MATE
Underwater Robot
Advanced Workshop
Introduction
• Why I want to do this workshop?
• U/W Cameras
– About Cameras
– Sealing Cameras
• Thruster Motors:
– Motor type
– The control
Introduction
• Ancillary (supplementary) Motors:
– Motor type
– The control
• LUNCH
Introduction
• Other Stuff:
– Camera Power supply
– Troubleshooting PWM Circuits
– Temp Sensor
– Joining wires
– O-rings
– Questions
Underwater Cameras
• Why do we need them?
• Several ways to make a camera waterproof
– Inside a sealed box.
– Epoxy’ed.
The Car rear view camera Model
ENOCH-1032
The Camera Frame
How we are doing this
• Two teams will come up here at a time.
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To weigh out the epoxy.
To mix it thoroughly.
To pour it into the camera tube.
To fit the gland into the tube.
DC Motors
• Three types :
– Stepper Motors.
– RC Servo Motors.
– Conventional DC Motors.
Stepper Motors
• Very precise in terms of position
• Full rotation possible
• Special connection to multiple coils in the motor
• The coils are energized in a sequence to make the
motor rotate
• The speed is controlled by the rate the sequence
occurs
Stepper Motors
Servo Motors
• Very precise in terms of position
• Partial rotation only.
• Feedback signal is used to determine the
position of rotation
• High overhead in maintaining positioning
signal
Servo Motors
Conventional Motors
• Speed control possible
• Can be feedback control
• Simple on/off switched
• Pulse Width Modulation (PWM) Control.
Conventional Motors
Thruster Motors
• Standard DC Motors
• Main drive for the robot
• Simple on/off - Reverse Switch or PWM
Control.
On / Off / Reverse Switch
One for each motor
What is PWM?
• PWM = Pulse Width Modulation.
• It is the switching off and on of a power
supply for different time periods.
Slow speed
Faster speed
PWM Signal Generation
Full on
Electronic Control
How is this used for Motor Control?
Power
PWM signal
Generation
Electronic
Power Switch
Motor
Speed
Control
Direction
Control
Discrete Electronics
Kitsrus DIY Kit 67
Kitsrus DIY Kit 166V2
DC Speed Controller
DC Speed Controller
HK$ 102
HK$ 145
Kit Notes
• Kit 166v2 is moderately
hard to construct:
– Two directions on one
pot.
– Watch the solder bridge
between layers.
– Easy to repair.
– Moderate efficiency.
– Low voltage 5~32V DC.
– Medium current 5A.
Kit Notes
• Kit 67 is moderately easy to
construct:
– Only one direction.
– Easy to repair.
– Moderate efficiency.
– Low voltage 5~16V DC.
– Medium current 7.5A.
• Kit 166v2 is moderately
hard to construct:
– Two directions on one
pot.
– Watch the solder bridge
between layers.
– Easy to repair.
– Moderate efficiency.
– Low voltage 5~32V DC.
– Medium current 5A.
Microprocessor Control
• Many microcontrollers can be used to
generate a PWM Signal.
• The Programmable Intelligent Computer
series from Microchip is quite popular.
• The advantage of using one is a reduction in
component count and a flexible
performance curve.
RS232C Control
possible
PIC
PWM Switching
Direction
Speed Control Pot.
M
Microprocessor Control
Oceanway 5A Controller
DC Speed Controller
HK$ 160
The Tricky Bit
• You need to know how to program the PIC.
• You need to watch for noise on the power
supply.
• You need some PIC equipment like
programmers in order to work with them.
Advantages
• Really flexible.
• Cheap.
• Remote control possible (RS232C?).
– Multi-units over a single control cable.
• 8 pin PIC unit suitable.
Ranger Teams
Lunch Time
Explorer Teams
Suffer
Optical Transmissometer
• Interesting problem
• RED light not that suitable since water absorbs
it.
• Need Blue Light.
• You need to be able to change the intensity if
the light and the sensitivity of the receiver.
Hands on time
• Need to split each team into two.
– First group needs more experience using a soldering
iron. They will assemble a cameras power supply.
– Second group will get the troubleshoot a PWM
drive.
Trouble
shooting
Did you find them all?
Trouble
shooting
Temperature Sensor
Joining Underwater cable
Working with “O” rings
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You need clean lint free cloth or paper.
Remove the “O” ring gently.
Clean the “O” ring and “O” ring groove.
Check for “O” ring damage.
Apply some silicon grease.
Replace the “O” ring.
The End
Questions