Discussion forum for UAVDevBoard, Sparkfun's 3-axis IMU-based autopilot board

This is the place to discuss the new open source IMU-based autopilot board by Bill Premerlani.

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no steve its not with landing gear, i just tried on my spare easy star model, it glide so beautifully in RTL mode
Thanks Bill ,
Its all possible because of you only. Thanks
what is the maximum distance range between two simultaneous waypoints limit , we can set in MatrixNav 8.0.
Hi Viky,

The range limitation for waypoints for MatrixNav8b, AileronAssist8b, and MatrixPilot2.0 is dictated by the fact that the waypoint is specified in meters as a 16 bit integer. So, the largest X or Y value that you can specify for a waypoint is approximately 32 kilometers, or about 20 miles.

So, the X and Y coordinates of each waypoint must be within 20 miles of the initialization point.

This also means that if you are flying in manual mode and switch to RTL mode, the plane must be within a square with a 40 mile edge, centered on the initialization point, when you switch from manual to RTL, in order for RTL to work.

Best regards,
Hi All,

I'm wondering, is the UAVDevBoard suitable for Quadcopter-project. The plan is to make it fully autonomous, but with the upgrade possibility to use radio to control the machine in the future. I have a few questions that I need answers to move on. I think this is the forum where is the best ackowledge:

1. I should use the Boards servo connections to control motors. Is it possible to connect this kind of ESC to the servo pins: http://www.headsuprc.com/servlet/the-1413/20A-POWER-UP-Brushless/De...

2. There is four motors in quadcopter, in the DevBoard is only three Servo connections. Is there any spare pins that I can use for the fourth motor?

3. Is it ok to connect one or two parallel 3 Cell LiPo batteries(11,1V) to all four ESCs and then connect all control lines of the ESCs to the servo pins in the UAVBoard?

4. If I understood correct, the ESC gives about 5V through BEC, so there is no danger of noise that comes from the motor and ESC? The Board should be working good?

5. The PWM pulse for the ESC should be 8kHz. Servos are controlled usually with 50Hz frequency. Can I increase the PWM output to 8kHz?

6. If I want to upgrade my UAV with CameraCntlr and telemetry link, will I run out of pins on the Board? :P

There is a lot of questions and I know that I need to code almost a new autopilot, but this is a long project, a hobby that I'm willing to use time :)

I think there might already be people working on using the UDB to control a Quadcopter, hopefully some of them might reply as well. In the mean time, I'll do my best to answer your questions.

1. Yes, you can connect most electronic speed controllers to the UDB. ESCs (like the one you linked to) read a 'servo' pulse and convert it into 'throttle' for electric motors.
2. The current matrix pilot firmware for the UDB implements up to six output channels using the 'spare' pins on the current UDB.
3. You can connect multiple batteries to multiple ESCs (I've done this on several multi engine airplanes already) but you need to be careful of three things. First, make sure that only one of the BEC (5v regulator built into most ESC) is active. In my planes, I do this by disconnecting the red wire (positive voltage) from the remaining ESCs. Secondly, remember Ohm's law (V=IR) and keep your power and voltage in line between the motors, ESCs, and batteries. Lastly, remember that without a very good ESC, the same setting on multiple ESC will not always produce the same output from the attached motors.
4. The noise has as much to do with the ESC as anything else. I've seen ESCs that have clean output from the BEC but still have all kinds of EMI and similar ones that have no noise. I don't know of a fool-proof solution to this other than diligent testing.
5. My ESCs all run just fine off the servo pulses (40Hz, generally) so I'm a little surprised that yours would be that different. Is it possible that the 8KHz is the frequency that the motor control is running at? Either way, the UDB is a very powerful hardware platform, so I would imagine it can support 8KHz if you wanted to, that would just require more customization of your firmware. Be careful also, that the current firmware updates all of the servos in the same frequency and 8kHz will do bad things to servos.
6. See above about using the extra pins for IO. There is already a second UART on the 'auxiliary' pins header which is designed for telemetry (and supported in the current firmware). We are also working on a new firmware that might support I2C expansion to external peripherals.

Good Luck,
Adam Barrow
Hi Adam,

Ok, I just found one UDB Quadcopter project. It is easy to find something if you know what to search. And thank you for quick answer! It's nice to have reply right away when is studing something and thirsty for information.

UDB still looks suitable for me. You did clarify many things that I have been thinking. This (PWM: 8 KHz FET: 12) was the line that made me to think that ESC needs 8kHz control pulses. Probably that 8kHz is the frequency of ESC.

I2C feature sounds really good! Is there some forum or site from where I can see what all new things you are working with? You did wrote that I2C expansion MIGHT be in the next release, so I did get curious that what IS coming :) Is the firmware ready in days, weeks or months? :P

Best regards,
yes, there is a UDB list on Google Groups (http://groups.google.com/group/uavdevboard/) where we discuss new features for the upcoming firmware releases. At this point, the next firmware release hasn't been set yet, but I'd guess it is at least three to four months out (May?). Of course, you can always check out the 'development' version of the firmware to use before then if you'd like to.

Adam Barrow
Will there be a UAVDevBoard 3? It seems the next version of ArduPilot is in the works, just wondering if the next UAVDevBoard is in the pipeline.

If its not too late I would like to see one with flat gyros, and more R/C inputs and ouputs.
Keep up the good work.
Hi JC,


There is a UAVDevBoard3 in the pipeline, we are just starting to design it. It will use the flat Invensense 500 degree/second gyros, which we have recently flight tested in planes and helicopters. They work great. No problems with vibration.

There will be 8 R/C inputs and 8 outputs.

Best regards,
Just to add to Bill's comment and say those gyros are beautifully flat and much smaller than what we had before.

I'm assuming those new gyros are retrofitted to the current board? If so, will that be an option for the rest of us? I'd love to know if they're more resistant to RF interference than the old gyros are.


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