Unity逐渐停止对称运动的物体

public class ShakeRun : MonoBehaviour
{
    //float rawY; //弹动的点
    float startY; // 物体一开始的点
    float curForce; //力量
    float speed = 20; //定值改编运动速度
    float currentY; //物体要运动的点
    float curVelocity; //速度
    [Range(0.000001f, 0.9999999f), SerializeField]
    float attenFac = 0.2f;

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.W))
        {
            startY = this.transform.position.y;
            SetTaily(startY + 1);
        }
        this.transform.position = new Vector3(this.transform.position.x,currentY,this.transform.position.z);
        if (Input.GetKey(KeyCode.W))
        {
            CheckForce();
        }
    }

    void CheckForce()
    {
        SetForce();
        curVelocity += curForce * Time.deltaTime * speed;
        currentY +=  curVelocity * Time.deltaTime * speed;
        curVelocity -= curVelocity * attenFac * Time.deltaTime * speed;
    }

    void SetForce()
    {
        curForce = (startY - currentY) * 0.8f;
        Debug.Log(curForce);
    }
    void SetTaily(float f)
    {
        currentY = f;
        SetForce();
        curVelocity = curForce;
    }
}