We have not finalized our demos yet but they will include autonomous flight with the Crazyflie and the Loco Positioning system. We also hope to show our brand new optical flow expansion deck that will enable positioning and autonomous flight when on a tight budget. We also plan to show integration with external computers running ROS or our own python library. If we are lucky there might even be a small swarm, even though the space is very limited.
We love to talk to people that are using our products or just interested in our technology, if you are at the conference please drop by and say hi and tell us what you are working on. We will arrive in Singapore on Saturday morning May 27, and if you want to hook up and say hi and have a coffee during the weekend, drop us an email.
Ever since we released the Alpha round of the Loco positioning system we’ve been talking about designing a more generic tag that could be used together with other robotics platforms for local positioning. We did a quick design of a prototype that we tested, but with the workload involved in bringing the LPS out of Early Access, finishing the Z-ranger and lots of other stuff , it’s remained on the shelf. But recently we’ve been getting more and more requests for this kind of hardware, so we thought it might be time to dust off the prototype and try to release it. One of the blockers (except workload) has been that we’re not sure how the tag should look mechanically and how to interface it electrically for it to be as useful as possible for our community. This post is for detailing the current status of the hardware/firmware and to see if we can get some feedback on what our community would like the finished product to look like.
The hardware
To make use of the firmware that’s been developed so far for the Crazyflie and the Loco positioning we aimed at making something similar to what we already have but with another form factor and slightly different requirements. As you might know the Loco positioning node can be configured as a tag, but there’s two drawbacks that we wanted to fix. First of all the Loco positioning node might be a bit big to put on smaller robots. Secondly the Loco positioning node can only measure the distances to the anchors, it doesn’t have an IMU to get attitude of the board and doesn’t have the processing power to run the same algorithms we have on the Crazyflie 2.0.
So for our Loco positioning tag prototype we decided to fix these. The prototype has the same sensors as the Crazyflie 2.0: Gyro, accelerometer, magnetometer and pressure sensor. It also has the same MCU as the Crazyflie 2.0: STM32F405. In addition to this it has the DWM1000 module for the ultra wide-band radio (used for positioning). We’ve also added the interfaces we have on the Crazyflie 2.0: SWD debugging, micro-USB for communication and power as well as a button. Looking at the pictures below you might also notice that we’ve added the Crazyflie 2.0 deck connector. So does this mean you can connect it to the Crazyflie 2.0? No, well not this prototype at least. The reason for adding it was we wanted to be able to use the same expansion decks as for the Crazyflie 2.0. So it’s possible to add the breakout deck for breadboard prototyping or the LED-ring for visual feedback.
So what’s the status of the hardware? Even though it’s the first prototype it’s fully functional and will give you positioning and attitude. What’s left is defining the electrical interfaces and the form-factor of the board so it can easily be attached to what ever you might want to track. The images below shows a side-by-side comparison with the current Loco positioning deck.
Loco positioning tag (on the right) compared to Loco positioning deck (on the left) (FRONT)
Loco positioning tag (on the right) compared to Loco positioning deck (on the left) (BACK)
The firmware/software
Like I wrote above we wanted to reuse as much of the firmware and software as possible. So the firmware running on the prototype is just a scaled down version of the Crazyflie 2.0 firmware. As you might have noticed the prototype looks a lot like the Crazyflie 2.0, except that it’s not a quadcopter and doesn’t have the nRF51 radio. So by “scaled down” I mean we’ve removed the motor and radio drivers, that’s about it. So how do you communicate with it? Well you can use one of the protocol available on the deck connector: SPI, I2C or UART. But the currently implemented way is using USB. Since it’s basically a Crazyflie you can use our client and python libraries to set parameters and log data values from it.
Conclusion
The current prototype is basically a USB dongle where you get position and attitude. It could easily be connected via USB to a Raspberry Pi, Beaglebone or any other SoC based platform or a computer. You can also interface it from an Arduino using the peripherals on the deck connector. The firmware is working and using the python library (or any other of our community supported libraries) you can easily get the position and attitude of the board. But to be able to take the next step and make something our community could make the most of we would love some feedback on the prototype. What kind of electrical interfaces and form-factor would you like?
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 ;-).
Seeedstudio has been our main distributor and manufacturer since we started and they have also acted as our main sales channel. A couple of years ago we started to discuss setting up our own E-shop and finally last year we decided to try our own wings. We wanted to start small and treated the E-shop as an experiment, since we are newbies at e-commerce and are learning as we are going. The E-shop has been up and running for almost 10 month now without really being official, but now we have decided to go all in!
We have definitely experienced different ups and downs this last 10 months but overall it has been a positive experience. Handling the logistics and balancing stock between different warehouses have been a challenge but in return we can now communicate with and support our customers in a better way. We have been able to release hardware early to our community through our Early access program, which has been very exciting and also given us a lot of useful feedback. We have also been able to continuously improve the overall user experience by for instance creating bundles and better information architecture.
Check our store out at https://store.bitcraze.io/ and let us know what you think! We are always trying to improve and all feedback is welcome.
Remember we still have all our great local distributors, if you prefer to buy locally please check out our distributor list.
Early on when we started to work on the Loco Positioning system, we came up with an idea of a Crazyflie autonomously flying into a light box, positioning it self for a few product pictures and then flying out again. The positioning system is now pretty mature and close to leave Early Access and this Friday we finally got around to do it. In this blog post we will share what we did and it also doubles as a brief howto on how to set up the system and fly a simple autonomous sequence.
We used a Crazyflie with a Loco Positioning Deck and eight Loco Positioning Anchors in our setup. Six anchors would have been fine too, but we happened to have eight in our flight lab.
When working with the Loco Positioning system the first step is always to make sure the anchors are set up correctly. We had an experimental version of the anchor firmware so we started out by pulling down the latest stock version of the source code and compiled it into a .dfu file. After that we fired up the brand new lps-tool that is used to flash firmware and configure the anchors. The anchors must be connected with a USB cable to the computer but the lps-tool reduces the flashing and configuration into a few clicks. When all anchors were updated we were ready for the next step.
The positions of the anchors are stored in the anchors them selves and the position is transmitted to the Crazyflie as a part of the ultra wide band messages used for measuring the ranges to the anchors. This way, the Crazyflie gets both anchor positions and ranges in the same process and has all the information needed to calculate its position. The second step is thus to store the positions in the anchors. In our “flight lab” we have fixed mounts for the anchors with known positions, so we could skip measuring the physical positions of the anchors.
We are working on making it possible to remotely configure the anchors to reduce the need to physically connect to them, and the position can now be set from the Crazyflie Client. We simply opened the “Loco Positioning” tab in the client, connected to a Crazyflie (with a Loco Positioning deck mounted), entered the anchor positions and hit the “Write to anchors” button. A few seconds later the anchor positions in the graphs were updated to indicate that the positions have been written to the anchors and then subsequently sent back through the ultra wide band messages to the Crazyflie.
Step three is to verify that the system is working as expected. First thing is to check that we did not mix the anchors up when configuring or placing them. In the “Loco Position” tab in the client, click the “Anchor Identification” button. In this mode anchors are lit up in the graphs when the Crazyflie gets close to them in the physical world. We went from anchor to anchor with the Crazyflie and checked that the correct anchor lit up on the screen. When confident that all was good we changed to “Position estimate” mode and verified that the estimated position matches the physical position of the Crazyflie. We have found that it can be very hard to understand, for instance that two anchors have been mixed up, by looking at the estimated position and that the “Anchor Identification” step simplifies the setup.
At this point we had a fully functioning Loco Positioning system ready for autonomous flight!
Now it was time to script a sequence. The easiest way to script a sequence is to start from the autonomousSequence.py example. Our intern Alfred took over at this point, he updated the uri to the correct settings and crafted a sequence to take off, fly into the light box, wait a while and then fly back out for a stylish landing in his hand!
Now we were ready for the actual photo shoot and Björn came down with the camera to shoot the product pictures. We hope you enjoy the results!
Lately the Crazyflie has been used more and more as a demonstration and reference platform by a number of sensor manufacturers, including Bosch Sensortec. The possibility to add expansion decks to the platform and that the project is open source makes the Crazyflie very suitable to test and demonstrate new sensors in real time. For us this is a further confirmation of the strengths of working with open source and it enables us to provide the community with new and cool expansion decks as early as possible.
We are glad that the industry sees the value in our open source project and is interested in collaborating with us. This will enable us to continue to evolve this and other exiting new hardware project in the future. If you and your company is interested in a collaboration, please read more on our “Used by the industry” section.
Bitcraze is not organized as most other companies, we are self organizing, strong believers in continuous improvement and are minimizing planing to be as agile and flexible as possible. We have written a few blog posts about this earlier. One result of this philosophy is that we don’t have a long term plan or road map to share, for instance of when a particular product will be released, but never the less we will tell you a bit about what we think lies ahead of us for the Loco Positioning system.
Our goal for the coming weeks is to finalize the first version of the positioning system, that is to leave the Early Access phase. The capabilities of the first release will be to autonomously fly one Crazyflie using two way ranging. The more advanced features such as TDoA will be considered experimental and requires compile time flags to be enabled.
We feel that the performance of the system is reaching levels that we think are good enough for many use cases, what is still lacking is ease of use. To fix that we are focusing on simplifying installation and configuration of the system by adding a few new tools.
We have found that one problem area is to install the system and get the anchor positions right. If the positions are not correct the estimated position of the Crazyflie will of course be wrong and it can be hard to understand what the cause of the problem is. To solve this we have added a new tab in the PC client (the LPS tab) that allows the user to see and configure the anchor positions as well as see the estimated position of the Crazyflie. There is also a mode in the client that is used to identify anchors by moving the Crazyflie around in the room, when close to an anchor that anchor lights up in the client to verify the setup.
Loco Positioning Tab
The anchor positions have up till now been stored in the Crazyflie or the client (ROS or python script), which is not optimal as data in the firmware or client becomes tightly coupled to the physical layout of the positioning system. If we move an anchor we either have to rebuild the Crazyflie firmware or have to transfer position data from the client to the Crazyflie before we can estimate the position. The solution is to move the anchor position into the anchor it self and send it as a part of the ultra wide band communication to the Crazyflie when ranging.
In the current Loco Positioning Node firmware, configuration changes and firmware updates are a bit cumbersome as it requires a few different external software packages. Further more different tools are needed depending on the OS of the host. To simplify this process we are working on a LPS-tool that will enable the user to configure and update the nodes using a GUI with clear feedback on the progress. The tool is written in python and the intention is that it will work on all our supported platforms.
We hope these improvements will lead to a positioning system that is easy to use and will enable all you people out there to do awesome stuff! As always, feedback is welcome.
We have spent most of our time working on the two way ranging in the Loco Positioning system lately, mainly on features that are not directly related to the actual ranging but such as making it easier to configure and upgrade the anchors. As a result we have not exercised the TDoA mode in a while, so on our Fun Friday we wanted to play a bit with that and try to fly a small swarm with some sort of coordinated autonomous flight.
Setup
We have a Loco Positioning system set up in the basement, we call it the flight lab to make it sound more fancy! The setup has been 6 anchors with three anchors in the ceiling and three on the floor, configured as triangles pointing in opposite directions. When using two way ranging that is fine as the positioning works pretty well outside the volume defined by the anchors. For TDoA on the other hand, the accuracy of the estimated position degrades rapidly when you go outside the convex hull. We decided to add two more anchors (to a total of eight) and arrange them as the corners of a box. A few hours and mounting/cabling later we were ready to try it out.
We modified the swarmSequence script to suite my (limited) space and set it up to fly four Crazyflies in a square, moving them to the next corner of the square every 5 seconds. Next problem was to find 4 working Crazyflies and Loco Positioning decks. We have a few Crazyflies lying around but a fair number of them have been modified in one way or another but finally we had the hardware we needed and could run the script. After a couple of failed tries (out of battery and such) we shot this video
Lessons learned
So what did we learn from this exercise? Adding two more anchors and changing anchor positions improved the positioning significantly. We have seen earlier that TDoA is less accurate than two way ranging, but better anchor positions reduces the problem. We could also fly the swarm using our example python script (not using ROS) without too much work and trouble, even though the TDoA mode still is very experimental.
In this flight we used the stock controller and just moved the set point to the next desired position for each copter. We are really looking forward to try out the improved controller and trajectory planning that we showed at Fosdem in combination with the TDoA mode, we think it will improve the performance a lot!
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.
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:
