The research conducted and led by Dr. Siegel has centered around the systems engineering problem of developing large, complex (both technically and social) societal systems. He has been the actual lead-designer &/or program manager for several such systems, has drawn lessons-learned from those experiences, has used the large volume of actual programmatic metrics available from those experiences to design research programs to create new insights into the root-cause of such failures, and created (and validated through his research programs) a set of novel techniques intended to provide better outcomes for such large system development programs. This has involved the creation of design patterns and design guidelines for such systems, methodological guidance, metrics for assessing the adequacy of a design, and guidance for how best to assign people to tasks on such teams. This research has been validated through its application to real development programs, with striking and significant positive results. He has identified novel root-causes of system-development failures, new methods to correct those root-causes, and at present, is working to apply of those new techniques to problem domains such as health, energy, and Government information systems.
An additional research focus has been how to implement large, mobile, ad-hoc radio networks over relatively low data-rate carriers, focusing on what he calls "infrastructureless" networks (e.g., wireless radio-frequency networks that have no fixed infrastructure, such as cell-phone towers, repeaters, etc.) and techniques for achieving acceptable dynamics through what he calls "force-structure-aware" networks. He has been a pioneer in large-scale deployments of GPS-enabled applications (like the Blue-Force Tracking system). Many of the techniques that he has developed in this area have been incorporated into almost every smart-phone and tablet computer on the planet.
He has been the sponsor for important research in the field of human-computer interaction, including the original patent for automatically rotating a computer display on a mobile device to match the cardinal points (another of his inventions that have been incorporated into countless devices). Other aspects of his human-computer interaction research has resulted in the controlling patents for computer multi-touch (e.g., controlling the action of a computer through touching a computer screen with multiple fingers simultaneously) and free-space gesture (e.g., controlling a computer through free-space gestures without having to wear specially-instrumented gloves, rings, or similar apparatus).