Published August 8, 2022 © GPL3+

Car Sentry

I park my car on the street and it has been broken into a lot. I built a robot sentry/scarecrow that scares people away and takes photos

AdvancedFull instructions provided3 days1,188

Things used in this project

Hardware components

Sony Spresense boards (main & extension)

Sony Spresense camera board

Sony Spresense LTE extension board

12v relay

RCWL-0516 Motion Detection Sensor

12V Red LEDs

12V Fuse Tap

CNC Shield

Stepper Motor

Software apps and online services

Arduino IDE

Story

My car gets messed with a lot. People cut into the cloth top, and I've had it cut again when replaced.

So I built a robot guard. I tapped into the fusebox in my car to find a circuit that is live when the car is off. There are two motion sensors on either side, and if the robot detects movement, it turns on its LEDs and evil eyes and rotates toward the direction of movement. I used WIFI radar sensors so that they would work through glass without having to be placed outside the car.

I made a 3D model of the head, but after several failed 12 hour prints, I just made it out of wood and painted it. I used an Arduino CNC shield run headless (without an arduino) with an A4998 driver. I limited the current on the step stick by following this guide: https://www.makerguides.com/a4988-stepper-motor-driver-arduino-tutorial/

I have the LTE board and camera hooked up with the goal of taking photos if motion is detected, and upload the photos to the cloud. That's still a TODO at this point, the making of the base and head, and wiring of the 8 LED strands, eyes, relay, radar sensors, CNC, and stepper motor took a lot of time.

The base has a CNC shield that requires both 12V and 5V power. The head has a 12V relay for the LEDs, and a regulator to step the power down to 5V. I followed this schematic with two capacitors to make a decoupling capacitor circuit:

The 5V powers the spresense, runs out to the radar sensors, and then had to be run back down to the base to power the CNC shield.

Code

Robot Sentry V1

#define enablePin 2 //Enable pin for CNC shield
#define dirPin 6 //Dir pin for CNC shield
#define xPin 5 //Pulse pin for CNC shield
#define relay 9 //LEDs are connected to this relay
#define radarL 3 //Left Radar
#define radarR 7 //Right Radar

void setup() {
    pinMode(enablePin, OUTPUT);
    pinMode(dirPin, OUTPUT);
    pinMode(xPin, OUTPUT);
    pinMode(relay, OUTPUT);
    pinMode(radarL, INPUT);
    pinMode(radarR, INPUT);
    digitalWrite(radarL, LOW);
    digitalWrite(radarR, LOW);
    digitalWrite(enablePin, LOW);
    digitalWrite(dirPin, HIGH);
    pinMode(LED_BUILTIN, OUTPUT);
    Serial.begin(115200);
}

void loop() {
    int turnWidth = 100;
    int delLength = 20;
    
    if(digitalRead(radarL) == HIGH)
    {
      Serial.println("radar L");
      digitalWrite(relay, HIGH); //turn on LEDs
      digitalWrite(enablePin, LOW); //enable motor
      digitalWrite(dirPin, LOW); //look left
      for(int i = 0; i < turnWidth; i++)
      {
         digitalWrite(xPin, HIGH);
         delay(delLength);
         digitalWrite(xPin, LOW); 
      }
      digitalWrite(enablePin, HIGH); //disable motor
      delay(2000);
      digitalWrite(relay, LOW); //turn off LEDs
      //TODO take photo
      //TODO upload photo with LTE
    } 
    else if(digitalRead(radarR) == HIGH)
    {
      Serial.println("radar R");
      digitalWrite(relay, HIGH); //turn on LEDs
      digitalWrite(enablePin, LOW); //enable motor
      digitalWrite(dirPin, HIGH); //look right
      for(int i = 0; i < turnWidth; i++)
      {
         digitalWrite(xPin, HIGH);
         delay(delLength);
         digitalWrite(xPin, LOW); 
      }
      digitalWrite(enablePin, HIGH); //disable motor
      delay(2000);
      digitalWrite(relay, LOW); //turn off LEDs
      //TODO take photo
      //TODO upload photo with LTE
    }else
    {
      Serial.println("no movement");
      digitalWrite(relay, LOW);
      digitalWrite(LED_BUILTIN, LOW);
      digitalWrite(enablePin, HIGH);
      digitalWrite(relay, LOW);
      delay(2000);
    }
    delay(200);
    
}

Credits

Alana Balagot

2 projects • 3 followers

Maker/Musician/Developer

Car Sentry

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

Sentry Circuit

Code

Robot Sentry V1

Credits

Alana Balagot

Comments

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Car Sentry

Car Sentry

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

Sentry Circuit

Code

Robot Sentry V1

Credits

Alana Balagot

Comments

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