Background

Setting up the Donkey Car software to run on your PC could be a challenging task, depending on your level of expertise in Python. It also depends on which platform you are using. Windows users tends to encounter more problems. If you are a teacher, you probably don’t want your students to spend 1 hour figuring out how to properly setup Conda or python without having any success running the Donkey Car software. How can we make the experience smoother?

One day, when I was preparing a talk to a group of teachers, I was wondering … how can I…


Donkey Car Controller is a mobile app designed to provide a “commandless” user experience to get started with the Donkey Car. This article gives a step-by-step guide on how you can use this app.

Requirement

Before you start, you need the followings:

  • A Donkey Car with Pi 4B (Jetson Nano is not yet supported)
  • A Mobile phone with iOS or Android

Install the mobile app

Robocar Controller is available on both Apple’s App Store and Google Play Store. Simply install this app on your phone.

p.s.: We actually want to call this app “Donkeycar Controller” but need some further work here to comply with Apple…


Pi 4 is good except one thing: It consumes much more power than Pi3B+, which is definitely not good for application such as Donkey car. My experience is that my pi3b+ can run for an hour on a 1700mah LiPo battery but only 30–40 mins (max) on a pi4.

Raspberry Pi 4 has released a new boot EEPROM which claimed that, according to this article on Hackaday, it could low power mode for the USB hub and therefore supposingly allow us to run the Pi 4 on full speed without throttling and consume less power so we can run it…


9/1/2020 更新: 根據前幾天的 Governance Poll, 現時 DSR 已由4%升至6%

隨著 MakerDAO 成功將 SAI 升級至 DAI 後,由 Maker 開發的 Oasis App 也正式投入服務。Oasis App 提供存款,借貨及交易服務。或許你之前已經聽過 DAI 可以透過 Compound 來賺取利息,那麼親生兒子 Oasis 跟 Compound 有什麼分別呢?

Oasis 與 Compound 的分別

  1. Oasis 現時的 DSR (Dai Saving Rate) 剛剛透過 governance poll 由 2% 升至 4%,比 Compound 現時大約 2.8% 更為吸引。有趣的是,現時 Stability Fee 也是4%,即是說 Maker 現時全心追求 DSR 的使用率。若留意一下 d …


Install the video 4 linux utils

sudo apt-get install v4l-utils

Run the command v4l2-ctl to check the device. It should show this output.

jetbot@jetbot:~$ v4l2-ctl --list-devices
vi-output, imx219 6-0010 (platform:54080000.vi:0):
/dev/video0

Further check using v4l2-ctl. This command must be run on a local terminal (not a remote terminal via SSH). Something like this should output

nvidia@nvidia:~$ v4l2-ctl -d /dev/video0 --set-fmt-video=width=1920,height=1080,pixelformat=RG10 --set-ctrl bypass_mode=0 --stream-mmap --stream-count=300
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.00 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.00 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.03 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.02 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.01 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.01 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.01 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.01 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 30.01 fps
<<<<<<<<<<<<<<<<<<<<<<<<<<<<

Finally, run this command and the live stream…


Today I am running my colab notebook to train the model for donkey car and notice that the default tensorflow runtime has been upgraded to tensorflow 1.15.0. I actually don’t care about it until I run the model on donkey car and the following error happen

loading model models/tub3.h5
Traceback (most recent call last):
File "/home/pi/env/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/input_layer.py", line 81, in __init__
raise ValueError('Unrecognized keyword arguments:', kwargs.keys())
ValueError: ('Unrecognized keyword arguments:', dict_keys(['ragged']))

I have omitted some of the error for simplicity but the problem looks like it is caused by incompatible version of tensorflow. The first thing I tried is to downgrade…


先旨聲明: 我唔係專家,只係講出過去用大量時間研究後既睇法,所講既野可能有錯漏,以下內容並不構成任何投資建議。不過,我承諾以下係我真誠既睇法,希望大家可以互相交流。

首先,買 Crypto 必須是閒錢

我舊老闆對閒錢既定義: 「你可以輸晒既錢」

唔係你供仔女讀書既錢,亦唔係你既養老金。你無左呢筆錢唔會死,亦唔會怨天怨地,最緊要係唔會怨我。你用黎買 crypto 既錢你預左要輸晒既,所以唔洗訓身,亦都千祈唔好訓身。

你必須接受Crypto有價值

認同同接受係兩件事。你可以唔認同一層200呎樓值400萬,但你必須接受佢係以400萬交易緊。

我係2013年做 Crypto exchange 既時候,我並唔認同 Bitcoin 有價值,我覺得 D 人用黎投機,最後一定爆煲 (股神巴菲特都係咁諗)。過左六年,BTC 個價上過又落過,但係仍未爆煲。所以,你要接受喺好多人眼中,BT …


1. Make sure you have a steady power supply

Coral draws significant amount of energy from the Pi USB 3 interface. If you are experiencing under voltage, the pi will be throttled

Use this handy one-liner to check the status.

vcgencmd version; vcgencmd get_throttled; vcgencmd measure_volts; vcgencmd measure_temp;vcgencmd measure_clock arm;

You can also stress test your Pi to see if your power supply is stable enough.

2. Take care of system cooling

Install a big heatsink like this before you start. Pi will be throttled and therefore affect the performance of the coral.

3. Install Edgetpu library

Follow official doc. On Pi 4, you might experience this error

edgetpu_api/install.sh: line 51: warning: command substitution: ignored null byte in input…


Update: If you can’t find the model trained by colab, read this article to solve version issue.

One of the most time consuming task after you built the Donkey car must be training the model. It could easily take you 30 minutes or more if you don’t have a GPU on your PC. I have been using AWS for training models via the Donkey Car Console. It has been great except that I have to pay for the EC2 spot instance. Recently I have been using Google Colab a lot and therefore have the chance to create a notebook that…


Update: If you are using newer Jetson software, note that you might need to use a newer isp profile. I haven’t verified it yet so please give it a shot and let me know.

Thanks Ville Saukkonen for mentioning this to me.

A lot of people are very interested in Nvidia recently announced Jetson Nano and JetBot. In many use cases including the JetBot and Donkey Car, we would want to use a wide angle camera. One of the recommended camera module for Jetson Nano is a Raspiberry Pi v2 camera module. This camera come with a standard camera lens…

Jonathan Tse

Love Self-driving technology and machine learning. Community leader in DIYRobocar Hong Kong.

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