Summary

This 3d printed project is a remote controlled toy robot that is driven by a single motor. It can move forward and steer left or right. The motor is an N20 gear motor. The battery is a 200 mah Eachine drone battery I got from Banggood. The remote control is a universal infrared remote unit set up to transmit 12 bit Sony codes. The ir commands are interpeted by a microcontroller and drive the motor through a L9110s motor driver. When the motor is driven forward it drives the selected wheels. When the motor is driven in reverse, it drives a cam assembly that cause the idler for each wheel to engage or disengage. A switch thats closed or opened by another cam is used to keep track of the position of the cams that engage the wheels. The single switch is the only feedback the mcu gets. The mcu just counts to keep track of which way it's moving. The system depends on being powered up with the cams set in the forward direction. It seems to work pretty well. I'm designing some other similar toys that will use the same system. I'll share them when they are finished.

There are two versions of the mcu board. One uses an Attiny85 and the other uses a Picaxe 08M2. I used to do a lot with the Picaxe and it's a nice fit for this project. It's Basic language is less intimidating than the Arduino C++ language. It also contains built in commands for reading Sony ir codes. I will include links to the EasyEda schematics and boards for both versions. You can order the boards through JCLPCB, PCBWay, or any place you choose. I got 5 of each board from JCLPCB for a under 20 dollars. You just have to watch which shipping method you pick. The only surface mount component on the boards is the L9110s but it's it can be easily hand soldered. The resitors are all 1/8 Watt. The gerber files for having the boards maufactured will be on the Github for either the Picaxe ar Attiny board.You will need to zip them up to send them to the pcb maufacturer. You can also open the project in EasyEda and get the zip files from there.

You will need some special hardware for the build. The two 51 mm brass shafts are cut from 1/8 inch rod but 3MM should work. I used 1/8 inch brass welding rod from a Tractor Supply. The screws are 3MMX20MM and 3MMX12MM button head machine screws. I got them off Ebay.The switch cam has a 3.1 MM wheel collars for rc airplanes glued into it. This is used to make the switch cam easily adjustable. Some double sided tape for mounting the switch and pcb. A spring from ball point pen.Some small rubber bands. I found them next to the hair combs at Wal Mart. Super glue. A 3mm drill. A 6mm tap. O rings for tires. I got the O rings in an O ring kit from Harbor Frieght. The inside dia is approximately 26 mm. Some female Dupont connectors to connect the switch and the motor to the controller board.

3D printing notes:
There are 2 versions of the switch cam. One needs the 3.1 MM wheel collar glued into it. The other can just be pressed onto the 1/8 inch shaft.
Any files with an X2 or X3 require 2 or 3 of the parts.
The file board_carrier_top.stl has to be printed with supports.
The file axle_8mm_X2.stl has to be printed with 100% infill on the threaded part.

Links:

Youtube video:

https://youtu.be/iZyNret8acI

If the above youtube link isn't showing up , there are links on the github wiki below.

Github Wiki for Picaxe code and pcb files:
https://github.com/Rick-100/Single-motor-3-function-toy-robot-Picxae-08M2-version/wiki

Github Wiki for Attiny85 code and pcb files:
https://github.com/Rick-100/Single-motor-3-function-toy-robot-ATTINY85-version/wiki

EasyEda Picaxe schematic and board:
https://easyeda.com/Rick100/ir_picaxe

EasyEda Attiny85 schematic and board:
https://easyeda.com/Rick100/attiny85-ir_motor_copy

Batteries:
description:
5PCS Eachine E010 3.7V 200mAh 30C Battery RC Quadcopter Spares Parts
link:
https://www.banggood.com/5PCS-Eachine-E010-3_7V-200mAh-30C-Battery-RC-Quadcopter-Spares-Parts-p-1081736.html?cur_warehouse=CN&rmmds=search

Wheel collars:
description:
20Pcs URUAV 1.6/2.1/2.6/3.1/4.1mm Landing Gear Stopper Set Wheel Collar for RC Helicopter Airplane - 3.1mm
link:
https://www.banggood.com/20Pcs-URUAV-1_6-or-2_1-or-2_6-or-3_1-or-4_1mm-Landing-Gear-Stopper-Set-Wheel-Collar-for-RC-Helicopter-Airplane-p-1382109.html?cur_warehouse=CN&ID=557984&rmmds=search

Screws:
description:
M3 M4 M5 M6 M8 Stainless Steel Button Head Socket Screw A2 Hex-Key Metric
link:
https://www.ebay.com/itm/383627902133?var=652040967292

Roller switch:
description:
5pcs Ultra Mini Roller Lever Actuator Micro Switch SPDT Sub Miniature Micro Switch
link:
https://www.banggood.com/5pcs-Ultra-Mini-Roller-Lever-Actuator-Micro-Switch-SPDT-Sub-Miniature-Micro-Switch-p-1047023.html?cur_warehouse=CN&rmmds=search