accelXY to double servo angles (for Node-RED demo)

transAccelsToAngles.js

/* Parse a string received as MQTT message to a JSON object */
var data = JSON.parse(msg.payload);

/* Extrace attributes stored in the JSON */
var accelX = data.accelX;
var accelY = data.accelY;

/* Compute the Theta and Phi from Acceleration along x/y axis */
var theta = - (Math.asin(accelY));
var phi = Math.asin(accelX/Math.cos(theta));

/* Compute the angles and translate them from radians to degrees */
var angleX = 180 * (theta / Math.PI) + 90;
var angleY = 180 * (phi / Math.PI) + 90;

/* Return the computed angles in a message format for Node-RED */
return {
	payload: {
		pwm0: angleX,
		pwm1: angleY
	}
};