public class GroundChecker : MonoBehaviour {

private Character player;
private void Start()
{
    player = GetComponentInParent<Character>();
}
 private void OnTriggerEnter2D(Collider2D collision)
   {
       if ( collision.gameObject.layer==8)//8 слой-слой с объектами по которым можно ходить
       {
           player.onGround = true;

       }

}
private void OnTriggerStay2D(Collider2D collision)
{
    if (collision.gameObject.layer == 8)
    {
        player.onGround = true;
    }
}

private void OnTriggerExit2D(Collider2D collision)//Проблемный участок       {
       if (collision.gameObject.layer==8)
       {
           player.onGround = false;

       }
   }}