Jecc

About the project

We build our own differentially driven NXP-Cup platform based on a 3D-printed chassis. We also developed our own control electronics around the FRDM-KL25z board.

NXP Cup Electromaker Innovation Challenge 2021 Contest WinnerNXP Cup Electromaker Innovation Challenge 2021 contest winner

Project info

Difficulty: Expert

Platforms: NXPArmKiCad

Estimated time: 4 weeks

License: GNU General Public License, version 3 or later (GPL3+)

Items used in this project

Hardware components

PLA PLA x 1
Brushless impellers Brushless impellers https://www.ebay.de/itm/EDF-Impeller-Brushless-Set-45-mm-436g-Schub-11-1V/191834541918?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 x 1
Gear motor 1000 rpm Gear motor 1000 rpm https://www.ebay.de/itm/DC-12V-25mm-5RPM-1000RPM-Getriebemotor-Motor-25GA-370-Low-Speed-Elektromotor-neu/323379372824?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 x 1

Software apps and online services

FreeCAD FreeCAD
KiCAD KiCAD
MCUXpresso MCUXpresso

Hand tools and fabrication machines

3D printer 3D printer x 1

Story

We decided to design and build our own NXP-Cup platform from scratch. This includes all the mechanics, electronics and software. 

Features

  • 3D-printed chassis
  • 2 Brushless impellers to improve the adhesion to the race track
  • 11,1 V 3S LiPo
  • Custom tires with silicone profile ( work in progress )
  • Usage of 4 linescan cameras ( work in progress )
  • pcb with reflectife sensors CNY70 for detecting the finish line ( work in progress )
  • IR LEDs for improving the camera performance ( work in progress )

Chassis

The platform is built around a 3D-printed mainchassis.

We used FreeCAD to do the design work. All design resources and production data for 3D printers are available on GitHub.

The robot is differentially driven. The front wheels and gear motors with 1000 rpm are off the shelf parts. 

The backwheel is a ball roller, which is easy to install and robust. The impellers on the back of the car are installed in a 45° angle and create a vacuum in a quadratic chamber under the car, that is almost touching the ground. The battery is also mounted very low behind the front axle of the car in order to make the vehicle more controllable. We will mount a pcb with the reflectife light sensors directly under the front axle.

Currently we are experimenting with custom 3D printed wheels and silicone profiles:

Electronics

We designed and tested our own electronics platform for autonomous vehicles, the "HighDriveUnit" ( https://gitlab.com/highdriveunit/ ):

The board is a shield for the FRDM-KL25Z and has the following fatures:

  • Power input with PTC fuse and reverse polarity protection (  6 - 15V DC )
  • Control of two DC motors ( up to approximately 20A ) with current sense, motor fault detection and back emf measurement
  • Control of two Servos at 6V DC with adjustable maximum current
  • HMI with 2 potentiometers, OLED Display connection, 8 dipswitches, 4 LEDs and two push buttons
  • Reset button
  • Power control LEDS ( 3V3, 6V and VBAT )
  • SD-Card slot
  • Connector for HC-SR05/6 Bluetooth module
  • Connectors for 2 Freescale linescan cameras
  • Connectors for 2 analog encoders
  • Breakout headers for breadboard
  • ID field
  • Demonstration of basic functionality:

    Schematics, diagrams and documents

    HighDriveUnit schematics

    Molex Award

    Our submssion for the Future of the NXP Cup Awward The Brennerglas challenge

    CAD, enclosures and custom parts

    3D design source

    Go to download

    Code

    NXP-Cup software

    Credits

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