AI in unity, need help

I need some help with my AI I was working on, my code below

 using UnityEngine;
 using System.Collections;
 
 public class NewAITest : MonoBehaviour
 {
     public float motionSpeed = 1f;
     
     void Update()
     {
         // Rays
         Vector3 upRay = transform.TransformDirection(Vector3.forward);
         Vector3 downRay = transform.TransformDirection(Vector3.down);
         
         // Up and down motion
         if(Physics.Raycast(transform.position,upRay,2))
         {
             transform.Translate(Vector3.back *  * Time.deltaTime);
         }
         
         else if(Physics.Raycast(transform.position,downRay,2))
         {
             transform.Translate(Vector3.forward * 1 * Time.deltaTime);
         }
     }
 }