P08456: Lighting System for an Underwater Robot

Concept Design Review

Jeremy SchieleJonathan LentRyan Seeber

Justin VanSlykeBenoit Hennekinee

Project Background

The design of an underwater LED lighting system that is multi-platform capable

Focus on modular, scalable & open source design

Housing design is in conjunction with Thruster design

Funding provided by the Dresser-Rand Corporation

Multi-Spectral Lighting Considerations

Chosen wavelength dependent on absorption and scattering of light by water and materials contained within

Best overall wavelength ~550-600nm

Absorption curve courtesy of Dr. Ientilucci

 LED Bulb System

LEDs Design Concepts:

Concept #1 - Single LED advantages: simple, only 1 LED to control

disadvantages: less powerful because only 1 LED per fixture, requires 4 lights, 2 per color

Concept #2- 6 small LEDsadvantages: tiny LED, multiple designs, adaptability, powerfuldisadvantages: more complicated to control

Concept #3 – 2 layersadvantages: intermediate solution, multiple LEDs in a larger housingdisadvantages: large housing design, difficult to design

Concept 2LUXEON REBEL CREE XLAMP XR-E Edison Opto EP5W-2E00

Selection Criteria Weight Rating Weighted Score Rating Weighted Score Rating Weighted Score

Brightness 35% 3 1,05 1 0,35 3 1,05

Low Power 10% 5 0,5 5 0,5 3 0,3

Luminous Efficiency 30% 5 1,5 4 1,2 2 0,6

Size 20% 5 1 4 0,8 4 0,8

Angle 5% 4 0,2 2 0,1 3 0,15

               

  100%   4,25   2,95   2,9

LED Bulb System

Choice of the LED:

For each concept, the Pugh’s Matrix has been established in order to choose the best LED. For the concept chosen, the LEDs are tiny and are able to be surface mounted on an circuit board.

LED DriverThe choice of the LED driver has been

made with the following specifications:

1A output at least, VOUT ≥ 12V, VIN = 24V, Allow PWM Dimming (dedicated

input), Step-down (buck) regulator with

efficiency as high as possible, Switching regulator control, Bulk as tiny as possible.

Linear Technology: - LT3474 - LT3496- LTC3783

National Semiconductor:

- LM3405- LM3404

MAXIM: - MAX5053 - MAX5035 - MAX5024 - MAX16819 - MAX16821 - MAX16831

TI:- TPS63000

LED Drivers that fit the criteria

Schematic of implementation of LEDs & Driver.

LED bulb and Driver schematic

Power Supply Schematic

The lighting system will be controlled over an RS-485 communication line. Inside the enclosure a microcontroller will accept the commands and execute them using the LED circuitry.

Control System

RS-485 Communication

Any computer with a serial port can be used as the master system for testing or in actual applications using this circuit to convert RS-232 to the RS-485 signals.

Circuit design provided by Dr. Reddy

Micro-controller SelectionThe Atmega168 was chosen for the microcontroller. This is an example circuit connecting the microcontroller to RS-485 and the LED circuitry.

Scoring Matrix of micro-controller options

Mounting Hardware

Dual or Single Ball Joint LED Mount Pros

Maximum adjustability Quick one/two screw

adjustment Extension away from ROV

chassis Cons

Less secure in holding a position

Mounting Hardware

Hinge Style LED Mount Pros

Two axes of adjustability Quick and secure method

of adjustment Simple, effective design

Cons Close to ROV chassis-

shares line of sight to object with video

Mounting Hardware

Thruster Hard Mount Extension Pros

Most secure with rigid attachment

Extension away from ROV chassis

Feasible for use with light units too

Cons No adjustability

Mounting Hardware

System: Mounting Hardware Weight HAI LED % Weight Raw ScoreWeighted Score Raw Score

Weighted Score Raw Score

Weighted Score Raw Score

Weighted Score

Security 12.00% 3 0.36 5 0.6 3 0.36 3 0.36 5 0.6Adjustability 15.00% 3 0.45 0 0 3 0.45 5 0.75 0 0Durability 10.00% 3 0.3 4 0.4 2 0.2 1 0.1 5 0.5Modularity 20.00% 3 0.6 3 0.6 4 0.8 3 0.6 2 0.4Scalability 15.00% 3 0.45 2 0.3 3 0.45 2 0.3 3 0.45Compact design 10.00% 3 0.3 3 0.3 3 0.3 2 0.2 2 0.2Stiffness of placement 6.00% 3 0.18 4 0.24 3 0.18 2 0.12 5 0.3Ease of manufacturing 5.00% 3 0.15 4 0.2 4 0.2 3 0.15 4 0.2Ease of adjustability 7.00% 3 0.21 3 0.21 4 0.28 3 0.21 0 0Total 100.00% 3 28 2.85 29 3.22 24 2.79 26 2.65

Single Screw SS Hinge SS Ball Joint Hard mount extension

Commonalities of all designs: Two hole bolt pattern for housing attachment

Allows any mounting system to be used with either housing Allows for quick attachment and detachment

Corrosion resistant material 316L S.S. or anodized Aluminum Prevents seizing of adjustment points Preserves aesthetic look of product

Scalable This option allows the housing to be the same design, yet sized

appropriately for application Theory: assume current is RP-10

Used on RP-1, 10, 100… RP-1 motor housing is RP-10 LED housing RP-10 LED housing is RP-1 motor housing

Interchangeable

This option allows for the same base housing for both thruster and light

End cap is interchangeable for swapping between thruster and light

Housing Design Scalable

Best option if motor diameter is significantly larger then LED diameter Interchangeable

Best option if motor diameter and LED diameter are similar Accounts for difference in length Simplified machining: one program, one size stock material Identical sub-parts: o-rings, clamps, etc. Hot swappable