Cyber-physical systems are computers equipped with sensors and actuators that enable them to interact with their surrounding environments. Ground vehicles, drones, and manufacturing robots are examples of such systems that require timing guarantees in addition to functional correctness to achieve their mission objectives. These systems often use multiple microcontroller boards for workload distribution and physical redundancy. The emergence of PC-class embedded systems featuring high processing capabilities and abundant resources presents an opportunity to consolidate separate microcontroller boards as software-defined functions into fewer computer systems. For instance, current automotive systems utilize upwards of 100 electronic control units (ECUs) for chassis, body, power-train, infotainment, and vehicle control services. Consolidation saves manufacturing costs, reduces wiring, simplifies packaging in space-limited situations, and streamlines software update delivery to end-users. However, consolidating functions on PC-class hardware does not address the real-time I/O challenges.
A fundamental problem in such real-time solutions is the handling of device input and output in a timely manner. For example, a control system might require input data from a sensor to be sampled and processed regularly so that output signals to actuators occur within specific delay bounds. Input/output (I/O) devices connect to the host computer using different types of bus interfaces not necessarily supported by PC-class hardware natively. Examples of such interfaces include Controller Area Network (CAN) and FlexRay, which are prominent in the automotive world, but are not found in PC-class embedded systems.
Universal Serial Bus (USB) is now ubiquitous in the PC-class domain, in part due to its support for many classes of devices with simplified hardware needed to connect to the host, and can be utilized to bridge this gap. USB provides the throughput and delay capabilities for next-generation high bandwidth sensors to be integrated with actuators in control area networks. However, typical USB host controller drivers suffer from potential timing delays that affect the delivery of data between tasks and devices.
This Ph.D. thesis examines the use of Universal Serial Bus (USB) as the physical fabric for host-to-device and host-to-host communication, without special switching hardware or protocol translation logic, and through a unified programming interface. Combined with the real-time scheduling framework of the Quest RTOS, this work investigates how to form networks of I/O devices and computing nodes over USB with end-to-end timing guarantees. The main contribution of this thesis is a USB-centric design solution for real-time cyber-physical systems with distributed computing nodes.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/47994 |
| Date | 01 February 2024 |
| Creators | Golchin, Ahmad |
| Contributors | West, Richard |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0018 seconds