Difference between revisions of "F15: ThunderBird"

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(Motor and I/O Controllers)
(Motor and I/O Controllers)
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ThunderBird is a 2 WD truck. It is equipped with a ARRMA BLX brushless DC motor connected to an BLX80 ESC(Electronic Speed Control). The ESC drives the DC motor according to the PWM(Pulse Width Modulation) signal. The truck's front wheels are connected to a waterproof ADS-7M Metal Geared Steering Servo. The servo and the DC motor are controlled using the PWM pins of the SJOne board.  
 
ThunderBird is a 2 WD truck. It is equipped with a ARRMA BLX brushless DC motor connected to an BLX80 ESC(Electronic Speed Control). The ESC drives the DC motor according to the PWM(Pulse Width Modulation) signal. The truck's front wheels are connected to a waterproof ADS-7M Metal Geared Steering Servo. The servo and the DC motor are controlled using the PWM pins of the SJOne board.  
  
===Pulse Width Modulation===
+
===Pulse Width Modulation - Controlling DC and Servo motors ===
 
[[File:F15_ThunderBird_pwm1_5.png|300px|thumb|right|text-top|Fig 1. Initializing pwm signal]]
 
[[File:F15_ThunderBird_pwm1_5.png|300px|thumb|right|text-top|Fig 1. Initializing pwm signal]]
 
[[File:F15_ThunderBird_pwm2_0.jpg|300px|thumb|right|text-top|Fig 2. Forward pwm signal]]
 
[[File:F15_ThunderBird_pwm2_0.jpg|300px|thumb|right|text-top|Fig 2. Forward pwm signal]]
 
[[File:F15_ThunderBird_pwm1_0.jpg|300px|thumb|right|text-top|Fig 3. Reverse pwm signal]]
 
[[File:F15_ThunderBird_pwm1_0.jpg|300px|thumb|right|text-top|Fig 3. Reverse pwm signal]]
Pulse width modulation is a technique which is used to encode the analog signal into a pulsating signal. The signal is represented as a series of pulses. This signal can be easily generated using the pwm pins of the SJOne board. The ESC is initialized upon passing a PWM signal which is sent by the RF module on the truck. The type of signal is observed by hooking the PWM pin to the digital oscilloscope. The initialization signal is shown in figure 1.
+
Pulse width modulation is a technique which is used to encode the analog signal into a pulsating signal. The signal is represented as a series of pulses. This signal can be easily generated using the pwm pins of the SJOne board. The ESC is initialized upon passing a PWM signal which is sent by the RF module on the truck. The type of signal is observed by hooking the PWM pin to the digital oscilloscope. The initialization signal is shown in figure 1. A resolution of 1ms is set on the oscilloscope. The PWM signal has a width of 1.5 ms. This signal initializes the ESC. Once the ESC's are initialized, the motors require a signal to accelerate and decelerate. The type of signals for moving the motor forward and backward are realized by hooking the output pin of the RF module to the digital oscilloscope. The forward and backward pwm signals at full throttle are shown in figures 2 and 3 respectively. The respective pwm signal pulses for moving the motors forward and backward are shown below.
  
A resolution of 1ms is set on the oscilloscope. The PWM signal has a width of 1.5 ms. The PWM signal is generated as a percentage of the signal frequency.
 
 
* The input signal is a 50 Hz frequency signal, it has a duration of 20 ms
 
* 7.5% of 20 ms is 1.5 ms
 
* So the initialization signal is sent by setting the PWM pin to 7.5
 
 
This outputs an initialization signal which triggers the ESC. Once the ESC's are initialized, the motors require a signal to accelerate and decelerate. The type of signals for moving the motor forward and backward are realized by hooking the output pin of the RF module to the digital oscilloscope. The forward and backward pwm signals at full throttle are shown in figures 2 and 3 respectively.
 
 
* Acceleration PWM signal
 
* Acceleration PWM signal
 
**Forward full throttle - 2 ms
 
**Forward full throttle - 2 ms
Line 485: Line 478:
 
**Reverse medium throttle - 1.2 ms
 
**Reverse medium throttle - 1.2 ms
 
**Neutral - 1.5 ms
 
**Neutral - 1.5 ms
 +
 +
The PWM value to be set is determined from these calculations:
 +
* PWM is a percentage of the signal frequency
 +
* The signal is of 50 Hz i.e. 20 ms duration
 +
* A 10% of the signal value gives a duration of 2 ms - 10/100 * 20 = 2 ms
 +
 +
The respective percentages for all the signal were calculated and the PWM signals were generated using the PWM.set function. The generated pulses from the SJOne PWM pin is passed to the ESC for initialization and controlling the DC motor. The ESC has 3 connections - Vcc, GND and PWM. SJOne board's GND and PWM are connected to the ESC. The Vcc is supplied from the battery pack.
 +
 +
A sample code demonstrating the PWM signals is written and the motors were controlled using the onboard SJOne switches.
 +
Click here for the demo.
 +
 +
The servo motor operates on 6V.
  
 
== GPS Controller ==
 
== GPS Controller ==

Revision as of 06:55, 17 October 2015

ThunderBird : Self Driving Car

Abstract

ThunderBird is a 1/10 2 WD electric short self-driving truck. The truck is equipped with sensors to detect obstacles, GPS for getting directions, Compass for the truck's orientation, Bluetooth for communicating with the android device and LCD for displaying the sensor values on screen. The modules are interfaced using 5 SJ One boards which features a Cortex-M3 LPC1758. CAN bus is used for communicating between the modules. Android device is used to enter the destination coordinates through bluetooth. When the sensors detect obstacles, it signals the motors to drive the car accordingly.

Objectives & Introduction

Team Members & Responsibilities

  • Master Controller and Android application
    • Sravani Aitha
    • Vishnu Vardhana Reddy Mandalapu
    • James Sushanth Anandraj
    • Athavan Kanagasabapathy
  • Motors and I/O
    • Dheeraj Dake
    • Akhil Bhargav Josyabhatla
  • Sensors
    • Nitesh Jain
    • Rajashree Kambli
  • GPS
    • Rishit Borad
    • Ravi Vanjara

Schedule

Motor and I/O Schedule

Sl. No Start Date End Date Task Status Actual Completion Date
1 10/6/2015 10/13/2015 Determining the ESC initialization sequence Completed 10/11/15
2 10/13/2015 10/20/2015 Testing the Servo and DC motor using SJ One board PWM's Completed 10/16/2015
3 10/20/2015 10/27/2015 Design motor control using messages from the CAN bus
4 10/27/2015 11/3/2015 Implement code to accept messages from other modules over CAN bus and display it on the LCD
5 11/3/2015 11/10/2015 Update motor speeds on the LCD in real time
6 11/10/2015 11/17/2015 Interface I/O and motor modules with master controller and establish communication
7 11/17/2015 11/24/2015 Fine turning motors for precise control
8 11/24/2015 12/01/2015 Fine tuning (buffer)
9 12/01/2015 12/08/2015 Testing and debugging

Geographical Position Controller Schedule

Sl. No Start Date End Date Task Status Actual Completion Date
1 10/6/2015 10/13/2015 Research & order GPS module Completed 10/8/2015
2 10/13/2015 10/20/2015 Interface GPS using I2C with SJOne board Ongoing
3 10/20/2015 10/27/2015 Interface Compass with SJOne board
4 10/27/2015 11/3/2015 Calibrate Compass and GPS
5 11/3/2015 11/10/2015 Parse raw data and create meaningful data
6 11/10/2015 11/17/2015 Implement CAN communication with SJOne board
7 11/17/2015 11/24/2015 Test and debug GPS & Compass locally
8 11/24/2015 12/01/2015 Integrate GPS/Compass module with Master board
9 12/01/2015 12/08/2015 Implement routing algorithm for Car
10 12/08/2015 12/15/2015 Test and Debug GPS/Compass integration with master

Sensor Controller Schedule

Sl. No Start Date End Date Task Status Actual Completion Date
1 10/5/2015 10/11/2015 Finalize and order the sensors Completed 10/11/2015
2 10/12/2015 10/18/2015 Wire the sensors and write a sample test code to check the sensors. Ongoing
3 10/19/2015 11/01/2015 Transfer the sensor data to master controller via can bus.
4 11/2/2015 11/9/2015 Implement and integrate the code for all the sensors.
5 11/2/2015 11/15/2015 Test and Debug the integrated module.
6 11/16/2015 11/29/2015 Collaborate with the other module teams to make sure that the sensors are in working condition.
7 11/30/2015 12/06/2015 Test for stability of sensors and report.
8 12/07/2015 12/13/2015 Prepare for Demo.

Master controller and android controller Schedule

Sl. No Start Date End Date Task Status Actual Completion Date
1 10/6/2015 10/13/2015 Car purchase ,dismantle and setup for project Completed 10/8/2015
2 10/13/2015 10/20/2015 Can setup components purchase, Can bus design and soldering Ongoing
3 10/20/2015 10/27/2015 Basic Can communication testing by sending and receiving data and can msg specification for all controllers and messages.
4 10/27/2015 11/3/2015 Development and implementation of Algorithm for driving car and obstacle avoidance.
5 11/3/2015 11/10/2015 Interface bt dongle with sjone board and android device and test with commands
6 11/10/2015 11/17/2015 Develop Android GUI and application to interact with car using bluetooth. Implement all necessary commands on sjone board for communication with android device. Interface with Motor and IO Controller.
7 11/17/2015 11/24/2015 Test and debug Master algorithm and Android interface locally and with Motor controller interfaced by providing predetermined directional commands.
8 11/24/2015 12/01/2015 Integrate Master Board with all boards and implement heartbeat protocol.
9 12/01/2015 12/08/2015 Test run 1 with all boards integrated and with all planned features developed.
10 12/08/2015 12/15/2015 Test run 2 after solving issues found in test run 1.

Parts List & Cost

S.R. Description Manufacturer Part Number Qty Total Cost
1 SJOne Board - - 5 $400.00
2 RC Car Furry Arrma - 2 Wheel Drive - 1/10 - 1 $185.00
3 Ultrasonic Sensor LV-MaxSonar - EZ1 MB1010 5 $140.00
4 1.8 Color TFT LCD display with MicroSD Card Breakout Adafruit ST7735R 1 $19.95
5 SparkFun Venus GPS with SMA Connector Sparkfun GPS-11058 1 $49.95
6 Triple-axis Magnetometer (Compass) Board Adafruit HMC5883L 1 $9.95
7 CAN Transceiver (Free Samples) Microchip MCP2551 6 $0.00
Total (Including Shipping and Taxes ----

Design & Implementation

The design section can go over your hardware and software design. Organize this section using sub-sections that go over your design and implementation.

Hardware Design

Discuss your hardware design here. Show detailed schematics, and the interface here.

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

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

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.

Sensor Controller

Motor and I/O Controllers

ThunderBird is a 2 WD truck. It is equipped with a ARRMA BLX brushless DC motor connected to an BLX80 ESC(Electronic Speed Control). The ESC drives the DC motor according to the PWM(Pulse Width Modulation) signal. The truck's front wheels are connected to a waterproof ADS-7M Metal Geared Steering Servo. The servo and the DC motor are controlled using the PWM pins of the SJOne board.

Pulse Width Modulation - Controlling DC and Servo motors

Fig 1. Initializing pwm signal
Fig 2. Forward pwm signal
Fig 3. Reverse pwm signal

Pulse width modulation is a technique which is used to encode the analog signal into a pulsating signal. The signal is represented as a series of pulses. This signal can be easily generated using the pwm pins of the SJOne board. The ESC is initialized upon passing a PWM signal which is sent by the RF module on the truck. The type of signal is observed by hooking the PWM pin to the digital oscilloscope. The initialization signal is shown in figure 1. A resolution of 1ms is set on the oscilloscope. The PWM signal has a width of 1.5 ms. This signal initializes the ESC. Once the ESC's are initialized, the motors require a signal to accelerate and decelerate. The type of signals for moving the motor forward and backward are realized by hooking the output pin of the RF module to the digital oscilloscope. The forward and backward pwm signals at full throttle are shown in figures 2 and 3 respectively. The respective pwm signal pulses for moving the motors forward and backward are shown below.

  • Acceleration PWM signal
    • Forward full throttle - 2 ms
    • Forward medium throttle - 1.8 ms
    • Neutral - 1.5 ms
  • Reverse PWM signal
    • Reverse full throttle - 1 ms
    • Reverse medium throttle - 1.2 ms
    • Neutral - 1.5 ms

The PWM value to be set is determined from these calculations:

  • PWM is a percentage of the signal frequency
  • The signal is of 50 Hz i.e. 20 ms duration
  • A 10% of the signal value gives a duration of 2 ms - 10/100 * 20 = 2 ms

The respective percentages for all the signal were calculated and the PWM signals were generated using the PWM.set function. The generated pulses from the SJOne PWM pin is passed to the ESC for initialization and controlling the DC motor. The ESC has 3 connections - Vcc, GND and PWM. SJOne board's GND and PWM are connected to the ESC. The Vcc is supplied from the battery pack.

A sample code demonstrating the PWM signals is written and the motors were controlled using the onboard SJOne switches. Click here for the demo.

The servo motor operates on 6V.

GPS Controller

Master Controller

Bluetooth Control and Android application

Testing & Technical Challenges

Describe the challenges of your project. What advise would you give yourself or someone else if your project can be started from scratch again? Make a smooth transition to testing section and described what it took to test your project.

Include sub-sections that list out a problem and solution, such as:

My Issue #1

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Conclusion

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Project Video

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Project Source Code

References

Acknowledgement

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References Used

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Appendix

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