EML 2023 – Motor Control
Lecture 4 –
DAQ and Motor Controller
Closed Loop Control
desired
position
analog speed
signal
Computer
and DAQ
Motor Driver
current
Motor
digital direction
signal
Encoder
sensed actual
position
EML 2023
Department of Mechanical and Aerospace Engineering
2
Let’s answer 3 questions.
1. How is the motor held in place and how is it connected
to the shaft that it is to rotate?
2. How does the encoder work and how is it physically
connected to the motor?
3. How do the DAQ and motor driver work?
desired position
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
sensed actual position
EML 2023
Department of Mechanical and Aerospace Engineering
3
Interface to Computer
• We will use a National Instruments USB-6009 data
acquisition (DAQ) device
• specs
– USB interface to PC
– 8 channels of analog input, 0-5V
– 2 channels of analog output 0-5V
5 mA each
– 12 channels of digital input/outputs
0 or 5V, (8.5 mA for outputs)
– 1 counter
EML 2023
Department of Mechanical and Aerospace Engineering
5
NI USB-6009
EML 2023
Department of Mechanical and Aerospace Engineering
6
Interface to Computer
EML 2023
Department of Mechanical and Aerospace Engineering
7
Honeywell / Clarostat 600128CN1
Allied Electronics part # 753-0059
cost:
$41.67
EML 2023
Department of Mechanical and Aerospace Engineering
8
Computer Interface
• Let’s start with digital inputs to interface to the optical
encoder.
notice that there
are four wires
EML 2023
Department of Mechanical and Aerospace Engineering
9
10
channels A & B will be either 0V or 5V
depending on whether that light detector
detects light through a slit or not
ground
channel A
channel B
+5V power
11
ground
channel A
channel B
+5V power
12
Computer Interface to Motor
• To control the motor:
– we have to control the current going to the motor (via the voltage)
– however, the typical analog voltage signal that a computer generates
from the DAQ does not have sufficient current to power the motor
– an amplifier is used*
• a power supply provides 24V (7.5 amp max for our case) to the amp
• the computer DAQ generates an analog voltage in the range of
-0 to +5V; 0V means the motor is to stop ; +5V means the motor is to
turn at a maximum speed
• a digital signal will give the desired direction (0 V, CCW, 5 V CW)
desired position
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
*
also called a ‘motor driver’ or ‘speed controller’
EML 2023
sensed
actual
position
Department of Mechanical and Aerospace Engineering
13
desired position
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
sensed actual position
14
EML 2023
Department of Mechanical and Aerospace Engineering
15
16
Change motor direction
To go CW, set this digital
output pin to TRUE (+5V).
To go CCW, set this digital
output pin to FALSE (0V).
EML 2023
Department of Mechanical and Aerospace Engineering
17
Homing Switch
0V
+5V
to input pin on USB DAQ
18
Interface to Computer
0V from USB-6009
+5V from USB-6009
EML 2023
Department of Mechanical and Aerospace Engineering
19
USB
desired position
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
sensed actual position
20
USB
desired position
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
sensed actual position
21
USB
digital direction signal
ground
analog speed signal
desired position
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
sensed actual position
22
24 volt supply
USB
desired position
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
sensed actual position
23
USB
desired position
5 volt, ground, channel A, channel B
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
sensed actual position
24
Let’s answer 3 questions.
1. How is the motor held in place and how is it connected
to the shaft that it is to rotate?
2. How does the encoder work and how is it physically
connected to the motor?
3. How do the DAQ and motor driver work?
desired position
analog speed signal
current
Computer and
DAQ
Motor Driver
Motor
digital direction
signal
Encoder
sensed actual position
EML 2023
Department of Mechanical and Aerospace Engineering
25
Design Project
• For each motor in your design:
–
–
–
–
include an optical encoder for motor position feedback
include a homing switch to initialize your position
include limit switches as needed
mount the motor driver
• For the project:
– mount the DAQ
EML 2023
Department of Mechanical and Aerospace Engineering
EML 2023
Department of Mechanical and Aerospace Engineering
EML 2023
Department of Mechanical and Aerospace Engineering
EML 2023
Department of Mechanical and Aerospace Engineering
EML 2023
Department of Mechanical and Aerospace Engineering