Issue giving object player's hand position

Question

I'm trying to put an object (for example a sword) in my player's hand. To do so i set the player's hand transform as the object's parent, in order to have the same movement for the object and the hand. No problem here.

The real issue starts as soon as i set the sword position to the hand position. My player starts to move backward.

One of my doubt was that my sword has a rigid body and my player too, so it could have an impact on it because I know that you can set a rigid body as a rigid body child.

So I was wondering if it's the right way to do it.

Edit

Here is my script to pickup an item:

 public void PickupItem()
    {
        Ray interactionRay = Camera.main.ScreenPointToRay(Input.mousePosition);
        RaycastHit interactionHit;

        if (Physics.Raycast(interactionRay, out interactionHit, InteractionMaxDistance))
        {
            if (interactionHit.collider.tag == "LootableItem")
            {
                Item item = interactionHit.collider.gameObject.GetComponent<Item>();
                GetComponent<CharacterStats>().AddStats(item.Stats);

                _hand = TransformUtil.FindChild("mixamorig:RightHandMiddle1", _player);
                item.GetComponent<Rigidbody>().isKinematic = true;
                item.GetComponent<Rigidbody>().useGravity = false;

                item.transform.parent = _hand;
                item.transform.position = _hand.position;
                item.transform.rotation = _hand.rotation;
            }
        }
    }

My script for player movement :

void Update()
    {
        float translation = (Input.GetAxis("Vertical") * Speed) * Time.deltaTime;
        float rotation = (Input.GetAxis("Horizontal") * RotationSpeed) * Time.deltaTime;
        transform.Translate(0, 0, translation);
        transform.Rotate(0, rotation, 0);

        if (Input.GetButtonDown("Jump"))
        {
            _animator.SetTrigger("triggerJump");
            return;
        }


        if (Math.Abs(translation) < 0.01 && Math.Abs(rotation) < 0.01)
        {
            Speed = 1;
        }
        else
        {
            if (Input.GetKey(KeyCode.LeftShift))
            {
                Speed = 4;
                RotationSpeed = 150;
            }
            else
            {
                Speed = 2;
                RotationSpeed = 200;
            }
        }

        _animator.SetFloat("speed", Speed);
        _animator.SetFloat("rotation", rotation);
        _animator.SetFloat("translation", translation);
    }

I took my character from Mixamo, same for the animaitons.

Answer 1

It sounds like the physics engine might be finding a collision between the player's dynamic collider and the sword's, and is trying to move them apart to resolve the collision.

If you want the player to ignore self-collisions with objects they've picked up, you can call:

Physics.IgnoreCollision(playerCollider, itemCollider, true);

Once you've dropped the item, you can re-enable collisions between it and the player using:

Physics.IgnoreCollision(playerCollider, itemCollider, false);

Answer 2

I found a solution, it's not the best but it works.

When I equip my sword I destroy the Rigidbody and set it's Collider to isTrigger in order to detect collisions.

Destroy(item.getComponent<RigidBody>);
item.getComponent<Collider>().isTrigger = true;

And once I drop it, i add a new rigid Rigidbody and I switch isTrigger to false.

item.addComponent<RigidBody>();
item.getComponent<Collider>().isTrigger = false;

ps: If anyone has a better solution I would really appreciate.