IMPLEMENTATION OF A

DC MOTOR SPEED CONTROL

MAE 576 [MECHATRONICS] LAB-3GROUP E

Chembrammel Elavunkal Srinivasan Vishwajeet

University at Buffalo, Mechatronics, Spring 2010

Problem Statement

Creation and calibration of digital sensors - Building and interfacing a digital encoder to quantize and measure angular motions with focus on angular velocity measurement

Interfacing actuators along with necessary drive electronics –specifically examining the interfacing a DC fan motor to the BS2.

Using different control laws to try to achieve desired performance criteria-specifically examining one or more of the following control schemes(on-off ,P, PI,PD,PID);

Quantitatively logging the resulting data to evaluate the actual performance –specifically examining creation of a real time logging interface using Stamp Plot.

Flow Chart

Plant layout

Circuit Diagram

Motor

System implementation

Calibration of optical switch

For white back ground

The binary value of the voltage switched states at 9mmThe range of operation is between 5mm and 9mm

For Black back ground

CALIBRATION OF OPTICAL SWITCH CONTD.

The encoder

Made out of QRB1114 The number of gradations on the

reflecting disc is 24 to get a count of 12 cycles per revolution Gives better RPM / count by the optical

sensor

Measurement Authenticity

PIN HighPWM (255 Duty)

MAX RPM = 6500 +/- 10%MAX VOLT = 10VRPM = 10/12 X 6500 = 5400

Motor drive

The motor is driven using PWM values changing the duty cycle

PWM

RPM

Range of operation

Calibration of PWM drive

PWM drive calibration result

The PWM cannot drive the motor below the 34% duty-cycle, which corresponds to 1.7 volts for the amplifier gain of 2. This corresponds to a cut-off voltage of 3.5V of the motor, and a motor speed of 1000 rpm.

The range of operation of the motor is 34% to 100% of maximum duty cycle of the input signal.

Tachometer testing

12V Input

Low noise

high noise

50 ms sampling time

100 ms sampling time

Tachometer calibration

On-OFF control

1000 ms

100 ms

50 ms

Differential Gap Control

Differential gap

P control

PI Control

PD Control

PID Control

Conclusion

Achieved Encoder Implementation

Familiarized Motor Drive Techniques

PWM with RC with OPAMP with BJT

Understood Open Loop Control methods

Achieved Closed Loop Control Using ON/OFF

ON/OFF with differential gap

PID family

Understood Limitations of Digital Systems