**Appendix A. A Kinetic Energy, Projection of the Angular Momentum on the Vertical Axis and Biped Parameters**

The expressions of the kinetic energy and the angular moment on the vertical axis of the model in Figure 2a are the following

$$\begin{array}{c} KE = 0.5 \cdot (I22 + m \cdot L^2) \cdot \omega^2 \\ + (I23 \cdot \cos(\theta) - I12 \cdot \sin(\theta)) \cdot \gamma \cdot \omega \\ + 0.5 \cdot (I33 \cdot \cos(\theta)^2 + I11 \cdot \sin(\theta)^2) \cdot \gamma^2 \\ - I31 \cdot \sin(\theta) \cdot \cos(\theta) \cdot \gamma^2 \\ + 0.5 \cdot m \cdot L^2 \cdot \sin(\theta)^2 \cdot \gamma^2 \end{array} \tag{A1}$$

*<sup>k</sup><sup>γ</sup>* <sup>=</sup> <sup>−</sup><sup>2</sup> · *<sup>I</sup>*<sup>31</sup> · *cos*(*θ*) · *sin*(*θ*) · *<sup>γ</sup>* (*I*23 · *cos*(*θ*) − *I*12 · *sin*(*θ*)) · *ω <sup>I</sup>*<sup>33</sup> · *cos*(*θ*)<sup>2</sup> · *<sup>γ</sup> <sup>I</sup>*<sup>11</sup> · *sin*(*θ*)<sup>2</sup> · *<sup>γ</sup> <sup>m</sup>* · *<sup>L</sup>*<sup>2</sup> · *sin*(*θ*)<sup>2</sup> · *<sup>γ</sup>* (A2)

The parameters of the model used in this paper, taken from [20], and representing a patient wearing an exoskeleton are shown in Figure A1.

**Figure A1.** the biped parameters.

#### **References**

