Are you diving into the exciting world of DIY car projects like the Elegoo car, and finding yourself wrestling with remote control coding? Many enthusiasts, especially beginners, encounter challenges when trying to get their robotic vehicles to respond correctly to remote commands. A common issue, and one that can be particularly frustrating, is uneven wheel movement – where some wheels respond perfectly while others seem unresponsive or erratic.
This article will guide you through troubleshooting problems in your Car Remote Control Coding, focusing on a typical scenario where one side of the car’s wheels isn’t behaving as expected. We’ll explore potential causes and offer practical steps to diagnose and resolve these issues, ensuring your project moves smoothly in the direction you intend.
Let’s consider a real-world example. Imagine you’re working on an IR remote controlled car project, and you’ve written code that should make the car move forward, backward, left, right, and stop. You’ve even used libraries and online resources to get your code in shape. But upon testing, you find that while the left wheels respond perfectly to all commands – forward, backward, and turning – the right wheels remain stubbornly still. You’ve checked the motors, and they seem fine when tested independently. What could be going wrong?
Let’s examine a piece of Arduino code often used as a starting point for such projects, and then delve into how to debug the kind of wheel control problem described.
#include <IRremote.h>
#define F 16736925
#define B 16754775
#define L 16720605
#define R 16761405
#define S 16712445
#define UNKNOWN_F 5316027
#define UNKNOWN_B 2747854299
#define UNKNOWN_L 1386468383
#define UNKNOWN_R 553536955
#define UNKNOWN_S 3622325019
int RECV_PIN = 12;
int in1=6;
int in2=7;
int in3=8;
int in4=9;
int ENA=5;
int ENB=11;
int ABS=250;
IRrecv irrecv(RECV_PIN);
decode_results results;
unsigned long val;
void _mForward() {
analogWrite(ENA,ABS);
analogWrite(ENB,ABS);
digitalWrite(in1,HIGH);//digital output
digitalWrite(in2,LOW);
digitalWrite(in3,HIGH);
digitalWrite(in4,HIGH);
Serial.println("go forward!");
}
void _mBack() {
analogWrite(ENA,ABS);
analogWrite(ENB,ABS);
digitalWrite(in1,LOW);
digitalWrite(in2,HIGH);
digitalWrite(in3,LOW);
digitalWrite(in4,HIGH);
Serial.println("go back!");
}
void _mleft() {
analogWrite(ENA,ABS);
analogWrite(ENB,ABS);
digitalWrite(in1,HIGH);
digitalWrite(in2,LOW);
digitalWrite(in3,HIGH);
digitalWrite(in4,LOW);
Serial.println("go left!");
}
void _mright() {
analogWrite(ENA,ABS);
analogWrite(ENB,ABS);
digitalWrite(in1,LOW);
digitalWrite(in2,HIGH);
digitalWrite(in3,LOW);
digitalWrite(in4,HIGH);
Serial.println("go right!");
}
void _mStop() {
digitalWrite(ENA,LOW);
digitalWrite(ENB,LOW);
Serial.println("STOP!");
}
void setup() {
pinMode(in1,OUTPUT);
pinMode(in2,OUTPUT);
pinMode(in3,OUTPUT);
pinMode(in4,OUTPUT);
pinMode(ENA,OUTPUT);
pinMode(ENB,OUTPUT);
_mStop();
irrecv.enableIRIn();
Serial.begin(9600);
}
void loop() {
if (irrecv.decode(&results)){
val = results.value;
Serial.println(val);
irrecv.resume();
switch(val){
case F:
case UNKNOWN_F:
_mForward();break;
case B:
case UNKNOWN_B:
_mBack(); break;
case L:
case UNKNOWN_L:
_mleft(); break;
case R:
case UNKNOWN_R:
_mright();break;
case S:
case UNKNOWN_S:
_mStop(); break;
default:break;
}
}
}Understanding the Code and Motor Control Logic
This code is designed for an Arduino-based car controlled by an IR remote. Let’s break down the key sections relevant to motor control:
- Pin Definitions:
in1,in2,in3,in4,ENA,ENBare Arduino pins connected to a motor driver module (like L298N).RECV_PIN(pin 12) is for the IR receiver. - Motor Control Functions:
_mForward(),_mBack(),_mleft(),_mright(), and_mStop()are functions that control the motors. These functions usedigitalWrite()to set the direction of current flow through the motors andanalogWrite()(viaENA,ENB) to control motor speed (ABS – Absolute Speed). - IR Remote Decoding: The
loop()function continuously checks for IR signals. When a signal is received and decoded, theswitchstatement executes the corresponding motor function based on the received command (F, B, L, R, S).
Looking at the motor control functions, you might notice a pattern. Typically, for a two-motor differential drive car:
- Forward: Both motors move forward.
- Backward: Both motors move backward.
- Left: Right motor moves forward, left motor either stops or moves backward.
- Right: Left motor moves forward, right motor either stops or moves backward.
- Stop: Both motors stop.
In the provided code, the _mleft() and _mright() functions seem to be attempting to turn the car by making one side move forward and the other side stop (or move backward, depending on the specific wiring and motor driver logic). However, _mright() function in the provided code snippet seems to be identical to _mBack(), which is likely the root cause of the problem where the right side wheels are not behaving as expected during a “right turn” command.
Diagnosing and Fixing Uneven Wheel Movement
If you’re facing the issue where only the left wheels are working, or the right wheels are not responding correctly, here’s a systematic approach to troubleshooting:
1. Code Review for Motor Control Logic
The first step is to carefully examine your code, especially the motor control functions (_mForward, _mBack, _mleft, _mright, _mStop).
-
Check
_mright()function: In the example code, the_mright()function is incorrectly defined as identical to_mBack(). This is a clear coding error. For a right turn, you typically want the left wheels to move forward (or backward) while the right wheels do the opposite or stop.Correct
_mright()function should be something like:void _mright() { analogWrite(ENA,ABS); analogWrite(ENB,ABS); digitalWrite(in1,HIGH); // Left motor forward digitalWrite(in2,LOW); digitalWrite(in3,LOW); // Right motor backward or stop digitalWrite(in4,HIGH); Serial.println("go right!"); }Note: The exact logic (HIGH/LOW for
digitalWrite) depends on your motor driver and how your motors are wired. You might need to experiment with these to find the correct directions.
2. Verify Wiring to the Motor Driver
Incorrect wiring is a very common cause of motor control issues.
- Double-check motor connections: Ensure that the motor driver pins (in1, in2, in3, in4, ENA, ENB) are correctly connected to the Arduino pins as defined in your code (
int in1=6; int in2=7;etc.). - Motor polarity: Make sure the motor polarities are consistent. If one motor is wired in reverse compared to the other, they will rotate in opposite directions for the same input signals. You might need to swap the motor wires if necessary.
- ENA and ENB pins: These enable pins control the speed of the motors. Ensure they are correctly connected and that you are using
analogWrite()on these pins to control speed if intended.
An example of a typical wiring setup for an Elegoo car or similar robotic car with motor control.
3. Test Motors and Motor Driver Independently
Isolate the problem to determine if it’s the code, wiring, motors, or motor driver itself.
-
Direct motor test: Disconnect the motors from the motor driver. Connect each motor directly to a power source (with appropriate voltage and polarity). Do both motors spin? If one doesn’t, the motor itself might be faulty.
-
Motor driver test (swap motors): If both motors are working, swap the motor connections on the motor driver. For example, if motors are connected to outputs A and B of the driver, swap them. Does the problem switch sides? If yes, the motor driver output for the right side might be faulty.
-
Motor driver test (with code): Use a very simple test code to control the motors directly, bypassing the IR remote part. For example, just make the right motor move forward and backward continuously. Does it work correctly? This helps isolate if the problem is in the IR decoding or the basic motor control.
void setup() { pinMode(in3, OUTPUT); // Right motor input 1 pinMode(in4, OUTPUT); // Right motor input 2 pinMode(ENB, OUTPUT); // Right motor enable } void loop() { analogWrite(ENB, 200); // Enable speed digitalWrite(in3, HIGH); // Motor forward digitalWrite(in4, LOW); delay(1000); digitalWrite(in3, LOW); // Motor backward digitalWrite(in4, HIGH); delay(1000); digitalWrite(in3, LOW); // Motor stop digitalWrite(in4, LOW); delay(1000); }
4. IR Remote Signal and Decoding
While the initial problem description suggests the left side works, it’s still worth verifying the IR remote signal reception.
- Serial Monitor output: The code includes
Serial.println(val);. Open the Arduino Serial Monitor (at 9600 baud rate). When you press buttons on your IR remote, do you see values being printed? Are these values consistent with the#definevalues at the beginning of your code (F, B, L, R, S, UNKNOWN_…)? - IR Receiver functionality: Ensure the IR receiver is correctly connected to the
RECV_PIN(pin 12 in the code) and that the libraryIRremote.his correctly included.
Conclusion: Systematic Debugging is Key
Troubleshooting car remote control coding, especially when you encounter issues like uneven wheel movement, requires a systematic approach. Start by carefully reviewing your code for logical errors, especially in the motor control functions. Then, meticulously check your wiring connections. Isolate the problem by testing motors and the motor driver independently. Finally, verify the IR remote signal reception and decoding.
By following these steps, you can methodically pinpoint the source of the problem and get your Elegoo car or similar project rolling smoothly under your remote control! Remember, debugging is a crucial skill in robotics and programming – each challenge overcome brings you closer to mastering car remote control coding and building more complex and exciting projects.
