x_{2} = \operatorname{piecewise}(0, t - k_{26} < 0, \operatorname{piecewise}(1, t - k_{26} > 0, 0)) \cdot \operatorname{piecewise}(0, 0 \ge k_{22} - k_{11} \cdot \left(t - k_{21}\right), k_{22} - k_{11} \cdot \left(t - k_{21}\right))