About Our Robotic Christmas Tree (Coed-Anne)
This Christmas tree project of ours has been running since 2016, when we made our first robotic Christmas tree in a hurry. We had the idea very close to Christmas that year, so the project had to be simple, which meant that pretty much everything was made from cardboard or paper. It was hastily thrown together with power from the 9v battery going straight to the motors. it only passed via the on/off switch (pictures in gallery below). It was very fast, and very chaotic, but it had no direction or ability to avoid obstacles.
When we decided to upgrade her this year (2021), we didn’t really know how we might tackle the build. Making a base for an autonomous robot was pretty easy, but making the cone would prove to be difficult. At first we tried some glitter card, and experimented with rolling it into a cone, and then securing it. We tried glue, then nuts and bolts (pictures below), and we did have some success, however we were not happy with the outcome, and we worried specifically that we would find difficulty when trying to secure LEDs nearer the end of the project.
Luckily while shopping, we found a christmas tree ornament in a poundshop, that was just a cone shaped cage, wrapped in tinsel. It was perfect for unwrapping, modifying and then re-wrapping.
So as she stands now, our Christmas Tree Robot (Coed-Anne), now has a base made out of board, although we did try both perspex and stainless steel before settling on the lighter material now being used. She uses an ultrasonic range finding sensor (HC-SR04), to send data to an Arduino Nano (using the code below), which then give instructions to an L298n dual h-bridge motor driver, that sends power to the motors as needed. The motors are rather nice, high rpm mini motors, that are attached to exposed brass gearboxes. The wheels and mounts are designed for these motors and can be found on Pi Hut.
She uses 4 x 1.5v AA batteries to power the Nano, the motor driver and the motors, and then 2 x 1.5v AAA batteries in a separate circuit for the 10 x flashing LEDs mounted on the tree frame.
To make sure that our robot continued on from our very first design, we have used a couple of components from our original robot, and we added the googly eyes for continuity.
She is perfectly autonomous and finds her way in and out of rooms with ease. She even manages to avoid obstacles that may have a gap beneath them, due to the rear tilt we gave her when mounting her wheels. She is moderate in speed.
• We are still undecided as to whether she will keep her tinsel, or be a skeleton robot tree.
• We have kept the servo code from our other robots in this modified code below, because we are still deciding whether or not we should build this system into our Christmas Tree Robot. We are still unsure, but this may happpen in a later version.
We would love to see your versions of this robot!
Full Stats:
Version: 2.5
Designation: Robotic Christmas Tree v2.5
Name: Coed-Anne (A play on the word Coeden, the Welsh word for tree)
Utility: Seasonal Fun
Purpose: Home Education
Weight (total): 360g
SingleTrack Width: 1.9cm
Whole Track Width: 17cm
Drive: 2WD
Motor: 40mA @ 6v, 360mA stall current @ 6v
Motor RPM (original): 13,000rpm
Motor Reduction Ratio: 50:1
Motor RPM (after reduction): 260rpm
Motor Torque: 10oz inches (0.0706155181 newton meters)
Relative Speed (to our other robots): Moderate
Microcontrollers: 1 x Arduino Nano board
Motor Driver: 1 x L298N Dual H Bridge
Sensor: 1 x HC-SR04 Ultrasonic
Sensor Holder: Clear Perspex
Switches: 1 x switch, built into battery holder
LEDs: 10 x RGB LEDs wired in parallel to 3v
Power (Main Drive/Avoidance Circuit): 4 x 1.5v AA batteries (6v total)
Power (Tree Lights Circuit): 2 x AAA batteries (3v total)
Wiring Diagram Here Soon
Video Here Soon
Our Robotic Christmas Tree – Gallery
