James Goppert
• Male
• West Lafayette, Indiana
• United States

684 members

1290 members

# James Goppert's Page

## Latest Activity

"Hey folks, I wanted to ask what is the process model that you recommend for EKF attitude estimation, and how do you find the optimal covariance matrices the Q and R. Are they time varying or constant ones? Thanks."
Apr 20
"That's really  great contributions. I am personally amazed by this great effort. I believe this is the right place to seek help from. I am also working on attitude estimation, but not as a major task in my research. However,…"
Apr 18
"I am happy that my small question started so good thread   :-) If only I was following better the mathematics course instead of thinking about girls  :-) Angelo"
Jan 25
"@Bill Ok thanks for that, the example helped. By psi_error I mean delta, the angle between the measured and 'expected' horizontal vector. As per my previous comment, the magnitude of the cross product = |Hxy| |Mxy| sin(psi_error) ]…"
Jan 24
"@Dan, I am not sure what you mean by psi_error. If you mean the difference between the actual and estimated value of the psi Euler angle, that is not what I am computing, that is something else entirely. What I am computing is the sine of the…"
Jan 24
"It is an awesome feeling seeing software that I contributed to and developed so recently helping to fly an aircraft on the other side of the world! I am really looking forward to getting some time for my own test flights. Thanks again guys for…"
Jan 24
"@Bill Thanks for the explanation. I believe your method is a elegant way to calculate the psi error (if desired) without calculating the magnetometer heading directly, i.e. Hxy (cross) Mxy = [ 0; 0; |Hxy| |Mxy| sin(psi_error) ] Where Hxy is the…"
Jan 24
"@Dan, Regarding using the magnetometer for yaw drift compensation, I am not sure if we are talking about the same thing or not. I am not using the tilt compensation method described here, which is the common way of doing it. The problem with that…"
Jan 24

## Profile Information

I'm a graduate student in Aerospace engineering at Purdue University. I'm working on unmanned aerial/ ground vehicle navigation in environments without GPS.
http://hsl.dynalias.com/hsl/index.php?page=unmanned-vehicles
Hometown:
Lake Lotawana, Missouri

## James Goppert's Blog

### PX4 Autopilot: New Software! Hardware Accelerated Extended Kalman Filter/ Sensor Level HIL/ OO Control Library

Posted on January 22, 2013 at 11:00am

The PX4 autopilot is an amazing open source platform for research. It is one of the first open source autopilots capable of running an on-board extended kalman filter and other advanced control and navigation algorithms. It is also mass…

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### ArkToolbox now released for Windows/ Mac as well as Linux

Posted on April 2, 2012 at 11:00pm

ArkToolbox is a toolbox for ScicosLab/ XCos (similar to Matlab simulink, but free). ArkToolbox is useful for drone control design, simulation, and testing and is compatible with FlightGear, MAVLink (QGroundControl/ArduPilotMega), and the JSBSim Trimming GUI software. This creates a completely open source toolchain for developing aircraft models, finding…

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### JSBSim Trimming Demo for F16 and Shadow UAS

Posted on February 2, 2012 at 12:30pm

A gui for JSBSim is demonstrated. The gui is capable of trimming any aircraft modeled in JSBSim at various flight conditions. It can simulate the aircraft at the calculated trim conditions, save the linearizations around these trim states, and output the linearization to a form readable by ScicosLab. The software is demonstrated on the standard f16 model included with JSBSim and a shadow UAV model, part of arkhangar. The linearized state space models output at the trim…

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### ArduPilotMega (ArduBoat) Sailboat Autopilot Heading Hold Test

Posted on December 9, 2011 at 12:00pm

This is a heading hold test for the ArduPilotMega based (ArduBoat) sailboat autopilot. The boat is sailed manually on a reach and then heads downwind holding a heading of 0 degrees and performs a jibe.We have waypoint guidance working in hardware-in-the-loop, so we expect to do waypoint testing soon. We might have to figure out a better solution for our digital wind…

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### Sailboat Autopilot Design for ArduPilotMega

Posted on December 2, 2011 at 12:30am

We just finished up modeling sailboat dynamics and implemented a controller. The dynamics were interesting due to the swinging airfoil. We modeled the winch system using a basic spring model that can only pull the sail in. It works well and can simulate irons, tacking, and jibing. All of the drag coefficients etc. are very rough at this point but the overall dynamics…

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At 8:14pm on July 22, 2010, PatrickD said…
Hey James,

Thanks for the info. I am only doing a longitudinal model of the easystar in Simulinkg to check elevator responses based on an optimal controller. I am using your datcom generated tables for the lift, drag and moment coefficients needed based on the angle of attack..
At 9:14am on July 26, 2010, PatrickD said…
At the moment, i have just put in a reasonable values for the lift and pitching moment coefficients due elevator deflection seeing as I had no data. I would be interested if you have more realistic data that you are willing to share. The simulink model is based on simplified longitudinal eq. of motions in wind axis. I have a mathematical constant speed controller in my model to enable it to trim at around 15m/s. I have also implemented an elevator controller based on my supervising teacher work in optimal control.
At 1:47am on November 21, 2010, KnutL said…
Hi James
tnaks for your help. I will give it a try
At 12:12am on February 4, 2011, Tomtom Express said…
Hi James,  I am allocating some time to learn how to fly again.  In the end, I want to control the plane using controls that are connected to the computer.  Have you done anything like this ?  Thanks, Harry
At 5:43am on March 7, 2011, Lars Ulfalk said…

Hi James

While trying to get a home-built autopilot to fly airplanes without ailerons I found your model of Easystar on the oooark. I've been trying to get the autopilot to fly it safely, but it seems my autopilot favors airplanes with ailerons since it has some problems flying that model. I just wanted to check if there's any problems with the model you're aware of, or if you're saitsfied with the way it behaves in the air.

Best regards

/Lars

At 8:01am on May 14, 2011, dmohankkvr said…

Hi James,

I want to interface ardupilot with scilab, and control my UAV from there. Could you please tell me what toolboxes you have used to interface with ardupilot. Is this simple? and how long does it take to develop this link? i'm totally new to microcontrollers.

Thanks & Regards,

Mohan

At 8:17am on May 14, 2011, dmohankkvr said…

I will be using Ardupilot Mega. Does this mavsim toolbox come along with scilab? or I have to download it separately and install it. My job is to test the control algorithms for controlling the aircraft. Developing the interface is not the main idea. But if it is readily available, I want to use that one. Can I command the servos as well with this toolbox?

Thanks

Mohan

At 12:36pm on May 27, 2011, Junior Sammy said…

What is the accuracy of ArduRover i.e. your http://www.youtube.com/watch?v=r1iJWIKbAQc video? Are there any test results such as how close the rc car stopped at the indicated stopping waypoint? Within 1m, 2metres etc? This info will be greatly appreciated, thanks. Also in that video is the magnetometer really needed? How much accuracy does it help with?

At 8:15am on June 20, 2011, Junior Sammy said…

Hi James,

I checkout out revision 177 of ArduPilotOne which I believe is the Ardurover version from the youtube video but when I try to compile it I get the error:

"MAVLINK_COMM_NB_HIGH" was not declared in this scope

How can I fix this? One of the libraries path may be wrong or not included?

At 8:26am on June 20, 2011, James Goppert said…
Ok, you will need to edit the svn externals to match the ardupilotmega library revisions at that date.

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