Characteristics of human stepping behaviour during walking towards and over regions of ground unavailable for foot placement

Abstract

Humans are capable of walking apparently without effort over terrain in which regions of ground are unsuitable for foot placement. It is known that humans make extensive use of visual information for real-time anticipatory control of locomotion. The set of control laws for approaching and stepping over unavailable ground using visual information are as yet unclear. The aim of this work was to show that humans integrate available visual information into a real-time optimisation of stepping in which the dynamics of every step can only be completely understood by knowing previously encountered terrain and the terrain ahead.

In a series of experiments, participants walked freely along a hard, flat, level track in a motion capture laboratory on which were areas of ground marked as unavailable for stepping. The kinematics of stepping behaviour was recorded using optical motion capture. By changing the shape and size and position of the areas of unavailable ground it was possible to characterise at a fundamental level, the control schemes used by humans to achieve safe, efficient passage.

Foot placement was adjusted over several steps both during the approach and at traversal over unavailable ground regions. Anticipatory control was capable of continuous adjustment of step length and direction, discrete choices of whether to add or remove steps on approach to an area to be stepped over, and whether to step over two adjacent regions of unavailable ground or whether to step between them. Control during the approach steps operated at stride level when there was an advantage in stepping over unavailable ground with a particular lead leg.

The body of work revealed that human walking is controlled by a sophisticated integration of relatively simple control laws that operate subconsciously in real-time to guide the width, length and direction of stepping.

Date of Award	6 Jan 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	J Burn (Supervisor) & Ute B Leonards (Supervisor)