Simple definition of adequate fixed time-step size of Szabad(ka)-II robot model

The current research is part of the building of a dynamic model for Szabad(ka)-II hexapod walking robot. The fixed-step solver type was used within the Simulink environment and the inverse dynamics was calculated using the Robotics Toolbox. The model based on rigid-body dynamics should comprise a sponge-coated foot. A simple approximate spring-damper model was implemented for the modeling of ground-foot contact which causes the fastest transient dynamic event. The calculation errors were measured and obtained at the deflection of the spring-damper in order to define the adequate accuracy. The aim was to find the optimal sampling when the calculation errors are negligible but without the use of unnecessary and too many calculations. This paper establishes three simple definitions for the estimation of the adequate fixed-step size.