S22: Firebolt

Abstract

Firebolt is battery powered autonomous RC car. The car uses four microcontrollers for communication between the nodes- driver node, motor node, bridge & sensor node, and geological node over the CAN bus. It is interfaced to the mobile application which sends GPS coordinates for the destination location to the driver node and reaches the destination by avoiding any obstacles that comes in the path. For obstacle detection and avoidance it uses Ultrasonic Sensor and makes the decision of steering and maintaining speed based on the bridge and sensor node's input.

Objectives & Introduction

Objectives

• RC car can communicate with an Android application to:
  • Receive new coordinates to travel to
  • Send diagnostic information to the application
  • Emergency stop and start driving
• RC car can travel to received coordinates in an efficient path while avoiding obstacles
• RC car can maintain speed when driving on sloped ground
• Design printed circuit board (PCB) to neatly connect all SJ2 boards
• Design and 3D print sensor mounts for the ultrasonic sensors
• Design a simple and intuitive user interface for the Android application
• Design a DBC file

Introduction

The Firebolt RC car uses 4 SJ2 boards as nodes on the CAN bus

1. Driver Node
2. GEO Node
3. Sensors and Bridge Node
4. Motor Node
5. Mobile Application

Team Members & Responsibilities

• Priyanka Rai
  • Geo Controller
  • Bridge and Sensor Controller
  • Wiki Page Update

• Ritu Patil
  • Motor Controller
  • Android Application
  • Integration Testing

• Ritika Beniwal
  • Driver Node
  • PCB Designing
  • Wiki Page Update

• Utsav Savaliya
  • Sensor Controller
  • Driver Node

Schedule

Week#	Start Date	Target Completion Date	Task	Actual Completion Date	Status
Week 1	03/06 03/08 03/12	03/10 03/10 03/12	Study and discuss previous project reports Brainstorm on the requirements for the project Identify and order/purchase the required components	03/10 03/10 03/12	Completed Completed Completed
Week 2	03/13 03/13 03/14	03/14 03/18 03/18	Distribute initial roles among the team members Study the datasheets and manual of acquired components Create and setup Gitlab Repository	03/14 03/18 03/18	Completed Completed Completed
Week 3	03/20 03/22 03/20	03/25 03/26 03/24	Write basic driver for ultrasonic sensor Analyze and decide the hardware placement of the RC Car Create SENSOR and DRIVER nodes to transmit and receive data	03/26 03/23 03/25	Completed Completed Completed
Week 4	03/27 03/27 03/27	04/04 04/01 03/28	Create the GEO node to get coordinates and cardinal directions from GPS and Compass Create the MOTOR node to drive the RC Car Design DBC file and create CAN signals for every node	04/02 04/04 04/01	Completed Completed Completed
Week 5	04/02 04/02 04/02	04/08 04/08 04/08	Finalize the DBC file Design obstacle avoidance and steering logic on the DRIVER node Design motor driving logic on the MOTOR node with the encoder	04/09 04/09 04/09 04/09 04/09	Completed Completed Completed
Week 6	04/ 04/ 04/ 04/	04/ 04/ 04/ 04/	Integrate GPS module with compass to get the current location. Write UART interface for Bluetooth integration on sensor node. Start and design the Bluetooth app xml for destination. Integrate GEO node to DRIVER node for navigation. Check whether the DRIVER node is receiving the coordinates.	04/ 04/ 04/ 04/	Completed Completed Completed Completed
Week 7	04/ 04/ 04/ 04/	04/ 04/ 04 04/	Communicate to the GEO node over Bluetooth via Android app Design driving decision logic based on the navigation data Start designing PCB Board Schematic for mounting the ECUs Collective Test 2: Drive the car to a hardcoded GPS destination	04/ 04/ 04/ 04/	Not Completed Not Completed Not Completed Not Completed
8 04/ to 04/	04/ 04/ 04/ 04/	04/ 04/ 04/ 04/	Design a dashboard on the LCD to display the values Add functionalities to display various sensor data on the Android app Design and 3D print the required components Design and order PCB Test and improve the RC car performance based on the changes Collective Test 3: Test the car driving with navigation data from the Android app	04/ 04/ 04/	Not Completed Not Completed Not Completed
9 04/ to 05/	04/ 04/ 04/ 05/	04/ 04/ 04/ 05/	Design individual architecture diagrams and algorithms for documentation Make any necessary improvements based on previous test results Complete the final version of the Android app Collective Test 4: Test car on various terrains and slopes	04/ 04/ 04/ 05/	Not Completed Not Completed Not Completed Not Completed
10 05/ to 05/	05/ 05/ 05/	05/ 05/ 05/	Replace the circuits with their corresponding PCBs and assemble Complete the RC Car structure and assembly with the 3D printed parts - Prototype 1 Refactor the code modules with necessary improvements Collective Test 5: Test the Prototype 1 with the aim of sending the car to return Preet's PCAN Dongle	05/ 05/ 05/	Not Completed Not Completed Not Completed
11 05/ to 05/	05/ 05/ 05/ 05/	05/ 05/ 05/ 05/	Revise and improve the wiki report to cover all the aspects of design and implementation Fix all the errors and make improvements Final testing of all the modules and car Collective Test 6: Have the final version of the project tested with all the functionalities	05/ 05/ 05/ 05/	Not Completed Not Completed Not Completed Not Completed
12 05/ to 05/	05/ 05/	05/ 05/	Demo Wiki Page Update	05/ 05/	Not Completed Not Completed Not Completed

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Parts List & Cost

Item#	Part Desciption	Vendor	Qty	Cost
1	RC Car	Traxxas [1]
2	CAN Transceivers MCP2551-I/P	Comimark [2]
3	Ultrasonic Sensors	Max Botix[3]
4	GPS and Antenna	Adafruit[4]
5	HC05 bluetooth RF Transreceiver	HiLetgo[5]
6	Triple-axis Accelerometer	Adafruit[6]
7	Traxxas RPM Sensor	Traxxas[7]
8	Discrete Electronic Components	Generic[8]
9	Buck-Boost Voltage Regulator	Generic[9]
10	Traxxas Telemetry Trigger magnet & holder	Traxxas[10]
11	Acrylic Sheet	Tap Plastic
12	Battery
13	Traxxas Battery and Charger

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Printed Circuit Board

PCB Schematic

PCB Design

CAN Communication

We use controller area network to broadcast data between the 4 nodes. All nodes are connected to each other through a physically conventional two wire bus. The wires are a twisted pair with 120 Ω resistors at each ends of the bus. 1s and 0s are transmitted as CAN High(0V difference) and Can Low(2v difference). A CAN frame has the following contents:

• Data Length Code (4bits)
• Remote Transmission Request.
• ID extend bit.
• Message ID (11 bit or 29 bit)
• Data bytes( depends on DLC)
• CRC

Arbitration: No two nodes will transmit at the same time because if arbitration. A lower Message-ID has a Higher priority on the CAN bus since 0 is the dominant bit.

Bit Stuffing: CAN bus stuffs extra bits when a long chain of multiple 1's or 0's occur to improve CAN integrity.

Sr. No	Message ID	Message function	Receivers
Driver Controller
1		speed and steering direction for the motor.	Motor
2		Destination reached	Sensor
Sensor Controller
1		Sensor sonars from front, back, left ,right sensor	Driver
Motor Controller
8		motor speed, motor direction	Driver
Geo and Bridge Controller
1		Bearing, Heading and Distance	Driver
Debug messages
1		Driver Debug	SENSOR,MOTOR,GEO_AND_BRIDGE
1		Motor Debug	SENSOR,MOTOR,GEO_AND_BRIDGE
1		Sensor Debug	SENSOR,MOTOR,GEO_AND_BRIDGE

Hardware Design

DBC File

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Sensor ECU

Sensor Controller Diagram

Hardware Design

Sensor Controller Schematic

Board Pin Connections

Sensors are interfaced with combination of GPIO, ADC Pins on SJTWo board. Below is the descriptive pin layout:

Software Design

Technical Challenges

Neighboring Sensor Interference:

Frequent noisy measurements:

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Motor ECU

Hardware Design

Software Design

Technical Challenges

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Geographical And Bridge Controller

Hardware Design

Software Design

Technical Challenges

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Driver Node

Hardware Design

The Driver Node has one peripheral connected to it and that is the LCD screen.

Software Design

• Driver Node Flow Chart

Technical Challenges

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Mobile Application

User Interface

Software Design

This app has mainly two activities, The main activity and maps activity.

Maps Activity

Bluetooth/WIFI

Technical Challenges

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Conclusion

Project Video

Project Source Code

Advise for Future Students

Acknowledgement

References

http://socialledge.com/sjsu/index.php/Industrial_Application_using_CAN_Bus