1. Satellites Formation Taxonomy Sónia Marques 2 nd ISLAB workshop 2003 18/0//03

2. Satellites Formation What’s a satellite?? Problems arised in satellites?............. Robôt? Monolithic versus synthetic! 2nd ISLAB workshop 2003 -18/0//03

3. Satellites Formation  Satellite Formation: are satellite cluster where its geometry is designed with purpose and operational steps are taken to maintain that geometry.  Satellite Cluster: a group of  2 satellites located in different but similar orbits performing a common mission for a local area. More satellites than required to assure no effect of individual failure to the mission.  Distributed Satellite System: identical to satellite cluster but the diference is that it serves a local area instead of global or larger area. 3 types of geometric architecure (due to mission): 2nd ISLAB workshop 2003 -18/0//03

4. Satellites Formation  Leader following: centralized implementation where the followers are meant to track the position and orientation of the leader with a predefined offset.  Behaviour structure: is a decentralized implementation with several desired behaviors prescribed for each satellite and then the control action applied to each satellite is a weighted average of the control of each satellite behavior.  Virtual or body structure: centralized implementation, the position among agents are required to be constant during all formation motions, such that the formation is treated as a single structure. 3 types of approaches to formation control problem: 2nd ISLAB workshop 2003 -18/0//03

5. Satellites Formation Attitude estimation problems: Relative and absolute distance within formation Accuracy Sensor failure Filter used ( EKF-linearize about a trajectory updated with measurments ) –Linearization, sensor failure (tempararly or occlusion), accuracy 2nd ISLAB workshop 2003 -18/0//03

6. Satellites Formation 3 types of estimation architecure :  Centralized: single formation estimator that collects the sensor measurements, control inputs and configurations of all satellite and estimates the formation attitude  Distributed: each satellite has its own local estimator and provides estimates to a master filter that combines the local estimates.  Descentralized: there is no master estimator. Each individual estimates the subset of formation state variables required for control 3 types of estimation architecure :  Centralized: single formation estimator that collects the sensor measurements, control inputs and configurations of all satellite and estimates the formation attitude  Distributed: each satellite has its own local estimator and provides estimates to a master filter that combines the local estimates.  Descentralized: there is no master estimator. Each individual estimates the subset of formation state variables required for control 2nd ISLAB workshop 2003 -18/0//03