Testing the Kalman Filter

灞波儿奔

Testing the Kalman Filter [Copy link]

The real temperature test data is measured by heating a basin of water with a heating rod. The X-axis is time in seconds and the Y-axis is temperature:

1) Before filtering

2) After filtering (p=10, q=0.0001, r=0.05, kGain=0;)

2) After filtering (p=10, q=0.00001, r=1, kGain=0;), the Y axis is enlarged 10 times and rounded

.

Related C language code:

#define LINE 1024

static float prevData=0;
static float p=10, q=0.0001, r=0.05, kGain=0;

float kalmanFilter(float inData)
{

    p = p + q;
    kGain = p/(p+r);

    inData = prevData+(kGain*(inData-prevData));
    p = (1-kGain)*p;

    prevData = inData;

    return inData;
}

char *ReadData(FILE *fp, char *buf)
{
    return fgets(buf, LINE, fp);
}

int main()
{
    FILE *fp, *fp2;
    char *p, *buf;
    size_t len = 0;
    ssize_t read;
    float inData[1000];
    float outData[1000];
    uint32_t i,cnt=0;

    fp = fopen("d2.txt", "r");
    if (fp==NULL)
        exit(1);

    buf = (char*)malloc(LINE*sizeof(char));
    p=ReadData(fp, buf);

    while(p) {
        inData[cnt]=atof(p);
        cnt++;
        p=ReadData(fp,buf);
    }

    fclose(fp);

    for(i=0;i<cnt;i++)
        outData=kalmanFilter(inData);
    }

    fp2 = fopen("d3.txt", "w");
    for(i=0;i<cnt;i++)
        fprintf(fp2, "%f\n",outData);
    }
    fclose(fp2);

}

Matlab code:

d2 = load('d2.txt');
plot(d2);

prevData=0.0;
p=10;
q=0.0001;
r=0.05;
kGain=0;
outData=[];

for i=1:length(d2)
p=p+q;
kGain=p/(p+r);
temp=d2(i);
temp=prevData+(kGain*(temp-prevData));
p=(1-kGain)*p;
prevData=temp;
outData(i)=temp;
end

plot(outData);

Note: d2.txt stores the input data, one per line. d3 is the output data.

The r parameter adjusts the closeness between the filtered curve and the measured curve. The smaller r is, the closer it is.

The q parameter adjusts the smoothness of the filtered curve. The smaller q is, the smoother it is.

combat

I learned it, thank you.