OpenRC 4-Wheel Drive Go-Kart with Ackermann Steering
The model is inspired by Lego Go-Kart 1972:
https://www.toysperiod.com/lego-set-reference/technic/model/race/lego-1972-go-cart/
The custom electronics has been designed around the Esp32 processor. The controlling software can be found in github at:
https://github.com/projunk/RaceCarESP32
Two configurations are currently supported:
- BR2830 850Kv motors with 2S Battery (NANO_TECH 4200)
see e.g.: https://www.amazon.in/Generic-Racerstar-BR2830-Brushless-Airplane/dp/B07PCMDCMF
Theoretical Top Speed: 113 Km/h
- 5010 360Kv motors with 4S Battery (MULTISTAR 4000)
see e.g.: https://nl.aliexpress.com/i/32479766898.html?gatewayAdapt=glo2nld
Theoretical Top Speed: 96 Km/h
The scale factor compared to Lego parts is 3.0
Printed Parts (already scaled):
- BatteryHolderPlateStraps_MultiStar4000.stl (2x) or BatteryHolderPlateStraps_NanoTech4200.stl (2x)
- ChairHolderHingePlate.stl
- ElectronicsBrick.stl
- ElectronicsPlate.stl
- Plate_1x2.stl (2x)
- Plate_2x8.stl
- Rim_motor_2830.stl (4x) or Rim_motor_5010.stl (4x)
- SlickTire_2830.stl (4x) or SlickTire_5010.stl (4x)
- servo_connector.stl
- technic_brick_ackermann_left.stl
- technic_brick_ackermann_right.stl
- technic_brick_motor_left.stl
- technic_brick_motor_right.stl
- technic_brick_servo.stl
- technic_pin_with_friction.stl
- technic_plate_toothed_end.stl (2x)
- technic_plate_toothed_end_ackermann.stl
- technic_steering_arm_motor_M8_left.stl
- technic_steering_arm_motor_M8_right.stl
Printed Parts (to be scaled in slicer with factor 3.0):
- HingePlate2Fingers.stl
- MinifigTorch.stl (2x)
- Plate_1x3.stl
- Plate_1x4.stl (2x)
- Plate_2x3.stl (4x)
- Plate_2x4.stl (3x)
- TileWithGrove.stl (2x)
- technic_axle_3.stl
- technic_axle_4.stl (2x)
- technic_axle_6.stl
- technic_axle_8.stl
- technic_axle_pin_no_friction.stl (2x)
- technic_brick_1x8_m4.stl (2x)
- technic_bush.stl (4x)
- technic_bush_toothed.stl (3x)
- technic_connector.stl (8x)
- technic_gear.stl
- technic_gear_rack.stl
- technic_wedge_belt_wheel.stl
- technic_wedge_belt_wheel_grip.stl
Optional printed parts:
- BodyTop.stl
- Helmet.stl
- Minifig_arm_left.stl
- Minifig_arm_left.stl (mirror in slicer)
- Minifig_body_bottom_plate_MultiStar4000.stl or BatteryHolderPlateStraps_NanoTech4200.stl
- Minifig_hand.stl (2x)
- Minifig_head.stl
Lego minifigure is based on:
https://www.printables.com/model/24298-lego-jo
Recommended Materials:
- PLA (30% infill)
- ABS (30% infill): axles,pins,technic connector, bushes, rims
- Ninja Flex (10% infill): technic_wedge_belt_wheel_grip.stl, SlickTire_2830.stl, SlickTire_5010.stl
Hardware:
Electronics:
- 4 in 1 ESC (30A)
- Power distribution board
- Acceleration sensor: MPU 6050
- receiver (fly sky 3 channel FS-GR3E)
- servo: MG 946R
- neopixel Ws2812: (2x)
- for other electronics parts see drawing: "Schematics_ESP32.png"
Software Features:
- webservice which either connects to local network or creates its own accesspoint if local network cannot be reached
- webservice shows telemetrics, speedo and settings. Settings can be updated on the fly and are saved
- Acceleration sensor input is used to help steering
- In case of taking a turn, the inner wheels are slowed down to help steering around a corner
- LED string shows status (armed/disarmed) and indicates driving directions
Remarks:
- a custom name can be generated for BodyTop.stl using the BodyTop.scad source file
- print technic_wedge_belt_wheel_half.stl twice and glue parts together
- print technic_wedge_belt_wheel_grip_half.stl twice and glue parts together
- print technic_gear_half.stl twice and glue parts together
Alternatives for the glued “half” parts have been added that can be printed as a single piece:
- technic_gear_rounded.stl
- technic_wedge_belt_wheel_easy_printable.stl
projunk
