Q: How to implement PID control for DC motor speed regulation?
Answer
DC motor PID speed control: (1) Measure speed with encoder or tachogenerator. (2) Calculate speed error: e = desired_speed – measured_speed. (3) PID output: u = Kp*e + Ki*integral(e)*dt + Kd*derivative(e). (4) Apply output to PWM duty cycle. Implementation tips: use anti-windup (clamp integral term when output saturates). Use derivative filtering (add first-order low-pass to D term to reduce noise). Discrete implementation: u[n] = u[n-1] + Kp*(e[n]-e[n-1]) + Ki*Ts*e[n] + (Kd/Ts)*(e[n]-2*e[n-1]+e[n-2]). Tune with Ziegler-Nichols or manually: set I=D=0 increase P until stable oscillation then tune. For motor control: inner current loop (PI) runs at 5-10 kHz; outer speed loop runs at 1-2 kHz. Use feedforward voltage: V_ff = Kt * desired_torque / Kv. Use tachogenerator for analog speed control or encoder + timer for digital.
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