Introduction: Tilted Chair With Motion Sensor

This is a tilted chair with an added motion sensor. The motion sensor goes off after 30 minutes, reminding the person to shift his/her weight. It was created using cardboard, 3D printing, coding.

Step 1: Cardboard- Side Panels

Cut 2 panels to act as the sides of the chair. Cut a third panel to be placed inside. The corrugation of the cardboard should be vertical for these panels.

Step 2: Cardboard- Base and Seat

Cut the seat of the chair with the corrugation of the cardboard running horizontally. The base is comprised of 2 panels. The panels should be cut with corrugation running in opposite directions (i.e. one vertical and one horizontal).

Step 3: Cardboard- Head Guard, Arm Rest, and Sliding Tray

2 panels should be cut to create the head rest. 4 panels should be cut to create the arm rest, 2 panels will be glued together to create the arm rest on each side. The sliding tray should include a tray (1 panel) slightly wider than the width of the chair (including the arm rests on either side). The tray will also need 4 smaller rectangular panels to create the slide for the tray to attach to the the arm rests.

Step 4: Assembling the Cardboard

First, hot glue the 2 panels of the bases together with corrugations in opposite directions. Next, attach the seat to the side panels. Attach 2 of the 4 side panels together with hot glue, creating 2 sets of side panels. Start by placing one set side panels on the edge of the seat panel. Bend the seat panels at the appropriate lengths to form the seat. Next, hot glue the side panel to the seat following the bends. Hammer dowel rods in to provide extra support. Repeat this process with the other set of side panels. Place the seat on the base and glue down.

To assemble the tray, glue the rectangular pieces so they create a slide to fit over the arm rest of the chair.

Step 5: Gum Tape, Primer, Paint, Polyurethane

Use Gum Tape to go over all edges of the seat, base, and tray. Make sure to pull the tape tight against the cardboard to prevent water from seeping through the corrugation. Next, primer the entire seat, base, and tray. After this has dried, use any color paint to decorate your seat. Finally, after the paint has dried, apply polyurethane to complete your chair.

Step 6: Sensor

Using Arduino, code

const int trigPin = 11;       //connects to the trigger pin on the distance sensor   
const int echoPin = 12;           //connects to the echo pin on the distance sensor    

const int buzzerPin = 10;         //pin that will drive the buzzer

float distance = 0;               //stores the distance measured by the distance sensor 
void setup()
{ Serial.begin (9600); //set up a serial connection with the computer
pinMode(trigPin, OUTPUT); //the trigger pin will output pulses of electricity
pinMode(echoPin, INPUT); //the echo pin will measure the duration of pulses coming back from the distantce sensor
pinMode(buzzerPin, OUTPUT); //set the buzzer pin to output } void loop() {
distance = getDistance(); //variable to store the distance measured by the sensor
Serial.print(distance); //print the distance that was measured
Serial.println(" in"); //print units after the distance
if(distance <= 6){ //if the object is close
//this code beeps the buzzer
tone(buzzerPin, 272); //buzz the buzzer pin
delay(1000); //wait 30 seconds
} else if(12 < distance && distance < 20){ //if the object is far away
// this code turn the buzzer off
} else if(12 < distance && distance < 20){ //if the object is far away
// this code turn the buzzer off } }


float getDistance()


float echoTime; //variable to store the time it takes for a ping to bounce off an object
float calculatedDistance; //variable to store the distance calculated from the echo time

//send out an ultrasonic pulse that's 10ms long

digitalWrite(trigPin, HIGH); delayMicroseconds(10); digitalWrite(trigPin, LOW);

echoTime = pulseIn(echoPin, HIGH); //use the pulsein command to see how long it takes for the
//pulse to bounce back to the sensor

calculatedDistance = echoTime / 148.0; //calculate the distance of the object that reflected the pulse (half the bounce time multiplied by the speed of sound)

return calculatedDistance; //send back the distance that was calculated }

Step 7: Sensor

Set up the bread board like the picture.

Step 8: Create a 3D Printed Box

The box will be mounted on the bottom of the tray. Inside the box, the Arduino board and battery pack will be positioned to sense the motion of the person in the chair. To create the boxes, we used TinkerCad. We used the measurements of the Arduino board and battery pack to create the dimensions of the box.

Step 9: Mount the Boxes

The 3D printed boxes will be mounted on to the tray with the sensor facing the seat. The boxes will be attached with velcro to easily allow for battery changes.