help! stuck with rigidbody behaviour

Hi all.

I'm so tired to fight with rigidbody. I'm using the following code to make my agent run.

Code (CSharp):

1.         switch (action)
2.         {
3.             case 1:
4.                 dirToGo = this.transform.forward * 1f;
5.                 break;
6.             case 2:
7.                 dirToGo = this.transform.forward * -1f;
8.                 break;
9.             case 3:
10.                 rotateDir = this.transform.up * 1f;
11.                 break;
12.             case 4:
13.                 rotateDir = this.transform.up * -2f;
14.                 break;
15.         }
16.         this.transform.Rotate(rotateDir, Time.deltaTime * 200f * 2.0f);
17.         rBody.AddForce(dirToGo * 2f, ForceMode.VelocityChange);
18.  
19.         Vector3 curVelocity = rBody.velocity;
20.         rBody.velocity = Vector3.ClampMagnitude(curVelocity, maxAgentSpeed);

My arena is flat and I expect to have Y Axis value as 0.5 for my agent. This the config of the rigidbody.


But at some point of training, after collision with another object starts to change it's Y axis value.

I'm trying to return it back to Y=0.5 checking Y value and calling Done() if it is higher than 0.6 or lower than 0.4. In AgentReset() I call the code below.

Code (CSharp):

1.         rBody.angularVelocity = Vector3.zero;
2.         rBody.velocity = Vector3.zero;
3.         rBody.Sleep();
4.         agent.transform.position = new Vector3(curPos.x, 0.5f, curPos.z);
5.         agent.transform.localPosition = new Vector3(curPos.x, 0.5f, curPos.z);

but it does not help, the agent starts resetting almost indefinitely and does not want to change Y back to 0.5.

I check all colliders on the scene, they all correct and intersect the arena by 90 degrees.

I also tried to Freeze Y position in Rigidbody interface, but in this case my agent stops moving at all.

I do not have an idea how to fix that. Parsed all Google, but still does not have a solution.
I still think it is something very silly and answer is simple and probably I just do not understand the logic of rigidbody.
Anyway if you can give an advice, it will be great.

Thanks in advance.