Pixhawk the new flight controller from 3DR

G

Gary Mortimer

Member
pixhawk_store.jpg


Pixhawk is an advanced autopilot system designed by the PX4 open-hardware project and manufactured by 3D Robotics. It features advanced processor and sensor technology from ST Microelectronics® and a NuttX real-time operating system, delivering incredible performance, flexibility, and reliability for controlling any autonomous vehicle.

The benefits of the Pixhawk system include integrated multithreading, a Unix/Linux-like programming environment, completely new autopilot functions such as Lua scripting of missions and flight behavior, and a custom PX4 driver layer ensuring tight timing across all processes. These advanced capabilities ensure that there are no limitations to your autonomous vehicle. Pixhawk allows existing APM and PX4 operators to seamlessly transition to this system and lowers the barriers to entry for new users to participate in the exciting world of autonomous vehicles.

The flagship Pixhawk module will be accompanied by new peripheral options, including a digital airspeed sensor, support for an external multi-color LED indicator and an external magnetometer. All peripherals are automatically detected and configured.


Note: Pixhawk is a PPM-input autopilot, which means that it gets RC input from a single cable to the receiver, either via the PPM port, the Futaba S.BUS port, or the special satellite receiver port for Spektrum gear. Most modern RC receivers (and all those sold by 3D Robotics) allow for PPM output, but some, such as non-S.BUS Futaba receivers, do not.


Specifications
32bit STM32F427 Cortex M4 core with FPU
168 MHz
256 KB RAM
2 MB Flash
32 bit STM32F103 failsafe co-processor
ST Micro L3GD20H 16 bit gyroscope
ST Micro LSM303D 14 bit accelerometer / magnetometer
MEAS MS5611 barometer

Interfaces
5x UART (serial ports), one high-power capable, 2x with HW flow control
2xCAN
Spektrum DSM / DSM2 / DSM-X® Satellite compatible input
Futaba S.BUS® compatible input and output
PPM sum signal
RSSI (PWM or voltage) input
I2C®
SPI
3.3 and 6.6V ADC inputs
External microUSB port

Power System and Protection
Ideal diode controller with automatic failover
Servo rail high-power (7V) and high-current ready
All peripheral outputs over-current protected, all inputs ESD protected
Monitoring of system and servo rails, over current status monitoring of peripherals

Dimensions
Weight: 38g (1.31oz)
Width: 50mm (1.96")
Thickness: 15.5mm (.613")
Length: 81.5mm (3.21")

https://store.3drobotics.com/products/3dr-pixhawk
 


jfro

jfro

Aerial Fun
For people like me, maybe someone would like to write a short piece on 3DRobotics, APM and Pixhawk.

Little about the company (from their website, 3D Robotics is a VC-backed startup with over 170 employees in North America and more than 26,000 customers worldwide. 3DR has business offices in Berkeley, CA, engineering operations in San Diego and manufacturing facilities in Tijuana, Mexico.)

I've heard the names APM and Pixhawk, but know nothing of what it takes to set up a system (parts and costs) and what they can do.

I thought when I bought my HFP, I was buying from the only U.S. based company for flight controllers.

Sounds like Pixhawk is based on open source, but exclusively designed and manufactured by 3DRobotics.

Tell us more!
 

M

mspencer1

Member
I myself have been a long time Hoverfly user and I still am. But of course with Hoverfly's lack of development of advanced features I decided to try the APM. It is a steep learning curve but if you already have experience in multi rotors I guess it could be steeper. I tested it out on a simple quad to start. I purchased the Ublox GPS/Mag and 900mhz telemetry radios. The Cost was around $370 for everything. First, the directions are very good! All in english, not choppy english. It is a highly detailed manual. Connecting the ESC's and other components is no more difficult than the Hoverfly. Initial setup is a bit more advanced than the Hoverfly due to so many settings. There is a bit of reading involved to understand each setting which took me some time. There is a setup wizard which makes life easy when configuring your ship. It takes you through all the basic settings. This unit does use PID settings and may need to be tweaked. The hardest part was understanding PID settings. But you have to be patient and make small adjustments and test fly. Once the normal flight behavior is looking normal then you can start with the GPS features. APM comes preloaded with settings that will get your ship in the air. It may not be smooth but it will fly. Then you make the fine adjustments. There is even an Auto Tune where the ship will learn what the PID's need to be. GPS features were nothing short of amazing. I didn't know one of these could hold a position and altitude in less than a meter. Usually its less then that. It has like 14 functions you can assign to a 3 way switch. You just select which ones you want. I Usually use Stabilize, AUTO (activate mission) and RTH. RTH climbs first to a preset altitude, flies home, hovers, then lowers to a soft landing if you'd like. Planning missions is also very easy. You simply click on the map to create a waypoint and tell it the desired altitude. You click Write Waypoints and they upload into the APM. I move my 3 position switch to AUTO and thats it. It will take off, fly its mission, RTH and land.
 

kloner

kloner

Aerial DP
were getting one of these to play with. Talking to them at the ama show something about the sd memory and the software weren't ready? is yours fully functional?
 

M

mspencer1

Member
I have a Pixhawk on order and I did get the same notification about the SD card. Currently i'm using the APM flight controller. It has all the same settings as the Pixhawk and uses the same mission planner software but the Pixhawk should be a faster controller. My APM controller is fully functional. I trust it to fly missions and come home every time. I even have the sonar and optical flow sensor installed now but not fully tested.
 

jfro

jfro

Aerial Fun
I ordered a Pixhawk 8-9 days ago and haven't heard anything other than paypal sent the money. Been doing a little reading and hoping the pixhawk/ apm setup will come with some directions so I don't have to hunt all over the internet for them and piece it together. Always a learning curve learning the pieces and what is the current software, drivers, firmware that is needed... Am looking forward using the open source APM, just hope it doesn't take too long to learn all the settings.....

I'm will now have a small, midsize, and large MR based on Naza V2 w/gps, Xaircraft SuperX and the Pixhawk. That should keep me busy for the coming year. All 3 will have gps, but just this one with way points.
 

M

mspencer1

Member
The pixhawk instructions are written into the instructions along with the APM and PX4 controller. Go to www.copter.ardupilot.com The mission planner software is how you do your initial setup. It has everything you need in one place. It gives instructions for setting up all of 3DRobotics flight controllers.
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
oy, still trying to finish my coaxial quad with the APM 2.6 controller! Pixhawk sounds great though!
 



Mactadpole

Mactadpole

Member
mspencer1 said:
I myself have been a long time Hoverfly user and I still am. But of course with Hoverfly's lack of development of advanced features I decided to try the APM. It is a steep learning curve but if you already have experience in multi rotors I guess it could be steeper. I tested it out on a simple quad to start. I purchased the Ublox GPS/Mag and 900mhz telemetry radios. The Cost was around $370 for everything. First, the directions are very good! All in english, not choppy english. It is a highly detailed manual. Connecting the ESC's and other components is no more difficult than the Hoverfly. Initial setup is a bit more advanced than the Hoverfly due to so many settings. There is a bit of reading involved to understand each setting which took me some time. There is a setup wizard which makes life easy when configuring your ship. It takes you through all the basic settings. This unit does use PID settings and may need to be tweaked. The hardest part was understanding PID settings. But you have to be patient and make small adjustments and test fly. Once the normal flight behavior is looking normal then you can start with the GPS features. APM comes preloaded with settings that will get your ship in the air. It may not be smooth but it will fly. Then you make the fine adjustments. There is even an Auto Tune where the ship will learn what the PID's need to be. GPS features were nothing short of amazing. I didn't know one of these could hold a position and altitude in less than a meter. Usually its less then that. It has like 14 functions you can assign to a 3 way switch. You just select which ones you want. I Usually use Stabilize, AUTO (activate mission) and RTH. RTH climbs first to a preset altitude, flies home, hovers, then lowers to a soft landing if you'd like. Planning missions is also very easy. You simply click on the map to create a waypoint and tell it the desired altitude. You click Write Waypoints and they upload into the APM. I move my 3 position switch to AUTO and thats it. It will take off, fly its mission, RTH and land.
Click to expand...

Very interested to know your thoughts on flight characteristics compared to Hoverfly. I know you were one of the first with HF too and have a lot of experience. I am using APM in a fixed-wing I am setting up and have a Pixhawk on order for multirotor.

Thanks,

Shawn
 


jfro

jfro

Aerial Fun
I went and read the short explanation on google docs (?) and this is a beta release for the sd card and a few others. Said if no issues, they release final in a week or so.

I have no history with this software, but have been using beta and "just " released software in computers for too many years. If I had my Pixhawk unit, I'd put it on and give it a spin on a small quad, maybe not so much on a big hex or octo...

I assume I'll see it in 1-4 weeks....
 

M

mspencer1

Member
I can say with certainty that the Hoverfly is still the smoothest. The APM doesn't hold angles very well when there is a large camera underneath. Trying to dampen out all the unwanted motion it makes is very difficult with or without a camera gimbal. But its not that bad. It still flies very well and you can't beat the GPS performance. However I haven't been able to get the GPS features (PH, loiter, RTH) working on the cinestar when there is a camera gimbal attached (heavy lift). Otherwise the GPS features work great without the camera gimbal (light lift). I haven't had enough time to mess with those settings. Trying to make it loiter with the default factory settings doesn't work during heavy lift . It will start dancing all over the sky. Its probably due to the loiter settings being to high for heavy lift. In general the APM makes less smooth movements than the Hoverfly.
Mactadpole said:
Very interested to know your thoughts on flight characteristics compared to Hoverfly. I know you were one of the first with HF too and have a lot of experience. I am using APM in a fixed-wing I am setting up and have a Pixhawk on order for multirotor.

Thanks,

Shawn
Click to expand...
 
Last edited by a moderator:


Mactadpole

Mactadpole

Member
Thanks! Hopefully they will get it there or HF will catch up with the pack and get a real GPS solution. I think for what I will be using it for (orthophotos) things should be fine.

mspencer1 said:
I can say with certainty that the Hoverfly is still the smoothest. The APM doesn't hold angles very well when there is a large camera underneath. Trying to dampen out all the unwanted motion it makes is very difficult with or without a camera gimbal. But its not that bad. It still flies very well and you can't beat the GPS performance. However I haven't been able to get the GPS features (PH, loiter, RTH) working on the cinestar when there is a camera gimbal attached (heavy lift). Otherwise the GPS features work great without the camera gimbal (light lift). I haven't had enough time to mess with those settings. Trying to make it loiter with the default factory settings doesn't work during heavy lift . It will start dancing all over the sky. Its probably due to the loiter settings being to high for heavy lift. In general the APM makes less smooth movements than the Hoverfly.
Click to expand...
 

Mactadpole

Mactadpole

Member
@mspencer1 - Just saw this exchange over on DIY and thought it might help if your not already aware:

Q: I am new to APM, coming from OpenPilot where I am used to having Rate mode configured so that, with enough I term, the copter will hold its angle, with no stick input. So far, in my attempts to tune Acro with the same quad, I cannot get this to happen. I can add Rate I, but it never really locks in, and instead slowly returns to level, and if I keep raising it, I get oscillations. This is not an autotune question, just a manual tuning one. Is this supposed to work? This is currently on 3.1rc5, and a basic 500-sized quad. Thanks in advance!
[edit] just found ACRO_TRAINER set at 2 (Leveling and Limited). Will try at 0. Assuming that makes a differnce, it is truly supposed to (theoretically) hold that angle indefinitely?

A: Yes, that is correct. With Trainer set to 2, it will self level. With it set to 0, it will hold the angle tenaciously as long as you have your PIDS setup right.
 

M

mspencer1

Member
Mactadpole said:
@mspencer1 - Just saw this exchange over on DIY and thought it might help if your not already aware:

Q: I am new to APM, coming from OpenPilot where I am used to having Rate mode configured so that, with enough I term, the copter will hold its angle, with no stick input. So far, in my attempts to tune Acro with the same quad, I cannot get this to happen. I can add Rate I, but it never really locks in, and instead slowly returns to level, and if I keep raising it, I get oscillations. This is not an autotune question, just a manual tuning one. Is this supposed to work? This is currently on 3.1rc5, and a basic 500-sized quad. Thanks in advance!
[edit] just found ACRO_TRAINER set at 2 (Leveling and Limited). Will try at 0. Assuming that makes a differnce, it is truly supposed to (theoretically) hold that angle indefinitely?

A: Yes, that is correct. With Trainer set to 2, it will self level. With it set to 0, it will hold the angle tenaciously as long as you have your PIDS setup right.
Click to expand...
I do recall the trainer mode setting. I had the same issue at first. The ship would always want to go level even in rate mode but I found the setting and changed it to 0. I can get it to hold its angle just as the Hoverfly does. Its pretty easy to achieve without payload (Even on a large octo). It just becomes more difficult for it to do it smoothly during heavy lift. The ship has a large weight hanging underneath it (low CG) and it naturally wants to return to level. Because of the heavy lift the props are spinning way faster and therefore make the settings too sensitive. So you have to turn everything down. But this seems to create other problems in its smoothness. Any moderate movement on the pitch or roll sticks will cause the copter to over bank/pitch. Then it tries to correct the angle error. The trouble is that turning up/down one setting means changing the other settings. The P is the primary gain, the I is the correction speed and the D is the overshoot. So I turn up the I and it holds its angle but overshoots. So I turn up the D until there is no overshoot. But then when I need to ascend slow to moderately the ship spins the props faster and oscillates. So its a fine balance of setting during heavy lift I haven't been able to achieve perfectly yet.
 

Mactadpole

Mactadpole

Member
I figured you probably had it figured out!

On another note - I did also read yesterday that some folks are reporting improved "smoothness" with Pixhawk because of processing power, etc., etc. It was then mentioned by a developer (if I recall correctly) that we should expect to see much improved flight performance with future firmware updates on Pixhawk because of the increased processing. Hopefully so.

Received my Pixhawk shipping notice yesterday so I guess they got the poor SD card quality issue worked out.

mspencer1 said:
I do recall the trainer mode setting. I had the same issue at first. The ship would always want to go level even in rate mode but I found the setting and changed it to 0. I can get it to hold its angle just as the Hoverfly does. Its pretty easy to achieve without payload (Even on a large octo). It just becomes more difficult for it to do it smoothly during heavy lift. The ship has a large weight hanging underneath it (low CG) and it naturally wants to return to level. Because of the heavy lift the props are spinning way faster and therefore make the settings too sensitive. So you have to turn everything down. But this seems to create other problems in its smoothness. Any moderate movement on the pitch or roll sticks will cause the copter to over bank/pitch. Then it tries to correct the angle error. The trouble is that turning up/down one setting means changing the other settings. The P is the primary gain, the I is the correction speed and the D is the overshoot. So I turn up the I and it holds its angle but overshoots. So I turn up the D until there is no overshoot. But then when I need to ascend slow to moderately the ship spins the props faster and oscillates. So its a fine balance of setting during heavy lift I haven't been able to achieve perfectly yet.
Click to expand...
 

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