Make rigidbody walk like character controller

I know I'm a bit late but this may help someone.

The RigidbodyFPSWalker script from the Unity Wiki don't work because it adds the velocity of the object the character is standing on to its own velocity, without checking the nature of this object which may cause a sudden increase of velocity in an unrealistic way. Also, it has an error where it does not make it zero when it's standing over an object which doesn't have a rigid body.

Well I put here the code with some fixes (C#). I think it works quite well now. And here is a LINK to download a sample project. Hope it helps.

 using UnityEngine;
 using System.Collections;
 
 [RequireComponent(typeof(Rigidbody))]
 [RequireComponent(typeof(CapsuleCollider))]
 
 public class RigidbodyFPS : MonoBehaviour
 {
     #region Variables (private)
 
     private bool grounded = false;
     private Vector3 groundVelocity;
     private CapsuleCollider capsule;
 
     // Inputs Cache
     private bool jumpFlag = false;
 
     #endregion
 
     #region Properties (public)
 
     // Speeds
     public float walkSpeed = 8.0f;
     public float walkBackwardSpeed = 4.0f;
     public float runSpeed = 14.0f;
     public float runBackwardSpeed = 6.0f;
     public float sidestepSpeed = 8.0f;
     public float runSidestepSpeed = 12.0f;
     public float maxVelocityChange = 10.0f;
 
     // Air
     public float inAirControl = 0.1f;
     public float jumpHeight = 2.0f;
 
     // Can Flags
     public bool canRunSidestep = true;
     public bool canJump = true;
     public bool canRun = true;
 
     #endregion
 
     #region Unity event functions
 
     /// <summary>
     /// Use for initialization
     /// </summary>
     void Awake()
     {
         capsule = GetComponent<CapsuleCollider>();
         rigidbody.freezeRotation = true;
         rigidbody.useGravity = true;
     }
 
     /// <summary>
     /// Use this for initialization
     /// </summary>
     void Start()
     {
 
     }
 
     /// <summary>
     /// Update is called once per frame
     /// </summary>
     void Update()
     {
         // Cache the input
         if (Input.GetButtonDown("Jump"))
             jumpFlag = true;
     }
 
     /// <summary>
     /// Update for physics
     /// </summary>
     void FixedUpdate()
     {
         // Cache de input
         var inputVector = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
 
         // On the ground
         if (grounded)
         {
             // Apply a force that attempts to reach our target velocity
             var velocityChange = CalculateVelocityChange(inputVector);
             rigidbody.AddForce(velocityChange, ForceMode.VelocityChange);
 
             // Jump
             if (canJump && jumpFlag)
             {
                 jumpFlag = false;
                 rigidbody.velocity = new Vector3(rigidbody.velocity.x, rigidbody.velocity.y + CalculateJumpVerticalSpeed(), rigidbody.velocity.z);
             }
 
             // By setting the grounded to false in every FixedUpdate we avoid
             // checking if the character is not grounded on OnCollisionExit()
             grounded = false;
         }
         // In mid-air
         else
         {
             // Uses the input vector to affect the mid air direction
             var velocityChange = transform.TransformDirection(inputVector) * inAirControl;
             rigidbody.AddForce(velocityChange, ForceMode.VelocityChange);
         }
     }
 
     // Unparent if we are no longer standing on our parent
     void OnCollisionExit(Collision collision)
     {
         if (collision.transform == transform.parent)
             transform.parent = null;
     }
 
     // If there are collisions check if the character is grounded
     void OnCollisionStay(Collision col)
     {
         TrackGrounded(col);
     }
 
     void OnCollisionEnter(Collision col)
     {
         TrackGrounded(col);
     }
 
     #endregion
 
     #region Methods
 
     // From the user input calculate using the set up speeds the velocity change
     private Vector3 CalculateVelocityChange(Vector3 inputVector)
     {
         // Calculate how fast we should be moving
         var relativeVelocity = transform.TransformDirection(inputVector);
         if (inputVector.z > 0)
         {
             relativeVelocity.z *= (canRun && Input.GetButton("Sprint")) ? runSpeed : walkSpeed;
         }
         else
         {
             relativeVelocity.z *= (canRun && Input.GetButton("Sprint")) ? runBackwardSpeed : walkBackwardSpeed;
         }
         relativeVelocity.x *= (canRunSidestep && Input.GetButton("Sprint")) ? runSidestepSpeed : sidestepSpeed;
 
         // Calcualte the delta velocity
         var currRelativeVelocity = rigidbody.velocity - groundVelocity;
         var velocityChange = relativeVelocity - currRelativeVelocity;
         velocityChange.x = Mathf.Clamp(velocityChange.x, -maxVelocityChange, maxVelocityChange);
         velocityChange.z = Mathf.Clamp(velocityChange.z, -maxVelocityChange, maxVelocityChange);
         velocityChange.y = 0;
 
         return velocityChange;
     }
 
     // From the jump height and gravity we deduce the upwards speed for the character to reach at the apex.
     private float CalculateJumpVerticalSpeed()
     {
         return Mathf.Sqrt(2f * jumpHeight * Mathf.Abs(Physics.gravity.y));
     }
 
     // Check if the base of the capsule is colliding to track if it's grounded
     private void TrackGrounded(Collision collision)
     {
         var maxHeight = capsule.bounds.min.y + capsule.radius * .9f;
         foreach (var contact in collision.contacts)
         {
             if (contact.point.y < maxHeight)
             {
                 if (isKinematic(collision))
                 {
                     // Get the ground velocity and we parent to it
                     groundVelocity = collision.rigidbody.velocity;
                     transform.parent = collision.transform;
                 }
                 else if (isStatic(collision))
                 {
                     // Just parent to it since it's static
                     transform.parent = collision.transform;
                 }
                 else
                 {
                     // We are standing over a dinamic object,
                     // set the groundVelocity to Zero to avoid jiggers and extreme accelerations
                     groundVelocity = Vector3.zero;
                 }
 
                 // Esta en el suelo
                 grounded = true;
             }
 
             break;
         }
     }
 
     private bool isKinematic(Collision collision)
     {
         return isKinematic(collider.transform);
     }
 
     private bool isKinematic(Transform transform)
     {
         return transform.rigidbody && transform.rigidbody.isKinematic;
     }
 
     private bool isStatic(Collision collision)
     {
         return isStatic(collision.transform);
     }
 
     private bool isStatic(Transform transform)
     {
         return transform.gameObject.isStatic;
     }
 
     #endregion
 }
 

You might want to take a look at the RigidbodyFPSWalker script on the Unity Wiki.

you can have constant velocity by disabling friction and drag and setting the velocity of the rigidbody directly to a value. you should not aply forces and you should just use the velocity property and set it to the value that you want. generally it's not a good idea to make your character move in this way. you should use ragdolls when you need physics and use character controllers when you don't need it. simulating human movements with physics is not an easy task and it will become very heavy. there is a great video about physics in unite 08. one of the problem that is described there is "character simulation using ragdolls or rigidbodies".

hope this helps

It may not be the Character Controller see

http://forum.unity3d.com/viewtopic.php?t=39946

directly controling Velocity ;)

 var speed:float=4;
 function FixedUpdate(){
     rigidbody.velocity=(Input.GetAxis("Horizontal")*transform.right+Input.GetAxis("Vertical")*transform.forward).normalized*speed;
 }