JetRacer ROS AI Kit

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JetRacer ROS AI Kit
JetRacer ROS AI Kit.jpg

UART, I2C, I/Os
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Overview

Introduction

This is a high-performance AI intelligent robot car specially made for students who learn and develop ROS systems. It adopts the ROS robot system and adopts dual controllers. The sub-controller adopts the Raspberry Pi RP2040 microcontroller, and the host controller adopts JETSON-NANO-DEV- KIT-A AI controller. The module integrates the OLED, servo motor drive circuit, battery protection circuit, an audio output circuit, etc., which saves you the trouble of soldering the circuit, supports unloading and charging and does not need to repeatedly remove the battery. Built-in IMU attitude sensor, DC encoder motor controls the speed through PID, and can output wheel odometer. The software is compatible with the NVIDIA Jetbot open-source project program, and supports AI deep learning, SLAM mapping and navigation, OpenCV visual processing, intelligent voice interaction, and other functions.

Features

  • Onboard 3 x 2600mah 18650 batteries, up to 12.6V voltage output, stronger motor power
  • Onboard S-8254AA + AO4407A lithium battery protection circuit, with anti-overcharge, anti-over-discharge, anti-over-current and short-circuit protection functions
  • The onboard INA219 chip is for real-time monitoring of battery voltage and charging current
  • Onboard 0.91-inch 128×32 resolution OLED, real-time display of car IP address, memory, battery power, etc.
  • The onboard MPU9250 IMU attitude sensor can accurately determine the direction of the car
  • Adopt coded DC gear motor, support PID debugging, output wheel odometer
  • Adopt Raspberry Pi RP2040 dual-core microcontroller, with better real-time performance and higher control accuracy
  • Using ROS robot system development, a large number of visual software tools, and more ways to develop powerful functions
  • Support IIC slave mode control, no need to transplant, fully compatible with NVIDIA Jetbot open-source project program, easy to achieve AI functions such as obstacle avoidance and autonomous line inspection

Interface Introduction

  • Highly-integrated Module

JetRacer ROS AI Kit001.jpg
JetRacer ROS AI Kit002.jpg

Usage Notice

  1. When the micro-control program of the module starts, the LED is on and the IMU is in the calibration state. After the calibration is completed, the LED flashes. If the LED does not flash, the program is not running normally, try pressing RESET to restart, or re-burn the firmware program.
  2. The robot needs to be in a horizontal stationary state when the IMU is in calibration. Otherwise, the IMU data will be inaccurate, and the coordinates of the car will be in a state of constant rotation. Put the flat and still, and press RESET to restart.
  3. The expansion board is connected to Jetson Nano through USB and I2C. After a normal connection, it will recognize the two serial devices /dev/ttyACM0 and /dev/ttyACM1, and will recognize the I2C address 0x60 device at the same time.
  4. The volume adjustment is too large, which will cause the sound of insufficient current to be stuck. Long-term high volume may damage the speaker. Please reduce the volume to an appropriate position.
  5. If there is an error in starting the chassis-related nodes, you can try to press RESET to restart the program and then run it. If the LED does not enter the blinking state after restarting, you can download the firmware program again.
  6. Connect the Type C interface of the expansion board to the computer, press and hold the BOOT button, and then press the RESET button to release, the RP2040 chip will enter the download state, the computer will recognize the USB flash drive, drag the firmware program to the U disk to download program.

Notes

Note 1: Before assembling, you need to turn the power switch to "OFF". Please disconnect the power supply at first. Otherwise, it can easily lead to short circuits and burn out the device, and the product may be damaged.
Note 2: When assembling, install the jetson nano first and then install the battery. When disassembling, remove the battery first and then remove the jetson nano. Otherwise, it is easy to cause a short circuit in the process of disassembly and assembly.
Note 3: Do not tighten the four studs when installing the jetson nano, tighten the four studs by half. Please adjust the position of the board to align with the pogo pins, and then press the board and then tighten it. Direct tightening will also cause the pogo pins to contact poorly.
Note 4: When the battery is connected for the first time, there may be no power output. It needs to be charged to activate the battery protection chip to output. The power switch needs to be turned to "ON".
Note 5: If the positive insulating pad of the battery is damaged, it is recommended not to continue to use it, which may cause a short circuit and fire. When removing the battery, do not use a screwdriver to pry the positive electrode of the battery, which may cause a short circuit. Please pry the negative electrode of the battery.

Precautions for the Lithium Batteries

  • Li-ion and Li-po batteries are quite unstable. They may cause fire, personal injury, or property damage if they're not properly recharged or used.
  • Do not reversely connect the polarities when recharging or discharging the battery. Do not use an inferior charger/charging panel to recharge the battery.
  • Do not mix old batteries with new ones when using, or use batteries with different brands.
  • When buying a Lithium battery, you should make sure the battery is compatible with the expansion board. Choose batteries from the formal manufacturer, and ensure the batteries will work stably and safely by aging test.
  • Lithium batteries have a cycle life, please replace the old battery with a new one when it reaches its service life or when it has been used for two years (whichever comes first).
  • Please place the battery carefully and properly, keep it away from inflammable and explosive articles, away from children, and avoid any safety accident caused by careless storage.

JetRacer ROS Kit User Guide

JetRacer ROS AI Kit Advanced Tutorial

JetRacer Tutorial Directory

JetRacer is an open-source project for autonomous AI racing using NVIDIA Jetson Nano.
JetRacer project library: https://github.com/NVIDIA-AI-IOT/jetracer

DonkeyCar for JetRacer ROS Tutorial

Donkeycar is an advanced automatic driving library written in Python, which realizes automatic driving by collecting images to train neural network models. For detailed tutorial materials, please refer to the official documentation of donkeycar.
donkeyCar project library: https://github.com/autorope/donkeycar
donkeyCar official documentation: https://docs.donkeycar.com/

Resource

Program

Schematic Dragram

Learning Material

Jetson Official Resources

Development Document

FAQ

Question:What battery does the JetRacer ROS smart car use?

 Answer:
Equipped with three 18650 batteries, that is, the diameter is 18mm and the length is 65mm. The standard voltage of a single cell is generally 3.7V, and the fully charged voltage is generally 4.2V.

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Question:The car is turning in the wrong direction?

 Answer:
When the motor rotates in the wrong direction, check whether the motor wires are reversed. You can open the receive topic node to see if the posted sports topic has a positive or negative value.

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Question:Can the Jetson Nano be powered by 12.6V?

 Answer:
The 12.6V power supply cannot directly supply power to the Jetson Nano. It is used to plug into the 12.6V port on the expansion board, charge the battery, and then power the Jetson Nano from the battery. Please do not directly connect to Jetson Nano. If you need to buy a Jetson nano power supply, you can click here to get it.

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Question:Charging indicator?

 Answer:
The charging indicator is on the charger, the green light is full, and the red light is charging.

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Question:What is the system account or password?

 Answer:
The account password of the JetRacer ROS AI Kit system is jetson.

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Question:Prompt to enter a password, but cannot enter the password or an error is reported?

 Answer:
The Linux system does not print the input content when entering the password, that is, touch typing is required. Type jetson directly on the keyboard and press Enter.

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Question:The battery is fully charged, but cannot power the car?

 Answer:
If you are installing the battery for the first time, or have disassembled the battery, please note that you need to connect the distributed power supply to charge the car for a few seconds, and then turn on the protection circuit before it can be used normally.

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Question:After programming the image of Jetson Nano, the TF card cannot be recognized on a Windows computer?

 Answer:
Due to the partition problem, the TF card with the image of the Jetson Nano programmed cannot recognize the drive letter normally on Windows computers. If you need to reformat it, search for disk management in the search bar of windows and open the disk management interface. Find the removable disk where the TF card is located (be careful not to mistake it for another disk), right-click and select Delete Volume, then create a new volume and format it by default. After the default format, the drive letter of TF will be recognized again. At this time, the space and memory of the TF card are incorrect. Note that you need to use the formatting software to quickly format the new drive letter again. After formatting, if the memory space of the TF card is normal, the new image can be re-programmed normally.

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Question:The motor shakes after power-on, and the motor speed is different during the movement?

 Answer:
The general reason is that the motor wire is loose, the interface is in poor contact, or the motor wire is entangled, and the Hall encoder is disturbed; please re-check whether the motor wire is plugged in tightly, and check whether the motor cable is entangled; you can also check the virtual machine terminal. Check the motor waveform to determine whether the output waveform is normal.

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Question:When starting a node, some topics are not loaded normally?

 Answer:
The reason is that these topics may conflict with other topics that have already been started. The solution is to check the running process, close it, and restart it; the most convenient method is to exit the node, long press the reset button, and then run it again.

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Question:During the process of slam mapping, the video sent by the camera is stuck and the slam mapping is not updated during remote control or automatic mapping. What is the reason? How to solve it?

 Answer:
The camera needs a large bandwidth and network speed to send back video and map updates. If the computer and the car are far away or the car is at a corner, the signal will be greatly attenuated, resulting in a stuck phenomenon. The recommended solution is that you can use the mobile phone to open the hotspot, connect the computer and the car to the hotspot at the same time to ensure normal communication, and place the mobile phone at the corner as a signal relay point. 【At this time, your data traffic is not used, and the mobile phone is only used as a signal transmission relay.】

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Support

If you require technical support, please go to the Support page and open a ticket.

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