效果
手指或鼠标拖动方向盘旋转，有角度限制，松手后自动回转。

代码
将代码添加到方向盘Image上。
注意需要赋值Canvas。

using UnityEngine;
using UnityEngine.EventSystems;

public class SteeringWheel : MonoBehaviour,IDragHandler,IEndDragHandler,IBeginDragHandler
{
    
    
    public Canvas CanvasRoot;//需要指定画布 

    private bool m_IsFirst = true;           //用于记录第一帧按下鼠标时鼠标的位置，便于计算
    private Vector3 m_CurrentPos;            //记录当前帧鼠标所在位置
    private bool m_IsClockwise;              //是否顺时针
    private float m_RoundValue = 0;          //记录总的旋转角度 用这个数值来控制一圈半
    private bool m_IsTuringSteeringWheel;    //是否在转方向盘 用这个判断复位

    public void OnDrag(PointerEventData eventData)
    {
    
    
        m_IsTuringSteeringWheel = true;
        Vector2 pos;
        if (RectTransformUtility.ScreenPointToLocalPointInRectangle(CanvasRoot.GetComponent<RectTransform>(),
#if !UNITY_EDITOR
                Input.GetTouch(0).position,
#else
                Input.mousePosition,
#endif
            CanvasRoot.worldCamera, out pos))    //获取鼠标点击位置
        {
    
    
            Vector3 pos3 = new Vector3(pos.x, pos.y, 0);                           //计算后鼠标以方向盘圆心为坐标原点的坐标位置
            pos3 = CanvasRoot.transform.TransformPoint(pos3); //转换为世界坐标

            if (m_IsFirst)
            {
    
    
                m_CurrentPos = pos3;
                m_IsFirst = false;
            }
            Vector3 currentPos = Vector3.Cross(pos3 - transform.position, m_CurrentPos - transform.position);             //计算当前帧和上一帧手指位置 用于判断旋转方向
            if (currentPos.z > 0)
            {
    
    
                m_IsClockwise = true;
            }
            else if (currentPos.z < 0)
            {
    
    
                m_IsClockwise = false;
            }

            if (m_CurrentPos != pos3)                                 //范围内让方向盘随着手指转动
            {
    
    
                if (m_IsClockwise)
                {
    
    
                    if (m_RoundValue <= MAX_ANGLE)
                    {
    
    
                        m_RoundValue += Vector3.Angle(m_CurrentPos - transform.position, pos3 - transform.position) * speedMul;

                        transform.Rotate(new Vector3(0, 0, -Vector3.Angle(m_CurrentPos - transform.position, pos3 - transform.position)) * speedMul);
                    }
                }

                else
                {
    
    
                    if (m_RoundValue >= -MAX_ANGLE)
                    {
    
    
                        m_RoundValue -= Vector3.Angle(m_CurrentPos - transform.position, pos3 - transform.position) * speedMul;

                        transform.Rotate(new Vector3(0, 0, Vector3.Angle(m_CurrentPos - transform.position, pos3 - transform.position)) * speedMul);
                    }
                }

            }
            m_CurrentPos = pos3;
        }
    }

    public void OnEndDrag(PointerEventData eventData)
    {
    
    
        m_IsFirst = true;
        m_IsTuringSteeringWheel = false;
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
    
    
        m_IsTuringSteeringWheel = true;
    }

    void Start()
    {
    
    
        CanvasRoot = GameObject.Find("Canvas").GetComponent<Canvas>();
    }


    void Update()
    {
    
    
        if (!m_IsTuringSteeringWheel && m_RoundValue != 0)               //复位
        {
    
    
            if (m_RoundValue >= 0)
            {
    
    
                m_RoundValue -= 8f;               //复位速度
                if (m_RoundValue < 0)
                    m_RoundValue = 0;
                transform.rotation = Quaternion.Euler(new Vector3(0, 0, -m_RoundValue));
            }
            else
            {
    
    
                m_RoundValue += 8f;
                if (m_RoundValue > 0)
                    m_RoundValue = 0;
                transform.rotation = Quaternion.Euler(new Vector3(0, 0, -m_RoundValue));
            }
        }
    }
}