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21 Nov 2009 Configurable Simulink Model for DC-DC Converters with PWM PI Control A Simulink model configurable to buck, boost and buck-boost DC-DC converters with PWM PI control Author: Yi Cao caizhi, zhang

Hi,Dr. Cao
  Thanks for your excellent work!
  I don't understand the PWMPID controler, Could you tell me why did you design the controler like that?
  Thanks!

17 Nov 2009 Bidirectional Branch and Bound Minimum Singular Value Solver (V2) A branch and bound solver to find the largest minimum singular values among all submatrices. Author: Yi Cao Hoeser, Stefan

16 Nov 2009 Hypervolume Indicator A tool to estimate the hypervolume indicator Author: Yi Cao Matteo

Thank you, it's perfect!

02 Nov 2009 Hungarian Algorithm for Linear Assignment Problems (V2.1) An extremely fast implementation of the Hungarian algorithm on a native Matlab code. Author: Yi Cao James

22 Oct 2009 Bivariant Gaussian Kernel Density Estimation A too for bivariant probability density estimation using Gaussian kernel function. Author: Yi Cao Jandreau, Tyler

21 Oct 2009 Pareto Front Two efficient algorithms to find Pareto Front Author: Yi Cao Buzatu, Pompilia

Can anyone explain to me how to use these files? :-/ Thank you!

27 Aug 2009 Kernel Smoothing Regression A non-parametrical regression (smoothing) tool using Gaussian kernel. Author: Yi Cao , cf

It works very well and friendly.

20 Aug 2009 Pareto Front Two efficient algorithms to find Pareto Front Author: Yi Cao Cao, Yi

Yes, you can. For a higher dimension, you have to provide much more data points.

HTH
Yi

19 Aug 2009 mvaverage moving average through filter Author: Yi Cao Ryan

Fast and simple code. Works as advertised.

12 Aug 2009 Pareto Front Two efficient algorithms to find Pareto Front Author: Yi Cao Subramanian, BASKAR

Hi,

Can we use this code for more than two objectives?
We are getting the scattered front when using more than two objectives.

11 Aug 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao icar, iasri

hi yi, would like to know if its appropriate to use EKF for forecasting of agricultural yields like fish ,rice etc. i am planning to use EXPAR with EKF for the problem stated above and would you kindly be able to give some of your ideas regarding the same.thankyou, with regards bishal.

20 Jul 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao Rathinasamy, maheswaran

08 Jul 2009 Efficient K-Means Clustering using JIT A simple but fast tool for K-means clustering Author: Yi Cao Kraft, Edgar

The code is very nice and well documented. In some cases, however, the clusters are not properly identified if no initial centroid vectors are provided. This could be improved by automatically trying a small number of different random initial guesses and chosing the configuration which yields the smallest sum of distance between points and centroids.

23 Jun 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Schenkel, Peter

ok for some reasion my previous posting got lost , so once again :

I am using UKF to estimate distances from radio signal strength. Eventhough the RSSI error (measurement equation) is gauss distributed UKF performs very poorly and I cannot understand why as it seems the perfect choice for this kind of problem. I set the measurment nois to the std I got from the training data. My system equations are

f=@(x)[abs(x(1)+x(2));abs(x(3)-x(1));x(1)] ;
h=@(x)[-log10(x(1))*10*pl-A];

for f :
x1: new distance = old distance + velocity
x2: velocity = difference(old distance, new distance)
x3: old distance

h is simply a given transformation from distance to radio singal strength

I cannot find any reason for the poor performance as it should be the best filter for this kind of application. Am I missing some important issues ?

23 Jun 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Schenkel, Peter

sorry...ekf should be ukf in the previous posting

21 Jun 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Cao, Yi

Peter,

This means the iteration of ukf is unstable. You have to adjust P, Q, etc to make it stable.

Yi

20 Jun 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Schenkel, Peter

Hi Yi Cao,

First of all, thanks for your contribution here. I do have a question though, I do get for some parameter combinations a complex covariance matrix, the parameters look like this :

z = -78
c = 1.7321e-004
P =
   1.2500 + 0.0000i 0.0000 - 0.0000i 0.0000 - 0.0000i
   0.0000 + 0.0000i 0.4438 + 0.0000i 0.0000 + 0.0000i
   0.0000 + 0.0000i 0.0000 - 0.0000i 1.2500 + 0.0000i

x =
   0.5807 - 0.0000i
  -5.5018 + 3.7078i
   0.7954 - 0.0000i

Then I get this error :
??? Error using ==> chol
Matrix must be positive definite with real diagonal.

I assume that this is due to the complex covariance matrix.
I have no idea how this matrix can become complex as in my oppinion the only way it can become complex is if c would be negative which it isn't here...

Additionally, I would like to measure distances using radio signal strength, therefore I have actually the distances from RSSI values and additional velocity from the last step to the current step, is it possible to process these information with this implementation as well ?

Thanks for any help!

Best
 Peter

08 Jun 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao tim

i wrote a very simple compound pendulum code, and some how this ekf algorithm does not work for that. only change that i had to do to that example file was change the states to 2 and rest
f=@(x)[x(2);-(g/l)*sin(x(1))];
this should give me sinusoidal waveform but it does not.
can you point out to me what could be wrong.

06 Jun 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Cao, Yi

Right. However, K=P12*inv(P2). Hence, K*P2 = P12.
This leads to K*P2*K' = P12*K'. Therefore, P=P1-P12*K'.

HTH
Yi

05 Jun 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Robers, Erik

I think the covariance updat should be:

P=P1-K*P2*K'

Erik

27 May 2009 Multivariable Subspace Identification: MOESP A tool for subspace identification using the MOESP algorithm. Author: Yi Cao Bizkevelci, Erdal

26 May 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao Heights, tim

if in EKF i have to add state noise compensation, any good example or guidance here. how can i add to the example given by Yi Cao.
secondly, any one who could also recommend some book about it.

23 May 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao Chao

13 May 2009 Configurable Simulink Model for DC-DC Converters with PWM PI Control A Simulink model configurable to buck, boost and buck-boost DC-DC converters with PWM PI control Author: Yi Cao colhn, colhano

28 Apr 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao Cao, Yi

For continuous-time EKF, please look at http://www.mathworks.com/matlabcentral/fileexchange/18485

28 Apr 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao Hippalgaonkar, Rohit

Hi I am looking for an example where the EKF is applied to a continuous-time non-linear system with non-zero inputs (say measurements are taken at regular time samples through a non-linear (even linear would do) measurement process. I have looked around for this kind of example in the standard texts but haven't found any. Also a good source showing the implementation of the EKF wherein we linearize about a single operating point (as against linearizing about the predicted state every time) would be really helpful! Thanks in advance! Rohit

28 Apr 2009 Unconstrained Optimization using the Extended Kalman Filter A function using the extended Kalman filter to perform unconstrained nonlinear optimization Author: Yi Cao Hippalgaonkar, Rohit

Hi I am looking for an example where the EKF is applied to a continuous-time non-linear system with non-zero inputs (say measurements are taken at regular time samples through a non-linear (even linear would do) measurement process. I have looked around for this kind of example in the standard texts but haven't found any.

Also a good source showing the implementation of the EKF wherein we linearize about a single operating point (as against linearizing about the predicted state every time) would be really helpful!

Thanks in advance!
Rohit

20 Apr 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Cao, Yi

It seems that your model is not stable. You may wish to adjust P, Q and R matrices to see if this helps.

Yi

20 Apr 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Chawah, Dapat

hello Dr.Yi
This code is working good for N<=150
but when N exceeds this limit, a nonsense happens
Is there any improvement to the code considering this error?

20 Apr 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao Chawah, Dapat

Sorry, this comment is meant to be in the unscented kalman filter file discussion

20 Apr 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao Chawah, Dapat

This code is working good for N<=150
but when N exceeds this limit, a nonsense happens
Is there any improvement to the code considering this error?

06 Apr 2009 Complex step Jacobian Calculate Jacobian using complex step differentiation Author: Yi Cao Cao, Yi

Angshul,

eps is the minimal distinguishable vnumer for a particular precision system. For double precision, eps = 2^(-52) and for single precision, eps = 2^(-23). Use "help eps" to find more details.

The complex step differentiation approach can use the minimum step size to get the maximum accuracy. Hence eps is the best step the algorithm can use.

HTH.

Yi

06 Apr 2009 Complex step Jacobian Calculate Jacobian using complex step differentiation Author: Yi Cao Majumdar, Angshul

the step size 'eps' is not specified? Do U suggest a value?

06 Apr 2009 Bidirectional Branch and Bound Solvers for Worst Case Loss Minimization Two branch and bound solvers using worst case loss criterion to select controlled variables. Author: Yi Cao Cao, Yi

Mohammad,

If you are a real user who is concerned about this issue, please drop me an email. I will clarify this to you.

Yi

05 Apr 2009 cholhilb Cholesky factorization of the Hilbert matrix of order n Author: Yi Cao Poor, V.

05 Apr 2009 Peg Solitaire Contest Solver An upgraded solver for the peg solitaire contest Author: Yi Cao Poor, V.

05 Apr 2009 recursive solver to peg solitaire contest a solver to push the 3-minute limit Author: Yi Cao Poor, V.

05 Apr 2009 mvaverage moving average through filter Author: Yi Cao Poor, V.

05 Apr 2009 fminconSym A wrap of fmincon to get gradient Author: Yi Cao Poor, V.

05 Apr 2009 lsqnonlinSym A wrap of lsqnonlin to get Jacobian Author: Yi Cao Poor, V.

05 Apr 2009 Simulink Library: Performance Index A small simulink library to provide performance index measurements. Author: Yi Cao Poor, V.

05 Apr 2009 UK Postcode to Lat/Long for GPS A small tool to convert a UK postcode to Lat/Long degrees for GPS Author: Yi Cao Poor, V.

05 Apr 2009 lsqnonlinCSD A wrap of lsqnonlin using complex step differentiation to get Jacobian Author: Yi Cao Poor, V.

05 Apr 2009 fminconCSD A wrap of fmincon using complex step differentiation to calculate gradient Author: Yi Cao Poor, V.

05 Apr 2009 Complex step Hessian Calculate Hessian using complex step differentiation Author: Yi Cao Poor, V.

05 Apr 2009 Complex step Jacobian Calculate Jacobian using complex step differentiation Author: Yi Cao Poor, V.

05 Apr 2009 Learning the Extended Kalman Filter An implementation of Extended Kalman Filter for nonlinear state estimation. Author: Yi Cao Poor, V.

05 Apr 2009 Learning the Unscented Kalman Filter An implementation of Unscented Kalman Filter for nonlinear state estimation. Author: Yi Cao Poor, V.

05 Apr 2009 Wakimapia A tool to locate the Wakimapia to specified latitude and longitude degrees Author: Yi Cao Poor, V.

05 Apr 2009 Learning the Kalman Filter in Simulink A Simulink model to learn the Kalman filter and Gassian processes. Author: Yi Cao Poor, V.

 

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