F14: Team5-Self Driving Car - AUG

Self Driving Car

Fig 2. Build in Progress

Team Members & Responsibilities

1. Sensor Controller (2 Members) - [Bailey Wu, Rishabh Sareen]
2. Motor Controller (2 Members) - [Abraham Ruiz, Sree Harsha, Arpit Amin]
3. I/O Unit (2 Members) - [Yoni Klein, Tejeswar]
4. Communication Bridge + Android (3 Members) - [Shaw Ken Chang, Arnold Bajet Jr., Thomas Pantels]
5. Geographical Controller (3 Members) - [Himanshu Saini, Divya Kamath]
6. Master Controller (3 Members) - [Akash Ayare, Sree Harsha, Karthik Vadiraja]

Schedule

Geographical Controller

Sl. No	Start Date	End Date	Task	Status	Actual Completion Date
1	1-Oct-2014	14-Oct-2014	Order Components and Make a schedule	Completed	14-Oct-2014
2	8-Oct-2014	14-Oct-2014	Decide commands that Geographical Controller will support	Completed	14-Oct-2014
3	7-Oct-2014	14-Oct-2014	Complete CAN RX task and subscription handling. Verify communication with other controllers	Completed	21-Oct-2014
4	14-Oct-2014	24-Oct-2014	Interface GPS module and Compass and develop drivers if needed	Completed	28-Oct-2014
5	24-Oct-2014	30-Oct-2014	Design and develop algorithm to calculate heading and bearing from GPS coordinates	Completed.	30-Oct-2014
6	24-Oct-2014	5-Nov-2014	Work on calibration of compass and heading calculation	In Progress
7	1-Nov-2014	10-Nov-2014	Test with the central and Bluetooth controller	communication works. Working on steering algorithm in central using geo data
8	10-Nov-2014	25-Nov-2014	Begin testing with fully assembled car	In Progress
9	25-Nov-2014	10-Dec-2014	Final Testing and changes as needed

Sensor Controller

Sl. No	Start Date	End Date	Task	Status	Actual Completion Date
1	10/3/2014	10/10/2014	Order ultrasonic sensor parts and develop simple test code for the sensors	Done	10/10/2014
2	10/10/2014	10/17/2014	Wire the ultrasonic sensors, develop and implement the sensors using analog to digital converter	Done	10/17/2014
3	10/17/2014	10/24/2014	Collaborate with the other sub teams to finish the CAN bus communication and allow the self driving car to drive autonomously	Done	10/24/2014
4	10/24/2014	11/1/2014	Develop, implement and test the ultrasonic sensors using the pulse width modulation and universal asynchronous receiver/transmitter	Done	11/1/2014
5	11/2/2014	11/9/2014	Develop, implement and test the front and back infrared sensors using analog to digital converter	Done	11/9/2014
6	11/10/2014	11/17/2014	Develop, implement and test the current/voltage sensor for the battery packs of the self driving car using I2C	Scheduled	Removed
7	11/18/2014	11/25/2014	Collaborate with the other sub teams to make sure that the sensors are in working condition	Done	11/25/2014
8	11/26/2014	12/5/2014	Collaborate with the other sub teams to debug any problems that may encountered	Done	12/5/2014
9	12/6/2014	12/13/2014	Prepare for Demo	Scheduled

IO Controller

Sl. No	Start Date	End Date	Task	Status	Actual Completion Date
1	10/7/2014	10/14/2014	Research and order LCD appropriate for this project	Finished	10/11/2014
2	10/7/2014	10/17/2014	Implement CAN RX/Subscription task	Finished	10/13/2014
3	10/7/2014	10/17/2014	Finalize Task Architecture	In Progress
4	10/18/2014	10/21/2014	Interface and test LCD	Finished	10/20/2014
5	10/21/2014	10/28/2014	Implement special button features
6	10/21/2014	10/28/2014	Implement auto scrolling feature
7	10/28/2014	11/4/2014	Design LCD UI with buttons

Communication Bridge + Android

Sl. No	Start Date	End Date	Task	Status	Actual Completion Date
1	16-Sep-2014	23-Sep-2014	Test bluetooth module using computer serial port and an android app(simple bluetooth terminal app downloaded from google play). Test the real life range and stability of the bluetooth module (HC-06). Modify the bluetooth chat example to work with the bluetooth module.	Done	20-Sep-2014
2	28-Sep-2014	12-Oct-2014	Draw UI design layouts for a basic android application that can view Google map as well as send GPS data through bluetooth by clicking on the map. Study google maps API and make a simple app that will post a short toast that shows the GPS location after a long press event.	Done	12-Oct-2014
3	7-Oct-2014	11-Oct-2014	Interface bluetooth module with SJSUOne board and able to verify that the connection is stable and that transaction via the bluetooth is accurate. This is done by adding a test button where if you press the button it send a command to the board. After receiving the command, the board should react with a response (LED light and/or text response to the android phone)	Done	19-Oct-2014
4	11-Oct-2014	19-Oct-2014	Integrate Google Maps and Bluetooth component together in Android app. After a long press on the map, the user should be prompted to start the car and set the location as the places the user selected. Add a textView to display the location selected by pressing on the map. Add a button for sending location to the car.	Done	27-Oct-2014
5	19-Oct-2014	26-Oct-2014	CAN infrastructure implmentation: Use our team's common CAN infrasturcture code and modify it specifically for our controller. First created the CAN communication table and then modify the infracturacture code to implement the broacasting as well as filtering of neccessary data. This only focuses on broadcasting a stop/start command and the destination GPS data (set by android) as well as getting car's current location data from the geological controller.	Done	07-Nov-2014
6	26-Oct-2014	1-Nov-2014	Test and implement car information reading as well as other functions of Android app	In Progress
7	2-Nov-2014	4-Nov-2014	Iterate UI design	In Progress
8	5-Nov-2014	16-Nov-2014	Implement 2nd UI design	In Progress

Motor Controller

Sl. No	Start Date	End Date	Task	Status	Actual Completion Date
1	10/1/2014	10/8/2014	PWM2 (used to control motors) and PWM3 (used to control servo) interface with the car servo and motor. Write a test code to operate the servo and motor from the terminal command.	Completed and Tested	10/11/2014
2	10/9/2014	10/18/2014	Design and code CAN receive task for subscription. Check for basic CAN message commands for throttle and steer control.	Completed and tested	10/26/2014
3	10/19/2014	10/28/2014	Design the CAN message table for motor control and servo control	Completed and tested	10/26/2014
4	10/29/2014	11/07/2014	Design acceleration Vs steer control function for smooth run. Check for other factors involved.	Completed and tested	11/22/2014
5	11/08/2014	11/14/2014	Research on RPM sensor. Interface the RPM sensor to calculate the Speed. Test the RPM sensor by running the car at different speed	Completed and tested with a hall sensor	11/22/2014
6	11/15/2014	11/21/2014	Fine tune motor control code and integrate with all the controllers for proper working.	Completed and tested	11/22/2014
7	11/22/2014	11/28/2014	Test and check if more features can be added to improve performance. Completed and tested	Completed and tested	11/28/2014
8	11/29/2014	12/05/2014	Testing and Debugging.	Completed and tested	12/05/2014
9	12/06/2014	12/18/2014	Final Testing and getting the car ready for Demo.	On Going

Central Controller

Sl. No	Start Date	End Date	Task	Status	Actual Completion Date
1	16-Sep-2014	23-Sep-2014	Develop API for CAN bus communication.	Done	23-Sep-2014
2	11-Oct-2014	15-Oct-2014	Develop communication table for all controllers.	In Progress
3	15-Oct-2014	20-Oct-2014	Broadcast message and target message setup.	In Progress
4	21-Oct-2014	28-Oct-2014	Co-ordinate all controllers and take major decisions.	Planned
5	28-Oct-2014	11-Nov-2014	Complete Building and fine-tuning of RC car.	Planned
6	21-Oct-2014	11-Nov-2014	Develop coordination mechanism to ensure controllers are initialized and ready	In Progress
7	21-Oct-2014	28-Oct-2014	Develop kill switch	In Progress
8	14-Oct-2014	21-Oct-2014	Build external power distribution circuit	Done	21-Oct-2014
9	28-Oct-2014	04-Nov-2014	Coordination algorithm between steering and throttle for smooth turns	Planned
10	04-Nov-2014	11-Nov-2014	Collision avoidance and cliff detection algorithms	Planned
11	04-Nov-2014	11-Nov-2014	Intermediate unit and functional tests	Planned
12	21-Oct-2014	4-Nov-2014	Initialize all boards with GPS-time	Planned
13	11-Nov-2014	25-Nov-2014	Functional tests and algorithm adjustments	Planned
14	25-Nov-2014	02-Dec-2014	Fine tuning and stretch goals (headlights, parallel parking, etc.)	Planned
15	02-Dec-2014	09-Dec-2014	Prepare for demo	Planned

Parts List & Cost

Qty	Description	Manufacturer	Part Number	Total Cost
3	LV-MaxSonar-EZ1 High Performance Ultrasonic Rangefinder	MaxBotix Inc	MB1010	49.90
1	Analog Distance Sensor	Sharp		Free

Backup Parts & cost

Qty	Description	Manufacturer	Part Number	Total Cost

Design & Implementation

Motor Controller

Summary

This module takes command input from central controller and steers the car to its destination; in addition, It has two main controlling parameters : Throttle and Steering. Throttle input moves the car forward and backward. Steer input turns the wheel left and right. The central controller takes feedback from the sensors and makes decision to move the car. Accordingly, it sends CAN commands accepted by the motor controller for navigation, and real time RPM signal to the controller.

Working

The car initially accepts the start command to begin navigation. Commands can then come to move the car forward or backward, steer left or right depending on intelligent decisions made by the central controller. The motor control has intelligence to avoid jerks and ensure smoother transitions between commands.

Kill switch

The remote control and receiver module pair up to provide a signal coverage of more than 100 meters. We make use of this to design our kill switch. When a constant PWM signal of 1000us is received from the remote, the car is in 'ARMED' state and moves the car according to CAN commands. The user has to hold the trigger gun for this state constantly and the car moves. When the user releases the trigger gun, the car stops receiving the PWM signal of 1000us and the car goes to 'DISARMED' state. In short, pull the trigger gun - ARMED, release the trigger gun - DISARMED.

RPM

The RPM sensor is based on a hall sensor switch which detect the North and South pole of a magnet located in the main shaft in the car. The hall sensor part number is 3177, and it has three pin. This sensor is uni-polar which give an output high signal when the sensor captures the North pole of the magnet; subsequently, the sensor give output low signal when the sensor captures the South pole of the magnet. Therefore, by using a the 3177 and a magnet in the shaft. the SJOne board can capture the output signal from the hall sensor as it toggles per shaft revolution. It is important to notice that the output signal of the 3177 is an open collector; therefore, we need a 10 Kohm resistor connected to Vcc. The following table shows the pinout of the 3177:

3177 Pinout

Pin	Description	Connected to
1	Vcc ( 4.5 V to 18 V)	SJONE P1_22
2	Ground	SJONE Ground
3	Output	SJONE P1_22 with a 10 KOhm

The following Block diagram shows an overview of the connection between the SJOne board, ESC, and the Hall sensor:

Controller Communication Table

Controller ID Table

Controller ID	Controller
0x01	Master Controller
0x02	Geographical Controller
0x03	Motor Controller
0x04	Sensor Controller
0x05	IO Controller
0x06	Communication (Bluetooth Bridge/Android App) Controller

Central Controller Communication Table

Sl. No	Message Number	Purpose	Data layout
1	0x501	Send Throttle and steering to motor	throttle steering
2	0x502	Start car
3	0x503	Stop car
4	0x101	Broadcast request revision
5	0x102	Broadcast Set time
6	0x103	Request TX count (broadcast)
7	0x104	Request RX count (broadcast)
8	0x105	Send TX count (LCD)
9	0x106	Send RX count (LCD)
10	0x107	All controllers initialize

Communication (Bluetooth Bridge/Android App) Controller Communication Table

Sl. No	Message Number	Purpose	Data layout
1	0x301	Broadcast Start command
2	0x302	Broadcast Stop command
3	0x303	Broadcast GPS destination set by Android	byte [0-3] : (float), Longitude byte [4-7] : (float), Latitude

Sensor Controller Communication Table

Sl. No	Message Number	Purpose	Data layout
1	0x501	Broadcast front sensors values	byte[0]: Right ultrasonic sensor value in inches byte[1]: Front ultrasonic sensor value in inches byte[2]: Left ultrasonic sensor value in inches byte[3]: Front bottom infrared sensor value in inches
2	0x502	Broadcast back infrared sensor value	byte[0]: Back infrared sensor value in inches
3	0x503	Broadcast battery sensor value	byte[0]: current/voltage sensor value in percentage
4	0x504	Broadcast light sensor value	byte[0]: light sensor value as integer
5	0x505	Broadcast tilt sensor value	byte[0]: X-Axis tilt sensor value as integer byte[1]: Y-Axis tilt sensor value as integer byte[2]: Z-Axis tilt sensor value as integer

Motor/Servo Controller Communication Table

Sl. No	Send Code	Description	Data
1	0x201	Heartbeat data	Controller id 1 byte
2	0x201	Heartbeat data	Controller id 1 byte
3	0x201	Heartbeat data	Controller id 1 byte
4	0x202	Mem info data	Sys-mem remaining 4bytes
5	0x501	RPM data send	RPM (2 bytes)
6	0x502	Speed data send	Speed (2bytes)
Sl. No	Receive Code	Description	Response
1	0x300	Kill	Receive only
2	0x301	Stop	Receive only
3	0x302	Straight	Receive only
4	0x307	move forward 25%	Receive only
5	0x30C	move forward 50%	Receive only
6	0x311	move forward 75%	Receive only
7	0x315	move forward 100%	Receive only
8	0x31A	move backward 25%	Receive only
9	0x31F	move backward 50%	Receive only
10	0x324	move backward 75%	Receive only
11	0x329	move backward 100%	Receive only
12	0x334	Steer right 25%	Receive only
13	0x339	Steer right 50%	Receive only
14	0x33E	Steer right 75%	Receive only
15	0x343	Steer right 100%	Receive only
16	0x348	Steer Left 25%	Receive only
17	0x34D	Steer left 50%	Receive only
18	0x352	Steer left 75%	Receive only
19	0x357	Steer left 100%	Receive only

Io Controller Communication Table

Sl. No	Message Number	Purpose	Destination
1	0x301	Start command for car	Central Controller
2	0x302	Stop command for car	Central Controller
3	0x303	Go to a predefined Destination.	Central Controller

Geographical Controller Communication Table

Message Number	Message Type	Purpose	Data layout
0x0301	Get Geo Data	Request for GPS Data (lat,long)
0x0302	"	Request for current compass heading and destination heading
0x0304	"	Request Time
0x0601	Response to 0x3xx request	GPS Data (lat,long)	dword[0] : [32-bit latitude] dword[1] : [32-bit longitude]
0x0602	"	Compass heading and destination bearing	dword[0] : [32-bit compass heading] dword[1] : [32-bit destination bearing]
0x0504	"	Time	dword[0] : [32-bit time 0x00hhmmss]
0x0501	Periodic Message	GPS data, broadcast periodically	dword[0] : [32-bit longitude] dword[1] : [32-bit latitude]
0x0502	"	Current and destination heading broadcast periodically	dword[0] : [32-bit compass heading] dword[1] : [32-bit bearing]

Testing & Technical Challenges

Sensors

The first challenge was the positioning and spacing between the sensors. The sensors were mounted on a 3D printed bracket for initial testing but the angle between the brackets seemed to cause interference and was not giving optimum values. The sensors were then individually mounted further apart to reduce interference. The detection distance was tweaked by trial and error and finally settled on the value of 36 inches for the front, left and right sensors and 7 inches for the back sensor.

The second challenge was dealing with erroneous values. Using ADC to interface sensors lead to certain erroneous values that didn't have the desired effect and after some testing, the sensor interface was changed to pulse width. This lead to more robust values after filtering.

Another challenge was the initial skewed alignment. It was difficult to detect whether the direction of the running car was changing because of the motor response to sensor values or the alignment of the tires. The group eventually decided to get a new car that rectified the alignment issue.

Motor Controller

Issue 1

As we were using Electric Speed Control (ESC) to control the speed of motor we faced issues based on inconsistency of the speed. This could have been solved easily if we used H-bridge chip. When ESC was supplied with particular PWM signal it would work at desirable speed but when turning off the ESC and turning on the ESC the speed would change for the same PWM signal supplied. This inconsistency of the speed can easily damaged the motor as it was hard to predict when the motor will switch from forward to backward motion. So to fix this issue we had to connect the ESC to oscilloscope and turn on the transmitter. As soon as the transmitter is turned on the transmitter send a fix signal to ESC for some time that could have been in milli seconds. By doing this the ESC get initialized and once the ESC has initialized the transmitter can send a signal to go forward or reverse.

So we wrote a code to initialize the ESC. Before we sends the signal to ESC to move forward or reverse we send a fix PWM signal to ESC for one second to initialize ESC and this signal was sent from the main function.

Issue 2

The servo that came with the RC car wasn't fast enough to respond to left and right movement of the car. Car would hit the obstacle and than the wheel would rotate in opposite direction. So we change the servo with faster response time.

Sl. No	Test Case	Test Description	Result

Future Enhancement

Sensors

It would be ideal to add another infrared sensor to the front lower portion of the car for cliff detection. It would also be good to have a bigger 3D printed bracket to mount the sensors that match our measurements requirements. This would add to the visual appeal and also reduce tangling mess due to the wires.

References

References Used

1. Preetpal Kang, Lecture notes of CMPE 243, Computer Engineering, Charles W. Davidson College of Engineering, San Jose State University, Aug-Dec 2014.
2. en.wikipedia.org/