I have successfully tested basic DroneKit scripts on a companion computer (Raspberry Pi) to achieve autonomous flight on Pixhawk controlled 3DR ArduCopter. The RPi is also connected to various sensors, and crunches that data in real time in the same python script- to influence the flight.
Is it possible to pilot the drone manually with a Taranis as usual, while RPi (with DroneKit running) remains connected to Pixhawk and overrides the radio when needed? For example, a background prevention mechanism that takes control and moves the copter away if the pilot is about to crash into a wall (which is easily sensed using a LIDAR).
Thank you!
While your vehicle is in any mode other than GUIDED, your dronekit script will not be able to control behaviour. However, the script can change the mode of the copter to GUIDED, send some commands, and then set the mode back to the previous mode when it is done.
The example you gave of using lidar for obstacle avoidance is already a feature in progress, being built directly into normal flight modes. Perhaps it's not documented well enough yet, but maybe try digging into the code to see how it works.
Related
I stumbled upon following problem:
I have a piece of software written in C++ and a device rk3399 (FriendlyELEC). The issue is performance of the code depends on whether or not display is attached to the device. If I ran my code via ssh (without display attached) I get 25% slower performance rather than if I ran code with display attached.
I figured it's a frequency scaling problem (device runs Lubuntu) I changed profile to performance (it was set to interactive initially), but that didn't help. I monitored voltage and cpu freq, all seems constant (1.2V, 1.12V) and (1.42 GHz, 1.8 GHz).
It's probably some control that tries to save battery and uses Display Port as decision flag. But I can't figure out what kind it is and where to find it.
Initially I was thinking I have problem with GCC flags (there could be some relevant info)
How to get the device to run with stable performance? What could be the problem?
Is there any way to query the system's date/time via USB without installing anything on the host computer (maybe just drivers)?
Background of the original problem
To avoid the XY problem, let me explain a bit what I'm trying to do.
To be able to calculate a TOTP token for 2FA (e.g. like Google Authenticator app does) you need a real-time clock to get the date and time.
There's this USB device called SC4-HSM that I would like to use to calculate the tokens, however it doesn't have a clock and according to the designer, adding one would be too expensive (needs a battery, etc).
Possible solution to the original problem
This device is going to be used with a computer which already has an RTC of course. Thus I had the idea of querying the system for a date/time which would solve the issue.
(Note: I know that a USB device can be connected to all sorts of hosts and not all hosts will have an RTC, but since this only needs to work with a computer, I thought this shouldn't be an issue)
My first thought was that there might be some USB device class that had date/time needs, so I could register the device as that type and then I would be able to query the values.
After going through the device class codes list (Internet Archive) nothing jumped at me as needing date/time. The closest ones I could think of were:
Content Security (PDF)
Personal Healthcare
Smart Card Class (PDF)
I skimmed the device class documents in the USB Implementers Forum but there's nothing in there even remotely related to date or time.
Current problem
Since the USB specs seemed like a dead-end I thought that maybe there was a way to write a very simple USB driver that can be auto-loaded when the device is plugged in to a computer and then we can use the driver to return the date/time when the device asks for it (unless I'm misunderstanding something).
I am now looking through USB development docs like Michael Opdenacker's Linux USB drivers course, I tried the Linux USB Project which seems dead. Skimmed through Driver Development for Windows NT just to get an idea, however I am still not able to figure out if this is possible or not, and how hard it would be.
I'm a complete beginner at this and maybe this is something out of my skill level, but I would like to figure out if will I need weird hacks and workarounds or is there a much more straightforward way to do this?
There seems to be little information about it or I'm just searching the wrong places.
Any ideas/or pointers on either solving the original problem or the current one?
system time is not necessarily the general time i.e. the 'atomic' time you get from a NTP server
the most obvious solution is to use autorun, this is also possible on linux but normally autorun is blocked so the user explicitely has to activate it
https://askubuntu.com/questions/642511/how-to-autorun-files-and-scripts-in-ubuntu-when-inserting-a-usb-stick-like-autor
the linux command to get the time is date or hwclock or if the computer is connected to the net it may be possible to contact a NTP server (if the firewall does not block this)
then your autorun program has to send the data to the SC4-HSM. i do not know what USB classes the SC4-HSM implements if it implements CDC ACM (virtual COM port) this is easy:
Unable to sync computer time to Arduino via USB
(something like echo "T$(($(date +%s)+60*60*$TZ_adjust))" >/dev/tty.usbmodemfa131)
maybe it is possible to access system time over the USB drivers, i do not know this right now
I am working on an indoor vision based navigation in a GPS denied environment, and I'm using a 3DR Solo. I want to be able to send movement commands to the Solo through the DroneKit API. Are these mavlink commands supported for modes other than GUIDED and AUTO, or is channel overriding my only option?
It depends on how you want to control it. If you want to control the position of the copter, you will need to make hardware modifications to the solo, because it does not have the right sensors to be able to hold position indoors. If you want to control the raw angle of the copter, the cleanest way to do this is to send a SET_ATTITUDE_TARGET message. The problem is that this is only supported in guided mode, and guided mode won't arm without gps (even though low-level control like SET_ATTITUDE_TARGET doesn't rely on GPS). Guided-NoGPS mode is currently on the todo list for ArduCopter, so comment on the issue here to let the devs know that you are interested in this feature.
On the DroneKit.io page, it mentions using DroneKit Python when creating Ground Control Stations for Windows. However, there appears to be no documentation for this.
Is it meant to simply simulate a com port and act as a proxy for other Ground Control Stations, which just makes it easier hijack the MAVLink?
Also, it mentions Python being used for low-latency processes. This seems to be oxymoronic. Is there a reason that it would be better than just using C/C++ for the purpose of hijacking the MAVLink?
Thanks!
DroneKit-Python can be used either to create a python-based ground station or it can be run on a companion computer. There is no practical difference between the two except how you set up the connection to the vehicle from the computer running the script. The different ways of starting MAVProxy for the different connections are covered in the Getting Started documentation.
The reason that there is no "specific" documentation on using DK-Python for GCS is primarily "marketing". The far bigger market for ground station GCS software is in tablets/phones that will use DK-Android or a future iOS port. DK-Python has been positioned solely as for use in the air interface. Even though there is no "specific" documentation, in fact all the existing documentation is relevant.
Is it meant to simply simulate a com port and act as a proxy for other Ground Control Stations, which just makes it easier hijack the MAVLink?
No. See above.
Also, it mentions Python being used for low-latency processes. This seems to be oxymoronic. Is there a reason that it would be better than just using C/C++ for the purpose of hijacking the MAVLink?
It doesn't mention low-latency processes, so the answer is "invalid question".
You're probably misreading the text "that require a low-latency link". The point here is that if you have dronekit-python running on a companion computer and connected by a fast link you can do real time handling of incoming sensor data. This allows computer vision control of the UAV. However if you run DK-Python on a ground control station you will have a much slower link. You can still control movement of the UAV but the latency will be much higher.
Hope that helps!
I have a WPF program that communicates with a specialized USB stick that is collecting data (in fact an ANT USB dongle). I noticed that the data collection simply stopped after a few hours. The reason was evident in the windows logs (system) where at the exact time the program stopped getting data, I see:
The system is entering sleep
Sleep Reason: System Idle
Questions
How do I programmatically prevent Windows from going to sleep so that I can continue to gather data?
2. Stepping backwards for the big picuture view... What's going on? Why does the computer going to sleep affect my program? Or is it just affecting the USB stick? Is it necessary to prevent sleep or should I do something else instead?
Einstein's answer is tantalizingly close. I just can't seem to get SetThreadExecutionState working in my C#/WPF program and can't find a lot of examples or discussions of it. Does it need to be called more than once? If so how? Is there a event that I receive that tell me to call it or should I call it every so often (5 minutes?) as suggested in:http://stackoverflow.com/questions/5870280/setthreadexecutionstate-is-not-working-when-called-from-windows-service
For now, I'm just going into ctrl panel -> power options and preventing sleep but it would sure be nice to have an elegant solution. Even on my own computer, I don't want to mess with the sleep settings. It's too hard to remember to set them back again!
You can prevent the computer from entering low power modes (sleep/suspend) by using the SetThreadExecutionState function.
As far as why going into low power mode is interrupting your data collection - well Windows suspends all processes in these modes and USB ports enter low power mode which likely means your USB device will not have power either. It's by design. After all, the whole reason we want our computers to go to sleep is so that the battery is not drained.
You can apply the above responses, o simply you can go in Control Panel -> Power Options and modify the settings, so your system never goes to sleep.
To 1): You can use SystemParametersInfo with one of the power related values on Windows versions less than Vista to turn on/off power savings settings. Starting with Vista, you should register for one of the power events instead, and the OS will notify you when it needs to for the event you request.
To 2): If the OS shuts down, the hardware it's managing shuts down. What else would you expect to happen? If the OS runs the USB device driver, which runs the USB device, what would you think would happen if the OS goes to sleep? The USB device begins running itself instead without the driver?