LAB: Line Tracing RC Car

Date: 2023-09-26

Author/Partner:

Github: repository link

Demo Video: Youtube link

PDF version:

Introduction

Design an embedded system to control an RC car to drive on the racing track. The car is controlled either manually with wireless communication or automatically to drive around the track. When it sees an obstacle on the driving path, it should temporarily stop until the obstacle is out of the path.

There can be more missions to complete.

image

Requirement

Hardware

• MCU

  • NUCLEO-F411RE

• Actuator/Sensor/Others: Minimum

  • Bluetooth Module(HC-06)

  • DC motor x2, DC motor driver(L9110s)

  • IR Reflective Sensor (TCRT 5000) x2

  • HC-SR04

  • additional sensor/actuators are acceptable

Software

• Keil uVision, CMSIS, EC_HAL library

Preparation

Tutorials:

Complete the following tutorials:

1. TU: Managing library header files

2. TU: Custom initialization

Use ecSTM32F411.h and void MCU_init(void) in your project code.

LABS:

You should review previous labs for help

1. LAB: ADC IR Sensor

2. LAB: USART Bluetooth

3. LAB: Timer & PWM

Problem Definition

Design your RC car that has the following functions:

1. Line tracing on the given racing track

2. has 2 control modes: Manual Mode to AUTO Mode

3. stops temporally when it detects an object nearby on the driving path

On the PC, connected to MCU via bluetooth

• Print the car status every 1 sec such as “ ( “ MOD: A DIR: F STR: 00 VEL: 00 ”)

Manual Mode

• Mode Change( MOD):

  • When 'M' or 'm' is pressed, it should enter Manual Mode

  • LD2 should be ON in Manual Mode

• Speed (VEL):

  • Increase or decrease speed each time you push the arrow key “UP” or “DOWN”, respectively.

  • You can choose the speed keys

  • Choose the speed level: V0 ~ V3

• Steer (STR):

  • Steering control with keyboard keys

  • Increase or decrease the steering angles each time you press the arrow key “RIGHT” or “LEFT”, respectively.

  • Steer angles with 3 levels for both sides: e.g: -3, -2, -1, 0, 1, 2, 3 // '-' angle is turning to left

• Driving Direction (DIR)

  • Driving direction is forward or backward by pressing the key “F” or “B”, respectively.

  • You can choose the control keys

• Emergency Stop

  • RC car must stop running when key “S” is pressed.

Automatic Mode

• Mode Change:

  • When 'A' or 'a' is pressed, it should enter AUTO Mode

• LD2 should blink at 1 second rate in AUTO Mode

• It should drive on the racing track continuously

• Stops temporally when it detects an object nearby on the driving path

• If the obstacle is removed, it should drive continuously

Procedure

1. Discuss with the teammate how to design an algorithm for this problem

2. In the report, you need to explain concisely how your system works with state tables/diagram or flow-chart.

   ● Listing all necessary states (states, input, output etc) to implement this design problem.

   ● Listing all necessary conditional FLAGS for programming.

   ● Showing the logic flow from the initialization

   and more

3. Select appropriate configurations for the design problem. Fill in the table.

Functions	Register	PORT_PIN	Configuration
System Clock	RCC		PLL 84MHz
delay_ms	SysTick
Motor DIR	Digital Out
	….
TIMER	TIMER1
	TIMER2
Timer Interrupt	...		10msec
ADC	ADC
	….
DC Motor Speed	PWM2
ADC sampling trigger	PWM3
RS-232 USB cable(ST-LINK)	USART2		No Parity, 8-bit Data, 1-bit Stop bit 38400 baud-rate
Bluetooth	USART1	TXD: PA9 RXD: PA10	No Parity, 8-bit Data, 1-bit Stop bit 9600 baud-rate

1. Create a new project under the directory \repos\EC\LAB\LAB_RCcar

• The project name is “LAB_RCcar”

• You can share the same code with your teammate. But need to write the report individually

Circuit Diagram

You need to include the circuit diagram

image

Code

Your code goes here: ADD Code LINK such as github

// YOUR MAIN CODE ONLY
// YOUR CODE with Comments

Results

Experiment images and results

Show experiment images /results

Add demo video link

Reference

Complete list of all references used (github, blog, paper, etc)

Troubleshooting

1. motor PWM duty ratio for different DIR

When, DIR=0 duty=0.8--> PWM 0.8 // 실제 모터에 전달되는 pwm

Whe, DIR=1 duty=0.8--> PWM 0.2 // 실제 모터에 전달되는 PWM

*** a solution ***

float targetPWM;  // pwm for motor input 
float duty=abs(DIR-targetPWM); // duty with consideration of DIR=1 or 0

PWM_duty(PWM_PIN, duty);

2. Print a string for BT (USART1)

Use sprintf()

#define _CRT_SECURE_NO_WARNINGS    // sprintf 보안 경고로 인한 컴파일 에러 방지
#include <stdio.h>     // sprintf 함수가 선언된 헤더 파일

char BT_string[20]=0;

int main()
{
	sprintf(BT_string, "DIR:%d PWM: %0.2f\n", dir, duty);    // 문자, 정수, 실수를 문자열로 만듦
	USART1_write(BT_string, 20);
	// ...
}

https://dojang.io/mod/page/view.php?id=352 **

3. Motor does not run under duty 0.5

SOL) Configure motor PWM period as 1kHa

4. Check and give different Interrupt Priority

Check if you have different NVIC priority number for each IRQs

5. Ultrasoninc sensor does not measure properly when MCU is connected with motor driver

SOL) Give independent voltage source to motor driver. Giving DC power from MCU to motor driver is not recommended