Automated Bridge Scour Inspection FSU/FAMU College of Engineering Team 7 Detailed Design Review and Test Plan 2/8/2011
Jan 19, 2016
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