If you want to play magician for a day, all you have to do is tell your friends that you are moving. Abra cadabra, alakazam, everyone will disappear right before your eyes. Nobody likes to move. Nobody. But Austin Allen has got an idea that could make it, if not fun, at least bearable. He has built the motorized furniture dolly that no one has been asking for, but that everyone wants a turn at driving around.
For locomotion, Allen replaced the original swivel casters with a set of two rigid and two swivel rubber wheels for a smoother and quieter ride. Powering these wheels are two Flipsky 7070 BLDC motors, each controlled by a Flipsky 75100 dual ESC running VESC firmware. This dual electronic speed controller allows for independent control of each motor, which was necessary for the steering mechanism.
An overview of the system’s electronics (📷: Austin Allen)
The mechanical transmission of power from the motors to the rear wheels is achieved through a chain drive system, reminiscent of a bicycle. Allen modified Tritan 55VX32 flat sprockets, drilling mounting holes and increasing the center bore to accommodate the wheel assembly. These modified sprockets are then attached to 3D-printed adapters, which are in turn mounted to the rear caster wheels using self-tapping wood screws. The motors are equipped with either 25-tooth (higher RPM) or 10-tooth (higher torque) Uxcell #25 chain roller sprockets, connected to the wheel sprockets via a length of #25 chain and master links. To ensure proper alignment and clearance for the sprockets and chain, Allen used an automotive brake pad spreader tool to widen the rear wheel brackets and incorporated 3D-printed spacers.
The system is controlled by a pair of ESP32-S3 microcontrollers. One is housed in a custom 3D-printed enclosure on the dolly itself, communicating wirelessly with a second ESP32-S3 based hand controller. The hand controller, featuring a custom-designed printed circuit board, utilizes two single-axis joystick modules for throttle and steering input. It is powered by a rechargeable 18650 Li-ion battery and includes a color TFT display with a capacitive touch panel for the user interface.
Wireless communication between the hand controller and the dolly-mounted ESP32-S3 enables real-time control of the motors. VESC Tool software was used to program the Flipsky ESCs, calibrating the motors and setting parameters for optimal performance. Additionally, Allen developed a rudimentary phone app using Flutter and Dart, offering an alternative control method via Bluetooth. The app features simulated joysticks, speed display, and controls for the onboard LED strip lights, which add some visual appeal to the dolly.
Moving in style! (📷: Austin Allen)
The dolly can be used for moving furniture, but since it is really a miniature electric vehicle, Allen couldn’t resist the temptation to mount a chair on it so that he could take it for a spin. Now that is some real incentive for friends to come and help with a move!
Remember, folks — safety third! Now that the dolly is complete, Allen is looking to add some additional safety measures, like seat belts, in the future. There are also plans to replace some of the 3D-printed plastic parts with metal, and to add battery monitoring and a slew of other enhancements. Stay tuned to see where this project goes next!
