Feedback quality and environmentally friendly use of domestic central heating systems

The study examined the influence of system-embedded feedback on user behaviour during the environmentally friendly operation of a central heating system. A PC-based simulation, called CHESS, was developed to model the critical features of a central heating system. After having received 30 min of training on the simulation task, 60 participants worked on a series of operational scenarios under different levels of system feedback. In addition to the collection of various performance measures (e.g. energy consumption, energy wastage), a range of user variables was collected (e.g. environmental concern). As hypothesized, the results showed that increased feedback resulted in improved environmentally friendly performance and, more importantly, the specific feedback indicator influenced the type of strategy used to improve human - machine system performance. A major implication is that system designers need to develop feedback indicators that are chiefly influenced by user behaviour and are largely immune to factors that are beyond the user's control (e.g. weather conditions).     

Designing for the home: a comparative study of support aids for central heating systems

The study examined the influence of different types of enhanced system support on user performance during the management of a central heating system. A computer-based simulation of a central heating system, called CHESS V2.0, was used to model different interface options, providing different support facilities to the user (e.g., historical, predictive, and instructional displays). Seventy-five participants took part in the study and completed a series of operational scenarios under different support conditions. The simulation environment allowed the collection of performance measures (e.g., energy consumption), information sampling, and system control behaviour. Subjective user evaluations of various aspects of the system were also measured. The results showed performance gains for predictive displays whereas no such benefits were observed for the other display types. The data also revealed that status and predictive displays were valued most highly by users. The implications of the findings for designers of central heating systems are discussed.     

Designing low-complexity electrical consumer products for ecological use

This study examined the environmental impact of low-complexity electrical consumer products during their use in a domestic context. In the experimental scenario, 48 users were asked to use a kettle under different conditions. On-product information (OPI), task instruction, and kettle design were employed as independent variables in a mixed multi-factorial design to examine their effects on different parameters of ecological performance (e.g., water and electricity consumption). Measures of user variables (environmental concern, knowledge, domestic habits, environmental control beliefs) were also taken to examine their relationship with performance parameters. The results revealed main effects of ecological task instruction, OPI and (partly) kettle design on ecological user behaviour. Habits, environmental concern and control beliefs were found to be related to performance parameters whereas knowledge was not. The implications of the results for product design are discussed against the background of a strong prevalence of habits and low ecological user motivation.     

Feedback equivalence of control systems

Cartan's method of equivalence is applied to the problem of equivalence of 2-state systems with scalar control under feedback. The differential invariants produced by the method completely characterize equivalence classes. The phenomenon of linearizability is associated with the presence of infinite Lie pseudogroups. The generic non-linearizable case has a geometrically defined variational problem which yields a time optimal closed loop control.     

Feedback invariance of SISO infinite-dimensional systems

We consider a linear single-input single-output system on a Hilbert space X, with infinitesimal generator A, bounded control element b, and bounded observation element c. We address the problem of finding the largest feedback invariant subspace of X that is in the space c ^⊥ perpendicular to c. If b is not in c ^⊥, we show this subspace is c ^⊥. If b is in c ^⊥, a number of situations may occur, depending on the relationship between b and c.     

Feedback linearization of discrete-time systems

We give necessary and sufficient conditions for a nonlinear discrete-time system to be locally linearizable by a change of state coordinates and a feedback. The conditions are expressed in terms of controllability distributions associated to the system.     

Environmental conservation in the domestic domain: the influence of technical design features and person-based factors

This article presents three experiments that examined proenvironmental behaviour during utilisation of electrical consumer products in the domestic domain. One experiment was carried out in the laboratory (N?=?48), two others in the field (N?=?18, N?=?24). First, the work aimed to evaluate various ergonomic measures with regard to their effectiveness to influence proenvironmental behaviour. Second, it examined the relation of person-based factors (e.g., environmental concern) and behaviour. Third, it examined the generalizability of findings from the laboratory to a field setting. The results suggested that design modifications of kettle (e.g., kettle size, integrated user support) are effective in improving proenvironmental behaviour (i.e., resource consumption). Relationships between person-based factors and behaviour have been found, though they were not consistent because the nature of the relationship may be modified by design features (e.g., integrated user support). There was general confirmation of the results from the lab-based experiment by field research, suggesting the suitability of laboratory work to research environmental issues in the domestic domain.     

Feedback linearization and driftless systems

The problem of dynamic feedback linearization is recast using the notion of dynamic immersion. We investigate here a generic property which holds at every point of a dense open subset, but may fail at some points of interest, such as equilibrium points. Linearizable systems are then systems that can be immersed into linear controllable ones. This setting is used to study the linearization of driftless systems: a geometric sufficient condition in terms of Lie brackets is given; this condition is also shown to be necessary when the number of inputs equals two. Though noninvertible feedbacks are nota priori excluded, it turns out that linearizable driftless systems with two inputs can be linearized using only invertible feedbacks, and can also be put into a chained form by (invertible) static feedback. Most of the developments are done within the framework of differential forms and Pfaffian systems.This work was partially supported by INRIA, NSF Grant ECS-9203491, GR Automatique (CNRS), and DRED (Ministère de l'Éducation Nationale). Part of it was done while the first author was visiting the Center for Control Engineering and Computation, University of California at Santa Barbara.     

Improving ecological performance of electrical consumer products: the role of design-based measures and user variables

This research is concerned with the ecological performance of electrical consumer products. It examines the influence of design-based measures on various ecological performance parameters and the relationship of user variables and performance. In the experimental scenario, 40 users were asked to clean a room with a vacuum cleaner under different conditions. In a multi-factorial design, the following independent variables were employed: on-product information, enhanced display-control labelling and proximity of controls. Measures of user variables (environmental concern, knowledge, habits) of ecological behaviour were also taken. The results showed that enhanced display-control labelling improved ecological performance but only when the label was placed close to the user. On-product information only resulted in behavioural change when it was in close spatial proximity to the control device. A positive effect on ecological performance was also observed when controls were in a proximal rather than distal position. Among user variables, habits were found to have an influence on behaviour shown in experimental scenarios. A practical implication of the findings for environmentally friendly design of consumer products is that there should be a stronger focus on system-based measures rather than information-based measures. Finally, the article discusses the theoretical implications of using operational scenarios rather than the information display board paradigm.     

Ecological performance of electrical consumer products: the influence of automation and information-based measures

Being concerned with the environmental impact of electrical consumer products, this article examines possibilities of influencing ecological user performance through design features. Furthermore, it looks at the relationship of user characteristics and ecological performance. The impact of level of automation and type of control labelling on ecological user performance was examined in a lab-based experimental scenario with 36 users. In addition to performance indicators, a range of user variables (e.g., self-reported domestic behaviour, environmental knowledge and attitude) was measured to assess their influence on user behaviour. The results showed that low-level automation improved ecological performance whereas no such positive effect was observed for enhanced display-control labelling. Furthermore, the results suggested that the user's mental model of ecological performance was rather limited. No relationship was found between environmental knowledge, attitude and performance. The findings pointed at the strong prevalence of habits in the domestic domain. The implications of the results for designers of consumer products are discussed.     

Feedback stabilization of discrete-time homogeneous semi-linear systems

For discrete-time semi-linear systems satisfying an accessibility condition asymptotic null controllability is equivalent to exponential feedback stabilizability using a piecewise constant feedback. A constructive procedure that yields such a feedback is presented.     

Feedback stabilization of dissipative impulsive dynamical systems

In this paper, we derive conditions under which a dissipative impulsive dynamical system is asymptotically stabilizable by a feedback controller. Specializing the obtained results to the case of dissipative linear impulsive dynamical systems with the quadratic supply rate, we establish the corresponding sufficient conditions. Finally, simulation results are given to demonstrate the effectiveness of our results.     

Feedback stabilization of real analytic systems in the plane

We investigate the local feedback stabilization of single input control affine analytic systems in the plane. New necessary and sufficient conditions for local stabilization with feedback laws of the form u = v(x₁,x₂), x2), (v/x₁(0, 0))² + (v/x₁ (0, 0))² 0≠ 0, v(0, 0) = 0, are obtained by using Lyapunov's stability theorems on two-dimensional analytic systems. If the sufficient conditions are satisfied, we also provide explicit feedback laws.     

Automation and decision support in interactive consumer products

This article presents two empirical studies (n = 30, n = 48) that are concerned with different forms of automation in interactive consumer products. The goal of the studies was to evaluate the effectiveness of two types of automation: perceptual augmentation (i.e. supporting users' information acquisition and analysis); and control integration (i.e. supporting users' action selection and implementation). Furthermore, the effectiveness of on-product information (i.e. labels attached to product) in supporting automation design was evaluated. The findings suggested greater benefits for automation in control integration than in perceptual augmentation alone, which may be partly due to the specific requirements of consumer product usage. If employed appropriately, on-product information can be a helpful means of information conveyance. The article discusses the implications of automation design in interactive consumer products while drawing on automation models from the work environment.     

Feedback classification of nonlinear control systems on 3-manifolds

We consider nonlinear control-affine systems with two inputs evolving on three-dimensional manifolds. We study their local classification under static state feedback. Under the assumption that the control vector fields are independent we give complete classification of generic systems. We prove that out of a singular smooth curve a generic control system is either structurally stable and thus equivalent to one of six canonical forms (models) or finitely determined and thus equivalent to one of two canonical forms with real parameters. Moreover, we show that at points of the singular curve the system is not finitely determined and we give normal forms containing functional moduli. We also study geometry of singularities, i.e., we describe surfaces, curves, and isolated points where the system admits its canonical forms.     

Feedback passivity of nonlinear discrete-time systems with direct input-output link

This paper is devoted to the study of the feedback passivity property in nonlinear discrete-time systems. The relative degree and zero dynamics of the non-passive system are related to the feedback passivity of the system. Two main results are presented. First, some relative degree-related properties of passive systems in general form are stated. Second, sufficient conditions in order to render a multiple-input multiple-output (MIMO) system passive by means of a static state feedback control law are obtained.     

一类切换系统极限环的反馈镇定研究

利用多Lyapunov函数法讨论一类切换系统极限环的反馈镇定问题．首先给出切换系统极限环的有界状态反馈、有界输出反馈以及动态反馈镇定定理;然后利用Jurdjevic—Quinn方法给出反馈控制器的具体形式,并证明了在给定反馈控制器的作用下,切换系统的极限环渐近稳定．仿真例子验证了结论的正确性．     

Feedback control of nonlinear stochastic systems for targeting a specified stationary probability density

In the present paper, an innovative procedure for designing the feedback control of multi-degree-of-freedom (MDOF) nonlinear stochastic systems to target a specified stationary probability density function (SPDF) is proposed based on the technique for obtaining the exact stationary solutions of the dissipated Hamiltonian systems. First, the control problem is formulated as a controlled, dissipated Hamiltonian system together with a target SPDF. Then the controlled forces are split into a conservative part and a dissipative part. The conservative control forces are designed to make the controlled system and the target SPDF have the same Hamiltonian structure (mainly the integrability and resonance). The dissipative control forces are determined so that the target SPDF is the exact stationary solution of the controlled system. Five cases, i.e., non-integrable Hamiltonian systems, integrable and non-resonant Hamiltonian systems, integrable and resonant Hamiltonian systems, partially integrable and non-resonant Hamiltonian systems, and partially integrable and resonant Hamiltonian systems, are treated respectively. A method for proving that the transient solution of the controlled system approaches the target SPDF as t→∞ is introduced. Finally, an example is given to illustrate the efficacy of the proposed design procedure.     

Feedback stabilization of discrete-time quantum systems subject to non-demolition measurements with imperfections and delays

We consider a controlled quantum system whose finite dimensional state is governed by a discrete-time nonlinear Markov process. In open-loop, the measurements are assumed to be quantum non-demolition (QND). The eigenstates of the measured observable are thus the open-loop stationary states: they are used to construct a closed-loop supermartingale playing the role of a strict control Lyapunov function. The parameters of this supermartingale are calculated by inverting a Metzler matrix that characterizes the impact of the control input on the Kraus operators defining the Markov process. The resulting state feedback scheme, taking into account a known constant delay, provides the almost sure convergence to the target state. This convergence is ensured even in the case where the filter equation results from imperfect measurements corrupted by random errors with conditional probabilities given as a left stochastic matrix. Closed-loop simulations corroborated by experimental data illustrate the interest of such nonlinear feedback scheme for the photon box, a cavity quantum electrodynamics system.     

基于POSIX线程库的线程池反馈算法的设计与实现

本文提出了一种基于POSIX线程库的线程池反馈算法,通过对线程池响应进间和吞吐量进行监控,对线程池的下一步行为进行决策,调整线程池中的线程数及线程单次处理的任务数。实验结果显示,这种算法能很好地稳定线程池吞吐量和响应时间,避免性能出现大幅波动。