In general, a MEMS attitude reference system (ARS) estimates attitude (roll and pitch) of the body relative to the reference frame by implementing gyro sensors and accelerometers on all three axes. Some system using a MEMS ARS like a small aerial vehicle has one or more actuators. These actuators generate the platform vibration which acts on dynamic acceleration of accelerometers and degrade the ARS performance. Since the vibration has a time-varying frequency and occurs continuously while the vehicle is maneuvering, it cannot be isolated or attenuated by simple low pass filter. For this reason, a 2nd order infinite impulse response notch filter has been designed and the filter coefficients have been adjusted based on the least mean square method so as to identify and reject the unknown time-varying vibration frequency. To evaluate the designed MES ARS, it has been mounted on the small quad-rotor helicopter and some experimental results of attitude estimation are given.

A practically applicable collision-free trajectory planning technique for two robot systems is proposed. The robot trajectories considered in this work are composed of many segments between which the robots stop to assemble, weld, or do other jobs by end-effector. The proposed method is based on the planning-coordination decomposition approach in which planning finds the trajectory of each robot independently according to their tasks and coordination finds velocity modification to avoid collision with each other. To fully utilize the convenience of independent trajectory planning and to ensure no geometrical path change after coordination, a simple technique avoiding collision by adding least delay-time in the local sense before moving along the next path-segment is developed. The least delay time is determined by a graphical method on the space called co-ordination space where collision between two robots and coordination of two robots are easily visualized.