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Author = Freudenberg, J.S.;
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Displaying Results 1  7 of 7 on page 1 of 1
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Feedback control performance over a noisy communication channel.
(2008)
Freudenberg, J.S.; Middleton, R.H.
Feedback control performance over a noisy communication channel.
(2008)
Freudenberg, J.S.; Middleton, R.H.
Abstract:
We consider the problem of minimizing the variance in the output of a plant that is driven by a Gaussian disturbance using measurements of the plant output obtained from a Gaussian channel. For the special case in which only the variance at the terminal time is penalized, we derive an optimal linear timevarying communication and control strategy, and argue that nonlinear strategies cannot achieve better performance.
http://mural.maynoothuniversity.ie/1753/
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Fundamental Limitations in SelfSensing Magnetic Bearings when Modeled as Linear Periodic Systems.
(2006)
Peterson, K.S.; Middleton, R.H.; Freudenberg, J.S.
Fundamental Limitations in SelfSensing Magnetic Bearings when Modeled as Linear Periodic Systems.
(2006)
Peterson, K.S.; Middleton, R.H.; Freudenberg, J.S.
Abstract:
In "Magnetic Bearing Measurement Configurations and Associated Robustness and Performance Limitations", Thibeault and Smith demonstrate that selfsensing magnetic bearings are impractical due to fundamental limitations in the achievable closedloop robustness. Due to experimental data which appeared to contradict these results, Maslen, Montie, and Iwasaki showed that significantly better robustness is achievable in "Robustness limitations in selfsensing magnetic bearings" if the magnetic bearing is modeled as a linear periodic (LP) system rather than the linear time invariant (LTI) system used by Thibeault and Smith. The present paper explores why modeling the selfsensing magnetic bearing as a LP system improves the achievable robustness. This is accomplished by utilizing lifting to analyze the LP model as a MIMO discrete LTI system.
http://mural.maynoothuniversity.ie/1782/
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Input Disturbance Rejection in Channel SignaltoNoise Ratio Constrained Feedback Control
(2008)
Rojas, A.J.; Middleton, R.H.; Freudenberg, J.S.; Braslavsky, J.H.
Input Disturbance Rejection in Channel SignaltoNoise Ratio Constrained Feedback Control
(2008)
Rojas, A.J.; Middleton, R.H.; Freudenberg, J.S.; Braslavsky, J.H.
Abstract:
Communication channels impose a number of obstacles to feedback control. One recent line of work considers the problem of feedback stabilisation subject to a constraint on the channel signaltonoise ratio (SNR). It has been shown for continuoustime systems that the optimal control problem of achieving the infimal SNR can be formulated as a linear quadratic Gaussian (LQG) control problem with weights chosen as in the loop transfer recovery (LTR) technique. The present paper extends this formulation to: discretetime systems; communications over channels with memory; and input disturbance rejection. By using this formulation, we derive exact expressions for the linear time invariant (LTI) controller that achieves the infimal SNR under the effect of timedelay and additive coloured noise. We then quantify the infimal SNR required for both stabilisation and input disturbance rejection for a relative degree one, minimum phase plant and a memoryless Gaussian channel.
http://mural.maynoothuniversity.ie/2245/
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Minimum Variance Control over a Gaussian Communication Channel
(2008)
Freudenberg, J.S.; Middleton, R.H.; Braslavsky, J.H.
Minimum Variance Control over a Gaussian Communication Channel
(2008)
Freudenberg, J.S.; Middleton, R.H.; Braslavsky, J.H.
Abstract:
We consider the problem of minimizing the response of a plant output to a stochastic disturbance using a control law that relies on the output of a noisy communication channel. We discuss a lower bound on the performance achievable at a specified terminal time using nonlinear timevarying communication and control strategies, and show that this bound may be achieved using strategies that are linear.
http://mural.maynoothuniversity.ie/2244/
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Optimal Signal to Noise Ratio in Feedback over Communication Channels with Memory
(2006)
Rojas, A.J.; Freudenberg, J.S.; Braslavsky, J.H.; Middleton, R.H.
Optimal Signal to Noise Ratio in Feedback over Communication Channels with Memory
(2006)
Rojas, A.J.; Freudenberg, J.S.; Braslavsky, J.H.; Middleton, R.H.
Abstract:
Communication channels impose a number of obstacles to feedback control, such as delay, noise, and constraints in communication datarate. One alternate line of recent work considers the problem of feedback stabilization subject to a constraint in the signaltonoise ratio (SNR). It has been shown for continuoustime systems that the optimal control problem arising in achieving minimal SNR can be formulated as a linear quadratic Gaussian (LQG) control problem with weights chosen as in the loop transfer recovery (LTR) technique. The present paper extends such LQG/LTR formulation to discretetime systems with feedback over channels with memory. By using such formulation, we derive exact expressions for the LTI controller and loop sensitivity functions that achieve minimal SNR under the effect of timedelay, non minimum phase zeros and colored additive noise. For the minimumphase case with white noise and no time delay, we show that the optimal feedback loop obtained after applying LTR...
http://mural.maynoothuniversity.ie/1789/
Marked
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Stabilization and Performance over a Gaussian Communication Channel for a Plant with Time Delay
(2009)
Freudenberg, J.S.; Middleton, R.H.
Stabilization and Performance over a Gaussian Communication Channel for a Plant with Time Delay
(2009)
Freudenberg, J.S.; Middleton, R.H.
Abstract:
Two problems that have received much attention are those of finding the minimum channel signal to noise ratio compatible with closed loop stability, and of finding the optimal performance, in terms of disturbance attenuation, for a channel with specified signal to noise ratio. In this paper, we study these problems for the case in which the plant has relative degree greater than one, and thus introduces a delay greater than one time step. We show that, unlike the relative degree one case, for the problem of stabilization linear time varying control and communication strategies may have advantages over linear time invariant strategies. We derive a lower bound on optimal disturbance response at a fixed terminal time. If the encoder has access to the state of the plant, then this bound is achievable using linear time varying communication and control.
http://mural.maynoothuniversity.ie/1643/
Marked
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Stabilization with Disturbance Attenuation over a Gaussian Channel
(2007)
Freudenberg, J.S.; Middleton, R.H.; Braslavsky, J.H.
Stabilization with Disturbance Attenuation over a Gaussian Channel
(2007)
Freudenberg, J.S.; Middleton, R.H.; Braslavsky, J.H.
Abstract:
We propose a linear control and communication scheme for the purposes of stabilization and disturbance attenuation when a discrete Gaussian channel is present in the feedback loop. Specifically, the channel input is amplified by a constant gain before transmission and the channel output is processed through a linear time invariant filter to produce the control signal. We show how the gain and filter may be chosen to minimize the variance of the plant output. For an order one plant, our scheme achieves the theoretical minimum taken over a much broader class of compensators.
http://mural.maynoothuniversity.ie/1722/
Displaying Results 1  7 of 7 on page 1 of 1
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