1. The problem statement, all variables and given/known data If the steady-state error of the proportional-plus-derivative-plus acceleration system is to be less than 10% determine a suitable value for Kp. 2. Relevant equations The input of the system is: v The output of the system is: y The transfer function of the system including the controller is: (23(Kp+4s+s^2)) / (s^3+19s^2+48s+96+23Kp) 3. The attempt at a solution With steady state: s = 0 Therefore: y steady state = v x (23Kp / (96 + 23Kp)) The error of the system is: v-y Therefore: error = v - (23Kp / (96+23Kp))v error = 96v / (96 + 23Kp) How can I correctly substitute the error of 10% now in this equation. I think (v-y)/y = 0.1 [error] But this will leave 3 variables in the equation... Thanks in advance!