Unity C# Rigidbody Character Control

using UnityEngine;
using System.Collections;

public class Player : MonoBehaviour {

    public int turnSpeed;
    public int moveSpeed;
    public int jumpForce;

    bool onGround;

    // Use this for initialization
    void Start () {

    }

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

        float h = Input.GetAxis("Horizontal");
        float v = Input.GetAxis("Vertical");

        transform.Rotate( 0, h * turnSpeed * Time.deltaTime, 0 );
        Vector3 moveAmount = transform.forward * v * moveSpeed;
        rigidbody.MovePosition( transform.position + moveAmount * Time.deltaTime );
        rigidbody.velocity = moveAmount + Vector3.Scale(rigidbody.velocity, new Vector3(0,1,0));

        if (onGround && Input.GetKey(KeyCode.Space))
        {
            rigidbody.AddForce( transform.up * jumpForce, ForceMode.Impulse );
            onGround = false;
        }
    }

    void OnCollisionEnter() {

        onGround = true;

    }

}