1,240 research outputs found
Control and Embedded Computing: Survey of Research Directions
This paper provides a survey of the role of feedback control in embedded realtimesystems, presented in the context of a new EU/IST Network of Excellence, ARTIST2.The survey highlights recent research efforts and future research directions in the areasof codesign of computer-based control systems, implementation-aware embedded controlsystems, and control of real-time computing systems
Control Aware Radio Resource Allocation in Low Latency Wireless Control Systems
We consider the problem of allocating radio resources over wireless
communication links to control a series of independent wireless control
systems. Low-latency transmissions are necessary in enabling time-sensitive
control systems to operate over wireless links with high reliability. Achieving
fast data rates over wireless links thus comes at the cost of reliability in
the form of high packet error rates compared to wired links due to channel
noise and interference. However, the effect of the communication link errors on
the control system performance depends dynamically on the control system state.
We propose a novel control-communication co-design approach to the low-latency
resource allocation problem. We incorporate control and channel state
information to make scheduling decisions over time on frequency, bandwidth and
data rates across the next-generation Wi-Fi based wireless communication links
that close the control loops. Control systems that are closer to instability or
further from a desired range in a given control cycle are given higher packet
delivery rate targets to meet. Rather than a simple priority ranking, we derive
precise packet error rate targets for each system needed to satisfy stability
targets and make scheduling decisions to meet such targets while reducing total
transmission time. The resulting Control-Aware Low Latency Scheduling (CALLS)
method is tested in numerous simulation experiments that demonstrate its
effectiveness in meeting control-based goals under tight latency constraints
relative to control-agnostic scheduling
Stabilizing Scheduling Policies for Networked Control Systems
This paper deals with the problem of allocating communication resources for
Networked Control Systems (NCSs). We consider an NCS consisting of a set of
discrete-time LTI plants whose stabilizing feedback loops are closed through a
shared communication channel. Due to a limited communication capacity of the
channel, not all plants can exchange information with their controllers at any
instant of time. We propose a method to find periodic scheduling policies under
which global asymptotic stability of each plant in the NCS is preserved. The
individual plants are represented as switched systems, and the NCS is expressed
as a weighted directed graph. We construct stabilizing scheduling policies by
employing cycles on the underlying weighted directed graph of the NCS that
satisfy appropriate contractivity conditions. We also discuss algorithmic
design of these cycles
Model-Free Design of Control Systems over Wireless Fading Channels
Wireless control systems replace traditional wired communication with
wireless networks to exchange information between actuators, plants and sensors
in a control system. The noise in wireless channels renders ideal control
policies suboptimal, and their performance is moreover directly dependent on
the way in which wireless resources are allocated between control loops. Proper
design of the control policy and the resource allocation policy based on both
plant states and wireless fading states is then critical to achieve good
performance. The resulting problem of co-designing control-aware resource
allocation policies and communication-aware controllers, however, is
challenging due to its infinite dimensionality, existence of system constraints
and need for explicit knowledge of the plants and wireless network models. To
overcome those challenges, we rely on constrained reinforcement learning
algorithms to propose a model-free approach to the design of wireless control
systems. We demonstrate the near optimality of control system performance and
stability using near-universal policy parametrizations and present a practical
model-free algorithm to learn the co-design policy. Numerical experiments show
the strong performance of learned policies over baseline solutions.Comment: Submitted to IEEE TS
Integrated feedback scheduling and control co-design for motion coordination of networked induction motor systems
This paper investigates the codesign of remote speed control and network scheduling for motion coordination of multiple induction motors through a shared communication network. An integrated feedback scheduling algorithm is designed to allocate the optimal sampling period and priority to each control loop to optimize the global performance of a networked control system (NCS), while satisfying the constraints of stability and schedulability. A speed synchronization method is incorporated into the scheduling algorithm to improve the speed synchronization performance of multiple induction motors. The rational gain of the network speed controllers is calculated using the Lyapunov theorem and tuned online by fuzzy logic to guarantee the robustness against complicated variations on the communication network. Furthermore, a state predictor is designed to compensate the time delay which occurred in data transmission from the sensor to the controller, as a part of the networked controller. Simulation results support the effectiveness of the proposed control-and-scheduling codesign approach
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