Motors: driving and stopping

Each motor is controlled by two contacts. Contact directions decides which way the wheel turns. Contact speed decides how strong: a number from 0 (worth it) to 255 (full power). The left motor is connected to the contacts 7 (direction) and 6 (speed).

1. Create a sketch L21_Left_Motor according to the template and write setup() himself: what should happen is said in the comments.

// Шаблон среднего уровня. Напиши код в разделе «Твоя часть» по целям в комментариях. const int LEFT_DIR_PIN = 7;const int LEFT_SPEED_PIN = 6;const int FORWARD = HIGH; // ===== Твоя часть: напиши сам ===== void setup() {  // Подготовь оба контакта левого мотора.  // Левое колесо крутится вперёд 2 секунды с силой 100 из 255 и останавливается само.} void loop() {}

2. Load the program with the motors power off.
3. Turn on the power to the motors and press the Reset button on the board: the program will start again.

The left motor is connected to the contacts 7 (direction) and 6 (speed). The forward direction on this set is level HIGH.

Requirement 1. Sketch L21_Left_Motor: the left wheel spins forward for exactly 2 seconds with the force from the named variable and stops itself. Pin numbers are named constants, not numbers in commands.

Acceptance.

1. On the stand, the partner uses a stopwatch to time how long the wheel spins.
2. Replace the direction level with the opposite one. What did the wheel do? Write down what level is on your robot - “forward”.
3. Explain in the journal why the wheel stopped, although loop() empty.

The right motor is designed in the same way as the left one: direction contact 4 and speed contact 5. The names of all four contacts are already in the template.

1. Create a sketch L21_Both_Motors according to the template and write setup() himself. Use your left motor program as a model.

// Шаблон среднего уровня. Напиши код в разделе «Твоя часть» по целям в комментариях. const int LEFT_DIR_PIN = 7;const int LEFT_SPEED_PIN = 6;const int RIGHT_DIR_PIN = 4;const int RIGHT_SPEED_PIN = 5;const int FORWARD = HIGH;int speed = 100; // ===== Твоя часть: напиши сам ===== void setup() {  // Подготовь контакты обоих моторов.  // Оба колеса крутятся вперёд со скоростью speed одну секунду и останавливаются.} void loop() {}

2. Upload and test with the robot on a stand.
3. Change speed by 60, then by 200. How does the rotation change?

Requirement 2. Both wheels spin forward for exactly one second at a speed from one named variable speed and stop. The right motor is connected to the contacts 4 (direction) and 5 (speed). Start with your program for the left motor and save it as L21_Both_Motors.

Research: at what date does the wheel start moving. Place on the stand speed = 20, 40, 60, 80... and write down for each wheel at what smallest number it begins to spin confidently.

void loop() {
  analogWrite(LEFT_SPEED_PIN, speed);
  analogWrite(RIGHT_SPEED_PIN, speed);
  delay(1000);
  analogWrite(LEFT_SPEED_PIN, 0);
  analogWrite(RIGHT_SPEED_PIN, 0);
}

1. Write your answer in your journal.
2. Suggest two different corrections and write them down with code: one - without loop(), the second - leaving the movement in loop().

void forward(int ms) {
  drive(FORWARD, speed, FORWARD, speed);
  delay(ms);
}

void setup() {
  // … настройка контактов
  forward(1000);
}

void loop() {
}

Requirement. Rewrite the program so that the movement remains in loop(), but the robot drove for exactly one second and did not move again. while (true) cannot be used.

1. Check it on the stand: the wheels spin for one second and stay there until you press Reset.
2. Explain in the log how your program “remembers” that the movement has already happened.

Writing four lines each time is inconvenient. Let's collect them in functions: forward(), backward(), stopMotors(). Functions drive and forward in the template is a sample.

1. Create a sketch L21_Moves according to the template. Write backward, stopMotors and movement in setup() himself.

// Шаблон среднего уровня. Напиши код в разделе «Твоя часть» по целям в комментариях.// Функции drive и forward ниже — образец. const int LEFT_DIR_PIN = 7;const int LEFT_SPEED_PIN = 6;const int RIGHT_DIR_PIN = 4;const int RIGHT_SPEED_PIN = 5;const int FORWARD = HIGH;const int BACKWARD = (FORWARD == HIGH) ? LOW : HIGH;int speed = 100; // ===== Твоя часть: напиши сам ===== void backward(int ms) {  // Оба колеса крутятся назад со скоростью speed ms миллисекунд.} void stopMotors() {  // Оба мотора стоят.} void setup() {  pinMode(LEFT_DIR_PIN, OUTPUT);  pinMode(LEFT_SPEED_PIN, OUTPUT);  pinMode(RIGHT_DIR_PIN, OUTPUT);  pinMode(RIGHT_SPEED_PIN, OUTPUT);  stopMotors();  delay(2000); // время убрать руки от робота   // Вперёд 1 секунду, остановка, пауза полсекунды, назад 1 секунду, остановка.} // ===== Образец — не меняй ===== void drive(int leftDir, int leftSpeed, int rightDir, int rightSpeed) {  digitalWrite(LEFT_DIR_PIN, leftDir);  digitalWrite(RIGHT_DIR_PIN, rightDir);  analogWrite(LEFT_SPEED_PIN, leftSpeed);  analogWrite(RIGHT_SPEED_PIN, rightSpeed);} void forward(int ms) {  drive(FORWARD, speed, FORWARD, speed);  delay(ms);} void loop() {}

2. Find where the functions described and where are they are called. Show it to your partner.

Requirement 3. Software L21_Moves is built from the functions:

• drive(leftDir, leftSpeed, rightDir, rightSpeed) is the only place where the direction and speed of the wheels are set;
• forward(ms) and backward(ms) - movement for a specified time, stopMotors() - stop;
• the direction "backward" is not written as a number, but is obtained from FORWARD: on another set FORWARD may be different;
• after turning on there are 2 seconds to remove your hands;
• in setup(): forward 1 second, stop, pause half a second, backward 1 second, stop.

1. Load the program on the stand and check: forward, pause, backward, stop.
2. Place the robot on the floor, mark the start with tape, turn on the power to the motors and press Reset.
3. Repeat three times. Each time, mark where the robot stopped, and measure with a ruler how many centimeters it moved forward, backward and sideways from the start.

4. Does the robot make the same mistakes in three runs? Write down the conclusion.

Find out how straight your robot is going and try to fix it with one change.

1. Test the program on the stand, then place the robot on the floor at the beginning of a meter strip of tape. Drive forward for 2 seconds. Measure how many centimeters the nose moves sideways from the stripe. Repeat three times.
2. Suggest one change that will reduce slip: for example, different speeds for the left and right wheels. Write down why you expect improvement.
3. Make the change and do three runs again. Has it gotten better? How long?

1. Make the robot travel forward twice as far and backward as before.
2. Make the robot shuttle three times in a row: forward, stop, backward, stop. Write calls to forward, stopMotors, backward only once. Need a cycle for from lesson 1.1.

Requirement 4. Function shuttle(times, ms) does "shuttle" times times: forward ms milliseconds, stop, back, stop. The movement calls are written only once.

Research: how far does a robot travel?

1. Run three times forward(1000) at speed = 100 and measure the path with a ruler in millimeters. Repeat when speed = 200.
2. Calculate how many millimeters per second the robot travels at each speed. How many times do the results differ? How do the numbers differ? speed?
3. Find the time backward so that after one shuttle the robot stands no further than 2 cm from the start. Write down why forward and backward times turned out different.