Unity - Di chuyen huong ngau nhien

using UnityEngine;
using System.Collections;

public class EnemyBehaviour : MonoBehaviour {
    public Rigidbody2D rd;
    // Use this for initialization
    void Start () {
        rd = GetComponent<Rigidbody2D> ();
        Vector3 targetDirection = Random.insideUnitSphere * 5;
        targetDirection.z = 0;
        rd.velocity = targetDirection;
    }

    // Update is called once per frame
    void Update () {

    }
}