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 and LCD
2. GEO and path finding
3. Sensors and bridge app
4. Motor

Team Members & Responsibilities

Priyanka Rai

• • Geographical Controller
  • Master Controller

Ritu Patil

• • Android Application Developer
  • Communication Bridge Controller

Ritika Beniwal

• • Master Controller

Utsav Savaliya

• • Sensors Controller

Dhanush Babu

• • Hardware Integration
  • PCB Designing

Schedule

Week#	Start Date	End Date	Task	Actual Completion	Status
1 02/28 to 03/06 Start of Phase 1	02/28 03/04 03/05	03/04 03/06 03/06	Study and discuss previous project reports Brainstorm on the requirements for the project Identify and order/purchase the required components	03/04 03/06 03/08	Completed Completed Completed
2 03/07 to 03/13	03/08 03/11 03/12	03/08 03/14 03/14	Create and setup Gitlab Repository Study the datasheets and manual of acquired components Distribute initial roles among the team members	03/04 03/17 03/15	Completed Completed Completed
3 03/14 to 03/20	03/15 03/15 03/19 03/18 03/15	03/18 03/18 03/21 03/21 03/27	Interface ultrasonic sensors and test the functionality Interface GPS and Compass and test the functionality Analyze and decide the hardware placement of the RC Car Create SENSOR and DRIVER nodes to transmit and receive data Identify the Android app requirements and start studying the Android framework	03/18 03/22 03/20 03/21 03/25	Not Completed Not Completed Not Completed Not Completed Not Completed
4 03/21 to 03/27	03/22 03/22 03/25 03/27 03/22	03/25 03/24 03/28 03/31 03/28	Create the GEO node to get coordinates and cardinal directions from GPS and Compass Interface the Bluetooth module to communicate with SJ-two board Create the MOTOR node to drive the RC Car Start designing the DBC file Develop an initial version of the Android app	03/24 03/24 03/28 03/30 03/28	Not Completed Not Completed Not Completed Not Completed Not Completed
5 03/28 to 04/03 End of Phase 1	04/02 03/29 03/29 03/29 03/31 04/03	04/03 04/01 04/01 04/01 04/03 04/04	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 Interface the LCD module with the DRIVER node to display messages Integrate sensor data on the SENSOR node Collective Test 1: Integrate all the completed modules and test on BusMaster	04/05 04/01 04/01 04/01 04/04 04/04	Not Completed Not Completed Not Completed Not Completed Not Completed Not Completed
6 04/04 to 04/10 Start of Phase 2	04/05 04/05 04/08 04/10	04/08 04/08 04/10 04/11	Tune the SENSOR and DRIVER nodes to drive the RC car Communicate to the DRIVER node over Bluetooth via Android app Debug and revise the integrated modules with necessary improvements Collective Test 2: Drive the car to a hardcoded GPS destination	04/08 04/08 04/08 04/08	Not Completed Not Completed Not Completed Not Completed
7 04/11 to 04/17	04/12 04/15 04/12 04/17	04/15 04/18 04/16 04/18	Integrate GEO node to DRIVER node for navigation Design driving decision logic based on the navigation data Design a dashboard on the LCD to display the values Collective Test 3: Test the car driving with navigation data from the Android app	04/15 04/18 04/16 04/18	Not Completed Not Completed Not Completed Not Completed
8 04/18 to 04/24 End of Phase 2	04/19 04/19 04/19 04/19	04/25 04/25 04/25 04/25	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	04/25 04/25 04/25	Not Completed Not Completed Not Completed
9 04/25 to 05/01 Start of Phase 3	04/26 04/26 04/26 05/01	04/30 04/30 04/30 05/02	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	04/30 04/30 04/30 05/02	Not Completed Not Completed Not Completed Not Completed
10 05/02 to 05/10	05/03 05/03 05/08	05/07 05/07 05/09	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	05/07 05/07 05/07	Not Completed Not Completed Not Completed
11 05/11 to 05/15 End of Phase 3	05/10 05/10 05/10 05/15	05/16 05/16 05/16 05/16	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	05/16 05/16 05/16 05/16	Not Completed Not Completed Not Completed Not Completed
12 02/28 to 03/06 End of the Project	05/16 05/18	05/20 05/20	Demo Wiki Page Update	05/20 05/20	Not Completed Not Completed Not Completed

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Parts List & Cost

Item#	Part Desciption	Vendor	Qty	Cost
1	RC Car	Traxxas [1]	1	$250.00
2	CAN Transceivers MCP2551-I/P	Comimark [2]	5	$7.00
3	Ultrasonic Sensors	Max Botix[3]	5	$150.00
4	GPS and Antenna	Adafruit[4]	1	$60.00
5	HC05 bluetooth RF Transreceiver	HiLetgo[5]	1	$12.59
6	Triple-axis Accelerometer	Adafruit[6]	1	$21.40
7	Traxxas RPM Sensor	Traxxas[7]	1	$12
8	Discrete Electronic Components	Generic[8]	1	$28.75
9	Buck-Boost Voltage Regulator	Generic[9]	1	$11.99
10	Traxxas Telemetry Trigger magnet & holder	Traxxas[10]	1	$6.35
11	Acrylic Sheet	Tap Plastic	1	$12
12	Battery	Amazon[11]	1	$26.99
13	Traxxas Battery and Charger	Amazon[12]	1	$55.94

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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	300	speed and steering direction for the motor.	Motor
2	310	Destination reached	Sensor
Sensor Controller
1	200	Sensor sonars from front, back, left ,right sensor	Driver
Motor Controller
8	700	motor speed, motor direction	Driver
Geo and Bridge Controller
1	400	Bearing, Heading and Distance	Driver
Debug messages
1	851	Driver Debug	SENSOR,MOTOR,GEO_AND_BRIDGE
1	811	Motor Debug	SENSOR,MOTOR,GEO_AND_BRIDGE
1	801	Sensor Debug	SENSOR,MOTOR,GEO_AND_BRIDGE

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Sensor ECU

Sensor Controller Diagram

Hardware Design

Board Pin Connections

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

Software Design

The sensor node mainly does two activity viz. 1) Read sensor values, 2) Transmit obstacle distance over CAN bus. Both of these activities happen in a 20Hz periodic callback.

1. Read Sensor Values

2. Transmit obstacle distance over CAN bus:

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Motor ECU

Hardware Design

The motor node(SJ-2) interfaces primarily interfaces with:

All these three components have 3 pins each. The functionalities of these pins are mentioned in the table below.

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Geographical And Bridge Controller

Software Design

The GEO controller is divided into 5 parts.

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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

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Mobile Application

Software Design

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

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Conclusion

References

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