直接上代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using UnityEngine;
using Random = UnityEngine.Random;

    public class Bat : MonoBehaviour
    {
        public Rect FlyRect;
        public float MoveSpeed;
        public float RotationLerpFactor;
        private Vector2 _flyTarget;
        private const float _targetSqDist = 1*1;

        void OnEnable()
        {
            FindNewFlyTarget();
        }

        void Update()
        {
            var pos = transform.position;
            var rot = transform.rotation;

            while (((Vector2) pos - _flyTarget).sqrMagnitude < _targetSqDist)
                FindNewFlyTarget();

            var direction = rot*new Vector3(0, 1, 0);
            var targetRot = Quaternion.Euler(0, 0, (_flyTarget - (Vector2)pos).AngleZ());
            transform.rotation = Quaternion.Lerp(rot, targetRot, RotationLerpFactor*Time.deltaTime);

            transform.position = pos + direction*MoveSpeed*Time.deltaTime;
        }

        void FindNewFlyTarget()
        {
            var x = Random.Range(FlyRect.xMin, FlyRect.xMax);
            var y = Random.Range(FlyRect.yMin, FlyRect.yMax);
            _flyTarget = new Vector2(x, y);
        }

        void OnDrawGizmosSelected()
        {
            Gizmos.DrawWireCube(FlyRect.center, FlyRect.size);
        }
    }

将该脚本附在要运动的物体上，设定范围

Done ！