【PyChrono's API】Can I record video of the simulation? save IMU data to CSV?

[Shunya]

Dear all,

I hava two questions about PyChrono's API.

Q1:Is it possible to record video of the simulation using PyChrono's API?

Q2: Is it possible to save IMU data to CSV using PyChrono's API?

Background of questions:

I am making the vehicle runnning model in PyChrono, referring to "demo_MBS_tracks.cpp".

I would like to save the data from IMU to CSV in order to check the running status.

And I would like to save the video of the nehicle running in the simulation.

Best regards,

[Nevindu Batagoda]

Hello Shunya,

For Q2, I don't believe there is a direct API call to do this but what you can do is, 

1. Push a data access filter for the IMU (either for the accelerometer, gyro, or magnetometer) after constructing it. Ex:   acc.PushFilter(sens.ChFilterAccelAccess())
2. Then during the simulation loop, access the IMU data and publish them into a CSV file. Here is an example of accessing and printing accelerometer data,

 while (ch_time < end_time):

        # Access the sensor data

        acc_data = acc.GetMostRecentAccelBuffer()

        # Check data is present

        # If so, print out the max value

        if acc_data.HasData():

            print("Accelerometer:",acc_data.GetAccelData().shape,"max:",np.max(acc_data.GetAccelData()))

A full demo can be seen here: https://github.com/projectchrono/chrono/blob/main/src/demos/python/sensor/demo_SEN_sensors.py

Let me know if there's anything else.

Best,

Nevindu M. Batagoda

[Luning Bakke]

For Q1, there's an API, WriteImageToFile(filename) ,  for taking a snapshot of the irrlicht visualization at each rendering frame, then you can stitch together the pictures to make a video.

 

vis.BeginScene()

vis.Render()

vis.EndScene()

 

if (steps % render_steps == 0):

        filename = 'img_'+ str(render_frame).zfill(4) +'.jpg'

        vis.WriteImageToFile(filename)

        render_frame += 1

 

Thank you,

Luning

[Shunya]

Thanks both of you!

I would like to ask an additional question.

About Q1:
I entered the code you gave me, but only the first render was saved.
I saved the code to an image, and I need some advice.

About Q2:
I would like the acceleration for each calculation step to be added in csv during the simulation.
In the current code (image), only the latest acceleration is saved in csv.
This question is far from PyChrono, but I would like to get some advice on how to implement it.

Best regards,

Shunya

2023年6月16日金曜日 16:38:08 UTC-5 lfa...@wisc.edu:

[Luning Bakke]

Hello Shunya,

I took a look at these two lines,

render_step_size = 1.0 / 100

render_steps = math.ceil((1.0 / render_step_size) / step_size)

the render_steps will be ceil(100/step_size), which means an image is written every (100/step_size) time steps.

You probably want to do something like,

render_steps = math.ceil((render_step_size) / step_size)

Thank you,

Luning

[Shunya]

Dear Luning,
I could fix the Q1.
Thank you!

Best regards,

Shunya

2023年6月20日火曜日 13:42:29 UTC-5 lfa...@wisc.edu: