Author: Arnaud

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Crazyradio: past, present and future

  2017-05-02  |     |    9 Comments

The past

The Crazyradio has been designed as a radio dongle to control the original Crazyflie 1. It is based on a Nordic Semiconductor nRF24LU1. It is basically the radio from Crazyflie 1, the nRF24L01, with a microcontroller and a USB device peripheral. Crazyradio has been designed from the beginning to be extended for other used: the code is completely open-source, can be powered with 12V and has an expansion port with possibility of implementing a serial port to communicate with the radio.

When we designed Crazyflie 2.0, we extended Crazyradio to make Crazyradio PA. It is basically the same hardware but we just added a power amplifier to make sure Crazyradio is transmitting with the same power as competing radio in the same 2.4GHz band: Wifi and Bluetooth. Crazyflie 2.0 is not using an nRF24 chip anymore but an nRF51822 which integrates a microcontroller and implements bluetooth low energy as well as nRF24 compatible radio.

 

The present

The Crazyradio (PA) has been used for a couple of hack like our glove controller. Another popular use has been by security researcher to experiment with the security of wireless mouse and keyboard. Indeed the nRF24 serie of chip is extensively used in wireless mouse, keyboard and even quadcopters ;).

We are often very quiet about the Crazyradio since ‘it just works’. It does not means that it is finished or perfect, there is actually a lot that was planned to make the radio link more efficient, to be able to control more Crazyflie per Crazyradio, etc… Some of this work has been done in the context of the Crazyswarm project by Wolfgang from USC but a lot more could be done. One of the main blockers for Crazyradio development is that it is based on a very old microcontroller, an 8051, and that it does not have a safe bootloader or (open) debugging access. It means that each modification is potentially a big commitment in time and since the radio already work quite well it is hard to put much time in it.

The absence of a safe bootloader means that if you flash a firmware that crashes, you will need an SPI programmer to recover the radio in working mode. This makes it quite stressful to work with the radio. However there are a couple of programmers made for this and we recently published a Hackster project about using a Raspberry Pi to recover the bootloader:

The future

We have been looking at making a Crazyradio with an nRF51-series chip, these chips have a Cortex-M0 CPU which means that they are much easier to program using a modern development environment. However none of the chip in the nRF51 series have USB which forced us to prototype the concept with an added microcontroller for USB. This creates a bigger and more populated Crazyradio:

We did not like this design very much since having 2 microcontrollers is always much more haste to program, debug and maintain. Thankfully Nordic semiconductor will release a nRF52 chip with USB support. Adding to that a powerful Cortex-M4 microcontroller, a lot of ram, still Bluetooth low energy and nRF24 radio compatibility but they also added iEEE802.15.4 2.4GHz (ie. the protocol used by Zigbee). This new chip is a very good candidate for the next Crazyradio.

We are very much in the pre-study phase for the next Crazyradio (and mass production for the new nRF52 is planned for Q4 2017 anyway…), so if there is functionality that you would like to see in a future Crazyradio it is time to speak up! Please tell us in the comment section bellow or in the forum ;-).

Crazyflie firmware and client release 2017.4 with Z-Ranger support

  2017-04-24  |     |    Leave a comment

We are happy to announce that we have released new versions of the Crazyflie Firmware and the Crazyflie client, both are now in version 2017.4. The main feature of the release is support for the new Z-Ranger deck.

To support the Z-Ranger, a new flight mode has been added to both the firmware and the client: the Height-hold mode. This mode allows to fly with the Z-ranger deck at a fixed height above the floor.

There are also a number of other improvements and bug fixes in the releases, mainly related to the Loco Positioning system and autonomous flight.

On the client side, this new release is also a come-back of the windows build. It means that it is now easier to get started and fly your Crazyflie directly from Windows as you can install it as a native app. We really want to build the client for Mac OS too but have met some problems. If anyone has experience in building pyqt apps for mac OS, with your help we might be able to have a mac build for the next client version ;-).

For instructions on how to upgrade see the getting started guide.

Have fun!

Updated autonomous flight using OpenCV and Kalman filter

  2017-04-03  |     |    Leave a comment

At Bitcraze we have some history with trying to fly our Crazyflie autonomously. The most recent step is the Loco Positioning System that allows us, and you, to fly in a full room. The Loco Positioning system has boosted development of advanced algorithms for onboard position estimation and control.

Our earlier attempts where mostly based on different kinds of cameras, either a 3D camera like Kinect or regular webcams. Though, at that point, we only had the camera for position estimation and where doing the position control on the PC and not onboard the Crazyflie. This has the disadvantage to be brittle and requires a very high quality positioning from the camera: any frame where we loose the Crazyflie has a huge impact on the control behavior since the position controller relies exclusively on the camera detection.

With the Kalman filter and onboard position controller, the Crazyflie can now handle lost position information for at least a couple of seconds without big problems. This has the potential of making webcam-based position detector much more robust!

To test this theory we have grabbed the 2 years old crazyflie-ar-detector from the dawer github, updated it to OpenCV 3.2.0, and fed the position output to the Crazyflie 2.0 external position port. The crazyflie-ar-detector program is using ZeroMQ to communicate position and so we made a simple external position tab for the Crazyflie Client that receives position from ZeroMQ and sends it to the connected Crazyflie.

Using the new position-hold mode recently introduced in the client we can test and fly the Crazyflie under the webcam. We have taken a short video to show the performance. The result is promising and we will continue to play with ways to fly the Crazyflie autonomously.

Porting the Crazyflie client to Qt5

  2017-03-20  |     |    2 Comments

The Crazyflie client, the software running on a computer that is used to control and get telemetry from the Crazyflie, is written in Python and used PyQt4 as graphical user interface framework. This has worked quite well and has the advantage of running on windows/mac/linux without much effort. However Qt5 and PyQt5 have been released for a long while now and what should happen is starting to happen: PyQt4 is starting to get depreciated.

The first sign came from macOS, a ticket was reported on the Crazyflie client github indicating that it was not possible anymore to install PyQt4 using the Homebrew package manager. The problem was solvable since PyQt4 was still there but moved in the Homebrew ‘backyard’, so for the time being it still works but is a bit worrying. More recently Python 3.6 was release and there will apparently not be a release of PyQt4 for Python 3.6, this means that if we do not do anything the client risk to not be supported on linux anymore (the next Ubuntu LTS is planned to use Python 3.6).

This was enough to push us to port the client to the new Qt/PyQt5. The port was started by sighmon when the first macOS related ticket was reported but we had a bad bug with the Gamepad reading on macOS, this bug was the main blocker but has been fixed last week so we are now very close to having the port functional!

If you are curious about it, we have the port in a branch on github. We are planing on merging it in the following days and releasing a new version of the client in the process.

We are also planing on releasing a Windows build and installer this time. The Windows installer has been built automatically in AppVeyor for a couple of month now and it seems stable enough to become an official version. We still want to make a macOS app out of the client but are still blocked in doing so. If you have experience making macOS app out of PyQt5-based software, we would greatly appreciate some help in getting a mac build, we have a github ticket for it.

Crazyflie 2.0 as an autonomous flying platform

  2017-03-06  |     |    1 Comment

Crazyflie has been used by hackers and researchers as an autonomous flying platform for a while, though it has required expensive or very special software and equipment. Universities and the industry have, in most cases used motion capture systems that are very precise but also comes with a hefty price tag. We have developed the Loco Positioning System as a more accessible way to achieve autonomous flight with the Crazyflie. Bitcraze has worked intensively with autonomous flight and together with the community, we have added a number of advanced algorithms to the Crazyflie firmware that not only serve the Loco Positioning System, but are useful for anyone interested in autonomous flight regardless of positioning system. The functionality is useful for anyone from researchers with motion capture systems to hackers with a couple of webcams!

Lately there has been a lot of activities around control and stabilization algorithms. The main piece of software that has been merged into the Crazyflie firmware is the Extended Kalman Filter. With it, the Crazyflie uses its inertial sensor together with positioning information in order to calculate an estimated position. One great advantage of the Kalman filter is that it can handle much lower quality or intermittent position measurements and still fly autonomously. Of course the better the position information, the better the flight performance, but things like camera tracking with occlusion becomes possible.

There has also been a lot of work on a new controller. The controller is the piece of software that looks at the position estimate and calculate control commands to reach a given set point (for example go to {x;y;z}). We are currently working on adapting the firmware architecture to merge a more advanced control algorithm that supports complex trajectory following capabilities. 

Finally there is a new commander architecture that adds the possibility to send complex set points to the Crazyflie via the radio. For manual flight all you need is 3 angles, roll/pitch/yaw, and the thrust. For a more advance controller you might need position, velocity and acceleration in X/Y/Z. For even more complex trajectories, we are working at merging a sequence generator to which we can send high level setpoints like spline coordinates. The sequence generator will calculate the required setpoints onboard in real time to follow the trajectory.

All these algorithms are currently work in progress, they are in various stages of completeness, but for example we have had the Crazyflie following circles in our lab last week using the on board sequence generator, so things work. However getting the code to work is only the beginning, until it is in the master branch it does not exists. Once the code land in master, like the Kalman filter did a while ago, it will be useful out of the box for anyone that wants to work with autonomous flight using any kind of localization system: Loco Positioning, Motion Capture, GPS, webcam, etc …

Back from FOSDEM 2017

  2017-02-13  |     |    4 Comments

For the third year some of us from Bitcraze visited Fosdem, the biggest open-source European conference. Like the other years we enjoyed being there a lot and we had a great time hanging-out with community members like Fred.

Fred presented a great lightning talk about the news in the Crazyflie galaxy, the video and slide are already available. 

Arnaud talked about the Loco positioning system. The talk and the demo, went well. Unfortunately the video from the talk is not available yet, we will tweet it and add it to this post as soon as it is online.

The Loco Positioning talk was a great opportunity for us to test the most recent bleeding edge additions to the Crazyflie autonomous algorithms. We flew the new non-linear controller from Mike Hammer using trajectory generation from Marcus Greiff. The non linear controller uses setpoints not only of position but also of velocity and acceleration to control the Crazyflie. This is where trajectory generation is useful: if you can generate a trajectory and calculate position, velocity and acceleration over time, you can feed all this information to the controller and the controller will be able to do a much better job following your trajectory. This enabled us to fly the Crazyflie fairly aggressively the week before the FOSDEM talk:

In this video the Crazyflie is accelerating to about 2g continuously to keep the trajectory. We were a bit concerned to fly such aggressive maneuvers in public without more testing so we designed a slightly safer demo the night before the talk in our hotel room:

This trajectory was successfully flown in the demo and shows the performance of this new controller. There has been a lot happening with the Crazyflie control algorithms lately: Marcus, Mike and Wolfgang have all made new controllers and Marcus has developed an on-board trajectory generator. There is still some work required in the firmware architecture to merge these into Master, but we hope this can be done in the coming weeks. Follow the Crazyflie firmware commits and github tickets if you are interested in the progress.

New decks and presentation at FOSDEM 17

  2017-01-30  |     |    Leave a comment

In this beginning of 2017 we are proud to announce that there are two new decks for the Crazyflie 2.0.

The first one has been in the works for quite some time, it is the Micro SD card deck. It enables read and write access to a SD-Card from the Crazyflie firmware (where we have also implemented FAT filesystem support). Our first use case for this deck has been to implement high speed logging of the IMU sensors: the SD-Card has much higher bandwidth than the radio so it allowed us to log all the sensor values for later analysis. Another use-case could be to read an autonomous sequence from a file on the SD-Card and implement fully autonomous sequencing in the Crazyflie when used in the Loco Positioning System for example. The SD-Card deck is already available on Bitcraze web-shop.

The Second deck is the Z-Ranger deck, it is a laser time-of-flight ranging deck that measures the distance to the ground. We talked about this deck in a previous post. The manufacturing of the deck should be finished soon and so it will be available in our shop shortly. When using this new deck, the altitude hold stability between 0 and 1.5 to 2m height is greatly improved.

On a final note, FOSDEM 2017 is this coming up this weekend and we are looking forward to meet you there. There will be two presentations related to the Crazyflie, if you want to meet us come at these presentations or get in touch in the comment or by mail. The two presentations are:

We hope to see you there!

News from the comunity

  2017-01-16  |     |    2 Comments

Quite a lot has happened in the community in the latest month so we though we would dedicate this Monday post to you :-).

On the firmware side, the loco positioning system has sparked a lot of contribution. Most prominently is the Extended Kalman Filter by Mike Hammer and later improvement by multiple contributors. The Crazyflie is getting more stable and capable week after week which is awesome. Wolfgang from USC has also pushed enhancement coming from its CrazySwarm which will one day gives to everyone the capability to fly big Crazyflie swarm more easily.

On the clients side, we just pushed a new version of the iOS app to the app-store. The main improvement is the new tilt control mode implemented by EMart002 and beta-tested by a community member.

There has also been a new release of the Android client by Fred. This new version adds support for log and param using the Crazyradio. This way it is possible to get telemetry from the Crazyflie like the battery voltage and there is an experimental implementation of altitude-hold when using gamepad.

Running a beta (test-flight) version for the iOS client has been a good experience as it allowed to get direct feedback on functionalities. If there is interest we could release and announce beta versions for both Android and iOS in the future.

Finally last but not the least, there will be a new Crazyflie client in town: The Crazyserver created by Mike Hamer and written in go. It is a cross-platform, install-less, dependency-less server for a fleet of Crazyflies. It exposes a language-independent API, an HTTP rest API, to be able to connect and control any number of Crazyflie from any programming language. It will also include sockets (UDP, TCP and Websockets) to carry real-time data like setpoint and telemetry. It is still very much work in progress and not ready for real-world usage but if you are curious and/or would like to help check the code is on github.

 

Bitcraze, Crazyflie and Loco Positioning System at FOSDEM17

  2017-01-09  |     |    Leave a comment

For the third year we will be at FOSDEM on Saturday 4 and Sunday 5 February 2017 in Brussels. The last two years we have been present and Fred, the Android client maintainer, has had a lightning talk about the Crazyflie.

This year Fred will present a lightning talk about “News from the Crazyflie universe” and Arnaud will have a talk about the Loco Positioning System in the embedded dev-room. The LPS talk will contain a demo of one or more autonomous Crazyflies.

If you are planing at being at FOSDEM and want to meet with us just tell us in the comment, we would be really happy to meet Crazyflie users. There will be almost all of the Bitcraze team and we will have Crazyflie and a Loco Positioning System so it might even be possible to do some flight or demo on the side.

Bosch developed MEMS sensor deck for the Crazyflie

  2016-12-13  |     |    6 Comments

At FOSDEM 2016 we met someone from Bosch Sensortec, he was very interested by the Crazyflie and got one. Apparently his college liked the Crazyflie too because soon later we where contacted by Bosch that wanted to make a deck for the Crazyflie containing a brunch of there sensor. We have been tweeting about this board before and now we just pushed the drivers for some of the sensors into the Crazyflie main branch.

The deck has an impressive list of sensor onboard:

  • BMI055: 6 Axis gyro and accelerometer, with closed loop technology gyroscope
  • BMI160: 6 Axis gyro and accelerometer
  • BMM150: 3 Axis magnetometer
  • BMP285: Pressure sensor
  • BME680: Environmental sensor (air, pressure, humidity, temperature).

Thats a lot of data, and there is also an non-populated footprint for a BMF055 which is a BMI055 and an Atmel ARM Cortex-M0 in the same package, this is something that could be very interesting to play with in the future. The drivers and the integration are still in early stage but what has been pushed so far is support for the BMI055 and BMI160. We look forward to tuning those sensors and testing the others as well!

Bosch has made most of the work with this deck them selves and we have provided mainly guidance and support, a big benefit of open source! That has been working great and it has been very fun working with them. We are not sure if this is going to be part of a product yet, as in releasing a deck full of sensors. Please tell us what you think and if anyone would have use for such deck.