How to do a quaternion transform in c#

Questions & Answers
1

I have a 9 DOF IMU sensor connected through an Arduino and the values are exposed as public static floats.

So I have float UnitySerialPort.x, y, z, w. Values are between -1 and 1. I want to use these values to transform/rotate an object. All the examples I can find are either in JS or just for euler x,y,z transforms only.

Anyone have an examples?

Thanks!

2

transform.rotation = new Quaternion(x, y, z, w);

3

The first thing I do is take an initial reading from my IMU to get the quaternion values before I move it.
X, Y, Z, W = 0.0181, -0.7184, 0.0104, 0.6953. If I apply that transform it’s going to immediately move my object. I only want to move it relative to this position. So I save these values into a Quaternion called initialQ. newQ are my readings that are updating 10 times per second. finalQ is what I then use to do the transform which should be relatively small movements.

If I do a Debug.Log(initialQ) I get back 0, -0.7, 0, 0.7. So clearly it’s rounding them which is going to be a problem because the initialQ won’t look much different than newQ because my movements are small. Even my finalQ comes back as 0, -0.7, 0, 0.7. If my initialQ and newQ are basically the same then shouldn’t finalQ end up as 0?

Even then with a finalQ like that I applied the transform and it didn’t move the object.

    void Start() {

    headIMUobj = GameObject.FindGameObjectWithTag("headTag");
    // connect to Arduino, get initial reading once (initialQ) and then loop to get newQ readings after that. 
    }

   	void Update () {

    		Quaternion newQ = new Quaternion (x, y, z, w);
    		Quaternion finalQ = new Quaternion ();
    		Quaternion inverseQ = Quaternion.Inverse (newQ);
    
    		finalQ = initialQ * newQ * inverseQ;
    		Debug.Log ("InitialQ: " + initialQ);
    		Debug.Log ("NewQ:" + newQ);
    		Debug.Log ("InverseQ: " + inverseQ);
    		Debug.Log ("FinalQ: " + finalQ);
    		//headIMUobj.transform.rotation = new Quaternion (x, y, z, w);
    		headIMUobj.transform.rotation = finalQ;
    		
    	}
    }