Abstract
Our dynamical model of locomotor behavior has separate components for (a) steering to a stationary goal, (b) avoiding a stationary obstacle, (c) intercepting a moving target, and (d) avoiding a moving obstacle (Fajen & Warren, 2003; submitted). Recent research has shown that these components can be linearly combined, with fixed parameters, to predict human paths with a moving target and a stationary obstacle (Bruggeman & Warren, VSS, 2005), and vice versa (Cohen, Bruggeman, & Warren, VSS, 2005). Here we test the model in situations where both the target and the obstacles are moving. We attempt to predict the paths participants take when intercepting a moving target while avoiding one moving obstacle (Experiment 1), or avoiding two moving obstacles (Experiment 2). Studies were conducted in the Virtual Environment Navigation Lab, a 12m x 12m ambulatory virtual environment with a head-mounted display (60° H x 40° V) and a hybrid sonic/inertial tracking system (latency 50–70 ms). Participants walked toward a moving target (blue pole) while avoiding moving obstacles (yellow poles). Objects moved on parallel trajectories in the frontal plane. Their speeds were manipulated to create situations in which the model predicts switching between paths ahead of and behind an obstacle. Human paths are close to the model paths and switch from ahead to behind an obstacle near the predicted speeds. The results generalize the steering dynamics model to more complex environments with multiple moving objects. Future work will seek to extend the model to situations with multiple competing goals.