VRBrain vs DJI Wookong M - latest firmware rev 3.0.3 available


Dear friends,

after hard work on firmware doing by Arducopter and Virtualrobotix Dev Team , we are happy to present the result of this incredible test ... this is only first test VRBrain vs DJI Wookong .

The firmware is ARducopter32 rev 3.0.3 , this revision of firmware use AP_HAL library to interface the Arducopter application . The firmware is mantain by Arducopter devteam , the last improvment doing by Leonard that solve some glitch in loiter , and gps override mode.

The result of work doing by Randy and the other member of the team is incredible , we fly the quad in gps mode and it fly as robot ... as Dji Wookong .


This is a video doing during VR Lab test of new VR Lifter frame.

But if you like fly in stabilize mode you can enjoy you a lot. :) I prefer a lot fly my quad in stabilize and acro mode it's nice.

The power of VRBrain with its STM32F4 microcontroller have 164 mhz of clock with internal dsp have a more power of DJI Wookong cpu that use SAM3X micro processor at only 96 mhz and don't have dsp processor for hardware math processing.

Now the new revision of VRBrain 4.5 can support also an external IMU so we can solve the vibration problem with mechanical patch.

Whe have a great new wiki page for support the user :


A new tools for update the firmware is available and will be release in the next days , so you can choose your code download local and program the board without problem.

We are very happy of VRBrain performances :)

original blog post : http://www.virtualrobotix.com/profiles/blogs/vrbrain-vs-dji-wookong...


Thanks to Marco Robustini for his great video :)


Roberto Navoni



Views: 3356

Comment by Rob_Lefebvre on July 22, 2013 at 2:18pm

Ah, the external IMU, nice.

Could you also program it to failsafe over to the built-in IMU should the external fail?  That would be a nice feature.

What is the difference between Arducopter V3.0.1 vs. what you are calling 3.0.3?

Comment by Roberto Navoni on July 22, 2013 at 2:44pm

Hi Robert,

yes we have two IMU available on VR Brain 4.5  one on the board and other outside ... in "old" 4.0 we had 2 IMU but was onboard and only for experimental purpouse for ST lab ... Now with new external imu we can switch fast from 1 imu to other and also we can use two imu active in realtime ...

On GIT is yet available a version of code with EXT_IMU , inside cli there is the code for manage two imu at the same time .... Emile working on this version of code !!!  In our hardware design the imu are on two indipendent SPI so you can use dma and transfer in realtime the data from sensor to memori ... this kind of feature is working progress inside the AP_HAL !

The ver 3.0.3 include last patch from Leonard about loiter i think .. but could be better ask Emile the exact difference , inside the code could be also the opportunity to use the external imu for evaluate the mechanical vibration damper that we are developing !

Comment by eko rahardjo on July 22, 2013 at 6:31pm

Cool, I'm very impressed..I send email today, pls check.

Comment by Jack Crossfire on July 22, 2013 at 6:43pm

Surprising DJI hasn't copied the source code, or maybe they have.

Comment by Boris Rabusic on July 23, 2013 at 2:47am

biggest question: is there any difference in flight stability (not program stability) between VR Brain and APM at this stage ?

Comment by Marco Robustini on July 23, 2013 at 3:35am

The result on my video is with the internal IMU on VR Brain, with external i think is better...

Comment by Roberto Navoni on July 23, 2013 at 5:58am

Hi Boris,

the main difference in VRBrain vs APM is that we have a lot of resource available.

The cpu is a 32 STM32F4 at 168 mhz of clock with 1 Mega Flash and 196 kbyte ram.

APM use  8 bit cpu at 16 mhz of clock 256 kbyte of program and 16 kbyte ram.Actually we are using only 30 % of cpu resource for Arducopter32 rev 3.0 at standard loop speed .

Some user are working on overclock revision of arducopter code and try to have more fast attitude speed control. 

The test is doing until 1 khz. At standard arducopter loop test we are manage two ahrs imu in realtime without problem. The main problem was on usb interrupt ... but during fly is not a problem because we use serial ttl for manage the telemetry.

So the main advantages is that the task is serve in exact time slot... we don't have any kind of delay. So the quality of fly is very smooth. In the overclock version the impression is the attitude is better .

Respect of PX4 we don't use O.S. on VRBrain so we don't have latency of O.S. in our implementation the approach is very similar to APM but with a lot of power available. We implement ap_hal based on standard ST library so is very simple to manage and improve the driver code.



Comment by Rob_Lefebvre on July 23, 2013 at 6:10am

Jack, that's exactly the type of thing I'm wondering.  How long before that happens?  I saw the new Blade quad and wondered... you never know.

Comment by Roberto Navoni on July 23, 2013 at 6:30am

We are working on ready to fly Quad - Okto platform ,too 

The electronic will be VRBrain as autopilot and VRGimbal for 3 axis cam control , the main problem that we have is not the design , but production ... We are evaluating to try the Crowdfunding approach or a entry level advanced carbon fiber  cnc version before to have a molded version of frame .

If some one are interested to join in the project are welcome !!


Comment by Lorenz Meier on July 23, 2013 at 12:48pm

Roberto, have you actually measured your latency? Have you measured the latency on PX4? Have you measured the latency of Arducopters internal scheduler? What you're writing about PX4 is pure speculation.

On top of that you're running Arducopter very likely at its default rates, and any APM 2.5/2.6 video would have provided the same result. Not to mention that the mainloop latency of Arducopter is orders of magnitudes higher than anything a RTOS would ever have.


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