S23: Meh-sla Automotive

1 Project Title
2 Abstract
- 2.1 Introduction
- 2.2 Team Members & Responsibilities
3 Schedule
4 Parts List & Cost
5 System Hardware Design
6 CAN Communication
- 6.1 Hardware Design
- 6.2 DBC File
7 Sensor and Bridge Controller
8 Motor ECU
9 Geological Controller
10 Communication Bridge Controller
11 Driver/LCD Controller
12 Master Module
13 Mobile Application
14 Conclusion

Project Title

¯\_(ツ)_/¯ Meh-Sla Automotive ¯\_(ツ)_/¯

Abstract

The ultimate goal of the project is to design an autonomous car which navigate from its current location to a destination. Along it's way it needs to avoid the obstacles and follow the waypoints. To achieve this we are using four SJ2 boards which communicates with each other via CAN bus along with required sensors and a mobile app which communicates with one of the SJ2 boards via Bluetooth. Through our experience, we knew that we wouldn't be the Worst-Sla. We say that we are Meh-Sla even though we know we are the Best-Sla.

Introduction

The project was divided into 5 modules:

1) Sensor and bridge controller:

Interfaced with 4 ultrasonic sensors for obstacle detection.
Interfaced with a Bluetooth module for the controller to mobile app communication.

2) Motor controller:

Interfaced with vehicle motor to control its speed and steering.
Interfaced with RPM sensors to get feedback about the vehicle's speed.

3) Geographical controller:

Interfaced with a magnetometer to get the current heading of the vehicle.
Interfaced with a GPS module to get the current location information.

4) Driver and LCD controller:

Process information from the sensor and geological board, and send speed and steering to the motor board based on obstacle avoidance and path determination algorithm.
Interfaced with an LCD module to display the vehicle status.

5) Mobile App:

Communicates over Bluetooth.
Sends destination location or start/stop signal to the car.
Receives sensor and other navigation status and displays it.

Team Members & Responsibilities

Gitlab Project Link

Tony Zunino

Team Lead
Motor Board

Sindhuja Ravi

Geo Board
Android App

Stephen Oneto

Driver and LCD Board

Karthigai Amutha Ezhilarasu

Sensor Board
Geo Board

Phil Bloxom

Hardware Setup
Software Testing

Schedule

Week #	Start Date	End Date	Task	Status
1	2/12/2023	2/18/2023	Read previous projects, gather information and discuss among group members	Completed
2	2/19/2023	2/25/2023	Brainstorm on the requirements for the project Create a high-level block diagram of the project	Completed Completed
3	26/2/2023	3/4/2023	Order the RC Car Order all the sensors	Completed Completed
4	3/5/2023	3/11/2023	Learning to use CAN BUSMASTER Test all the parts received and order any missing or damaged parts Test RC Car is functional	Completed Completed Completed
5	3/12/2023	3/18/2023	Establish CAN transmit and receive functionality, start formatting DBC messages DBC file discussed and implemented	Completed Completed
6	3/19/2023	3/25/2023	Discuss modules needed for PCB, any feature requests Purchase PCBs	Completed Completed
7	3/26/2023	4/1/2023	Finalize preparations and research during Spring Break Start working on way point algorithm Start working on obstacle avoidance algorithm	Completed Completed Completed
8	4/2/2023	4/8/2023	Work on the power supplies for boards Interface Bluetooth for bridge controller Integrate the GEO sensor and controller Interface with RC car and start working on DRIVER and MOTOR nodes Write a basic implementation of the sensor controller	Completed Completed Completed Completed Completed
9	4/9/2023	4/15/2023	Integrate compass Install RPM Sensor Start Mobile Application development Finalize power supply choice and how it integrates with PCB Finish PCB designs for each subsystem Begin design of entire RC car assembly First outdoor tests commence	Completed Completed Completed Completed Completed Completed Completed
10	4/16/2023	4/22/2023	Finish 1st vehicle prototype Complete basic mobile application Interface motor and steering together Begin implementation of RPM sensor for PID control Connect all boards to PCB and begin implementation Write motor test routines to define in mobile application Continue outdoor test	Completed Completed Completed Completed Completed Completed Completed
11	4/23/2023	4/29/2023	Populate PCB and prepare for installation Finalize GPS module + create unit_tests First final draft MR for motor_board branch First final draft MR for bridge_controller branch First final draft MR for sensor_board branch First final draft MR for geo_board branch Continue outdoor tests	Completed Completed Completed Completed Completed Completed Completed
12	4/30/2023	5/6/2023	Finish mobile application Begin working on wiki Begin PID control for motor on hill Integrate initial mobile application features First North Garage tests commence	Completed Completed Completed Completed Completed
13	5/7/2023	5/13/2023	Fix bugs with altogether integration Finalize PID control Clean up code for branches --> update master branches More North Garage tests	Completed Completed In-Progress Completed
14	5/14/2023	5/19/2023	Add RC Car designs (pirate ship flag, argh!) Begin working on wiki report More North Garage tests	Incomplete :( In-Progress In-Progress
15	5/20/2023	5/26/2023	Final code cleanup Finalize wiki report Final North Garage tests	In-Progress In-Progress Incomplete

Parts List & Cost

Item#	Part Desciption	Vendor	Qty	Cost
1	RC Car	Traxxas	1	$250.00
2	SJ2 board	From Preet [1]	4	$50.00
3	CAN Transceivers (SN65HVD230)	Waveshare [2]	4	Free Samples
4	RC Car RPM	Traxxas [3]	1	$8.23
5	Adafruit Bluetooth BLE Friend	Adafruit [4]	1	$17.5
6	GPS Module	Adafruit [5]	1	$29.95
7	Compass Module	Adafruit [6]	1	$12.50
8	Ultrasonic Sensors	Adafruit [7]	4	$3.95
9	LCD Screen	Amazon [8]	1	$12.89

System Hardware Design

Block Diagram

CAN Communication

Hardware Design

DBC File

Gitlab link to DBC file

VERSION ""

NS_ :
	BA_
	BA_DEF_
	BA_DEF_DEF_
	BA_DEF_DEF_REL_
	BA_DEF_REL_
	BA_DEF_SGTYPE_
	BA_REL_
	BA_SGTYPE_
	BO_TX_BU_
	BU_BO_REL_
	BU_EV_REL_
	BU_SG_REL_
	CAT_
	CAT_DEF_
	CM_
	ENVVAR_DATA_
	EV_DATA_
	FILTER
	NS_DESC_
	SGTYPE_
	SGTYPE_VAL_
	SG_MUL_VAL_
	SIGTYPE_VALTYPE_
	SIG_GROUP_
	SIG_TYPE_REF_
	SIG_VALTYPE_
	VAL_
	VAL_TABLE_

BS_:

BU_: DBG DRIVER MOTOR SENSOR GEO

BO_ 100 DRIVER_HEARTBEAT: 1 DRIVER
 SG_ DRIVER_HEARTBEAT_cmd : 0|8@1+ (1,0) [0|0] "" SENSOR,MOTOR

BO_ 101 MOTOR_SPEED: 1 DRIVER
 SG_ DC_MOTOR_DRIVE_SPEED_sig : 0|8@1+ (0.1,-10) [-10|10] "kph" SENSOR,MOTOR

BO_ 102 MOTOR_ANGLE: 1 DRIVER
 SG_ SERVO_STEER_ANGLE_sig : 0|8@1+ (1,-45) [-45|45] "degrees" SENSOR,MOTOR


BO_ 200 SENSOR_SONARS: 4 SENSOR
 SG_ SENSOR_SONARS_left : 0|8@1+ (1,0) [0|158] "inch" DRIVER
 SG_ SENSOR_SONARS_right : 8|8@1+ (1,0) [0|158] "inch" DRIVER
 SG_ SENSOR_SONARS_front : 16|8@1+ (1,0) [0|158] "inch" DRIVER
 SG_ SENSOR_SONARS_rear : 24|8@1+ (1,0) [0|158] "inch" DRIVER

BO_ 202 GPS_DESTINATION_LOCATION: 8 SENSOR
 SG_ GPS_DEST_LAT_SCALED_1000000 : 0|32@1- (1,0) [0|0] "Degrees" GEO
 SG_ GPS_DEST_LONG_SCALED_1000000 : 32|32@1- (1,0) [0|0] "Degrees" GEO

BO_ 203 GEO_STATUS: 8 GEO
 SG_ GEO_STATUS_COMPASS_HEADING : 0|12@1+ (1,0) [0|359] "Degrees" DRIVER,SENSOR
 SG_ GEO_STATUS_COMPASS_BEARING: 12|12@1+ (1,0) [0|359] "Degrees" DRIVER,SENSOR
 SG_ GEO_STATUS_DISTANCE_TO_DESTINATION : 24|16@1+ (0.01,0) [0|0] "Meters" DRIVER,SENSOR

BO_ 204 GPS_CURRENT_INFO: 8 GEO
 SG_ GPS_CURRENT_LAT_SCALED_1000000 : 0|32@1- (1,0) [0|0] "degrees" DRIVER,SENSOR
 SG_ GPS_CURRENT_LONG_SCALED_1000000 : 32|32@1- (1,0) [0|0] "degrees" DRIVER,SENSOR
 
BO_ 205 GPS_CURRENT_DESTINATIONS_DATA: 8 GEO
 SG_ CURRENT_DEST_LAT_SCALED_1000000 : 0|32@1- (1,0) [0|0] "Degrees" DRIVER
 SG_ CURRENT_DEST_LONG_SCALED_1000000 : 32|32@1- (1,0) [0|0] "Degrees" DRIVER

BO_ 206 BRIDGE_APP_COMMANDS: 1 SENSOR
 SG_ APP_COMMAND : 0|2@1+ (1,0) [0|0] "" MOTOR

BO_ 300 MOTOR_STATUS: 3 MOTOR
 SG_ MOTOR_STATUS_wheel_error : 0|1@1+ (1,0) [0|0] "" DRIVER,IO
 SG_ MOTOR_STATUS_speed_kph : 8|16@1+ (0.001,0) [0|0] "kph" DRIVER,IO
 
BO_ 401 MOTOR_DEBUG: 1 MOTOR
 SG_ IO_DEBUG_test_unsigned : 0|8@1+ (1,0) [0|256] "sec" DBG

BO_ 402 COMPASS_RAW_DEBUG: 6 GEO
 SG_ COMPASS_RAW_X : 0|15@1- (1,0) [0|0] "" DBG
 SG_ COMPASS_RAW_Y : 16|15@1- (1,0) [0|0] "" DBG
 SG_ COMPASS_RAW_Z : 32|15@1- (1,0) [0|0] "" DBG

BO_ 403 SENSOR_BEFORE_AVERAGE_DEBUG: 4 SENSOR
 SG_ SENSOR_BEFORE_AVG_left : 0|8@1+ (1,0) [0|0] "inch" DBG
 SG_ SENSOR_BEFORE_AVG_right : 8|8@1+ (1,0) [0|0] "inch" DBG
 SG_ SENSOR_BEFORE_AVG_front : 16|8@1+ (1,0) [0|0] "inch" DBG
 SG_ SENSOR_BEFORE_AVG_rear : 24|8@1+ (1,0) [0|0] "inch" DBG

CM_ BU_ DBG "The debugging node for testing dbc with the car";
CM_ BU_ DRIVER "The driver controller driving the car";
CM_ BU_ MOTOR "The motor controller of the car";
CM_ BU_ SENSOR "The sensor controller of the car";
CM_ BU_ GEO "The geological Controller of the car";
CM_ BO_ 100 "Sync message used to synchronize the controllers";
CM_ SG_ 100 DRIVER_HEARTBEAT_cmd "Heartbeat command from the driver";
CM_ SG_ 101 DC_MOTOR_DRIVE_SPEED_sig "The speed in kph to set the motor speed. TODO: choose kph/mph";
CM_ SG_ 102 SERVO_STEER_ANGLE_sig "The direction in degrees to set the RC car servo direction.";

BA_DEF_ "BusType" STRING ;
BA_DEF_ BO_ "GenMsgCycleTime" INT 0 0;
BA_DEF_ SG_ "FieldType" STRING ;

BA_DEF_DEF_ "BusType" "CAN";
BA_DEF_DEF_ "FieldType" "";
BA_DEF_DEF_ "GenMsgCycleTime" 0;

BA_ "GenMsgCycleTime" BO_ 100 1000;
BA_ "GenMsgCycleTime" BO_ 200 50;
BA_ "FieldType" SG_ 100 DRIVER_HEARTBEAT_cmd "DRIVER_HEARTBEAT_cmd";

VAL_ 100 DRIVER_HEARTBEAT_cmd 2 "DRIVER_HEARTBEAT_cmd_REBOOT" 1 "DRIVER_HEARTBEAT_cmd_SYNC" 0 "DRIVER_HEARTBEAT_cmd_NOOP" ;

Sensor and Bridge Controller

Bridge Controller Gitlab link

Hardware Design

Bridge controller connections

Ultrasonic Sensors

We used HC-SR04 ultrasonic sensors for obstacle detection. It could provide a range from 2 cm to 400 cm non-contact measurement. The ranging accuracy is approximately 3mm and the effectual angle is less than 15°. It needs to be powered by a 5V power supply. We are using 4 HC-SR04 sensors in the RC car(front, rear, left, and right).

HC-SR04 specifications

Operating voltage: +5V
Theoretical Measuring Distance: 2cm to 450cm
Practical Measuring Distance: 2cm to 80cm
Accuracy: 3mm
Measuring angle covered: <15°
Operating Current: <15mA
Operating Frequency: 40Hz

The pinout and the timing diagram of the HC-SR04 sensor are shown in the following figures. The module includes an ultrasonic transmitter, a receiver, and a control circuit. The basic principle of work: When the trigger pin is set HIGH for at least 10us, the module automatically sends a 40 kHz ultrasonic wave from the Ultrasonic transmitter. This wave travels in the air and when it gets obstructed by any material it gets reflected back toward the sensor. This reflected wave is observed by the Ultrasonic receiver module. Once the wave is returned the Echo pin goes high for a particular amount of time which will be equal to the time taken for the wave to return back to the sensor. The amount of time during which the Echo pin stays high is measured by the SJ2 board as it gives the information about the time taken for the wave to return back to the Sensor. Using this information the distance is measured as explained in the above heading. From that duration, the distance at which the object is present can be measured using the formula, Distance = Speed × Time.

HC-SR04 Pinout

HC-SR04 Timing Diagram

HC-SR04 Working Principle

Bluetooth Module

For the communication between the mobile and the RC Car, we are using Adafruit Bluefruit LE UART Friend - BLE module. This module communicates with the SJ2 board through UART at a baud rate of 9600. It also has the capability of working in two modes (data mode and command mode). We can toggle between the two modes using the MOD pin through a GPIO signal or manually using the onboard switch. It supports AT command set, which can be used to control the device's behavior. In data mode, the data written to the UART in the form of a string will be sent through Bluetooth.

Adafruit Bluefruit specifications

ARM Cortex M0 core running at 16MHz
256KB flash memory
32KB SRAM
Transport: UART @ 9600 baud with HW flow control (CTS+RTS required)
5V-safe inputs
On-board 3.3V voltage regulation
Bootloader with support for safe OTA firmware updates
Easy AT command set to get up and running quickly

Software Design

We read about the signal interference of adjacent sensors from many of the past projects. So we decided to avoid that interference by triggering two non-adjacent sensors at a time. The FRONT_REAR sensor pair is triggered first. Once both of the sensors compute the distance from the obstacle, then the next pair, RIGHT_LEFT is triggered. For the ultrasonic sensors, we used a separate task instead of the periodic callbacks since this task sleeps on a semaphore which might affect the other functions in the periodic callback function.

Ultrasonic Sensors

SONAR task

void sonar_task(void *p) {
 sonar__init();
 front_rear_echo_received = xSemaphoreCreateBinary();
 left_right_echo_received = xSemaphoreCreateBinary();
 lpc_peripheral__enable_interrupt(LPC_PERIPHERAL__GPIO, sonar__interrupt_dispatcher, "sonar_timing_handler");
 NVIC_EnableIRQ(GPIO_IRQn);
 while (1) {
   sonar__send_trigger_for_10us(FRONT_REAR);
   if (xSemaphoreTake(front_rear_echo_received, 100)) {
     sonar_pair_info[0].distance_from_obstacle_sonar1 = sonar__compute_obstacle_distance_single_sensor(FRONT_SONAR);
     sonar_pair_info[0].distance_from_obstacle_sonar2 = sonar__compute_obstacle_distance_single_sensor(REAR_SONAR);
   }
   vTaskDelay(10);
   sonar__send_trigger_for_10us(LEFT_RIGHT);
   if (xSemaphoreTake(left_right_echo_received, 100)) {
     sonar_pair_info[1].distance_from_obstacle_sonar1 = sonar__compute_obstacle_distance_single_sensor(LEFT_SONAR);
     sonar_pair_info[1].distance_from_obstacle_sonar2 = sonar__compute_obstacle_distance_single_sensor(RIGHT_SONAR);
   }
   sonar__averaging_sensor_values();
 }
}

Technical Challenges

Issue: Sometimes the front sensor was detecting some obstacles even though there was nothing in front.

Solution: We included a delay of 10ms in between triggering the first and second pair of sensors.

Motor ECU

Traxxas Antenna PWM Connections

Traxxas TQ Top Qualifier Module

Motor Controller Gitlab link

Hardware Design

PCB Design

Phil to talk about PCB design and choices for layout

Battery Management

Phil to talk about the peripheral battery and main motor battery separation

Software Design

RPM Module

Tony will write about how the RPM module was implemented using triggers.

void sonar_task(void *p) {
  Test
}

Motor Module

Tony will write about the motor and how forward/reverse works

static float test_task(float lol) {
  Just wanted to see if this is cool;
}