Massimo Tipaldi

Survey on Fault Detection, Isolation, and Recovery Strategies in the Space Domain

past 18 years. In that time, he has conducted and overseen software development activities for a variety of projects, mainly in the area of satellite systems or experimental equipment for the International Space Station. The categories of software productsdevelopedinthis contextareembeddedandflightsoftware, softwarefor test facilities(electrical ground support equipment, special check out equipment), satellite reference databases, satellite simulators, software verification facility (SVF) applications, and ground control software. Mr. Bruenjes obtained his Dipl.-Ing. from the Hochschule Bremen in 1983 after studying electrical engineering and information technology. Since then, he has worked as an electronics and software developer for several companies in the fields of communication systems, computer technologies, and automotive systems. He joined OHB System AG in 1991, and he has since worked on softwareengineeringdisciplinesasconceptandarchitecturedefinitions, teamorganizationandleadership,aswellas the software development tool chain and related methodology implementation. He has special interests in standardized software architectures and building blocks, fault detection, isolation and recovery, future onboard computer architectures, and innovative data and control bus systems for space applications.

A Survey on Model-Based Mission Planning and Execution for Autonomous Spacecraft

Different drivers are nowadays leading spacecraft toward an increased level of on-board autonomy. In this paper, we survey model-based techniques as a vehicle to implement highly autonomous on-board capabilities for spacecraft mission planning and execution. In this respect, spacecraft reconfiguration approaches based on Markovian Decision Process are explored, and then compared with other model-based alternatives. The integration of planning systems and dynamic reprogramming capabilities into the on-board software is presented. Finally, operational concepts for mission planning and execution in recent European space projects as well as the implementation of in-flight adaptive mission operations via on-board control procedures are also analyzed.

Model Predictive Control for Luminous Flux Tracking in Light-Emitting Diodes

Luminous flux tracking and junction temperature stress minimization are typical objectives in the regulation of high-brightness light-emitting diodes (LEDs). In this brief, a solution based on a model predictive controller approach is proposed. The state estimation is obtained using an LED photoelectrothermal dynamic model whose parameters are tuned through datasheets and dedicated experiments. By exploiting the dynamic separation within the thermal state variables of the model, the junction temperature is predicted using LED current and heat sink temperature measurements. The effectiveness of the proposed approach is verified through simulations and experiments on different heat sinks and samples of the same LED family, thus confirming the achievement of the luminous flux tracking under current and temperature constraints typically featuring LED applications.

State aggregation approximate dynamic programming for model-based spacecraft autonomy

Spacecraft autonomy is a crucial aspect of currently developed and future space projects. This paper presents a Markovian Decision Process (MDP) based framework as a way of modeling spacecraft on-board autonomy mechanisms. Its applicability to the three layered autonomous space systems architecture is shown. Special attention is given to its deliberative layer, where Approximate Dynamic Programming (ADP) state aggregation techniques are applied to determine the corresponding sub-optimal policies. An example of such approach is presented, where it is shown how the MDP structure can determine some important properties of the calculated policy, such as the balancing of the spacecraft safety versus the completion of relevant mission objectives.

Photoelectrothermal model predictive control for Light Emitting Diodes

Light Emitting Diodes (LEDs) are one of the most promising technology for the future of lighting. The flexibility required by the dimming regulation introduces different and sometimes conflicting objectives which make challenging the control design. In this paper, a photoelectrothermal model of LED integrated with the dynamics of the power converter is presented. The model is used to design a model predictive control which allows the regulation of current, temperatures and luminous flux by satisfying the typical constraints on the control variable and on thermal and electrical state variables. The effectiveness of the proposed controller is verified though simulations by using a LED model whose parameters are tuned from commercial datasheets.

Fault detection and resolution based on extended time failure propagation graphs

FDIR functionalities are investigated since the very beginning of a space mission and play a relevant role in the definition of its autonomy, reliability and availability objectives. In this paper, an analytical methodology derived from the Timed Failure Propagation Graph (ETFPG) is proposed. TPFG is a causal model that captures the temporal aspects of failure propagation in a wide variety of engineering systems. It has been extended in order to incorporate the recovery actions as well as to accommodate the dependencies on the mission phases and spacecraft operational modes in the related graphs. The proposed methodology has proved to be very useful in the context of the trouble identification and shooting of complex system, such a satellite.