F14: Team3-Self Driving Car - Optimus Prime

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Contents

Grading Criteria

  • How well is Software & Hardware Design described?
  • How well can this report be used to reproduce this project?
  • Code Quality
  • Overall Report Quality:
    • Software Block Diagrams
    • Hardware Block Diagrams
      Schematic Quality
    • Quality of technical challenges and solutions adopted.

Optimus Prime: The Self-driving Car

This project report is about designing and building a self governing car, capable of sensing its environment and navigating without human input. The car senses its surroundings and is capable of updating their maps based on sensory input, allowing the vehicle to keep track of its position.

Abstract

This project is about developing a self driven car. It consists of 6 controllers - Master, Motor, Sensor, GPS, Communication Bridge and I/O, which communicate with each other over the CAN bus as shown below. Each controller sends out the information over the CAN bus in the form of messages. Every controller receives only the required messages and performs the necessary task. The path navigation is achieved by the GPS. Thus the controllers do the task of a driver and navigate the path by avoiding the obstacles.

Project Block Diagram

Parts List & Cost

Item# Part Desciption Vendor Part Number Qty Cost
1 RC Car Amazon.com Traxxas 37076 Rustler VXL 1 $380.57
2 RC Car Battery Amazon.com Traxxas 2926 NiMH 8.4V Hump 3000mAh TRA Connector 2 $67.38
3 CAN Transceiver Texas Instrument SN65HVD232D 15 $75.00
4 Assembly Components Amazon.com, Anchor & HSC PCBs, Mechnical & Electical Components NA $110.80
5 Power Supply Pololu.com 6V Battery, 5V Regulator 1 $34.85
6 Sonar sensor Maxbotix LV-MaxSonar-EZ1 MB1010 3 $99.55
7 Sonar sensor Given by Preet LV-MaxSonar-EZ1 MB1010 1 Free
8 Compass Module Given by Preet HoneyWell: HMC 6352 1 Free
9 LCD Display New Haven NHD-0216B3Z-FL-GBW-V3-ND 1 $$$.$$
10 Battery Status Amazon.com Dc 4.0-30v LED Digital Display Voltage Meter 1 $6.91
Total Cost $$$.$$

Introduction

CAN Bus: A brief introduction

The Six Controllers

Design & Implementation

Controller Communication Table

Controllers
Controller ID Controller Type
0x01 Master Controller
0x02 Motor Controller
0x03 Sensor Controller
0x04 Geographical Controller
0x05 IO Controller
0x06 Bridge Controller
Common Communication Table
Message Number Purpose / Data layout
0x101 Get version and boot info
0x102 Get general info
0x103 Synchronize (set) time: 
byte [0-3] : System time
0x201 
byte [0-3] : Version Info
byte [4-7] : boot timestamp
0x202 
byte [0-3] : Current time
byte [4]   : CPU usage %
Subscription Rate Info
Byte 0 Effect
0 Off
1 1Hz
5 5Hz
10 10Hz
20 20Hz
50 50Hz
Any other value Invalid date rate

Master Controller

Group Members: 

Bhargava Leepeng Chandra
Shashank Tupkar
Preeti Benake

Master Controller Team Schedule

Week No. Start Date Planned End Date Task Status Actual End Date
1 9/30/2014 10/7/2014 
* Implement Basic CAN Hardware to communicate between 2 Controllers
  • Completed
We are able to send a message from Tx over CAN and perform a specific operation at the Rx.
 10/7/2014
2 10/7/2014 10/14/2014 
* Design CAN Acceptance Filter among different Controllers
* Define and Implement CAN Frame structure for proper communication
  establishment
  • Completed
Only messages with in range of acceptance filter are received, Decided on CAN frame structure using 11-bit frame.
 10/11/2014
3 10/14/2014 10/21/2014 
* Develop Inter-Controller Communication over CAN
* Test point-to-point and Broadcast message transmission
* Implement a Counter to count and display number of messages
  • Completed
CAN Communication among multiple boards achieved, Point-to-Point & Broadcast modes are working, Able to display the count on 7-Seg Display on SJOne board.
 10/19/2014
4 10/21/2014 10/28/2014 
* Layout blueprint for Controller and Module positioning 
* Assemble the RC Car with all the controllers and Modules
* Define the Message List by working with other teams
* Start working on CAN Periodic message structure
  • Completed
RC car design and module assembly is completed. Need some fine tuning for connections. Message list is generated and periodic message implementation started.
 10/28/2014
5 10/28/2014 11/04/2014 
* Complete CAN Periodic message structure to transmit Broadcast
  messages over CAN and establish controlled communication among
  different controllers 
* Implement Start condition detection and Fetch boot status from
  all controllers and display the status of each controller
  • Completed
Periodic Message Setup done. Able to receive boot status. Need to work on display of status.
 11/03/2014
6 11/04/2014 11/11/2014 
* Design 'Kill Switch' in co-ordination with Motor Controller team
  and Bridge Controller team
* Develop a 'CAN Bus Crash' detection and reset CAN Bus methodology
* Design Automatic Head Light turn ON/OFF functionality by
  working with Sensors Controller team
  • Completed
Kill Switch implemented through Bridge controller. Head Lights implemented. LCD display of Status achieved.
 11/11/2014
7 11/11/2014 11/18/2014 
* Implement File Log saving to SD Card at periodic intervals
* Work on Restoring to last known Status if the system crashes while running
* Develop Detection technique if controllers are reaching 'Error State'
  • Completed
File Log implemented. Error State is partially implemented. Obstacle detection achieved. Needed refinement in Direction control logic. Need to implement reverse logic.
 11/18/2014
8 11/18/2014 11/25/2014 
* Project Integration and testing Basic Self_Drive Capability of the Car
* Check the Functionality and behavior of all controllers in all the known 
  contexts
* Perform modifications (if any) to eliminate any bugs to make the car work
  seamlessly
* Final Integration of car and testing there after
  • Completed
Integration Started. Faced difficulty in synchronization.
11/26/2014
9 11/25/2014 12/02/2014 
* Final Integration and testing Self_Drive Capability of the Car
  • Ongoing
 --/--/----

Hardware Design

Include Block Diagram

Hardware Interface

Include Pin Diagram, Pin Connectivity Table

Master Controller Pin Connectivity Table
Description Your Device Port SJOne Development Board Port Commands Note
Supply Voltage
Ground GND
CAN Transceiver Pin no. 1 Driver Input

Pin no. 4 Receiver Output

P0.1 CAN TD1

P0.0 CAN RD1

Software Design

Implementation

Include Communication Table

Master Controller Communication Table
Message Number Purpose Data Byte Pattern
0x101 Ask for Boot and Version Info. of all Controllers 
Byte[0]: Send a '1'
0x103 Sync. Master System Time on all Controllers 
Byte[0-3]: System Time [HH:MM:SS]
0x201 Master Gets Status Update from all controllers 
Byte[0]: Boot Status
Byte[1]: Version Info.
0x203 Master Gets current Time from all Controllers 
Byte[0-3]: Time in [HH:MM:SS]
0x301 Master Enable Main UI in Android 
Byte[0]: Send a '1'
0x302 Master set GPS Destination on Geo Controller 
Byte[0-3]: Latitude Value
Byte[4-7]: Longitude Value
0x303 Master set Longitude Way-Points on Geo 
bytes [0-1] : Total Way-Points count
bytes [2-3] : Way-Point index
bytes [4-7] : Longitude(float)
0x304 Master set Latitude Way-Points on Geo 
bytes [0-1] : Total Way-Points count
bytes [2-3] : Way-Point index
bytes [4-7] : Latitude(float)
0x305 Master Send GPS FIX Ack to Bridge 
Byte[0]: Send a value '1'
0x306 Master Send Dest. Reached Ack to Bridge 
Byte[0]: Send a Value '1'
0x500 Display Boot and Version Info. on LCD 
Byte[0]: Boot Status Response
Byte[1]: Version Info.
0x501 Display Controllers Time on LCD 
Byte[0-3]: Time in [HH:MM:SS]
0x502 Display Destination Has Reached 
Byte[0]: Send a '1'
0x503 Master Set Speed and Direction of Motor 
Byte[0]: LEFT/RIGHT (or) FRONT/BACK command
0x504 Display Speed of Motor on LCD 
Byte[0]: Speed Value
0x505 Display GPS and Compass values on LCD 
Byte[0-1]: New Degree to Head
Byte[2-3]: Dist to Destination
Byte[4-5]: Current Degree value
0x506 Display Sensor Values on LCD 
Byte [0]: Front sensor value in inches
Byte [1]: Front Left sensor value in inches
Byte [2]: Front Right sensor value in inches
Byte [3]: Back sensor value in inches
0x507 Display Battery Status on LCD 
Byte[0]: Battery Status Value

Testing and Technical Challenge

Motor Controller

Group Members: 

Shashank Tupkar
Naghma Anwar
Shiva Moballegh

Motor Controller Team Schedule

Week No. Start Date Planned End Date Task Status Actual End Date
1 9/30/2014 10/7/2014 
* Study SJOne board's motor controller concepts and PWM
  • Completed
Very simple code. Just two lines. Set the frequency. Set the duty cycle.
 10/7/2014
2 10/7/2014 10/14/2014 
* Open up RC Car's motor and servo connections 
* Study the Electronic Speed Control's functions
  • Completed
Motor and Servo operate on the same frequency
ESC needs calibration each time it is switched on. Need to find a solution for this.
 10/11/2014
3 10/14/2014 10/21/2014 
* Define the duty cycles for proper motor and servo signals
  • Completed
Using trial and error, figured out the duty cycle for constant speed and turns
 10/19/2014
4 10/21/2014 10/28/2014 
* Add CAN frame structure to the motor functions 
* Test for communication between motors and sensors for prototype demo 
* Define the Message List by working with other teams
  • Completed
 11/04/2014
5 10/28/2014 11/04/2014 
* Start working on CAN Periodic message structure
* Start looking for speed sensors
  • Completed
Bought magnetic speed sensor from Traxxas telemetry
from local RC Car store
 11/04/2014
6 11/04/2014 11/11/2014 
* Attach speed sensors to the motor
* Test CAN communication between motor controller and other controllers
  • Completed
Speed sensors attached
 11/11/2014
7 11/11/2014 11/18/2014 
* Work on speed sensors. Figure out the way to send sensor data to master controller. 
* Test for proper and accurate CAN communication
  • Completed
 11/18/2014
8 11/18/2014 11/25/2014 
* Project Integration and testing basic self drive capability of the car
* Check the functionality and behavior of the motor controller in all the known 
  contexts
* Perform modifications (if any) to eliminate any bugs to make the motor work
  seamlessly
* Final Integration of car and testing there after
  • Ongoing
 --/--/----

Hardware Design

Include Block Diagram

Hardware Interface

Include Pin Diagram, Pin Connectivity Table

Motor Controller Pin Connectivity Table
Description Your Device Port SJOne Development Board Port Commands Note
Supply Voltage 6V from NiMH battery N/A
Ground GND (Black Wire) GND
ESC 
 Control (White Wire)

 P2.0 PWM

 PWM motor(PWM::pwm1, 101);
 motor.set(14.5);

 Sets PWM signal of 101 Hz
 Sets duty cycle of 14.5% for forward movement
Servo 
 Control (White Wire)

 P2.1 PWM

 PWM servo(PWM::pwm2, 101);
 servo.set(15);

 Sets PWM signal of 101 Hz
 Sets duty cycle of 15% for no turn
CAN Transceiver 
 Pin no. 1 Driver Input
 Pin no. 4 Receiver Output

 P0.1 CAN TD1
 P0.0 CAN RD1

 TI CAN Transceiver SN65HVD232D
 Pin 7 - CAN H & Pin 6 - CAN L

Software Design

Include Flow Chart

Implementation

Include Communication Table

Motor Controller Communication Table
Message Number Purpose Data layout
0x508 Speed Sensor Data 
byte [0] : Speed sensor value in rpm
0x509 Vehicle Direction/Movement Data 
byte [0] : Movement Control
     0x1 : Forward
     0x2 : Reverse
     0x3 : Stop
byte [1] : Steering Control
     0x1 : Left
     0x2 : Right
     0x3 : Straight

Testing and Technical Challenge

Sensor Controller

Group Members: 

Deepak Yadav
Vinod Pangul

Sensor Team Schedule

Sl.No Start Date End Date Task Status Actual Completion Date
1 10/6/2014 10/18/2014 Order Ultra Sonic Sensors Completed [Got two sensors (front and back), 2 more (front right & left) to order ->Completed.] 10/19/2014
2 10/9/2014 10/9/2014 Sensor Data Sheet review with the team Completed 10/9/2014
3 10/9/2014 10/16/2104 Sensor code development Completed (Implementing filter (HW/SW) to get more accurate data ->(Done). Add logic to get the rest of the three sensor(front right/left and back data)->(Done) (Note: Delayed due to the implementation of CAN structure and calibration of IR sensor) 10/21/2014
4 10/22/2014 10/25/2014 Sensor software testing Ongoing
5 10/25/2014 10/28/2014 Sensor real time testing Ongoing
6 10/13/2014 10/15/2014 Light sensor code Development Completed 10/14/2014
7 10/13/2014 10/15/2014 Accelerometer sensor code Development to detect tilt Completed 10/14/2014
8 10/15/2014 10/15/2014 Light Sensor and Accelerometer Testing Completed 10/15/2014
9 10/29/2014 10/31/2014 Battery status controller circuit Design Ongoing
10 11/01/2014 11/02/2014 Battery status-circuit Testing
11 11/03/2014 11/04/2014 Common Communication SW code implementation and testing
11 11/04/2014 11/09/2014 Complete Hardware testing-1
12 11/10/2014 11/15/2014 Complete Hardware testing-2

Hardware Design

Include Block Diagram

Sensors : Sonar Sensors + IR Sensors

A) Sonar Sensor:

  • The ultrasonic sensors are in air, non-contact object detection and ranging sensors that detect objects within an area.
  • We are using 3 such sensors in front to get wide angle vision for the car.
  • Ultrasonic sensors use high frequency sound to detect and localize objects in a variety of environments. Ultrasonic sensors measure the time of flight for sound

that has been transmitted to and reflected back from nearby objects. Based upon the time of flight, the sensor then outputs a range reading.

B) Infrared Sensor (IR):

  • The basic principle of operation of an infrared sensor is based on infrared light that is reflected when its hits an an obstacle. An IR receiver captures

the reflected light and the voltage are measured based on the amount of light received.

  • IR Sensors have 3 pins to connect to SJOne Board:


1) Ground (GND)
2) +Vcc (5 V)
3) Vo (ADC-4 is on P1.30, select this as ADC0.4)

IR Sensor Block Diagram
Calibrated voltage output with distance

Hardware Interface

Include Pin Diagram, Pin Connectivity Table

Sensor Controller Pin Connectivity Table
Description Your Device Port SJOne Development Board Port Commands Note
Supply Voltage
Ground GND
Sonar Sensor
IR Sensor
CAN Transceiver Pin no. 1 Driver Input

Pin no. 4 Receiver Output

P0.1 CAN TD1

P0.0 CAN RD1

Software Design

Include Flow Chart

Implementation

Include Communication Table

Sensor Controller Communication Table
Message Number Purpose Data layout
0x510 Front/Back Range Sensor Data 
byte [0] : Front sensor value in inches
byte [1] : Front Left sensor value in inches
byte [2] : Front Right sensor value in inches
byte [3] : Back sensor value in inches
0x511 Accelerometer/Light/Battery Sensor Data 
byte [0] : X axis Value
byte [1] : Y axis Value
byte [2] : Z axis Value 
byte [3] : Light sensor value
byte [4] : Battery status value

Testing and Technical Challenge

Geographical Controller

Group Members: 

Bhushan Gopala Reddy
Ryan Marlin
Rishikesh Nagare

Geographical Team Schedule

Sl.No Start Date End Date Task Status Actual Completion Date
1 10/4/2014 10/13/2014 Research and Order GPS module Received GPS module 10/7/2014
2 10/7/2014 10/18/2014 Interface GPS module with LPC1758 Finished 10/17/14
3 10/14/2014 10/18/2014 Receive Compass module from Preet Received 10/9/2014
4 10/18/2014 11/4/2014 Parse GPS data and setup constructs to send appropriate data Ongoing
5 10/14/2014 10/18/2014 Interface the Compass Module Finished 10/16/2014
6 10/25/2014 11/4/2014 Calibration of Compass Code completed. Need to test using the car --/--/----
7 11/4/2014 11/11/2014 Integrate GPS and Compass data Ongoing
8 10/25/2014 11/09/2014 Testing and mapping of GPS co-ordinates Ongoing
9 11/18/2014 11/25/2014 Final integration and testing

Hardware Design

Include Block Diagram

Hardware Interface

Include Pin Diagram, Pin Connectivity Table

Geographical Controller Pin Connectivity Table
Description Your Device Port SJOne Development Board Port Commands Note
Supply Voltage Vcc 3v3
Ground GND GND
GPS Module 
Channel 1 -> Rx, Channel 2 -> Tx 

Channel 1-> Tx P2.8, Channel 2-> Rx P2.9
Compass 
SCL
SDA

SCL2 -> P0.11
SDA2 -> P0.10
CAN Transceiver 
Pin no. 1 Driver Input
Pin no. 4 Receiver Output

P0.1 CAN TD1
P0.0 CAN RD1

Software Design

Include Flow Chart

Implementation

Include Communication Table

GPS Controller Communication Table
Message Number Purpose Data layout
0x518 Send GPS Data to Master 
 byte [0] : New Degree
 byte [1] : Distance
 byte [2] : Current Degree
0x519 Send GPS FIX ACK to Master 
 byte[0]: Send a '1'
0x52A Send Destination Reached ACK to master 
 byte[0]: Send a '1'

Testing and Technical Challenge

Android & Communication Bridge Controller

Group Members: 

Chia Pin Tseng
Johnny Yam
Kevin Beadle

Communication Bridge & Android Team Schedule

Sl.No Start Date Planned End Date Task Status Actual End Date
1 9/30/2014 9/30/2014 Obtain Bluetooth Module (already had one) Done 9/30/2014
2 9/30/2014 10/14/2014 Develop Basic Android App with Bluetooth Sensor Communication Done 10/7/2014
3 10/11/2014 10/14/2014 Interface Bluetooth Module with SJSU Dev Board Done 10/11/2014
4 10/12/2014 10/19/2014 Be able to send bi-directional arbitrary messages between Android App and Dev Board via Bluetooth Done 10/14/2014
5 10/14/2014 11/21/2014 Subscribe to all CAN messages and dump all of them via Bluetooth to Android App or web interface Done 11/24/2014
6 10/14/2014 11/21/2014 Ajax & Websocket server remote structure Done 11/01/2014
7 10/14/2014 11/21/2014 Be able to input GPS coordinates through either (or both) Android App and web interface and send through Bluetooth then CAN bus Done 11/24/2014
8 10/21/2014 11/24/2014 Android App and webpage GUI enhancements (Google Maps, Google Drive) Done 11/24/2014
9 10/21/2014 11/30/2014 Data visualization (status, compass, speed, location,....) On going TBD

Hardware Design

  • In order to facilitate wireless communication between the SJSU One Board and a Android device, a Bluetooth Bee module is used. This module was chosen because it can connect and mount directly onto the SJSU One Board's XBee breakout socket.
  • The Bluetooth Bee is a Serial Profile Port (SPP) Bluetooth interface that connects with the SJSU development board's UART3.
Bluetooth Bee Module

Hardware Interface

The relevant pin connectivity table between the Bluetooth Bee module and the SJSU One Development Board is shown below:

Communication Bridge Pin Connectivity Table
Description Bluetooth Bee Port SJSU Development Board Port CAN Transceiver
3.3V Supply Voltage 3V3 3V3 3V2
Ground GND GND GND
UART Channel 1 TX RX
UART Channel 2 RX TX
CAN TXD CAN TD1 TXD
CAN RXD CAN RD1 RXD

The Bluetooth Bee Module interfaces with an Android device through Bluetooth. In addition, various commands and data are then sent and received to and from the CAN bus through the Bluetooth Module to the Android device.

Software Design

  • The bridge controller and Android APP work as routers

Bridge Controller

  • Bridge controller translates CAN bus data into plain text and send it to android platform
  • The Bridge controller is comprised of the SJSU Development Board with the Bluetooth Bee Module.
  • The Bluetooth Bee Module can be configured by writing to UART3 specific commands as specified in the Bluetooth Bee Seeedstudio Wiki.
  • The Bluetooth Bee Module was configured as SLAVE MODE via the command: \r\n+STWMOD=0\r\n (The Android device will act as the Bluetooth Master)
  • The Bluetooth device name was set to "Yam_BluetoothBee" using the command: \r\n+STNA=Yam_BluetoothBee\r\n
  • Allowing other devices to connect to the Bluetooth Module was enabled using the command: \r\n+STOAUT=1\r\n
  • Finally the Bluetooth Bee Module started broadcasting/inquiring to connect to another device using the command: \r\n+INQ=1\r\n
  • There are many other commands, such as to change the default pincode value, but they were not used for this project.


Bridge framework

Android Controller

  • Android platform receives the text data from bridge controller, then, transmit the data through ajax or websocket
  • External controller could be any TCP accessible device (simple pebble watch program (20 lines) are used to control start and stop)
  • One administrator(control and receive), multiple observers(only receive)
  • Number of way points and routing is dynamically determined and done using the Google Maps API


Bridge framework
cross platform


Intro
Intro
Intro
Intro


Implementation

Communication Bridge Communication Table
Message Number Purpose Data layout
0x528 Set Car Speed (Kill Switch) - temporary allow for other non-zero value for demo byte[0] - speed value
0x529 Destination GPS location

bytes [0-3] : latitude (float) bytes [4-7] : longitude (float)

0x52A Turn to degree

bytes [0-3] : degree(float)

0x52B Way points longitude 
bytes [0-1] :total waypoints count
bytes [2-3] :waypoint index
bytes [4-7] : longitude(float)
0x52C Way points latitude 
bytes [0-1] :total waypoints count
bytes [2-3] :waypoint index
bytes [4-7] : latitude(float)
0x52D remote status (ie. Android connection status) 
bytes [0]=>
0:disconnected(passive send)
1:on disconnect(active)
2:connected(passive)
3:on connect(active)
0xFF:error(active/passive)

Testing and Technical Challenge

I/O Unit Controller

Group Members: 

Shreeram Gopalakrishnan
Sreeharsha Paturu Gangadhara

IO Team Schedule

Sl.No Start Date End Date Task Status Actual Completion Date
1 10/7/2014 10/13/2014 Research and Order LCD Display Ordered LCD Display 10/13/2014
2 10/14/2014 10/21/2014 Interfacing LCD Display with LPC1758 Completed 10/21/2014
3 10/21/2014 10/28/2014 Implementing CAN structure with LCD tasks. Completed 11/30/2014
4 10/28/2014 11/04/2014 Subscribe data from motor, sensor and GPS controller,display it on LCD. Ongoing
5 11/04/2014 11/11/2014 Setup hardware and write code for START, STOP and Headlight buttons. TBD
6 11/11/2014 11/18/2014 Testing and mounting hardware on car. TBD
7 11/18/2014 11/25/2014 Final Testing TBD

Hardware Design

Include Block Diagram

Hardware Interface

Include Pin Diagram, Pin Connectivity Table

I/O Controller Pin Connectivity Table
Description Your Device Port SJOne Development Board Port Commands Note
Supply Voltage 5V supply 
 Receives 5V supply that is used to power up all the boards
Ground GND GND
LCD Display 
 Rx pin
 Tx pin 

 Rx ---> TXD2 (Port 2.8)
 Tx ---> RXD2 (Port 2.9)

 u2.putline("F0")
 u2.putline("$CLR_SCR")
 u2.putline("$GOTO:3:0")

 Initialization command for LCD
 Clears the screen
 Point the cursor to line number 0 and character number 3
CAN Transceiver 
 Pin no. 1 Driver Input
 Pin no. 4 Receiver Output

 P0.1 CAN TD1
 P0.0 CAN RD1

Software Design

Include Flow Chart

Implementation

Include Communication Table

IO Communication Table
Message Number Purpose Data layout
0x520 Subscribe to Sensor data bytes [0-5] : Sensor Value in Inches
0x521 Subscribe to Motor data bytes [0-2] : Vehicle Direction
0x522 Subscribe to Compass Data bytes [0] : Compass Data in degrees
0x523 Subscribe to Battery Status bytes [0] : Battery Status Value

Testing and Technical Challenge

I/O Unit:

  • The IO Control Unit manages the LCD Display, switch to start and stop the car
  • It receives CAN data from the Master controller and accordingly processes to display on the LCD through UART
  • The 7 segment LED displays the CPU usage

LCD Display

  • The LCD Display is placed on the rear side of our RC Car
  • It displays the sensor and GPS values in real time.
LCD Software Interface



Hardware Interface

Motor Controller

Hardware Design

Anatomy of The Rustler

Parts and their functions
Velineon 3500 Brushless Motor

Motor : Our RC car came with Velineon 3500 Brushless Motor. One of the main drawbacks of brushless motor is that it requires a speed controller to change the field polarity. We can't just give power to the motor directly and expect it to go. We can almost consider the controller as an integral part of the motor itself.

Velineon VXL-3s ESC

ESC : Electronic speed controller was the trickiest part to deal with, since it comes with a previously programmed microcontroller inside it. It needs callibration, for which you need to refer to the user manual. An electronic speed controller basically controls the power given to the motor. Our RC car came with VXL-3s ESC, which accepted 100 Hz PWM input signal whose duty cycle varied from 10% to 20%. When supplied with a 15% duty cycle at 100 Hz, the ESC responded by turning off the motor attached to its output.

Steering Servo : Our RC car was equipped with a digital servo (Traxxas part #2075) for steering control. It does not require an ESC to operate. We can give PWM signal directly to the servo from the SJOne board. The servo accepted 100 Hz PWM input signal whose duty cycle varied from 10% to 20%, where 10% represents extreme right turn and 20% represents extreme left turn.
Steering Servo

Speed Sensor : To measure the RPM and speed of our car, we used the speed sensor provided by Traxxas Telemetry. This magnetic speed sensor worked on Hall effect. To learn more about Hall effect sensors, you can click on this wikipedia article. Since the sensor was provided by the same brand of our car, the installation was quick and easy. Here's a reference video on how to attach magnetic speed sensor to the RC car.

Traxxas 7-Cell 8.4V NiMH Battery Pack

Battery : We used 7 Cell NiMH (Nickel-Metal Hydride) battery pack for our car but would recommend others to use Lipo (Lithium Polymer) batteries instead. NiMH batteries tend to discharge very quickly. Also we realized later that since this car was made for racing purpose, its speed was too fast for our project. We reduced the voltage by removing 2 cells from the 7 cell battery pack. So, go for the 5 cell battery pack instead. A Traxxas EZ-Peak Charger would help a lot while doing testing.

Hardware Interface

Motor and Servo Interface

Capture13.PNG

Speed Sensor Interface

Software Design

Master Controller

The software implementation of the master controller is explained by the flowchart.

CMPE243 Team3 MASTER.jpeg

Testing & Technical Challenges

Sensor Controller

  • Front and Back Sensors Controller
    • Describe how you tested the Sensors and calibration of the sensors

Mention the Issues you faced and also the solutions you'll used to overcome the problem.

Motor Controller

  • Motor Controller
    • Describe how you tested the motors. Explain the speed control methods used and difficulties you faced during calibration.

Mention the Issues you faced and also the solutions you'll used to overcome the problem.

I/O Controller

LCD junk values

->Junk values being printed:

  • Although this error was not a show stopper, LCD printed junk values whenever it was on and any of the boards were programmed.
    • So, the only solution was to never program the board (connect the board to laptop) when LCD is on.

->Coding improvement

  • In the code, initially, the GPS, Sensor values were being printed in one line in the code. So, either the values were overwritten or there was shifting of those values. This was a synchronization issue.
    • Resolved it by, clearing each line in the LCD before printing it and used individual line in the code to print the values.

Communication Bridge

TESTs

  • 100000 message(20bytes per message) Bluetooth transmission between board and android under 200fps with range <5m
    • 100% success

ISSUE

  • 3G network server could not be access(3G network is used for long range communication)
    • might use google sheet or external server to communicate

Geographical Controller

  • Geographical Controller
    • Describe how you tested the Compass and explain how did you manage to achieve the maximum accuracy.

Mention the Issues you faced and also the solutions you'll used to overcome the problem.

Master Controller

  • Master Controller functions as the brain of car. The only challenge was integrating the master controller with the remaining five controllers.
    • Describe how you tested the Master Controller and problems faced while integrating it with all the other controllers.

Mention the Issues you faced and also the solutions you'll used to overcome the problem.

Conclusion

Project Video

Project Source Code

References

Acknowledgement

References Used

http://www.ti.com/product/sn65hvd232

http://www.socialledge.com/sjsu/index.php?title=Self-driving_Car

http://www.nxp.com/documents/user_manual/UM10360.pdf

http://www.socialledge.com/sjsu/images/d/de/2012SJOneBoardSchematic.pdf

http://www.maxbotix.com/documents/MB1010_Datasheet.pdf

http://www.sharpsma.com/webfm_send/1208

https://www.sparkfun.com/datasheets/Components/HMC6352.pdf

http://www.seeedstudio.com/wiki/Bluetooth_Bee

Appendix

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