JetBot ROS AI Kit

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JetBot ROS AI Kit
JetBot ROS AI Kit.png

Jetson Nano
UART I2C I/Os
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Overview

Introduction

This is a high-performance AI Jetbot for people who learn and develop the ROS system. It adopts the ROS system and two controllers: the microcontroller of Raspberry Pi RP2040 and the AI host controller of JETSON-NANO-DEV- KIT-A. As the expansion board integrates OLED, servo motor drive circuit, battery protection circuit, the audio output circuit and so on, you do not need to weld the circuit. It can be charged without unloading, so you do not need to remove the batteries repeatedly. It features the built-in IMU posture sensor, and the DC encoder motor controls the rotating speed through PID, which can output wheel odometry data. In terms of the software, it is compatible with NVIDIA JetBot open source project program, supports AI deep learning, SLAM mapping and navigation, OpenCV visual processing, intelligent voice interaction, etc.

Features

  • Onboard 3 x 2600mah 18650 batteries, its voltage output is up to 12.6V with stronger motor power.
  • Onboard S-8254AA + AO4407A lithium battery protection circuit, it can prevent overcharge, over-discharge, overcurrent, and has short circuit protection.
  • The onboard INA219 is convenient for real-time monitoring of battery voltage and charging current.
  • With 0.91-inch 128 × 32 resolution OLED, it can display real-time data from the car, such as IP address, memory, battery power, etc.
  • Featured MPU9250 IMU posture sensor, the direction of the robot can be accurately judged.
  • With the coded DC gear motor, it supports PID debugging and outputs wheel odometry data.
  • With Raspberry Pi RP2040 dual-core micro-controller, it has better real-time performance and higher accuracy in control.
  • Adopting the ROS system and a series of visual software, it can be developed more.
  • Support I2C slave mode control, it is fully compatible with NVIDIA JetBot open source project program without porting and is easy to achieve AI functions such as obstacle avoidance and autonomous line tracking.

Expansion Board Introduction

RosKit2.jpg

Operating Hints

1. When the micro-control demo on the expansion board starts, the LED light is always on and the IMU is in the calibration state. After the calibration, the LED flashes. If the LED does not flash, the program is not running normally, please try pressing RESET to restart, or flash the firmware demo again.
2. The JetBot needs to be still and horizontal when calibrating the IMU, or the wrong IMU data will keep the robot rotating. Please place the car on the level and keep it still, then press RESET.
3. Please connect the expansion board to I2C and Jetson Nano by USB, and it will be recognized after connecting correctly.
4. If the volume is too large, The sound is stuck when the current is insufficient. Please reduce the volume to an appropriate position.
5. If there is an error when starting the related nodes of the chassis, you can try pressing RESET to restart the program. If the LED does not blink 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. The RP2040 chip will enter the download state. The computer will recognize the U disk and you can put the firmware program to the U disk to download.

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.

JetBot ROS AI Kit Basic Tutorial

JetBot ROS AI Kit Advanced Tutorial Directory

JetBot User Guide

Resource

Program

Schematic

Drawing

Learning Materials

NVIDIA Official Resource

Development Document

FAQ

Question:1. What battery does the JetBot use?

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


Question:2. Why does the car turn in the wrong direction?

 Answer:
Answer: When the motor rotates in the wrong direction, please check whether the motor wire is reversed. You can open the receive topic node to check whether the posted sports topic is a positive or negative value.


Question:3. Can I provide 12.6V to the Jetson Nano?

 Answer:
A: 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.


Question:4. Charging indicator?

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


Question:5. What are the account and passwords?

 Answer:
A: The account password of the JetBot system is jetbot.


Question:6. You are prompted to enter a password, but the password cannot be entered or an error is reported?

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


Question:7. The battery is fully charged, but it cannot supply power to the robot?

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


Question:8. After flashing the image of Jetson Nano, the TF card cannot be recognized on a Windows computer?

 Answer:
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 mobile 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 not correct. 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.


Question:9. The motor vibrates after power-on, and the motor speed is different during the movement?

 Answer:
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; Check the motor waveform at the machine terminal to determine whether the output waveform is normal.


Question:10. When starting a node, some topics are not loaded normally?

 Answer:
Answer: The reason is that these topics may conflict with other topics that have 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.


Question:11. During the process of slam map building, there is a phenomenon that the video returned by the camera is stuck and the slam map is not updated during remote control or automatic map building. What is the reason? How to solve it?

 Answer:
A: 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 use your mobile phone to turn on 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 to solve the problem [By now, your data traffic is not used, the mobile phone is only As a signal transmission relay.]


Question:12. I have got a jetbot ai kit, and ttyACM0 and ttyACM1 are not showing with the command ls /dev. How do I fix this?

 Answer:

Please check if you have connected the USB adapter properly. And you need to turn on the PWR switch for the lidar.
JETBOT ROS AI KIT09.png

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