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I have a question about the friction force experiment. #1669

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2-woo-10 opened this issue May 16, 2024 · 2 comments
Open

I have a question about the friction force experiment. #1669

2-woo-10 opened this issue May 16, 2024 · 2 comments
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question Request for help or information

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@2-woo-10
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Hello.

I am conducting a test to check the sensor data provided by Mujoko.

What I want to do at the moment is to change the contact parameters and find the optimal contact parameters.

To this end, we are conducting the following experiment.

  • This is an experiment to check the accelerometer, velocimeter, attached to the rectangular parallelepiped when a force is applied to the rectangular parallelepiped with xfrc_applied.

It is an experiment in which an object moves when a force greater than the friction force is applied by increasing the magnitude of the applied force.

In my opinion, if you apply about 10N to a rectangular parallelepiped with 1kg mass in the x-axis direction, the value will not be measured in the accelerometer.

This is because vertical drag x friction coefficient (coefficient of friction is 1) = approximately 10N.

However, when you apply force, the object appears to rotate without maintaining contact with the floor.
Also, when I look at the data on the sensor, it shows 10m/s^2, can you explain this?

Also, why does an object move more and more when you apply a force to 10N, and the object rolls around?

The following is an image of sensor data.
d->xfrc_applied[(mj_name2id(m, 5, "object")*6)] = 10;

image

minimal XML 
<!-- Background -->
<texture type="skybox" builtin="gradient" rgb1="0.3 0.5 0.7" rgb2="0 0 0" width="512" height="3072"/>
<texture type="2d" name="groundplane" builtin="checker" mark="edge" rgb1="0.2 0.3 0.4" rgb2="0.1 0.2 0.3"
markrgb="0.8 0.8 0.8" width="300" height="300"/>
<material name="groundplane" texture="groundplane" texuniform="true" texrepeat="5 5" reflectance="0.2"/>

<light pos="0 0 1.5" dir="0 0 -1" directional="true"/>
<geom name="floor" size="0 0 0.05" type="plane" material="groundplane"/>


<body name="object" pos="0.0 0.0 0.05">
  <joint type="free"/>
  <geom name="object" type="box" mass="1" size="0.20 0.20 0.050" rgba="0. 0 0. 1" condim="1" friction="1 0.005 0.0001" priority="1"/>
  <site name="sensor" type="box" size="0.00001 0.00001 0.00001 " />
</body>

Here is a screenshot / video, illustrating my question:
@2-woo-10 2-woo-10 added the question Request for help or information label May 16, 2024
@2-woo-10
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The second graph came out incorrectly, and a force is currently being applied to 10N in the x-axis direction.

@yuvaltassa
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Can you post a video of what's happening in the scene?

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@yuvaltassa @2-woo-10