Difference between revisions of "F16: AutoNav"

Revision as of 08:26, 21 December 2016

Project Title

• Autonomous RC Car

Abstract

This project report describes an attempt to develop an autonomous RC car which navigates from a source point to destination avoiding any obstacles in between. The project was divided into five modules namely Motor & Input/output Controller, Sensor Controller, Geo Controller, Communication Bridge & Android Controller and Master Controller, each performing specific set of tasks. Each of the five modules were established using SJOne Boards. Communication between all the five modules was established using CAN Bus.

• Motor & I/O Controller - This controller was responsible for driving Brushless DC Motor interfaced through ESC, driving the stepper motor for steering and displaying the status of the RC car (speed, obstacle distance etc.) on the LCD.
• Sensor Controller - This controller was responsible for obstacle detection and avoidance, interfacing done with Ultrasonic Ping Sensors.
• Geo Controller - This controller focused on providing orientation (heading and bearing) and navigation route to the car.
• Communication Bridge & Android Controller - Co-ordinates for navigation were provided by this controller using an android application. Communication was established via Bluetooth.
• Master Controller - This controller was responsible for collecting the data from all the controllers, develop and implement obstacle avoidance algorithm to guide the car towards the final destination.

Objectives & Introduction

The main objectives of this project include:

• To develop an autonomous RC Car.
• To navigate from a set source to destination.
• To avoid any obstacles in between.
• To establish all communication between controllers via CAN bus.

The following peripherals of LPC 1758 were used to establish communications:

• CAN Peripheral: Communicate between all the controllers on a common CAN bus.
• UART Peripheral: Communicate between GEO Controller and GPS module, Bluetooth controller and Bluetooth module.
• GPIO: Communicate between sensors and sensor controller.
• PWM: Vary the speed of Brushless DC motor and Stepper motor via ESC interfaced through Motor Controller.

The block diagram below gives an overview of the various peripherals used:

Peripheral block diagram

Team Members & Responsibilities

Sensor Controller:

• Vishwanath Balakuntla Ramesh

Motor & I/O Controller:

• Sameer Saran
• Jaswanth Bhimanapalli

Bluetooth (Communication Bridge) & Android Controller:

• Sucharitha
• Karthikeya Rao G V

Geographical Controller:

• Arpita Ramanath
• Veena Manasa Kanakamalla

Master Controller:

• Ajai Krishna Velayutham
  
• Goutam Madhukeshwar Hegde

Schedule

Consolidated Team Schedule

Parts List & Cost

DBC File Implementation

DBC files are widely used to define the system of CAN messages and their constituent signals. This allows CAN data to be accessed in terms of human-usable signal values, with different data types and scaling, instead of just raw message bytes. Below is the DBC file that we implemented in our project.

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_: DRIVER BLUETOOTH SENSOR MOTOR GEO

BO_ 100 KILL_SWITCH: 1 DRIVER
 SG_ killSwitch : 0|1@1+ (1,0) [0|0] "Stop=1" MOTOR

BO_ 110 STOP_CMD: 1 BLUETOOTH
 SG_ BLUETOOTH_STOP_CMD_signal : 0|1@1+ (1,0) [0|0] "Stop=1" DRIVER

BO_ 120 MOTOR_SYNC: 1 MOTOR
 SG_ Motor_Sync : 0|1@1+ (1,0) [0|0] "MotorSync=1" DRIVER

BO_ 130 GEO_SYNC: 1 GEO
 SG_ Geo_sync_cmd : 0|1@1+ (1,0) [0|0] "GeoSync=1" DRIVER
  
BO_ 140 BLUETOOTH_SYNC_CMD: 1 BLUETOOTH
 SG_ BLUETOOTH_SYNC_CMD_signal : 0|1@1+ (1,0) [0|0] "BluetoothSync=1" DRIVER
  
BO_ 150 SENSOR_SYNC: 1 SENSOR
 SG_ Sensor_Sync : 0|1@1+ (1,0) [0|0] "SensorSync=1" DRIVER,MOTOR,BLUETOOTH
 
BO_ 160 ERROR_COMM_DRIVER: 1 DRIVER
 SG_ Sync_Miss_Info : 0|8@1+ (1,0) [0|0] "ErrorMsgType" MOTOR
 
BO_ 170 DRIVER_SYNC_ACK: 1 DRIVER
 SG_ Sync_Miss_Info : 0|1@1+ (1,0) [0|0] "DriverSync=1" MOTOR,BLUETOOTH,SENSOR,GEO
 
BO_ 180 MOTOR_CONTROL: 2 DRIVER
 SG_ steer : 0|8@1+ (1,0) [0|0] "DirectionType" MOTOR    
 SG_ speed : 8|8@1+ (1,0) [0|0] "SpeedType" MOTOR  
  
BO_ 181 MOTOR_RPS: 2 MOTOR
 SG_ Rps_Sensor : 0|8@1+ (1,0) [0|0] "RotationsPerSecondENum" DRIVER,BLUETOOTH
 SG_ Rps_Value : 8|8@1+ (1,0) [0|0] "RotationsPerSecondValue" BLUETOOTH,DRIVER

BO_ 190 SENSOR_SONAR: 5 SENSOR
 SG_ Sensor_Sonar_Front : 0|8@1+ (1,0) [0|0] "FrontDistance" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Sonar_FrontRight : 8|8@1+ (1,0) [0|0] "FRightDistance" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Sonar_FrontLeft : 16|8@1+ (1,0) [0|0] "FLeftDistance" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Sonar_Back : 24|8@1+ (1,0) [0|0] "BackDistance" DRIVER,MOTOR,BLUETOOTH
 
BO_ 200 GEO_SEND_LOCATION: 8 GEO
 SG_ Geo_latitude : 0|32@1+ (0.000001,-90.000000) [-90|90] "latitude" DRIVER,BLUETOOTH,MOTOR
 SG_ Geo_longitude : 32|32@1+ (0.000001,-180.000000) [-180|180] "longitude" DRIVER,BLUETOOTH,MOTOR

BO_ 210 GEO_SEND_HD_BR: 8 GEO
 SG_ Geo_heading : 0|29@1+ (0.000001,0) [0|360] "" DRIVER,MOTOR
 SG_ Geo_bearing : 29|29@1+ (0.000001,0) [0|360] "" DRIVER,MOTOR

BO_ 220 NAVIGATION_WAYPOINT: 2 BLUETOOTH
 SG_ Bluetooth_CurrWaypoint : 0|5@1+ (1,0) [0|0] "CurrentWaypointNumber" DRIVER,GEO
 SG_ Bluetooth_NumWaypoint : 5|5@1+ (1,0) [0|0] "NumberOfWaypoints" DRIVER,GEO

BO_ 250 LATITUDE_LONGITUDE: 8 BLUETOOTH
 SG_ Bluetooth_latitude : 0|32@1+ (0.000001,-90.000000) [-90|90] "latitude" DRIVER,GEO
 SG_ Bluetooth_longitude : 32|32@1+ (0.000001,-180.000000) [-180|180] "longitude" DRIVER,GEO

BO_ 230 START_CMD: 1 BLUETOOTH
 SG_ BLUETOOTH_START_CMD_signal : 0|8@1+ (1,0) [0|0] "" DRIVER
 
BO_ 240 SENSOR_BATTERY: 8 SENSOR 
 SG_ Sensor_Battery_Voltage : 0|8@1+ (0.1,0) [0|0] "Volts" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Battery_SOC : 8|10@1+ (0.1,0) [0|0] "Percent" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Light : 18|10@1+ (0.1,0) [0|0] "LightPercentValue" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Tilt_X : 28|12@1+ (0.1,0) [0|0] "TiltValueX" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Tilt_Y : 40|12@1+ (0.1,0) [0|0] "TiltValueY" DRIVER,MOTOR,BLUETOOTH
 
BO_ 500 DRIVER_TEST: 1 DRIVER
 SG_ Driver_Test_Msg : 0|8@1+ (1,0) [0|0] "" MOTOR,GEO,SENSOR,BLUETOOTH

BO_ 600 MOTOR_TEST: 1 MOTOR
 SG_ Motor_Test_Msg : 0|8@1+ (1,0) [0|0] "" DRIVER,GEO,SENSOR,BLUETOOTH
 
BO_ 700 SENSOR_TEST: 1 SENSOR
 SG_ Sensor_Test_Msg : 0|8@1+ (1,0) [0|0] "" DRIVER,MOTOR,GEO,BLUETOOTH
 
BO_ 800 GEO_TEST: 1 GEO
 SG_ Geo_Test_Msg : 0|8@1+ (1,0) [0|0] "" DRIVER,MOTOR,SENSOR,BLUETOOTH
 
BO_ 900 BLUETOOTH_TEST: 1 BLUETOOTH
 SG_ Bluetooth_Test_Msg : 0|8@1+ (1,0) [0|0] "" DRIVER,MOTOR,GEO,SENSOR
 
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 geo controller of the car";
CM_ BU_ BLUETOOTH "The bridge 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_ 500 10;
BA_ "FieldType" SG_ 180 steer "steer";
BA_ "FieldType" SG_ 180 speed "speed";
BA_ "FieldType" SG_ 181 Rps_Sensor "Rps_Sensor";
BA_ "FieldType" SG_ 190 Sensor_Sonar_Front "Sensor_Sonar_Front";
BA_ "FieldType" SG_ 190 Sensor_Sonar_FrontRight "Sensor_Sonar_FrontRight";
BA_ "FieldType" SG_ 190 Sensor_Sonar_FrontLeft "Sensor_Sonar_FrontLeft";
BA_ "FieldType" SG_ 190 Sensor_Sonar_Back "Sensor_Sonar_Back";

VAL_ 190 Sensor_Sonar_Front 3 "far_f" 2 "mid_f" 1 "near_f" 0 "danger_f" ;
VAL_ 190 Sensor_Sonar_FrontRight 2 "far_fr" 1 "mid_fr" 0 "near_fr" ;
VAL_ 190 Sensor_Sonar_FrontLeft 2 "far_fl" 1 "mid_fl" 0 "near_fl" ;
VAL_ 190 Sensor_Sonar_Back 2 "far_b" 1 "mid_b" 0 "near_b" ;
VAL_ 180 steer 4 "right" 3 "sright" 2 "sleft" 1 "left" 0 "straight" ;
VAL_ 180 speed 4 "brake" 3 "reverse" 2 "normal" 1 "slow" 0 "stop" ;
VAL_ 181 Rps_Sensor 2 "high" 1 "equal" 0 "low" ;

Design & Implementation

Please refer to the system block diagram below:

System Block Diagram

Description

Assuming the car would be given the necessary connections and be powered up to navigate, we would give the first signal to start the car from the Bluetooth device by sending a start signal of "1". Once the Start signal is received by the Master controller, it would receive the signals from the sensors and the GPS as well. Based on the data from all these systems, Master controller decides the command to be given to the Motor controller. Motor on receiving the instructions from the Master would move in a particular direction suggested by Master. Motor would also revert the path in which it is going, RPM values to Master, Bluetooth and LCD display over the CAN. Meanwhile the Bluetooth would be fetching the messages from the CAN and would filter out on the messages by their ID's and later send the required signals such as GPS and RPM values to the Android device, which is displayed to the user in their respective text boxes.

CAN BUS

Below is the screenshot of the CAN Bus while Testing the CAR after integration.

CAN BUS

P-CAN Dongle

P-CAN would be connected to RX-480 Port on the CAR and other end to the system via USB on the system, shown in the image above.This would enable the user to view the CAN messages on the CAN Bus on his screen and would largely help to debug the error on all the controllers.

Sensor Controller

Team Members:

Vishwanath Balakuntla Ramesh

Hardware Design

We used 3 Parallax Ping ultrasonic distance sensors for obstacle detection and avoidance. Non-contact distance can be measured from about 2 cm (0.8 inches) to 3 meters (3.3 yards).

The PING))) sensor works by transmitting an ultrasonic burst and providing an output pulse that corresponds to the time required for the burst echo to return to the sensor. By measuring the echo pulse width, the distance to target can easily be calculated.

Three sensors were placed in front (front_left, front_center, front_right).

Parallax ping sensor

Hardware Interface

Three parallax ping sensors are used (front, left and right). As shown above, in the hardware design of parallax ping sensor, VCC pin of all the three sensors is connected to 5V, GND is connected to ground and SIG of all the three sensors is connected to P2.0, P2.1, and P2.2 of SJ One board.

Parralax Ping Sensor Operation

Sensor Ping Operation

Software Design

Sensor Fields and Ranges

Sensor_Sonar_Front_E calculate_range_front(double distance)
{
	if(distance>5&&distance<120)
		return danger_f;

	else if(distance<180)
		return near_f;

	else if(distance<250)
		return mid_f;

	else
		return far_f;
}


Sensor_Sonar_FrontRight_E calculate_range_frontRight(double distance)
{
	if(distance<100)
		return near_fr;

	else if(distance<200)
		return mid_fr;

	else
		return far_fr;
}


Sensor_Sonar_FrontLeft_E calculate_range_frontLeft(double distance)
{
	if(distance<100)
		return near_fl;

	else if(distance<200)
		return mid_fl;

	else
		return far_fl;
}


void start_trigger(GPIO trigger)
{
	trigger.setAsOutput();
	trigger.setHigh();
	delay_us(5);
	trigger.setLow();
}

Implementation

Sensor Controller Flow Diagram

Motor & I/O Controller

Team Members:

Sameer Saran
Jaswanth Bhimanapalli

Hardware Design

Block Diagram for Motor

Hardware/Software Interface

I/O Interface - LCD The LCD is used to display some of the features to its application in our project.The sensor, GPS and current coordinates are displayed on LCD. The LCD we bought is from 4D systems and is very convenient and efficient to use. It has its own software which enables us to work in 4 different modes. We chose the mode which gave us different tools to build the compass, buttons and the angulometer. Bluetooth to serial converter is used to program the LCD with the software. We used the tools (that came with the LCD Module), to picturize our LCD screens. We loaded the program into LCD's memory card. The program that we burned on LCD will use the data bytes we send from our microcontroller and will print those bytes appropriately on different elements that we had created. For example, there are 360 degrees values to show on angulometer. The microcontroller will give a value from 0-360 based on the CAN frame which consists of car speed, heading and bearing values broadcasted by the Geo controller. In this way, almost every parameter being exchanged on the CAN bus of the car is displayed.

The following is the link to the main page of the LCD. It contains everything you need to know to run this LCD and run it to the highest feature. It has the datasheet as well as the info regarding the software too. Go through the software datasheets as well as we will need that software to run the LCD initially. The LCD accepts any data from our microcontroller only if it is programmed that way by the software. http://www.4dsystems.com.au/product/uLCD_32PTU/ Next link is to the to the collection of go through materials for each every object the LCD uses. http://old.4dsystems.com.au/appnotes.php

Now, if you have gone through the software datasheets, you will be already have accustomed with the software and its fun too. Select your tool accordingly your requirement. Be creative. We needed to show magnetometer values, from 0 to 360 in order to debug whether the compass is pointing towards north exactly or not. So we used an angularometer under the Gauges tab. It will have all the properties associated with the object. You can test each of them. Now, the data sent from the microcontroller will be directly printed on the LCD to its position on the angulometer. In this way, we can easily know the direction of True North with the help of LCD. Alon with this there are some strings used on LCD which shows longitude, lattitude, etc. This string is also sent from the microcontroller. When you are done with the tools, put a memory card with a maximum of 2 GB of memory into your LCD and connect it serially to your PC. USB to serial converter is to be used here. Burn the software image onto your LCD. At this point, your LCD is programmed to show all the images and the tools and is ready to accept all the data from the controller and print them on itself. So now we have got to do, is only connect the controller with LCD and send data bytes with help of UART.

Below are the snaps of the LCD Screens:

LCD Screen 1

LCD Screen 2

LCD Screen 3

LCD Screen 4

LCD Screen 5

Tasks

Brushless DC Motor

void drive_DC(speed_E speed,int rpm)
{
	if(speed==reverse)
	{
        //Set DC to Reverse PWM Value
	}
	else if (speed==brake)
	{
	//Set DC to Brake PWM Value	
	}
	else if (speed == stop)
	{
	//Set DC to Stop/Idle PWM Value
	}
	else
	{
	        ReqRPM=get_rpm(speed);

		if(DC Value id with in safe range)
		{
			if(rpm>ReqRPM)
			{
			//If current RPM is greater then Required RPM then Reduce Speed
			}
			else if(rpm<ReqRPM)
			{
			//If current RPM is lesser then Required RPM then Increase  Speed
			}

			else if(rpm==ReqRPM)
			{
		        //If current RPM is equal to required RPM the maintain same Speed
			}
		}
	}

}

Servo Motor

class MotorCtrl : public SingletonTemplate<MotorCtrl>
{
	public:
		MotorCtrl() : steerServo(PWM::pwm1),driveDc(PWM::pwm2)
		{
			//Constructor
		}
		void set_servo(float value) {steerServo.set(value);}
		void set_dc(float value){driveDc.set(value);}
		friend class SingletonTemplate<MotorCtrl>;

	private:
		PWM steerServo;
		PWM driveDc;

};

#define MotorCtrl MotorCtrl::getInstance()

Bluetooth and Bridge(Android) Connections

Team Members:

Sucharitha Sirigreddy
Karthikeya Rao G V

This section includes high level implementation details regarding the Android app connectivity with the Bluetooth module of the RC car. It gives a overview of building the android app, communication between the Bluetooth and Android app on a mobile device, and routing mechanisms during the navigation.

Bluetooth Controller Pin Connections

Below attached is the image of the Bluetooth Module HC-06.

Bridge Controller Design

Hardware Interface

Below is the representation of the bridge communication.

Bridge Controller Design

Hardware Interface between the Bluetooth controller and the car system has been wired through the CAN bus. P0.1 is connected to CAN Tx and P0.0 is connected to CAN Rx, where communication between the Bluetooth module and other modules happen. RXD and TXD pins are connected to Bluetooth HC-06 to enable communication between the Android mobile device and the Bluetooth module. Power supply and Ground pins to SJone board i.e Bluetooth module is provided by battery, which would power up all the SJone boards. Power to the HC-06 module is given by the SJone Bluetooth board 3.3V and GND pins. Thus enabling the Interface between Bluetooth module and the other controllers.

Software Design

Software interface between HC-06 and Android device is enabled via Bluetooth transmission and reception.

Below attached is the image showing the Android Application Development.

Stages of Android Application Development

Initially we developed the Application with just Enable and Disable Bluetooth Buttons, after which we added the Start and Stop Signals Button. Start and Stop buttons were given the functionality to send "1" and "0" respectively. In the next phase, we integrated the application with Google maps with few more buttons and obtained our location from the Google maps and cell phone GPS and marked our location on the App screen. In the Final phase we were able to display the application with all the values which we received from the Bluetooth controller, which includes RPS and Locations.

Below diagram represents the different app screens in the selection sequence.

Android Application Screens

In the above image, we initially turn on the Bluetooth device. Once done, we set up the start and destination on the map, marked as red and green flags respectively. Clicking on the Start signal would enable the Car to receive the Signals Route button would send out the way points to the Bluetooth controller and the Master sending the signal to move the car in the way points direction.

Flow Chart:

Flow Chart of the Bluetooth and Android design is as follows.

Android and Bluetooth Controller Flow Chart

Android-Bluetooth Controller Button's Functionality Table

Implementation

Through the Android application the Bluetooth would be paired with HC-06 module on click of BTon button, which turns on the Bluetooth on the android phone and connects to Car’s HC-06 Bluetooth device. Post which, we would send a start signal from the app, which would sync and start the car. This signal is hardcoded as ‘1’, and is encoded before sending from the android. This signal when received from the Bluetooth module, would decode and read the message and later encode and pass it on over the CAN to the Master.

After this syncing, the Master would initiate other modules; post which GPS module would send the location signal over the CAN. This signal is again decoded and sent over to the Android as a line having latitude and longitude and prefixed with respective signals, ex: RPM for RPM values and post-fixed with “!” , for easier identification in the Android. Location button would enable the current location of the device, which would be marked on the map, this would be enabled on click of start itself. This would also enable Bluetooth module to detect the messages over the CAN to be displayed on the app, like RPM values and GPS data. These are again encoded and sent over to Android, which would display them in respective text boxes.

Route Button on the app would be initiated once we set these and the source and destination by 2 clicks on the maps in the app and start getting the GPS location from HC-06. Route Button on click would detect the GPS location from the car and send out next way points till the destination. The Kill switch is implemented as Stop Button, which sends of “0” signal, which is received by the Bluetooth and sent over the CAN Bus to master, to stop the Motor.

Geographical Controller

Team Members:

Veena Manasa Kanakamalla
Arpita Ramanath

Hardware Design

System Block Diagram

SJ One board is interfaced to GPS module and IMU through UART.

Hardware Interface of GeoController

Geographical Controller Hardware Design Components

Adafruit MTK3339 GPS: This GPS unit is interfaced via UART with build in antenna. The GPS provides latitude and longitude accurately up to 5-10 meters with a strong satellite fix with update rate of 10Hz. By default, the baud rate is 9600bps. Power usage for this module is 20mA during navigation. The GPS module comes with following capabilities: -165 dBm sensitivity, 10 Hz updates, 66 channels 5V friendly design and only 20mA current draw Breadboard friendly + two mounting holes RTC battery-compatible Built-in datalogging PPS output on fix Internal patch antenna + u.FL connector for external active antenna Fix status LED We chose this part because it provided the base functionality we needed along with many other functions that would be fun to play with and try to include in the project. The antennae options and voltage regulator were also very enticing. We get raw GPS "NMEA sentence" output from module. The most important NMEA sentences include the GGA which provides the current Fix data, the RMC which provides the minimum gps sentences information, and the GSA which provides the Satellite status data. We are filtering the data for GGA (Time, Position and Fix type data), which will look similar to: GGA- essential fix data which provide 3D location and accuracy data. $GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47 GGA Global Positioning System Fix Data 123519 Fix taken at 12:35:19 UTC 4807.038,N Latitude 48 deg 07.038' N 01131.000,E Longitude 11 deg 31.000' E 1 Fix quality: 0 = invalid 1 = GPS fix (SPS) 2 = DGPS fix 3 = PPS fix 4 = Real Time Kinematic 5 = Float RTK 6 = estimated (dead reckoning) (2.3 feature) 7 = Manual input mode 8 = Simulation mode 08 Number of satellites being tracked 0.9 Horizontal dilution of position 545.4,M Altitude, Meters, above mean sea level 46.9,M Height of geoid (mean sea level) above WGS84 ellipsoid (empty field) time in seconds since last DGPS update (empty field) DGPS station ID number *47 the checksum data, always begins with *		GPS
GPS Pin Connections GPS Pin Connections 9 Degrees of Freedom- Razor IMU: In our project, we used IMU module to get the heading of the device. The 9DOF Razor IMU provides nine degree of inertial measurement incorporates three sensors - an ITG-3200 (MEMS triple-axis gyro), ADXL345 (triple-axis accelerometer), and HMC5883L (triple-axis magnetometer). The outputs of all sensors are processed by an on-board ATmega328 and output over a serial interface. UART interface is used for interfacing with SJ One board and it is connected via UART3 with LPC board and is operated at 3.3V. Features: 9 Degrees of Freedom on a single, flat board: ITG-3200 - triple-axis digital-output gyroscope ADXL345 - 13-bit resolution, ±16g, triple-axis accelerometer HMC5883L - triple-axis, digital magnetometer Outputs of all sensors processed by on-board ATmega328 and sent out via a serial stream Autorun feature and help menu integrated into the example firmware Output pins match up with FTDI Basic Breakout, Bluetooth Mate, XBee Explorer 3.5-16VDC input ON-OFF control switch and reset switch		9DOF-IMU

IMU Pin Connections

IMU Pin Connections

Hardware Interface

Geographical Controller H/W Interface

• Below table shows the pin connections of GPS and IMU module with SJ One Board. Both the modules are interfaced with Controller using UART interface. The operating voltage of GPS and IMU is 5V.

1 -> Rx
2 -> Tx

1 -> Tx P4.28
2 -> Rx P4.29

1 -> Rx
2 -> Tx 

1 -> Tx P2.8
2 -> Rx P2.9

Software Design

Geographical controller uses two modules to get GPS data and heading. These are:

• GPS module
• IMU module

Tasks

Flowchart

GeoController Flow Diagram

Implementation

Receiving and parsing GPS data

The first task was to interface the GPS module to the SJOne board (using UART3), and receive raw data over it. The module was configured to receive only GPGGA NMEA sentence at 9600 bps baud rate. The received NMEA data is a string, that has to be parsed to obtain current latitude and longitude values. This location data is continuously sent to the Master controller on the CAN bus at 10 Hz.

Heading Calculation

Heading of the car is the direction that the car is moving, with respect to true north. A compass gives heading with respect to magnetic north. True heading is calculated by adding magnetic declination at that particular location, to the magnetic heading.

The IMU module has to be calibrated initially. The board comes programmed with the 8MHz Arduino bootloader (stk500v1) and some example firmware that demos the output of all the sensors (accelerometer, magnetometer, gyroscope). The calibration was done by following this tutorial at https://github.com/Razor-AHRS/razor-9dof-ahrs/wiki/Tutorial. Calibration compensates for the magnetic field around the IMU. So this process has to be done once after mounting the IMU on the car.

The IMU module is interfaced to the SJOne board using UART2. The IMU firmware is updated such that it gives only Yaw readings. Yaw (or magnetic heading) is used to calculate the true heading using the below formula.

Heading = Yaw data from IMU + Magnetic Declination

Magnetic declination in San Jose is +13° 29'.

Bearing calculation

Bearing is the direction that the car desires to travel along, i.e., the direction of the destination. It is calculated using the current location coordinates and the destination coordinates (or next checkpoint coordinates). The formula to calculate bearing is

   X = cos(lat2) * sin(dLong)
   Y = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLong)
   Bearing = atan2(X,Y)
  
   where,
   (lat1, long1) are the current location coordinates
   (lat2, long2) are the checkpoint coordinates
   dLong is (long2 - long1) 

Distance calculation

The distance between the current location and the next checkpoint is calculated using the below formula.

Haversine formula to calculate distance

  a = sin²(Δφ /2) + (cos φ1 ⋅ cos φ2 ⋅ sin²(Δλ/2))
  c = 2 x atan2( √a, √(1−a) )
  Distance d = R x c
       Where,
            Φ is latitude
            λ is longitude
            R is Earth’s radius = 6371 Km
            Δφ = latitude2 – latitude1
            Δλ = longitude2 – longitude1

A flag is set when the distance to the final checkpoint becomes zero, and sent to the Master controller, to indicate that the destination has been reached.

Master Controller

Team Members:

Ajai Krishna Velayutham
Goutam Madhukeshwar Hegde

The Master Controller receives obstacle information from the Sensor Controller, navigation data from the Geo Controller and routing information from the Bluetooth Controller, collates all this information and provides driving directions to the Motor Controller.

Hardware Design

The diagram shows the connections for the Master Controller

Master Controller Interface

Hardware Interface

In this section, you can describe how your hardware communicates, such as which BUSes used. You can discuss your driver implementation here, such that the Software Design section is isolated to talk about high level workings rather than inner working of your project.

Software Design

Obstacle avoidance algorithm: Obstacle avoidance is done according to the enum values sent from the sensor controller. In the master controller, obstacle avoidance is handled separately in danger,near and medium regions. If sensor indicates danger region,it means that there is an obstacle very near to front sensor. So in this case car takes a reverse turn until the front sensor enters near region.So in this way car avoids obstacle very near to it. If sensor indicates near region,master enters a states machine to intelligently avoid the obstacle as shown the above figure. If sensor indicates medium region,master enters another state machine to handle the obstacles in medium region.

Obstacle Avoidance State Diagram for Near Region

Obstacle Avoidance State Diagram for Mid Region

Navigation Algorithm:

Steer control based on turn angle

GPS Navigation is done based on the heading and bearing values from GEO controller.Master controller calculates the desired turn angle to reach the destination path.

Turn angle= GPS bearing-GPS heading;

Turn angle is a value between 0 to 360 degree.Entire 360 degrees is divided into various sub-regions based on the desired turn angles as shown in the above figure. GPS navigation is done with the help of a state machine.Turn angle is the input for the state machine based on which state machine determines the command to issue to the motor.

Implementation

This section includes implementation, but again, not the details, just the high level. For example, you can list the steps it takes to communicate over a sensor, or the steps needed to write a page of memory onto SPI Flash. You can include sub-sections for each of your component implementation.

Testing & Technical Challenges

Motor & I/O Issues

• Reverse Current from Motor: One of our boards got burnt while testing Brushless DC Motor. We would highly recommend using an Optoisolator such as ILQ74 for additional protection from reverse current etc. if you are synchronizing with the ESC for the first time.

• ESC Synchronization: The slowest speed of Brushless DC motor was too fast for us. We tried to change ESC synchronization and reprogram it to change PWM frequency but it didn't work out for us. We recommend having Brushed DC Motor that is reprogrammable to any PWM frequency.

• ESC Modes: ESC Board was only set to forward and reverse mode. So we were not able to control the speed to stop the motor, even after sending stop signal it would hit the obstacle. So we reprogrammed the ESC to forward, reverse and brake. Synchronizing took time and effort. ESC has various modes we can program it into.

• Going Reverse issues: If we wanted to go reverse first without going forward, car would go full speed in reverse. So every time we got reverse command from master, we initialized the DC motor to idle and then go to reverse.

• LCD Refresh Rate Issue: For debugging, we wanted to run LCD at 10hz but it took long time to refresh, so data didn't get printed. Hence we were forced to debug especially at 1 Hz.

Bluetooth Bridge Controller and Android application Issues

Issues

• During the initial phase we were finding difficult to connect to the Bluetooth Module HC-06, later on proper UUID was given which solved the connection issue.
• Sending out Start and Stop messages of "1" and "0" respectively continuously was a challenge. This was required to detect when Bluetooth goes out of range. We solved this issue using threads.
• We had tested the application by hard coding the values from the Bluetooth controller end, which was displayed as messages on the application. The requirement was to display the CAN messages, therefore once we integrated on board, we faced issues like receiving junk and ? character on the application. We solved this by introducing circular buffers.
• On integrating with on board GPS, we were unable to send out all the Navigation way points, say if we got 8 way points, we were able to send only first 4 of them. This was due to buffer size which we had set to 100. Once we updated it to 500, we were able to receive all the CAN messages flawlessly.

Testing

• At Module level, we tested the communication between the Bluetooth Controller and the Android by sending out characters through UART and displaying the received messages on the app screen.
• We increased the number of characters to 960 characters that was being sent on UART to check whether we were able to receive on the app.
• Verified the Location of the maps on the app with the Google maps application.
• Verified the messages displayed on the Bus Master and LCD with the app screen post integration.

Project Hardware Issues

Geo controller Issues

• While initially testing IMU in raw data mode, the module was providing improper data values. We had to calibrate the Gyrometer and Magnetometer to get exact angles with precision of +/- 2 degrees. Even after this, the magnetometer's readings were changing when any soft/hard iron object was taken near the sensor. In order to remove electromagnetic interference generated from DC motor, we had to place our IMU far from DC Motor. The IMU has to be calibrated once again after mounting it on the car to avoid drift in the Yaw values.

• The GPGGA sentence received via UART was incomplete sometimes, resulting in incorrect parsing. This turned out to be an issue with the UART receive queue size. When this queue size was increased, complete NMEA sentences were received.

• Initially, the coordinates received from the GPS module were pointing to Santa Clara, around 30 km away from our present location. This was due to incorrect parsing of the NMEA sentence from the GPS module. The latitude and longitude values from the GPS module are given in the form of ddmm.mmmm and dddmm.mmmm and not decimal degrees. The minutes have to be converted to degrees and added to the degrees value.

Master Controller Issues

Miscellaneous Issues

Conclusion

In a span of 3 months, we had an awesome experience in working together for the AutoNav project. We learnt a lot about GIT and CAN bus along with implementing DBC and working on real hardware. We were able to implement all these embedded concepts effectively from our course work. All essential phases of software development cycle such as design, implementation and testing were executed in stages effectively and debugging with CAN bus was really helpful in working. Finally it was an enchanting experience and we hope that we were able to share some of our learnings and difficulties we faced in this report, which would help the future students joining the course.

Project Video

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GitLab Source Code

• Git Code for Team AutoNav

References

Acknowledgement

Any acknowledgement that you may wish to provide can be included here.

References Used

List of references used in the project.

[1] Preetpal Kang's lecture notes of CMPE 243, Computer Engineering, San Jose State University, Aug-Dec 2016.
[2] LPC1758 User Manual
[3] Parallax Ultrasonic Sensor
[4] Razor IMU
[5] Razor IMU Tutorial
[6] Adafruit Ultimate GPS Breakout - 66 channel w/10 Hz updates - Version 3
[7] Calculate distance between two points
[8] Programming Guide
[9] Google Maps Guide
[10] Video guide for Google maps implementation

Appendix

You can list the references you used.