How to move character inside circle ?like super sonic. Unity 2D

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ı want to move my character inside this circle like super sonic. He will turn around inside circle then will exit from circle. I did entering and exiting parts but cant do movement.

( ruCollider : Collider 2D component of round-up object , rdCollider is for round-down)

Here is my Code

enter code here private void OnCollisionEnter2D(Collision2D col)
{

        if(col.gameObject.name=="downright"|| col.gameObject.name=="topright")
        {
            downleftcol.enabled = true;
            topleftcol.enabled = true;

        }
        for (float timeStart = 0; timeStart < 3; timeStart += Time.deltaTime)
        {

            if (col.gameObject.name == "topleft"|| col.gameObject.name=="downleft")
            {
                downrightcol.enabled = false;
                toprightcol.enabled = false;
            }

        }

ı have a circle like this. Its made of 4 parts top-left , top-right , bot-left, bot-right but i cant move inside of it .What should i add to my code ?

I forgot to say how i can rotate my character inside circle ?