How to Control Large Linear Actuators with Arduino

This article will show you how to use an Arduino and two buttons to perform basic manual control of a large linear actuator. In the first set of code, the first button extends the actuator and the second button retracts the actuator. In the second set of code, the two buttons move the linear actuator to a preset position.

Large linear actuators traditionally have five wires. Two wires are used to power the motor and three wires go to an internal potentiometer to read the position. The two relays are used to switch the positive and negative power to the motor to determine the direction the piston will travel. The first bit of the code does not use this, the second does to achieve the target position. Let's get started.

Step 1: Wiring

Step 2: Code 1 - Manual Control

This section of code shows how to use an Arduino and two buttons to do basic manual control of a large linear actuator. The first button extends the actuator and the second button retracts it.

const int button1Pin = 2; // the number of the pushbutton1 pin

const int button2Pin = 4; // the number of the pushbutton2 pin

const int relay1Pin = 7; // the number of the Realy1 pin

const int relay2Pin = 8; // the number of the Relay2 pin

// variables will change：

int button1State = 0; // variable for reading the pushbutton status

int button2State = 0; // variable for reading the pushbutton status

const int sensorPin = 0; // select the input pin for the potentiometer

int sensorValue = 0; // variable to store the value coming from the sensor

void setup（） {

//start serial connection

Serial.begin（9600）;

// initialize the pushbutton pin as an input：

pinMode（button1Pin， INPUT）;

pinMode（button2Pin， INPUT）;

// initialize the relay pin as an output：

pinMode（relay1Pin， OUTPUT）;

pinMode（relay2Pin， OUTPUT）;

}

void loop（）{

// read the value from the sensor：

sensorValue = analogRead（sensorPin）;

//print out the value of the pushbutton

Serial.println（sensorValue）;

// read the state of the pushbutton values：

button1State = digitalRead（button1Pin）;

button2State = digitalRead（button2Pin）;

// check if the pushbutton1 is pressed.

// if it is， the buttonState is HIGH：

// we also ensure tha the other button is not pushed to avoid conflict

if （button1State == HIGH && button2State == LOW） {

// turn relay1 on：

digitalWrite（relay1Pin， HIGH）;

}

// When we let go of the button， turn off the relay

else if （digitalRead（relay1Pin） == HIGH） {

// turn relay1 off：

digitalWrite（relay1Pin， LOW）;

}

// repeat the same procedure for the second pushbutton

if （button1State == LOW && button2State == HIGH） {

// turn relay2 on：

digitalWrite（relay2Pin， HIGH）;

}

// When we let go of the button， turn off the relay

else if （digitalRead（relay2Pin） == HIGH） {

// turn relay2 off：

digitalWrite（relay2Pin， LOW）;

}

}

Step 3: Code 2 - Preset Position Using Position Feedback

This section of code shows how to do basic control of a large linear actuator using an Arduino and two buttons, each preset to a position.

const int button1Pin = 2; // the number of the pushbutton1 pin

const int button2Pin = 4; // the number of the pushbutton2 pin

const int relay1Pin = 7; // the number of the Realy1 pin

const int relay2Pin = 8; // the number of the Relay2 pin

const int sensorPin = 0; // select the input pin for the potentiometer

// variables will change：

int button1State = 0; // variable for reading the pushbutton status

int button2State = 0; // variable for reading the pushbutton status

int sensorValue = 0; // variable to store the value coming from the sensor

int goalPosition = 350;

int CurrentPosition = 0;

boolean Extending = false;

boolean Retracting = false;

void setup（） {

//start serial connection

Serial.begin（9600）;

// initialize the pushbutton pin as an input：

pinMode（button1Pin， INPUT）;

pinMode（button2Pin， INPUT）;

// initialize the relay pin as an output：

pinMode（relay1Pin， OUTPUT）;

pinMode（relay2Pin， OUTPUT）;

//preset the relays to LOW

digitalWrite（relay1Pin， LOW）;

digitalWrite（relay2Pin， LOW）;

}

void loop（）{

// read the value from the sensor：

CurrentPosition = analogRead（sensorPin）;

// print the results to the serial monitor：

Serial.print（“Current = ” ）;

Serial.print（CurrentPosition）;

Serial.print（“ Goal = ”）;

Serial.println（goalPosition）;

// read the state of the pushbutton values：

button1State = digitalRead（button1Pin）;

button2State = digitalRead（button2Pin）;

if （button1State == HIGH） {

// set new goal position

goalPosition = 300;

if （goalPosition 》 CurrentPosition） {

Retracting = false;

Extending = true;

digitalWrite（relay1Pin， HIGH）;

digitalWrite（relay2Pin， LOW）;

Serial.println（“Extending”）;

}

else if （goalPosition 《 CurrentPosition） {

Retracting = true;

Extending = false;

digitalWrite（relay1Pin， LOW）;

digitalWrite（relay2Pin， HIGH）;

Serial.println（“Retracting”）;

}

}

if （button2State == HIGH） {

// set new goal position

goalPosition = 500;

if （goalPosition 》 CurrentPosition） {

Retracting = false;

Extending = true;

digitalWrite（relay1Pin， HIGH）;

digitalWrite（relay2Pin， LOW）;

Serial.println（“Extending”）;

}

else if （goalPosition 《 CurrentPosition） {

Retracting = true;

Extending = false;

digitalWrite（relay1Pin， LOW）;

digitalWrite（relay2Pin， HIGH）;

Serial.println（“Retracting”）;

}

}

if （Extending = true && CurrentPosition 》 goalPosition） {

//we have reached our goal， shut the relay off

digitalWrite（relay1Pin， LOW）;

boolean Extending = false;

Serial.println（“IDLE”）;

}

if （Retracting = true && CurrentPosition 《 goalPosition）{

//we have reached our goal， shut the relay off

digitalWrite（relay2Pin， LOW）;

boolean Retracting = false;

Serial.println（“IDLE”）;

}

}

The above is all the functional code required for the project, and it can be accepted at this step.

Step 4: Expand

Now that you can control a large linear actuator, what are you going to do with it? You could make a table that can be transformed to allow you to sit or stand. You could also use some light sensors to make a solar panel that tracks the sun.