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it is my final report of control system
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Proportional-integral - derivative (PID) controllers are the most widespread controllers used in industrial automation operations because of its straightforward structure and good efficiency in a wide variety of operating conditions. The design of such a controller involves three parameters to be identified: proportional gain, integral time constant and time constant derivatives. The PID controller parameters Kp, Ki , and Kd (or Kp, Ti, and Td) can be modified to create different response curves from a given system.
𝑺^ (^ 𝑱^ 𝑿^ 𝒔^ 𝑿^ 𝒃)^ 𝑿^ 𝜽(𝒔)^ =^ 𝒌^ 𝑿^ i(s) (𝒗^ −^ 𝒌^ ). (s).^ 𝜽(𝒔)^ =^ 𝒊(𝒔)^.^ (𝑳^ 𝑿^ 𝒔^ +^ 𝑹) The open loop transfer function is 𝜽 𝑽 = 𝒌 ( (^) 𝑱 𝑿 𝒔 𝑿 𝒃) (^) 𝑿 (𝑳 𝑿 𝒔 + 𝑹) (^) + 𝒌𝟐 ⁄
First, the motor with an input voltage of 1volt can only rotate at 0.1 rad / sec. The steady state error of motor speed will be below 1 percent. The motor will accelerate to its steady-state speed as soon as it switches on, the settling time should be under 2 seconds. We would like an overflow of less than 5 percent because a speed faster than the reference will harm the equipment. Mat Lab Code: clear all clc b=0.1; k=0.01; J=0.01; R=1; L=0.5; A=k; B=[(JL) ((JR)+(Lb)) ((bR) + k^2)]; step(A,B,0:0.01:5) title('OL Response')
sys_c3 = feedback(DP_motor,1); Kp = 70; E = pid(Kp); sys_c4 = feedback(EP_motor,1); Kp = 100; F = pid(Kp); sys_c5 = feedback(F*P_motor,1); step(sys_cl,sys_c3,sys_c4,sys_c5,'g--',t) grid on title('Response with Proportional Control') legend('pd=10', 'pd=50','pd=70','pd=100') Fig. 2. Closed loop response with different values of kp kp Rise time(sec) Maximum OS (%) Peak amplitude Steady State error 10 0.491 - 0.5 0. 50 0.159 12.8 0.94 0. 70 0.126 18.4 1.04 0. 100 0.099 24.9 1.14 0. The proportional controller kp reduces the raise time for kp=10 from (0.49sec) to (0.099sec) for kp=100 and will never eliminate the steady-state error from (0.5) for kp=10 to (0.909) for kp=100.
So, by increasing the gain kp, the response becomes more rapid. However the maximum overshoot will increase from (12 per cent to 25 per cent).
The settling period is still too long, we have to raise the gain ki with kp=100,. Mat Lab Code: J = 0.01; b = 0.1; K = 0.01; R = 1; L = 0.5; s = tf('s'); P_motor = K/((Js+b)(Ls+R)+K^2); Ki = 10; C = pid(Kp,Ki); sys_cl = feedback(CP_motor,1); t = 0:0.01:2; Ki = 50; D = pid(Kp,Ki); sys_c3 = feedback(DP_motor,1); Ki = 70; E = pid(Kp,Ki); sys_c4 = feedback(EP_motor,1); Ki = 100; F = pid(Kp,Ki); sys_c5 = feedback(F*P_motor,1); step(sys_cl,sys_c3,sys_c4,sys_c5,'g--',t) grid on title('Response with Integral Control') legend('pi=10', 'pi=50','pi=70','pi=100') ki settling time(sec) Rise time (sec) Maximum OS% Peak amplitude Steady state error 50 - 0.107 17.9 1.18 0. 70 1.69 0.106 19.6 1.2 0. 100 1.03 0.104 22.2 1.22 0. 200 0.774 0.0989 30.5 1.3 0 The settling time becomes 0.774 sec for ki=200, and the steady-state error becomes very small and eliminated.
Fig. 4. closed loop response with different values of kd. If we use a pid controller with: kp=100,ki=200 and kd=10. All our design objectives are fulfilled and the response could very well look like below. Fig. 5. Closed loop response with PID control
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