Autonomous Following RObot Critical Design Review

Transcription

1 Autonomous Following RObot Critical Design Review James Tse (Leader) Wei Dai Travis Frecker Peter Verlangieri Professor John Johnson ECE 189A Fall 2012

2 Critical Design Review: Project Description A robot that follows and traces existing lines. Applications: Redrawing existing sports fields, e.g. basketball, tennis, football, soccer Repainting fading street lines Perimeter security Warehouse item retrieval/storage

3 Critical Design Review: Project Description (II) Base proof of concept goals: Following a line with high precision and accuracy. Using a set of rules to be able to find and trace existing lines, without user input. Navigating to specific coordinates of a grid.

4 Critical Design Review: Project Description (III) Combination of sensors and positioning systems: IR Sensors Sonar Reflectance Sensor Array Digital Compass Rotary Encoders

5 Critical Design Review: Subsystem Development Responsibility James (leader) - schematic/pcb, optical sensor Wei - schematic/pcb, digital compass Travis - mechanical - servo, reflective sensor, power Peter - mechanical - motors,wheels, rotary encoders, power All: chassis design/fabrication, schematic, processor

6 Critical Design Review: Block diagram

7 Critical Design Review: Basic Design 1. Reflectance Sensor Arrays 2. Ultrasonic/IR Sensors 3. Freewheels 4. Wheels 5. Rotary Encoders 6. Processor, SDRAM, compass, motor controller.

8 Critical Design Review: Chassis Design

9 Parts: Processor NXP LPC2478 ARM7 Processor External memory interface Integrated ADC I2C Bus PWM Output UART

10 Parts: SDRAM Micron 16bit 128Mb SDRAM 2 MEG X 16 X 4 BANKS 54-PIN TSOP Package Connects to LPC2478 external memory interface

11 Parts: Reflectance Sensor Arrays 2 x QTR-8RC Reflectance Sensor Array 16 total IR Emitters/Detectors will allow us to detect the lines. Consistently polled by the processor Sensing distance: 3-9.5mm to ground Direct digital interface to processor through GPIO Metal Shade will go over them to minimize effects of ambient light.

12 Parts: Digital Compass LSM303DLHC High Performance E-Compass Outputs heading via I2C 5V voltage only Polled by processor

13 Parts: Servo Motor The servo is used to position a marker for drawing lines. HS-55 Micro Servo Motor 3-5V Operation PWM Enable control signal from processor Running Current: 150mA Idle Current : 5.4mA $9.99

14 Parts: IR sensor Sharp GP2Y0A21YK0F IR Range Sensor Object avoidance Detects objects of distance from 10cm to 80cm (4'' to 32''). Output: Analog to Digital V, supply current: 30mA Data Polled by processor

15 Parts: Ultrasonic Sensor Maxbotix LV-MaxSonar-EZ0 Object avoidance Detects objects of distance from 0 to 6.45 meters. (0 to ~21 ft). RS V, at 5V - 3mA Polled by processor

16 Parts: Motors 2x Pololu 12V Metal Brushless DC Gear Motors 67:1 Gear Ratio 250mA Free-Run Current Forward/Backward/Brake/Pivot 75rpm free run speed 0.40m/s using 100mm diameter wheels.

17 Parts: Rotary Encoders Rotary encoders provide feedback to the microprocessor via GPIO. Frequency of output signal provides speed of the motor and distance traveled. Using encoders on both the right and left wheel allows the microprocessor to calculate and correct offset in traveling in the straight line.

18 Parts:Motor Controller Acts as intermediate device between processor, power supply and motors. Provides the high voltage and current requirement the motors need and protects the processor from back EMF Solarbotics L298 Compact Dual Motor Driver Kit Two independent PWM enable signals 4 GPIO logic singles control rotational direction

19 Parts: Voltage Regulators 6V Battery 6V -> 5V LM Amp 3-Terminal Adjustable Regulator R1 = 240ohm R2 = 720ohm 5V ->3.3V LM Amp 3-Terminal Adjustable Regulators R1 = 240ohm R2 = 394ohm Vout = 1.25V(1+R2/R1)

20 Parts: Connectors All of the peripherals will be mounted onto chassis. Jumper cables will be used to attach the devices to connectors on the board. Cost!! Ability to rearrange parts on chassis and test individual device.

21 Schematic rev. 1.9

22 Schematic rev. 1.9

23 Schematic rev. 1.9

24 Schematic rev. 1.9

25 Schematic rev. 1.9

26 Schematic rev. 1.9

27 Schematic rev. 1.9

28 Critical Design Review: Bill of Materials Quantity Part Unit Cost Total Cost 1 Digital compass $19.95 $ Reflectance sensor array $14.94 $ Ultrasonic sensor $26.95 $ IR Sensor $13.89 $ Motor and Rotary Encoders $39.95 $ Motor Controller $18.28 $ Servo Motor $9.99 $9.99 Voltage Regulators, Passive Components ~$30.00 Connectors ~$20 Chassis, Wheels, Mechanical Component, Batteries ~$100 Total $361.85

29 Critical Design Review: Software Overview Software: GCC toolchain: Yagarto WinARM GNUARM QP-Nano ARM7 Framework Eclipse

30 Critical Design Review: Critical Elements Motor control Keeping the bot in a straight path to avoid rough traces. Reflectance Sensor Array Being able to detect a line in an outdoor environment and use that data to accurately position AFRObot.

31 Questions? Suggestions?