# Planning and Execution of Dynamic Whole-Body Locomotion for a Hydraulic Quadruped on Challenging Terrain

## TL;DR

This paper introduces a real-time, model-based framework for dynamic quadrupedal locomotion over challenging terrain, combining environment modeling, search algorithms, and whole-body control to achieve faster and more stable movement.

## Contribution

It presents a novel integrated approach using online environment modeling, A* search, and ZMP-based optimization for dynamic quadruped locomotion on difficult terrain.

## Key findings

- Traverses terrain at nearly 6 times the previous speed
- Uses on-board environment modeling with occupancy grids
- Achieves stable, natural dynamic motions through ZMP optimization

## Abstract

We present a framework for dynamic quadrupedal locomotion over challenging terrain, where the choice of appropriate footholds is crucial for the success of the behaviour. We build a model of the environment on-line and on-board using an efficient occupancy grid representation. We use Any-time-Repairing A* (ARA*) to search over a tree of possible actions, choose a rough body path and select the locally-best footholds accordingly. We run a n-step lookahead optimization of the body trajectory using a dynamic stability metric, the Zero Moment Point (ZMP), that generates natural dynamic whole-body motions. A combination of floating-base inverse dynamics and virtual model control accurately executes the desired motions on an actively compliant system. Experimental trials show that this framework allows us to traverse terrains at nearly 6 times the speed of our previous work, evaluated over the same set of trials.