Stepping motor smooth control method Control method Sudden change of speed Rotating, may result in step-slipping Speed Time Rotatin Gradual change of a g speed speed will solve the step-slipping problem CEG2400 Ch16: feedback control Vlf
CEG2400 Ch16: feedback control V7f 16 Stepping motor smooth control method • Control method Rotating Speed 1 Rotatin g speed 1 Sudden change of speed may result in step-slipping Gradual change of speed will solve the step-slipping problem Time
3)open-loop and closed-loop control Feedback control Pid theory and implementation CEG2400 Ch16: feed back control v7f 17
3) open-loop and closed-loop control Feedback control PID theory and implementation CEG2400 Ch16: feedback control V7f 17
Open-loop motor control and its problems Change motor supply power change speed Problem: How much power is right? Ans: don't know, depends on internal/external frictions of individual motors Problem: How to make the robot move straight? How to control power(Ton by isr an MCU? Solution: Use feedback control to read actual wheel Slower, increase power(+ ton) Faster, reduce power( ton) CEG2400 Ch16: feed back control v7f 18
Open-loop motor control and its problems • Change motor supply power change speed • Problem: How much power is right? – Ans: don’t know , depends on internal/external frictions of individual motors. • Problem: How to make the robot move straight? • How to control power (Ton) by ISR & an MCU? – Solution: Use feedback control to read actual wheel: – Slower, increase power (+ Ton) – Faster, reduce power (- Ton) CEG2400 Ch16: feedback control V7f 18
Exercise When using the open-loop control method with a constant PWM signal for both wheels, explain why the robot would slow down when climbing up hi∥ Ans: When climbing up hill, energy is used to act against gravity hence the robot is running slower. CEG2400 Ch16: feed back control v7f 19
Exercise • When using the open-loop control method with a constant PWM signal for both wheels, explain why the robot would slow down when climbing up hill. – Ans: When climbing up hill, energy is used to act against gravity, hence the robot is running slower. CEG2400 Ch16: feedback control V7f 19
Feedback contro The real solution to read the real speed of the wheel and control the speed using feedback control Require speed encoder to read back the real speed of the wheel at real time CEG2400 Ch16: feed back control v7f
Feedback control • The real solution to read the real speed of the wheel and control the speed using feedback control • Require speed encoder to read back the real speed of the wheel at real time. CEG2400 Ch16: feedback control V7f 20