Lack of Exercise / sofa potato
Machine/Furniture going on strike

Supplies

1 × Arduino Uno R3
1 × Breadboard
2 × Ultrasonic Distance Sensor sensors (HC-SRF05)
4 × Continuous Servo FS90R
4 × Roller
50 × Dupont Thread
1 × Power Supply Cable 5,5×2,1 mm

Step 1: Concept

Geometric Functions by steps - Original

The Chair will stand on it if no one wants to sit on it. If there is one approach to the chair, the distance is smaller than 60 cm. It will lay back once the distance is smaller than 10 cm. The chair will give up and lay on the floor.

Step 2: Workflow

Ultrasound Sensors detect the people's distance around the chair. Once its distance are shorter than the ideal distance, the server will start work, pulling the chair to lay back.

Step 3: Method Development

One ultrasound sensor has 30 degrees detect radius. And with the help of two sensors, It can detect in which direction people are approaching the chair. Then the chair will lay back to another direction.

Step 4: Actuator

The four legs of the chair ate designed with wood sticks with two ball joints. It allows the leg moves freely in a large area. Then the string is used to connect the leg and the server. Once the server rolls clockwise, the string will pull the leg. And once the server rolls counterclockwise, the string will release the leg.

Step 5: Geometric Relations

This diagram shows the relationship between string length and the chair layback degrees. It can reply to the server, and calculate how many degrees should each server rolls.