ErgoDesk : Automatic height adjustment of a desk

Abstract: The purpose of this project was to track the posture of a person sitting by a desk, and then use the information to adjust the desk to achieve an optimal height for the user. The solution was to track the angle of the users forearm relative to the desk’s horizontal plane, which should be around zero degrees for an ergonomic posture. Two Light Emitting Diodes (LEDs) in different colours were attached to the user, one at the elbow and one at the wrist. The LEDs were tracked with a camera connected to a laptop running Open Source Computer Vision Library (OpenCV). Window tinting was placed on the camera lens so that only the LEDs and other strong light sources were visible. By using OpenCV, coordinates for the two LEDs were given. With the coordinates found, the angle of the users arm could be calculated and the height of the desk evaluated. Information about necessary height adjustments were sent from the laptop to an Arduino via Bluetooth. The Arduino then controlled a stepper motor by sending signals to a stepper driver, making the motor rotate, thus adjust the height of the desk. The desk was a single leg laptop desk. The leg consists of two tubes. The lower, outer tube was connected to the foot while the upper inner tube, which ran freely in the outer tube, was connected to the tabletop. The height was adjusted with a lead screw positioned parallel to the leg.The nut on the lead screw was connected to the outer lowertube. When the motor rotated so did the lead screw, lifting the table top up or lowering it.