LQR
 Linear Quadratic Regulator (LQR) allows the design of a regulating system that tends to zero, but also considers the control effort.
 The basic function for evaluating the controller is defined below. The integral is evaluated to reduce the value. Ideally the state value will go to zero (it is a regulator), and the plant input will be minimized. It is assumed that D=0. Here a new state ’z’ is defined. It should reflect the system state values that should be regulated to zero.
 the design process involves adjusting the r value to obtain the desired result.
