Hi All,

I just completed my Pixhawk equipped 4WD Slash chassis complete with dual GPSs and a 3DR 915MHZ telemetry radio.

The GPSs are mounted at each end of the chassis. The 3DR GPS/Compass module is in the front of the chassis and 3DR uBlox LEA-6 v1.1 is in the rear. Both are protected by the chassis bumpers

The rest of the components are mounted on a navigation platform above the battery.

The rover is powered by a Traxxas 3500 brushless motor and VXL-3s ESC and is using a Spektrum Remote Receiver to communicate with a Spektrum DX8 Transmitter.

I have beefed up the body mounts with extruded aluminum "L" rails to help prevent damage during a rollover.

Unlike my 2WD Slash rover, the battery can be removed for charging without taking the navigation platform off of the chassis.

Here are some pictures of the new rover:

Front View

Side View

Top View

Rear View


TCIII ArduRover2 Developer

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I originally started with two APM equipped Traxxas Slash 2WD rovers and have been slowly upgrading them.

The rover I won the Sparkfun 2013 AVC Peloton Class with has been shipped to Boulder, CO for the AVC competition. It is a Pixhawk equipped 2WD brushless Slash rover with dual GPSs.

The Pixhawk equipped 4WD brushless Slash rover is built up from parts from my second APM equipped 2WD Slash rover. The theory is that you can get better steering/cornering with the 4WD version.

Also, I am using the 4WD Slash to validate any ArduRover2 firmware changes prior to leaving for the AVC this Thursday.


TCIII ArduRover2 Developer


Thanks for the kudos, much appreciated.

I am always trying new ways to mount and populate the navigation platform with each build.


TCIII ArduRover2 Developer

Whats the difference between the pixhawk and apm 2.6?


The Pixhawk has a 32bit processor while the APM2.6 has a 8 bit processor.

The Pixhawk can support dual GPSs, dual compasses, and can run the Extended Kalman Filter (EKF) firmware that is far superior to the Defined Cosine Matrix (DCM) heading knowledge processing.

There is a price difference with the Pixhawk being more expensive than the APM.

As far as I am concerned, the EKF firmware is the only way to go for improved heading knowledge and accurate waypoint steering in a rover.


TCIII ArduRover2 Developer

Hello Tom,

Nice build. I am intrigued with your dial GPS setup. Did you modify the stock firmware to select the one that has more sat at any time? On which ports are these two modules connected?

Hi Hugues,

Thanks for the kudos, much appreciated.

The Pixhawk ArduRover2 firmware has had the dual GPS capability since the beta versions of v2.45/2.46 came out.

The primary GPS/Compass is connected at the Pixhawk GPS input  and the secondary GPS is connected to Serial 4 (Pins 2&3). The debug UART was moved to Serial 5 (Pins 4&5).

You will need to enable the use of the secondary GPS by setting the parameter GPS_TYPE2 to 1.

The present beta firmware will select the GPS that has the most satellites at any given moment.


TCIII ArduRover2 Developer

Wow thx that is a great feature. Will that be ported to APM:copter and plane too?


I believe that Tridge has already integrated that dual GPS feature into the Arduplane firmware.

I do not know about the Arducopter firmware.


TCIII ArduRover2 Developer

What is LCG?

Low Center of Gravity.

Ha! thats a no brainer, now i feel stupid. Thx 4 the answer. 

I have to jump in here.

I have a couple of questions, sorry... :)

I am set up with a 1240 on the left and right sides of my rover. I have not yet deployed them, they are a long way down the list of things to tune.

I have built this drone for fun, and to see just how silly one can be. Manually driven, speeds closer to 150km/h than 100km/h can be achieved. Manual control at these speeds is crazy, as is keeping it stuck to the deck.

A faster response time is therefore desirable for object avoidance (I am not necessarily meaning at those speeds though!).

So with the LIDAR, TCIII, when you say test what do you mean? Is code written for the Lidar / infrared systems and it just needs to be tuned or do you mean writing it into the code?

Is anyone else interested in starting a group for coding / testing and implementation of the LIDAR for the APM:rover?

In regards to the dual GPS. I noticed you mentioned this in another thread. I have a couple of the 3DR gps/mag combos spare so I could throw an extra in the rover. In my mind I would not connect the second magnetometer (truth be told without it in front of me I am having trouble picturing where I could connect it). Is this correct?

Is there any known builds with the uBlox M8 or NavSpark GPS installed and running with APM (whether it be rover/plane/copter)?

What is the Kalman filter?

I apologise for all the questions, especially if it turns out google could answer them.

Thanks team.


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