An Attitude and Heading Reference System (AHRS) provides orientation information of an object such as an Unmanned Air Vehicle by fusing sensor data from a magnetic and inertial measurement unit (MIMU). A MIMU consists of three components, which are a gyroscope, an accelerometer and a magnetometer. There are different fusion or filter algorithms available of which we have chosen the Mahony, the Madgwick, and the weighted filter. One of the shortcomings of all algorithms is that there is a control parameter involved in each which needs to be determined before applying the algorithms. Only an algorithm with an optimized control parameter achieves the best orientation information. Thus, a Particle Swarm Optimization algorithm is used to identify the control parameter of each filter algorithm. Experimental results show the influence the control parameter has on each algorithm.