploration missions.

Abstract

Legged rovers provide enhanced mobility compared to wheeled platforms, enabling navigation on steep and irregular planetary terrains. However, traditional legged locomotion might be energetically inefficient and potentially dangerous to the rover on loose and inclined surfaces, such as crater walls and cave slopes. This paper introduces a preliminary study that compares the Cost of Transport (CoT) of walking and torso-based sliding locomotion for quadruped robots across different slopes, friction conditions and speed levels. By identifying intersections between walking and sliding CoT curves, we aim to define threshold conditions that may trigger transitions between the two strategies. The methodology combines physics-based simulations in Isaac Sim with particle interaction validation in ANSYS-Rocky. Our results represent an initial step towards adaptive locomotion strategies for planetary legged rovers.
Paper Structure (23 sections, 12 equations, 7 figures, 1 table)

This paper contains 23 sections, 12 equations, 7 figures, 1 table.

Table of Contents

  1. Introduction
  2. System Description
  3. Motion generation
  4. Trajectory generator.
  5. Kinematic solver.
  6. Impedance controller.
  7. Controller switch.
  8. Controller switch.
  9. Simulation
  10. CoT estimation
  11. Simulation Setup and Evaluation
  12. Robotic System and Simulation Platforms
  13. Evaluation Scenarios
  14. Isaac Sim ramp scenarios.
  15. ANSYS Rocky granular scenarios.
  16. ...and 8 more sections

Figures (7)

  • Figure 1: System structure integrating walking and sliding controllers with the simulation environment and data logging for CoT analysis.
  • Figure 2: a) Generated trajectory for a single foot (Left Front - LF) in the task space. b) Isometric view of the trajectories for the robot legs. c) 3D view of the simulated robot with the legs in the home configuration. d) Frontal view of the robot with the legs in the home configuration.
  • Figure 3: Simulation environments used for evaluation. a) Isaac Sim ramps with variable inclination $\alpha$, supporting both walking and sliding under closed-loop control. b) ANSYS Rocky granular ramps, used exclusively for sliding through offline replay of leg joint trajectories.
  • Figure 4: CoT of walking in Isaac Sim over downhill slopes from 0° to 35° and commanded base velocities of 0.1, 0.2, and 0.3 m/s.
  • Figure 5: CoT for sliding in Isaac Sim across slope inclinations from 0° to 35° and static friction coefficients ($\mu_s = 0.4$--$0.8$).
  • ...and 2 more figures