Automated Bridge Scour Inspection

FSU/FAMU College of EngineeringTeam 7

Detailed Design Review and Test Plan2/8/2011

-Vertical DC motor-Motor Controller-2 SLA Batteries

-MicroController-Sonar-NiMH Battery-Tilt Servo-Circular DC Motor

Vertical Guide Rail

Circular Rail

Vertical Motion Drive

Design Updates:

• Revised gearhead selection

• Previously a 28:1 Ratio

• Now a 26:1 Ratio

• Trade-off: Availability vs. Over-specification

• Comparable Performance:

• Slightly slower ascent

• Moderately higher percentage of motor output ability

Vertical Motion Drive

Design Updates:

• Revised encoder selection

• Previously using Magneto-Resistant (MR)

• Now using Optical

• Trade-off: Availability vs. Cost

• Comparable Performance:

• 500 CPR vs. 512 CPR

Vertical Motion Drive

Mechanical Test Plan:

• Part One:

• Confirm rated no-load output velocity

• Measure angular velocity with tachymeter

• Part Two:

• Prior to full integration, simulated mass lift

• Confirm loaded output torque ability

• Protect components prior to integrated test

Circular Motion Drive

Design Updates:

• Unchanged Motor/Encoder/Gearhead

• Revised drive-surface interaction

• Previously: Geared drive-surface on guiderail

• Now: High-friction contact drive

• Trade-off: Manufacturability vs. Precision

Circular Motion Drive

Mechanical Test Plan:

• Part One:

• Confirm rated no-load output velocity

• Measure angular velocity with tachymeter

• Part Two:

• Prior to full integration, full-speed revolution

• Confirm loaded output torque and velocity

• Protect components prior to integrated test

SONAR Tilt Servo Drive

Design Updates:

• Unchanged Servo Motor selection

• Low risk of failure under load

• Focus on adequate positioning

SONAR Tilt Servo Drive

Mechanical Test Plan:

• Prior to SONAR integration

• Simulate moment arm to represent transducer

• Demonstrate loaded angular range of motion

• Confirm inspection range capability

Vertical Motion Updates

•Material

•Aluminum vs Stainless

•Rollers

•Drivers

•Idlers

•Bearings

•Size Constraint

Bearings and Rollers

Circumferential Motion Updates

•Material

•Design

•Driver

•Idlers

•Expectations

Circular Guide Rail

• Changes

• Size and Shape

• Material

• Connection

• Manufacturing

• Ideas

• Simplify

Testing

•Vertical and Circumferential Motion

• Degrees of Freedom

•Waterproofing

•Step by Step

Electrical Design

Updated Plan- Use two Battery sources Higher-Power →Motor Controller,DC motors Lower-Power →Microcontroller,servo,

sonar

Higher-Power Design

• Battery →Sealed Lead Acid Battery (SLA)

- Most likely will be 12 Volt, 3 Ahr SLAs

- Will need 2 of these to make 24V in series

Fuse and Switch on positive battery wire to motor controller

High-Power Design

Why use 2 -12 Volt 3Ahr Battery? The Vert. DC motor → 24V ~3A continous

Running for < 3 minutes for a final test run. The Circular motor → 12V ~300mA cont.

Running for < 10 minutes for a final test run.

# of Test Runs

Amps Drawn by Vert. motor Amps drawn by circ. motor Total Ahr

1 <3 min... 3/60 * 3A= .15Ahr <10min...10/60 *0.3A= .05 Ahr 0.2

2 0.3 0.1 0.4

3 0.45 0.15 0.6

4 0.6 0.2 0.8

5 0.75 0.25 1

6 0.9 0.3 1.2

7 1.05 0.35 1.4

8 1.2 0.4 1.6

9 1.35 0.45 1.8

10 1.5 0.5 2

Estimate Current Draw per Test

Lower-Power Design

• Battery → NiMH

• MicroController needs 5V ~500mA ..Max 2A

• Voltage regulator to get constant 5V

• May need heat sink

• Power to servo and sonar sensor as well

• Battery size depends on final servo, sonar choice. Neither should be current demanding components

The Beaglejuice

$88

4500 mAh battery

5V output

1.5A current delivery

powers a BeagleBoard for at least 6.5 hrs

on/off switch

Possible option for battery source, mounts below the microcontroller, space saver

Microcontroller

Version: Xm Version: rev. C4

1 GHz ARM Cortex A8

600MHz ARM Cortex A8

512MB LPDDR 256MB LPDDR

4 USB 1 USB

RS-232 Serial & I2C RS-232 Serial & I2C

Expansion Board

Zippy2

• I2C 1.8v to 5v

• 2nd RS-232 port

• 2nd SD slot

• Ethernet

Programming – Autonomous Movement

Motor Controller & Motors Coding

• Sabertooth: In simplified Serial Mode

• RS-232 port

• Using single 8byte commands to control speed & direction of motors

• Each motor 7bits of Resolution

• Motor1: 1-127

• Motor2: 128-255

Programming – Autonomous Movement

Encoders & Servo Coding

• I2C interface

• Encoders: Counting the leading & falling edge to determine distances

• Servo: PWM (Pulse Width Modulation)

Testing

Autonomous Movement Program

• Program Simulations: I/O Signals

• MCU & Oscilloscope: PWM - Pulse Widths approx.: 1ms to 2ms - Period: 10ms to 2ms

• MCU & Signal Generator: Simulate encoder input (Square Waves)

SONAR – Control Test

• Humminbird HDR 650• Transducer/Display combo• 2ft. – 600ft.• Verify data accuracy from

other transducers• ~ 1.2in. Resolution• 200kHz• Strictly handheld; will not

be connected to MCU

SONAR Transducer

• Furuno USA• 235 kHz• 7 degrees• 0.04m – 100m• NMEA 0183 – ASCII serial

communications • Sentence structure: DDBT, DDPT

NMEA 0183 Sentence Structure

•8 bits•4800bps•Checksum = hexadecimal; XOR of all char between $ and *

Microcontroller 1 $170.00 $170.00

Motor Control Unit 1 $137.00 $137.00

12V DC Motor/encoder 1 $40.00 $40.00

SONAR 3 $200.00 $600.00

SLA Battery 12V 3.2Ahr 2 $12.00 $24.00

24V DC Motor/encoder 1 $431.05 $431.05

Beagle Juice (Battery) 1 $88.00 $88.00

Mounting Materials $100.00

Circular Ring 1 $300.00 $300.00

High-Friction Rollers 3 $1.20 $3.60

Ball Bearings 4 $12.00 $48.00

Shaft 1 $5.00 $5.00

Square Vertical Rail 1 $10.00 $10.00

Servo 1 $20.00 $20.00

Wires, fuses. i.e N/A N/A $5.00

Software Licenses $100.00

Test Supplies $120.00

Soldering Kit 1 $15.00 $15.00

Robot casing and fittings

$50.00

Total Cost= $2266.60