FIG. 3.

Traditional observer model architecture (after Merfeld et al. 1993). The observer functions by comparing the output and the estimated output to generate a feedback signal that is passed through an internal model of motor dynamics to generate the state estimate. The state estimate, in turn, is passed through the model of sensor dynamics to generate the estimated output, which is used to generate a feedback signal, and so on. For passive observers, the input, u(t), is set to 0, motor dynamics are not relevant (i.e., set to unity transfer), and there is no comparison between estimated and desired states to generate a control signal (omit gray lines). Passive observers are suited to modeling passive perception.