S22: Road Runner

1 Road Runner
2 Abstract
- 2.1 Introduction
- 2.2 Team Members & Responsibilities
3 Schedule
4 Parts List & Cost
5 Electrical Wiring and Powering the System
6 CAN Communication
- 6.1 Hardware Design
- 6.2 DBC File
7 Sensor and Bridge Controller
8 Motor Controller
9 Geographical Controller
10 Driver and LCD Module
11 Physical Mounting
12 Mobile Application
13 Conclusion

Road Runner

Abstract

Road Runner is a self navigating car built with the ability to drive to a specified geo-location within its battery range, while avoiding any physical obstacles that come on its way and successfully reaching its destination, with no human intervention apart from commanding the destination location . The car’s infrastructure has four important nodes (Driver, Sensor and Bridge, Geo and Motor) communicating within themselves over internal CAN Bus and with the end user over a mobile application. The car always strives to stay on and maintain its path to the destination by periodically sensing and processing all the relevant information from the nodes to arrive at an informed decision. It is built on top of a hobby grade RC car chassis with all the necessary adjustments and components to achieve its intended objective of self navigating and object avoidance, one of the basic requirements and functionality of an autonomous vehicle.

Introduction

The project was divided into 5 modules:

Bridge and Sensor Controller
Motor Controller
Geo Controller
Driver / LCD Controller
Android app interface

Team Members & Responsibilities

Road Runner Firmware: GitLab Repo

Team Members:

Dhruv Choksi

Jonathan Doctolero

Tudor Donca

Hisaam Hashim

Saicharan Kadari

Kyle Kwong

Project Subteams:

Bridge and Sensor Controller:
- Tudor Donca
- Saicharan Kadari

Motor Controller:
- Dhruv Choksi
- Hisaam Hashim

Geological Controller:
- Kyle Kwong
- Jonathan Doctolero
- Saicharan Kadari

Driver and LCD Controller:
- Hisaam Hashim
- Kyle Kwong

Android Application:
- Jonathan Doctolero
- Tudor Donca

Integration and System Testing:
- Tudor Donca
- Dhruv Choksi
- Hisaam Hashim
- Saicharan Kadari
- Kyle Kwong
- Jonathan Doctolero

Schedule

Week#	Start Date	End Date	Task	Status
1	03/06/2022	03/12/2022	Read previous projects, gather information and discuss among the group members. Discuss each team-member's preference and assign controller roles Create parts list for the RC car, discuss, and decide on each item	Completed
2	03/13/2022	03/19/2022	Design interface for Bridge and Sensor Controller, with unit tests Design interface for Motor Controller, with unit tests Design interface for Driver and LCD Controller, with unit tests Integrate Bridge/Sensor Controller to CAN bus with DBC, handling messages Integrate Motor Controller to CAN bus with DBC, handling messages Integrate Driver Controller to CAN bus with DBC, handling messages Order all parts from list and save tracking/price info	Completed
3	03/20/2022	03/26/2022	Connect Sensor, Motor, and Driver controller together on CAN bus and verify messages Connect all nodes together on the CAN bus, connect android app, verify messages across all nodes Design interface for Geological Controller, with unit tests Design basic android app connection and communication	Completed
4	03/27/2022	04/02/2022	Integrate Geological Controller to CAN bus with DBC, handling messages Integrate Android app with Bridge/Sensor controller, sending/receiving messages both ways Integrate Motor and Steering with PWM control, figure out the working ranges Integrate Bluetooth module to Bridge/Sensor controller, with UART logic Connect Android app to Bridge/Sensor controller, send test message All parts received	Completed
5	04/03/2022	04/09/2022	Connect all nodes together on the CAN bus, connect android app, verify messages across all nodes Mobile app can send coordinates to Bridge controller Start RPM sensor logic implementation and add it to Motor controller MILESTONE - All individual modules considered "Roughly Working" with hardware interfaced	Completed
6	04/10/2022	04/16/2022	Integrate GPS and Compass peripherals, writing the driver and unit tests Have Driver node process GPS position/heading/bearing messages and incorporate in the driver logic Complete RPM sensor and integrate with Motor controller for reliable PID control Bridge sends to mobile app car status / telemetry data Compile additional parts list and order them MILESTONE - Basic car driving ability with basic obstacle avoidance	Completed
7	04/17/2022	04/23/2022	Create a on-board battery power supply for all components Complete the Compass I2C integration and read values from the peripheral Have PWM signals reliably controlling the motor speed, start working "backwards driving mode" Interface LED ring on the Driver controller and display heading direction MILESTONE - Integrated, reliably "heading" towards provided destination bearing, basic obstacle avoidance First Demo (Apr. 26)	Completed
8	04/24/2022	04/30/2022	3D print sensor housings, mounting for the whole platform Design and solder the prototype board with all SJTwo boards Add data to display on the LCD screen Outdoor testing for longer range trips, and complete necessary enhancements MILESTONE - Integration part 2, perform obstacle avoidance and destination bearing Second Demo (May 3)	Completed
9	05/01/2022	05/07/2022	Verify that the electrical and mechanical work is complete MILESTONE - Integration and outdoor testing, adding necessary software changes Third Demo (May 10)	Completed
10	05/08/2022	05/15/2022	Add "beep beep" sound with speaker MILESTONE - Integration testing, deal with uneven terrain, reliable waypoints navigation and obstacle avoidance Fourth Demo (May 17)	Completed

Parts List & Cost

Item#	Part Description	Vendor	Qty	Cost
1	RC Car	Redcat [1]	1	$153.00
2	CAN Transceivers	Various	6	$55
3	Ultrasonic Sensors	Max Botix[2]	3	$134.00
4	Adafruit Bluetooth UART Tranceiver	Adafruit[3]	1	$33.90
5	GPS Module and Antenna	Adafruit[4][5]	1	$59.50
6	Compass Module	Adafruit[6]	1	$29.00
7	Wheel Speed RPM Encoder		1
8	Discrete Electronic Components	Generic[7]	1	$

Electrical Wiring and Powering the System

CAN Communication

We used CAN Communication setup between all the nodes of the RoadRunner setup. This CAN Bus is terminated with the use of two 120 ohm resistors at both the ends of the Bus. Message IDs were chosen based upon an agreed priority scheme and Bus arbitration scheme. We assigned high priority IDs to messages that controlled the motor, thereby controlling the actual physical movement of the car, followed by sensor and GEO messages, and lowest priority messages were for debug and status messages from the respective nodes . More technical details to fill in..

Hardware Design

DBC File

Gitlab link to the RoadRunner 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_BRIDGE GEOLOGICAL
 
BO_ 100 MOTOR_CMD: 4 DRIVER
 SG_ MOTOR_steer_direction : 0|9@1- (1,-2) [-2|2] "steer direction" MOTOR
 SG_ MOTOR_speed_kph : 9|20@1- (0.1,-10.1) [-10.1|10.1] "kph" MOTOR
 SG_ MOTOR_drive_mode : 29|3@1+ (1,0) [0|0] "mode" MOTOR
 
BO_ 101 MOTOR_STATUS: 4 MOTOR
 SG_ actual_steer_degrees : 0|9@1- (1,-2) [-2|2] "steer direction" DRIVER,DBG
 SG_ actual_speed_kph : 9|20@1- (0.1,-10.1) [-10.1|10.1] "kph" DRIVER,DBG
 SG_ actual_drive_mode : 29|3@1+ (1,0) [0|0] "mode" DRIVER,DBG
 
BO_ 102 MOTOR_TEST_CONTROL_OVERRIDE: 8 DBG
 SG_ override_steer_pwm : 0|24@1+ (0.01,0) [5.01|15.01] "duty" MOTOR
 SG_ override_motor_pwm : 24|24@1+ (0.01,0) [5.01|15.01] "duty" MOTOR
 SG_ override_enable : 48|1@1+ (1,0) [0|1] "flag" MOTOR
 
BO_ 200 SENSOR_SONARS: 8 SENSOR_BRIDGE
 SG_ SENSOR_SONARS_left : 0|10@1+ (1,0) [0|500] "cm" DRIVER
 SG_ SENSOR_SONARS_right : 10|10@1+ (1,0) [0|500] "cm" DRIVER
 SG_ SENSOR_SONARS_middle : 20|10@1+ (1,0) [0|500] "cm" DRIVER
 SG_ SENSOR_SONARS_back : 30|10@1+ (1,0) [0|500] "cm" DRIVER
 
BO_ 201 GPS_DESTINATION: 8 SENSOR_BRIDGE
 SG_ GPS_DESTINATION_latitude : 0|28@1- (0.000001,-90.000000) [-90|90] "Degrees" GEOLOGICAL
 SG_ GPS_DESTINATION_longitude : 28|28@1- (0.000001,-180.000000) [-180|180] "Degrees" GEOLOGICAL
 
BO_ 202 WAYPOINT: 8 SENSOR_BRIDGE
 SG_ WAYPOINT_latitude : 0|28@1- (0.000001,-90.000000) [-90|90] "Degrees" GEOLOGICAL
 SG_ WAYPOINT_longitude : 28|28@1- (0.000001,-180.000000) [-180|180] "Degrees" GEOLOGICAL
 
BO_ 203 BRIDGE_CAR_CONTROL: 8 SENSOR_BRIDGE
 SG_ DRIVER_start_stop : 0|1@1+ (1,0) [0|1] "" DRIVER
 
BO_ 350 GEO_STATUS: 8 GEOLOGICAL
 SG_ GEO_STATUS_COMPASS_HEADING : 0|12@1+ (1,0) [0|359] "Degrees" DRIVER,SENSOR_BRIDGE
 SG_ GEO_STATUS_COMPASS_BEARING : 12|12@1+ (1,0) [0|359] "Degrees" DRIVER,SENSOR_BRIDGE
 SG_ GEO_STATUS_DISTANCE_TO_DESTINATION : 24|24@1+ (1,0) [0|0] "Meters" DRIVER,SENSOR_BRIDGE
 
BO_ 360 GEO_CURRENT_POSITION: 8 GEOLOGICAL
 SG_ GEO_CURRENT_POSITION_latitude : 0|28@1- (0.000001,-90.000000) [-90|90] "Degrees" DRIVER,SENSOR_BRIDGE
 SG_ GEO_CURRENT_POSITION_longitude : 28|28@1- (0.000001,-180.000000) [-180|180] "Degrees" DRIVER,SENSOR_BRIDGE
 
BO_ 500 DEBUG_SENSOR_BRIDGE: 8 SENSOR_BRIDGE
 SG_ sensor_left_raw_value : 0|12@1+ (1,0) [0|0] "" DBG
 SG_ sensor_right_raw_value : 12|12@1+ (1,0) [0|0] "" DBG
 SG_ sensor_middle_raw_value : 24|12@1+ (1,0) [0|0] "" DBG
 SG_ sensor_back_raw_value : 36|12@1+ (1,0) [0|0] "" DBG
 
BO_ 505 DEBUG_MOTOR_CONTROL: 8 MOTOR
 SG_ target_steer_direction : 0|8@1- (1,-2) [-2|2] "steer direction" DBG
 SG_ target_speed_kph : 8|12@1- (0.1,-10.1) [-10.1|10.1] "kph" DBG
 SG_ current_raw_motor_pwm : 20|20@1+ (0.01,0) [5.01|15.01] "duty" DBG
 SG_ current_raw_servo_pwm : 40|20@1+ (0.01,0) [5.01|15.01] "duty" DBG
 SG_ is_override_enabled : 60|1@1+ (1,0) [0|1] "flag" DBG
 
BO_ 506 DEBUG_MOTOR_RPM: 8 MOTOR
 SG_ computed_rpm : 0|12@1+ (1,0) [0|4000] "rpm" DBG
 SG_ computed_kph : 12|12@1- (0.1,-10.1) [-10.1|10.1] "kph" DBG
 SG_ computed_pid_increment : 24|20@1- (0.01,-5.01) [-5.01|5.01] "duty" DBG
 SG_ total_encoder_tick_count : 44|20@1+ (1,0) [0|0] "ticks" DBG
 
BO_ 510 DEBUG_DRIVER: 8 DRIVER
 SG_ driver_intention : 0|8@1+ (1,0) [0|0] "" DBG
 SG_ driver_steer_direction : 8|8@1+ (1,0) [0|0] "" DBG
 SG_ driver_drive_direction : 16|8@1+ (1,0) [0|0] "" DBG
 
CM_ BU_ DRIVER "The driver controller driving the car";
CM_ BU_ MOTOR "The motor controller of the car";
CM_ BU_ SENSOR_BRIDGE "The sensor and bluetooth bridge controller of the car";
CM_ BU_ GEOLOGICAL "The GPS and compass controller of the car";
CM_ BO_ 100 "Sync message used to synchronize the controllers";
 
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" ;
 
BA_ "FieldType" SG_ 510 driver_intention "driver_intention";
VAL_ 510 driver_intention 1 "DESTINATION_HEADING" 0 "OBSTACLE_AVOIDANCE";
 
BA_ "FieldType" SG_ 510 driver_steer_direction "driver_steer_direction";
VAL_ 510 driver_steer_direction 2 "TURN_RIGHT" 1 "TURN_LEFT" 0 "STRAIGHT";
 
BA_ "FieldType" SG_ 510 driver_drive_direction "driver_drive_direction";
VAL_ 510 driver_drive_direction 2 "BACKWARDS" 1 "FORWARDS" 0 "STOPPED";
 
BA_ "FieldType" SG_ 100 MOTOR_drive_mode "MOTOR_drive_mode";
VAL_ 100 MOTOR_drive_mode 2 "DRIVE_BACKWARDS" 1 "DRIVE_FORWARDS" 0 "NEUTRAL";
 
BA_ "FieldType" SG_ 100 MOTOR_steer_direction "MOTOR_steer_direction";
VAL_ 100 MOTOR_steer_direction -2 "STEER_MAX_LEFT" -1 "STEER_SLIGHT_LEFT" 0 "STEER_STRAIGHT" 1 "STEER_SLIGHT_RIGHT" 2 "STEER_MAX_RIGHT";

Sensor and Bridge Controller

Sensor Controller Master Branch

Hardware Design

Roadrunner uses three HRLV-MAXSonar-EZ0 MB1003[8] as its eyes and ears on the front. The HRLV-MAXSonar-EZ0 comes in five different models for the ultrasonic sensor. The HRLV-MAXSonar-EZ sensor line is the most cost-effective solution for applications where precision range-finding, low-voltage operation, space-saving, and low-cost are needed. This sensor line features 1mm resolution, target-size and operating-voltage compensation for improved accuracy, superior rejection of outside noise sources, internal speed-of-sound temperature compensation, and optional external speed-of-sound temperature compensation.

These models are the MB1003, MB1013, MB1023, MB1033, and MB1043. The models are based on the beam width of the sensor. It was observed that MB1003 has the optimal beam pattern and was better suited for our objective of object detection. If the beam pattern is too wide given the, there is a greater chance of cross talk between sensors. If the beam pattern is too narrow, there may be blind spots which must be accounted for. Thus, three HRLV-MAXSonar-EZ0 MB1003 sensors were used and the possible unavoidable cross talk is contained by the optimal positioning and software configuration.

Front view of the HRLV-MAXSonar-EZ0 MB1003 000

Rear view of the HRLV-MAXSonar-EZ0 MB1003 000 with pin labels

Beam pattern of the HRLV_MAXSonar-EZ0 MB1003

Sensor Mounts and Placement

It is decided to place the ultrasonic sensors on 3d- printed mounts and a custom setup to reduce the cross talk and also position them to capture the most field of view and possibly avoid any blind spots for the car movement.

Sensor Readings Extraction

To extract range readings from the MB1003, the "AN" pin which represents analog output was utilized. A range reading is commanded by triggering the "RX" pin high for 20us or more. From the details of the sensor datasheet it is observed that the output analog voltage is based on a scaling factor of (Vcc/512) per inch. As in our setup, all four of the sensors were powered from the SJTWO board, thus a 3.3v VCC was supplied to each sensor. According to the HRLV-MaxSonar-EZ datasheet, with 3.3v source, the analog output was expected to be roughly 6.4mV/inch. However, when initially testing the output range readings, the output was inaccurate. We were thankful for the past students' experiences to notice that the ADC channels for the SJTWO are configured at start-up to have an internal pull up resistor. Disabling this pull up resistor will be discussed more in Software Design and this made the range readings more accurate. The readings were tested by having multiple objects placed in front of each sensor and measuring the distance of the object to the sensors physically. Although the range readings accuracy is improved by the pull-up resistor modification, it was found that the range readings did not necessarily follow the expected 6.4mV/inch. Hence, we decided to calibrate the sensors to xx mV/inch. This value was extracted by placing objects around the sensors and checking if the analog output to inch conversion matched to the actual measured distance.

SJ2 Board Pin Connections with Ultrasonic sensors

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

Sensors pin layout
Sr. No.	SJTwo board Pin	Maxbotix sensor Pin	Function
1	ADC2 - P0.25	AN (Middle sensor)	ADC Input (sensor output) from front sensor
2	ADC4 - P1.30	AN (Left Sensor)	ADC input from left sensor
3	ADC5 - P1.31	AN (Right Sensor)	ADC input from right sensor
4	GPIO - P0.6	RX (Middle Sensor)	Trigger Input for left sensor
5	GPIO - P0.7	RX (Left Sensor)	Trigger Input for front sensor
6	GPIO - P0.8	RX (Right Sensor)	Trigger Input for right sensor