Figure 2

Measurement and analysis of the electrothermal actuation of the linkage. (a) Scatterplot showing that a third-order polynomial empirically models the displacement of the translating link D in response to the square of the voltage applied to the electrothermal actuator v². Dashed gray lines indicate electromechanical characteristics of the joint pertaining to play. (b) Scatterplot showing that a piecewise quadratic function empirically models the rotation of the rotating link θ in response to v². Play in the joint results in hysteretic motion of the rotating link. The horizontal-axis intercept of the response function for section 2 of the hysteresis loop gives v_min. For an input of this value, the model in (a) outputs $D_{\mathrm{play}}^0$. Uncertainties are smaller than the data markers.