$$\begin{array}{mm}{\varphi }_{sys}& =\varphi +{\left(\frac{2-\frac{|\varphi |}{{\varphi }_{max}}-\frac{|\theta |}{{\theta }_{max}}}{2}\right)}^4(u-0.5)r_{error}\pi \\ {\theta }_{sys}& =\theta +{\left(\frac{2-\frac{|\varphi |}{{\varphi }_{max}}-\frac{|\theta |}{{\theta }_{max}}}{2}\right)}^4(u-0.5)r_{error}\pi \end{array}$$