Although the IT transformation in the 20th century appeared revolutionary, a bigger change is probably yet to come. The terms "Cooperating-Objects" or "Cyber-Physical Systems (CPS)" have come to describe the research and technological effort that will ultimately efficiently allow interlinking the real world physical objects and cyberspace. Actually the integration of physical processes and computing is not new. Embedded systems have been in place since a long time to denote systems that combine physical processes with computing. The revolution will come from extensively networking embedded computing devices, in a blend that involves sensing, actuation, computation, networking, pervasiveness and physical processes. Such extreme networking poses considerable technical challenges ranging from the (distributed) programming paradigms (languages still lacking temporal semantics, suitable concurrency models and hardware abstractions) to networking protocols with timeliness as a structuring concern, and including systems theory that combines "physical concerns" (control systems, signal processing, etc.) and "computational concerns" (complexity, schedulability, computability, etc.).
On Going Research
Highly Scalable Aggregate Computations in Cyber-Physical Systems
One of our main running efforts is related to solve the problem of performing scalable and efficient information processing in large-scale and dense cyber-physical systems.
In such large scale dense networked systems, the simple problem of computing an aggregate quantity such as the minimum (MIN) sensed temperature among the nodes becomes a non trivial problem: communicating sensor data individually makes the time-complexity of computing MIN is a function of the number of nodes.
In fact, the problem of performing scalable and efficient information processing emerges as being one of the major unsolved problems in large-scale dense cyber-physical systems. With “efficient information processing” we mean that the desired computation is performed while consuming very little resources such as energy, communication links, memory and processor. With “scalable”, we mean that the consumption of resources increases slowly or not at all as the number of sensor readings to be processed and/or the number of embedded computer nodes increase.
We have been developing a novel approach which excels the co-design of (i) distributed algorithms for sensor data processing and (ii) underlying networked distributed computing systems with corresponding resource management schemes such that the utilization of resources is low.
We have recently introduced a family of Medium Access Control (MAC) protocols that are inspired on Dominance (or, Binary-Countdown) protocols. For more details, check out our PrioMAC webpage. By associating the priorities of messages to physical quantities (such as temperature, gas concentration, lightness), several high-performance algorithms for data processing can be devised in which time-complexity is independent of the number of nodes. We denote this simple, but powerful, mechanism as Physical Dynamic Priority Dominance ((PD)2) protocol. We advocate its use as a key component in sensor applications where it is crucial to compute aggregate quantities with low time complexity in large-scale, dense systems. The (PD)2 protocol is in fact an example where communication and computation are tightly connected with the physical environment, which is a fundamental feature of CPS.
For more details on this take a look on the keynote talk by Eduardo Tovar at the at the 16th International Conference on Real-Time and Network Systems (RTNS'08):
You can also take a look at the CPS-SEED (Cyber Physical Systems with ScalablE and Efficient Data processing) research framework webpage.
This framework has been also exploited in the domain of wired networks, and in particular the CAN bus. For more details, checkout our WiSe-CAN webpage.
Projects & Leadership
We are one of the core partners in the European Network of Excellence on Cooperating Objects (CONET).
Under CONET we are leading the cluster on Scalable Data Processing (SDP).
We are one of the key partners of the CIRA (Critical Infratsructures and Risk Assessment) initiative of the Portugal-CMU partnership.
International Workshop on Cyber-Physical Systems Challenges and Applications (CPS-CA'08).
Keynote talk at the 16th International Conference on Real-Time and Network Systems (RTNS'08) on "Highly Scalable Aggregate Computations in Cyber-Physical Systems: Physical Environment Meets Communication Protocols".
Guest editors of a Special Section on "From Embedded Systems to Cooperating Objects" of the IEEE Transactions on Industrial Informatics.
- The RTCSA 2006 paper that describes the implementation of the Wireless Dominance-based (WiDOM) protocol;
- The RTSS 2007 paper on the WiDOM soultion for wireless networks with multiple broadcast domains;
- The RTN 2008 paper that introduces the concept of the Physical Dynamic Priority Dominance ((PD)2) protocol;
- The 2008 IEEE Transactions on Industrial Informatics paper that describes the scalable interpolation scheme based on the ((PD)2) protocol and implemented for CAN networks;
- The RTAS 2009 paper that describes the wireless solution for the scalable interpolation scheme based on the ((PD)2) protocol and implemented for wireless motes.