Hexapod walking: From Reality to Simulation

Wednesday, June 3, 1998 - 11:00am - 12:00pm
Keller 3-180
Fred Delcomyn (University of Illinois at Urbana-Champaign)
Most insects walk using a stereotyped alternating tripod gait in which two triplets of legs, front, rear, and opposite middle, step alternately. Experiments involving perturbations of the locomotor system suggest that sensory feedback aids coordination by providing critical timing cues and ensuring gait stability during walking. Nevertheless, exactly how the nervous systems orchestrates coordination during locomotion is still not entirely clear.

Simulation can in principle be a useful tool to study neural mechanisms of locomotor control because it allows rapid testing of hypotheses about how the nervous system generates patterned motor output. Here, a system for the simulation of an insect, including sense organs, muscles, body, and legs, will be introduced. The simulation system, written in C++, allows users to study elements ranging from isolated leg segments to whole animals with multi-jointed legs. The program assembles the object to be simulated according to information provided in separate, user-prepared configuration files, placing muscles and sense organs where desired. A user may then test hypotheses about how coordinated movements are generated by encapsulating these hypotheses in control algorithms that operate the simulated elements. Because the specification of the input and output variables to which control algorithms have access is made in configuration files rather than in the simulation code itself, algorithms for the control of movements can be written by users who have no knowledge of the simulation code.

The system was developed for the study of neural mechanisms of coordination during walking in insects, but by specifying in configuration files the physical parameters of a hexapod robot and the performance characteristics of its actuators and sensors, it is possible to investigate control mechanisms for these devices as well.