Solar-Powered RC Car with Hub-less Front Wheels by ChisTompso

Last crawled date: 2 years, 11 months ago

This is a radio controlled solar powered car, that has no wheel hubs for the front wheels. It is a tricycle configuration with two front wheels and one rear wheel. The rear wheel is driven by a single brushed motor, and steered with a single servo in a pull/pull set-up. The solar cells are mounted on the top such that no other vehicle component can cast a shadow on them. The hub-less front wheels use standard M3 bore 3D printer belt pulleys that many users might already have in their spare printer parts collection (which is what inspired this idea).
7/31/2019 - Car is still working great after nearly a year, but noticed it kind of sags where the motor mount interfaces with the steering assembly mount. The reason was I had a 2 mm radius hole for a 1.5 mm radius screw. I have tightened that up to a 1.7mm radius hole (don't want it to be too tight). I've also replaced the copper wire steering lines with 6 lb. test fishing line.
9/8/2018 - Design is complete. The car ran well today with partly cloudy skies. See video below. It does not run well through thick tree shade. Eventually, I plan to experiment with a small battery charging off the cells to power through tree shades along the road in my neighborhood. Overall, it controls and drives quite well. It is not fast, but the motor is geared for torque, not speed, which is what you want to power up hills and over bumps in the road. You’ll notice the top center panels in some of my pictures are a bit bowed. This has been corrected in the .stl files. I shaved 1 mm off each end of these (TopClampV2.stl), so that issue is fixed. Some construction notes:
If you want to pack all of the electronics inside, you need to snip off the ESC switch and solder the wires to close the circuit. You’ll also want to snip the male JST connector from the ESC (since you’ll be soldering to the motor wires anyway). Solder that male JST connector to the front left solar panel. This way, you can connect it to the female JST connector that hangs out of the side of the body. This will allow you to swap out the solar cell for a battery for indoor use or cloudy days.
There are only files uploaded for a left front wheel assembly. For the right side, just tell your slicer to mirror the left files.
Solar cells are wired together in parallel. Individual cells provide sufficient voltage, but multiple cells in parallel are required to provide the necessary current. When you solder them, take care to note which corner you need the JST connector, and where you'll locate the left-to-right cross-over wire. There is a cut-out int he top of the body (Spine.stl) to accommodate that wire cross-over.
8/24/2018 - Printed one of the frame quadrants. Solar cell didn't fit. That's what I get for not doing a fit check in the model. Anyway, got that fixed, and updated SolarCellFrameV2.
8/18/2018 - Initial design complete. Now to assemble, test, and tweak!
8/15/2018 - Designed the servo mount for steering. Added the latest top level assembly photo to reflect that.
8/13/2018 Update - Surprisingly, the first version of the motor mount worked like a charm with no design revisions needed. Solar cell mounting frame design is now in-work. Added an incomplete top-level assembly picture to show where the overall layout is headed. Still need to design the center primary core frame to tie it all together, but coming along nicely.
8/10/2018 Update - Added the motor mount and a FreeCad screen snip of the Control Assembly, which includes the motor, motor mount, and drive wheels. The two tabs on the front of the motor mount will be for pull/pull control wires to the steering servo.
8/6/2018 Update - Wheel assembly design is complete (see new pics). All prototypes wheel assemblies fit and function properly. I'll likely reduce the screws required to hold the aft drive wheel assembly together from 4 to 3, but that's minor. Now time to design the main body frame and steering mechanism! Debating if I want this thing to have batteries for driving through shady areas or not... Maybe I'll at least add provisions for the future growth.
PARTS! PARTS! PARTS!!!!
All parts listed below are from Amazon
*4 Solar Cells - ALLPOWERS 2 Pieces 2.5W 5V/500mAh Solar Panel DIY Battery Charger Kit Mini Encapsulated Solar Cell Epoxy for Battery Power LED 130x150mm (Solar Panel Only)
*1 ESC - Hobbypower Rc ESC 10a Brushed Motor Speed Controller for Rc Car Boat W/o Brake
*1 Brushed Motor - Doradus 5Pcs DC 3V-6V Dual Axis Gear Reducer Motor For Arduino Smart Car
*6 Belt Pulleys - WINSINN 2GT GT2 Aluminum Timing Belt Idler Pulley 20 Toothless 3mm Bore For 3D Printer 6mm Width Timing Belt (Pack of 5Pcs)
*1 Servo Actuator - ElectroBot 2X Pcs Sg90 Micro Servo Motor 9G Rc Robot Helicopter Airplane Boat Controls
*Miscellaneous M3 screws, nuts, and washers + wire, solder, heat shrink, etc.