How to calculate speed by accelerometer in C?

Question

I placed the sensor on the window, and moved the window to get the speed and distance of x-axis direction. But when I stop moving, the speed reading is not zero, this causes error in distance measurement.

How to get accurate calculation speed?

code:

      static float acceleration[3] = {0.0, 0.0, 0.0};
      static float pre_velocity = 0.0;
      static float velocity     = 0.0;
      static float position     = 0.0;

     //get physical acceleration
      LSM6DSO_FIFO_OutRawGet(acceleration);
      lsm6dso_from_fs2_to_mg(acceleration);
      acceleration[0] = (acceleration[0] /1000) * 9.81f;
      acceleration[1] = (acceleration[1] /1000) * 9.81f;
      acceleration[2] = (acceleration[2] /1000) * 9.81f;

      //low pass filter
      acceleration[0] = LPF2pApply_1(acceleration[0]);
      acceleration[1] = LPF2pApply_2(acceleration[1]);
      acceleration[2] = LPF2pApply_3(acceleration[2]);

     //accel mechanical noise filter
      if(fabs(acceleration[0]) <= ACC_MECHANICAL_FILTER_TH)
      {
        acceleration[0] = 0;
      }
      // Double integration
      if(acceleration[0] != 0)
      {
        velocity = pre_velocity + (acceleration*dt);
        position = position + pre_velocity*dt + (0.5*acceleration*dt*dt);
        pre_velocity = velocity;
      }

I believe you should pass the `acceleration` by reference, not by value, try adding the `&` like this: `LSM6DS0_FIFO_OutRawGet(&acceleration)` — campescassiano, Jun 09 '20 at 02:55
Also, you are using `acceleration` as an array (`acceleration[1]`, for example), but you have declared it as a simple variable (`static float acceleration = 0.0`). — campescassiano, Jun 09 '20 at 02:59
@campescassiano I just modified the content. I have verified that the acceleration value read out is correct. — 張簡麒耀, Jun 09 '20 at 03:02
How many samples do you take? That is, how many times do you measure acceleration? — Beta, Jun 10 '20 at 13:49

How to calculate speed by accelerometer in C?

0 Answers0