F16: Spartan and Furious

1 Project Title
2 Abstract
3 Objectives & Introduction
4 Team Members & Responsibilities
5 Schedule
6 Parts List & Cost
7 Car Framework and Components
8 CAN BUS Design
9 ECUs
10 Motor Controller
11 Android and Communication Bridge
12 Geographical Controller
13 Sensor and I/O
14 Master Controller
15 Conclusion
- 15.1 Project Video
- 15.2 Project Source Code
16 References

Project Title

Android Application controlled Self-Driving Car using CAN bus.

Abstract

This section should be a couple lines to describe what your project does.

Objectives & Introduction

Show list of your objectives. This section includes the high level details of your project. You can write about the various sensors or peripherals you used to get your project completed.

Team Members & Responsibilities

Android and Communication Bridge:
- Manali Deshmukh
Geographical Controller:
- Harsha Gorantla
- Shaurya Jain
Master Controller:
- Ankita Singhal
- Sukriti Choudhary
Motor Controller
- Shilpa Srinivasan
Sensor and I/O Controller:
- Bhushan Muthiyan
- Karthik Parameswaran

Schedule

Legend:

Motor Controller , Master Controller , Android Controller, Geo Controller, Sensor and I/O Controller , Team Goal

Week#	Date	Task	Actual	Status
1	9/17/2016	Purchasing RC car.	Purchased RC car.	Complete.
2	9/24/2016	Individual module distribution. Project report setup. Git setup. Order components for individual modules.	Members identified for modules. Wikipage project report template and Git were setup. Ordered GPS module and CAN transceivers.	Complete
3	10/01/2016	Define scope of each module. Determine Git flow. Follow up on component procurement. Determining and analyzing the duty cycle for servomotor and DC motor of the car. Implement basic CAN communication CAN between two SJ-One Boards.	Initial flow of each module defined. Identified the branches and decided on merge process. Ordered additional ultrasonic sensors and LCD. Tested the car servo and DC motor using Digital Oscilloscope. Observed and noted the duty cycle wave forms . Successfully tested CAN communication between two SJ-One boards.	Complete
4	10/08/2016	Create branches in Git Follow up on component procurement Basic testing of Servo and DC motor. Testing speed of car with variable PWM. Research on the CAN bus, tasks and scheduling. Decision regarding flow of the master controller. Download software for LCD	Created Master branch on Git All ordered parts received by 10/07. Implemented test code to interface SJOne board with a servo motor to control the direction and verified the same on the car. Speed testing in progress. Learnt about the working of CAN bus and decided on flow for the master controller. Installed 4D System Workshop4 IDE (for LCD).	Complete
5	10/15/2016	Developing drivers for both motors. Android app prototype. Parse GPS data and format the data to be transmitted. Decision making regarding various messages to be sent on CAN bus. Design basic sensor algorithm for range finding.	Algorithm developed for both the motors. Basic App Screen layout designed. GPS latitude & longitude coordinates extracted from NMEA format. Identified various messages for different nodes. Designed basic algorithm for range finding.	Complete
6	10/22/2016	Define CAN signals for each module. Testing the car with developed drivers. Interface Bluetooth module with SJ-One board. Implement source code and fetch Magnetometer reading. Design of CAN bus hardware. Test basic working for IR.	CAN signals along with their priorities identified (DBC file format generated). Testing for developed motor drivers in progress. Testing of Bluetooth interface in progress. Implemented the Magnetometer source code, Testing in progress. Tested for hardware integrity. Developed algorithm for obstacle detection.	Complete.
7	10/29/2016	Fine tuning motor control code. Transmitting and receiving messages between Android App and SJ-One board. Test the extracted GPS data for consistency and check the update rate. Basic interfacing of master controller with motor module. Integrate IR sensor for gauging speed.	Testing in Progress for the motor control code. Successfully established communication interface between app and SJ-one board Latitude and Longitude parsed data tested, observed few NMEA strings with wrong checksum values. Testing in Progress of the interface over CAN bus. Developed algorithm for obstacle detection. Speed sensing was delegated to motor team as suggested by Preet.	Complete.
8	11/05/2016	Integration of modules for first demo.	Integration and Testing completed for the first demo.	Complete.
9	11/12/2016	Design of Feedback Control mechanism for car. Initial algorithm development of GPS module for heading calculation. Integration of master module with bluetooth module . Develop LCD code for displaying all sensor information and car vitals. Decide upon additional I/O such as lights.	Developed algorithm for motor feedback mechanism. Initial algorithm developed for GPS heading calculation and tested. Communication between bluetooth and master module established successfully . Created project in Workshop4 IDE for all elements to be displayed by LCD. Found UART commands to control each element in the LCD display. I/O hardware was decided upon.	Complete.
10	11/19/2016	Speed synchronization of car using speed sensor and testing. Interfacing Android controller with the GPS module Algorithm for distance and heading calculation. Coding and Calibration of GPS module. Interface of master module with I/O module and testing to ensure predicted output. Integrate sensor and I/O code.	Integrated speed sensor for calculating the speed and controlling motor speed. Communication between I/O module and master module established successfully . Algorithm implemented for distance and heading calculation. Calibration of Magnetometer ongoing. LCD code completed and sensors adjusted to work in tandem with obstacle avoidance logic.	Complete
11	11/26/2016	Testing and debugging for second demo.	Integration and testing complete for second demo.	Complete
12	12/03/2016	Fine tuning, debugging and integration.	Fine tuning on Geo, Android and I/O module algorithm.	Complete
13	12/10/2016	Final testing and fine tuning Report preparation	In Progress

Parts List & Cost

Item#	Part Description	Vendor	Qty	Cost
1	SJ One Board (LPC 1758)	From Preet	6	$480
2	RC Car	Sheldon Hobbyist	1	$309.99
3	Accelerometer/Magnetometer LSM303	Adafruit	2	$40.00
4	Bluetooth Module	From Preet	2	$0
5	CAN Transceivers	From Microchip.	10	$0 (Free Samples)
6	Battery Pack	From Sheldon Hobbist	1	$49.99
7	Ultra Sonic Sensor	From Maxbotix	5	$91.15 (at 40% student discount)
8	LCD Display	From Digikey	1	$94.21
9	GPS Module	From Adafruit	1	$43.34
10	General Components	From HSC electronics	-	$83.17
11	DC Current Sensor	From Adafruit	1	$14.39
12	PCB	From Amazon	1	$10.66
13	Corrugated Sheet for chasis	From Home Depot	1	$6.74

Car Framework and Components

Stampede 4X4 is built on the advanced shaft-driven 4WD system and innovative modular design of the Slash 4X4. The chassis fully integrates the electronics and battery compartment for an efficient and compact layout, and maintains the high center ground clearance. It uses just three gear meshes to drive all four wheels, eliminating the need for a multi-gear transmission. The highly efficient drive train spins effortlessly on rubber-sealed ball bearings, and is integrated seamlessly into the unique chassis for optimum performance and easy maintenance. A single center driveshaft connects the front and rear drive assemblies for maximum power transfer. To harness the torque of the Titan 12-turn motor, Traxxas bolted in the high-performance, waterproof XL-5 electronic speed control. EZ-Set one-button setup makes it easy to adjust or change profiles.

Car Framework

CAN BUS Design

CAN 11-bit ID Format

SRC	DST	MSG
3 bits (10-8)	4 bits (7-4)	4 bits (3-0)

Controller ID Table

Controller ID	Controller Type
0	System Command
1	Master Controller
2	Sensor Controller
3	BLE Controller
4	Geo Controller
5	Motor Controller
5	I/O Controller

CAN Communication Table

Sr. No	Message ID	Message function	Message Data	To
System Commands
1	10	System communication command	0 - Communication Stop 1 - Communication Start	Master
Master Controller Commands
2	100	Master System Command for the all modules to start or stop processing	0 - System Stop 1 - System Start	BLE, Geo, I/O, Motor, Sensor
3	151	Steer and Drive command for the Motor module		Motor, I/O
4	162	Display the active state of each module and Can bus utilization		BLE, I/O
Sensor Controller Commands
5	211	Obstacle Data		Master, I/O
6	214	Heartbeat		Master
BLE Controller Commands
7	314	Heartbeat		Master
8	341	Checkpoints		Geo
9	361	Start location of the car		I/O
10	362	End location of the car		I/O
Geo Controller Commands
11	411	Calculated Direction for the car		Master
12	413	Destination Reached flag		Master, I/O
13	414	Heartbeat		Master
14	431	Start point		Master
15	461	Compass data		I/O
Motor Controller Commands
16	514	Heartbeat		Master
17	561	Car speed		I/O
I/O Controller Commands
18	614	Heartbeat		Master

DBC File

Git DBC File Link

ECUs

Motor Controller

Group Members

Shilpa Srinivasan

Design & Implementation

The motor controller is responsible for generating the driving and steering action of the car. For this purpose, we have two types motors viz DC motor for driving and Servo motor which is used for changing directions of the car. The motor controller is also interfaced with a speed encoder for generating a feedback mechanism to automatically control and monitor the speed of the car. Our car came equipped with a Servo motor and brushed DC motor which is connected Electronic Speed Control (ESC).

Hardware Design

Motor Hardware Schematics

Hardware Specifications
- 1. DC Motor

DC Motor

Our car came with Titan 12T 550 brushed motor and waterproof ESC. The ESC drives the DC motor based on the Pulse Width modulation (PWM) applied to it. The power supply required for this motor is 8.4 V. Maximum speed of upto 30mph can be achieved. The rotational speed is proportional to the EMF generated in its coil and the torque is proportional to the current.The main connection pins driving the motor are VCC,GND and the Control pin (PWM). The pin P2.1 of SJ-one board is connected to supply the required PWM to the motor. The basic working principle of DC motor is illustrated in the following figure : Since the preprogrammed controller has to be replaced by using our design ,the DC motor is then tested with Digital Oscilloscope for getting the frequency of operation and equivalent PWM values for full throttle condition in the forward as well as backward condition. It was observed from the waveform that the frequency of operation is 100Hz. The range of operational duty cycle is 10% to 20% with 15% being the neutral value or the stop condition. In order to accelerate the car a PWM value in the range of 15.6%-20.0% is applied. The 15.6 is the minimum pickup PWM that should be supplied in order to get the car moving at full load.

- 2. Servo Motor

Servo Motor

The servomotor used in the car is #2056 a waterproof all weather-action and double the steering power as compared to standard servos. The servo motor is responsible for controlling the steering action of right or left by applying a suitable PWM pulse. The servo motor can be driven with 3.3 V power supply. The pin P2.0 of SJ-one board is connected to supply the required PWM to the motor. After testing the servo motor, we found that the frequency of operation is 100Hz and the operational duty cycle range is 10.0%-20.0% with 15% being the neutral value. For a full right deflection, we provide input PWM pulse ranging from 15.0-20.0% and for full deflection to the left we apply 10.0-15.0% of PWM.

Digital Oscilloscope readings for the motors.

3. Speed Sensor

The speed feedback is monitored through the speed encoder which works on the Hall-effect principle. The Hall-effect speed sensor works as a transducer whose output voltage varies in response to the magnetic field. The sensor is mounted on the Spur gear instead of the wheel. The sensor would detect the rotation of axle. The motor controller would detect whenever the magnet is aligned with the sensor. This would generate a pulse. The pulse is detected in the form of rising-edge interrupt. This gives the wheel rotation count. The wheel rotates for every 1/4th rotation of the spur gear. The rotation count can then be converted to rpm to calculate the speed of the car.

Traxxas RPM Telemetry Speed Sensor.

Hardware Interface

Software Design

Show your software design. For example, if you are designing an MP3 Player, show the tasks that you are using, and what they are doing at a high level. Do not show the details of the code. For example, do not show exact code, but you may show psuedocode and fragments of code. Keep in mind that you are showing DESIGN of your software, not the inner workings of it.

Implementation

The motor controller receives all its signals from Master controller from the CAN bus. The motor controller receives the steer and drive command from the master. The motor controller receives the System start command which boots and decodes further drive signals to the motor controller. Upon receiving the drive command the motor controller decodes the steering action. Upon receiving suitable data about the obstacle from sensor controller the master controller relays appropriate steering action. To achieve better performance in steering, the turn is categorized as FULL and HALF. This gives better precision in turning.

Speed Regulation:

Upon detection of uphill the pulse received from the speed encoder reduces. This is detected and the motor feedback is designed such that the speed is increased by providing higher value of PWM value to drive the DC motor. Similarly, for downhill the pulse count received increases which is detected by the speed encoder and the speed is reduced by applying reduced PWM.

Testing & Technical Challenges

Wheel Alignment Error

Though the neutral value of PWM is 15% at which the servo is supposed to be aligned straight. In practice, however when we tested the car for straight run slight deflection towards right was observed when the PWM pulse width was set to 15.0 %. Thus, to correct this, we provided correction value of -0.98 giving a resultant PWM pulse width of 14.02%. Thus, we fixed the wheel alignment and obtained the desired straight path traversal.