MATE MATE Underwater Robot Underwater Robot Advanced Workshop - - PDF document

MATE MATE Underwater Robot Underwater Robot

Advanced Workshop

Introduction Introduction

• Why I want to do this workshop?
• U/W Cameras

– About Cameras – Sealing Cameras

• Thruster Motors:

– Motor type – The control

Introduction Introduction

• Ancillary (supplementary) Motors:

– Motor type – The control

• LUNCH

Introduction Introduction

• Other Stuff:

– Camera Power supply – Troubleshooting PWM Circuits – Temp Sensor – Joining wires – O-rings – Questions

Underwater Cameras 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 The Car rear view camera Model ENOCH ENOCH-

• 1032

1032

The Camera Frame The Camera Frame How we are doing this

• Two teams will come up here at a time.

– 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 DC Motors

• Three types :

– Stepper Motors. – RC Servo Motors. – Conventional DC Motors.

Stepper 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
• ccurs

Stepper Motors Stepper Motors Servo 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 Servo Motors Conventional Motors Conventional Motors

• Speed control possible
• Can be feedback control
• Simple on/off switched
• Pulse Width Modulation (PWM) Control.

Conventional Motors Conventional Motors Thruster Motors Thruster Motors

• Standard DC Motors
• Main drive for the robot
• Simple on/off - Reverse Switch or PWM

Control.

On / Off / Reverse Switch On / Off / Reverse Switch

One for each motor

What is PWM? 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 Full on

PWM Signal Generation PWM Signal Generation

Electronic Control Electronic Control

How is this used for Motor Control? How is this used for Motor Control?

Motor PWM signal Generation Speed Control Electronic Power Switch Direction Control Power

Discrete Electronics Discrete Electronics

Kitsrus DIY Kit 67 DC Speed Controller HK$ 102 Kitsrus DIY Kit 166V2 DC Speed Controller HK$ 145

Kit Notes 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 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 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.

PIC

PWM Switching

Speed Control Pot.

RS232C Control possible

Direction M

Microprocessor Control Microprocessor Control

Oceanway 5A Controller DC Speed Controller HK$ 160

The Tricky Bit 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 Advantages

• Really flexible.
• Cheap.
• Remote control possible (RS232C?).

– Multi-units over a single control cable.

• 8 pin PIC unit suitable.

Lunch Time

Ranger Teams Explorer Teams

Suffer

Optical Transmissometer 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 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? Did you find them all?

Trouble shooting

Temperature Sensor Temperature Sensor Joining Underwater cable Joining Underwater cable

Working with Working with “ “O O” ” rings rings

• 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 The End

Questions