Global dynamic feedback for a class of nonholonomic systems with bounded controls

Climate models remain the best tools for predicting the impact of climate change on quantities relevant to human activity, such as precipitation, surface temperature and occurrence of severe weather events. Since many of these changes scale with the models equilibrium climate sensitivity, it is crucial to understand the differences in climate sensitivity between the models, which are primarily driven by inter-model differences in cloud feedbacks. Inter-model differences in cloud feedbacks are largest in the equatorial Pacific. Focussing on the area from 10°S - 10°N, and 160°E – 270°E, we find an inter-model standard deviation in cloud feedback of ~1.36 W m-2 K-1. Using appropriate weighting to account for the area of this region, this equates to a contribution to the global mean cloud feedback uncertainty of ~ 0.07 W m-2 K-1, which represents approximately 20% of the inter-model spread in global mean cloud feedback. Local differences in cloud feedback between models in this region are even larger and may have implications for regional circulation and precipitation changes. This region is also notable as an exception to the high correlation in cloud feedbacks between coupled and atmosphere-only models. In this presentation we will describe analysis of the causes of the inter-model spread in cloud feedbacks in this region. We shall demonstrate that the spread in domain-mean feedback in this region is due to inter-model differences in both dynamic and thermodynamic cloud feedbacks and show how this relates to changes in the properties of different cloud types amongst different models. We will also describe the use of empirical orthogonal function analysis to identify consistent cloud feedback patterns in this region across the ensemble of models and explain the causes of these patterns.

In this technical note, two problems have been investigated. The first one concerns the global asymptotic feedback stabilization of homogeneous systems. For these systems, it is shown that local asymptotic stabilization implies the global dynamic feedback stabilization one. The second problem consists to show that under a weak assumption on the observability, if a state affine system is locally asymptotically stabilizable then it becomes globally asymptotically stabilizable by using a discontinuous output feedback.

SummaryThis paper is concerned with the global output feedback stabilization for a class of nonholonomic systems with unknown parameter, polynomial‐of‐output, and unmeasurable states dependent growth. A dynamic high‐gain observer is first designed to reconstruct the unmeasurable system states and, in addition, to compensate the serious parameter unknowns in nonlinear drifts. Then, we design a compact adaptive controller without invoking the backstepping technique, which reduces the complexity of controller. Additionally, a switching control strategy is employed to overcome the smooth feedback obstacle associated with nonholonomic systems. It is shown that the proposed control laws guarantee that all closed‐loop system states are globally bounded and ultimately converge to zero. The simulation results demonstrate the effectiveness of the proposed control strategy.

Purpose Railway infrastructure development is a complex socio-technical system with significant implications for sustainable development. Past studies often analyse implementation barriers separately, ignoring their interconnectedness. This reductionist view misses the intricate nature of rail projects, which require a holistic approach. Therefore, this study uses a socio-technical systems (STS) lens to examine these barriers' systemic interdependencies, shifting from fragmented views to understanding the dynamic friction between social and technical factors. Design/methodology/approach To ensure rigorous systemic validation beyond traditional linear approaches, this study employed a mixed-methods explanatory sequential design grounded in the context of a single-case project (MRT Putrajaya Line). First, quantitative data were analysed using exploratory factor analysis (EFA) and correlation analysis to validate constructs and test relationships. Subsequently, qualitative data from group model building were modelled using causal loop diagrams (CLD) to empirically map the dynamic feedback mechanisms driving the ecosystem. Findings The EFA confirmed barriers as two constructs: “Strategic-Governance” and “Technical-Operation”, supporting the social-technical system distinction. Correlation analysis shows “Strategic-operational decoupling”, where high-level policies do not translate into ground-level action. The CLD reveals systemic lock-in, in which four loops (governance, economic, capability and global feedback) reinforce one another, maintaining unsustainable practices and eroding technical skills. Originality/value This study uses a dynamic approach to barrier identification, applying STS theory in a developing country. It introduces the Hierarchy of Intervention, showing social subsystem barriers as upstream constraints affecting technical subsystems. The findings indicate the sector suffers from governance issues, not engineering gaps, needing regulatory intervention to fix the feedback loop.

The dynamic linear state feedback control problem is addressed for a class of nonlinear systems subject to time-delay. First, using the dynamic change of coordinates, the problem of global state feedback stabilization is solved for a class of time-delay systems under a type of nonhomogeneous growth conditions. With the aid of an appropriate Lyapunov-Krasovskii functional and the adaptive strategy used in coordinates, the closed-loop system can be globally asymptotically stabilized by the dynamic linear state feedback controller. The growth condition in perturbations are more general than that in the existing results. The correctness of the theoretical results are illustrated with an academic simulation example.

Global stabilization by output dynamic feedback for triangular systems

We provide a global framework for flatness-based motion planning and dynamic feedback linearization of the quadcopter dynamics. It allows us to avoid the singularity difficulty that comes from the use of the yaw angle in flat output construction and dynamic feedback linearization. We construct eight differentially flat charts the union of which covers the entire configuration space of the quadcopter dynamics so that we can do global motion planning without encountering any singularity. In each differentially flat chart we transform the 12-dimensional quadcopter system via dynamic feedback to a 14-dimensional linear controllable system, which makes tracking controller design straightforward, so that we can switch from one controller to another to track a globally planned trajectory. The central theme of this paper is the global approach to the quadcopter motion planning and tracking.

In this paper, new results are obtained for the global tracking of a class of non-holonomic dynamic systems via state and output feedback. The tracking controllers are systematically constructed on the basis of a recursive technique and a full exploitation of the system structure. When disturbances occur in a non-holonomic chained system, it is shown how to modify the controller design procedure to yield robust tracking control laws. The proposed method is demonstrated and discussed by means of a benchmark non-holonomic knife-edge mechanical system.

This paper presents an output feedback control strategy for adaptive regulation of nonholonomic systems with strongly nonlinear uncertainties and time-delay. To facilitate the feedback design, by applying input-state transformation and rescaling transformation, the original model investigated is transformed into a new system. A dynamic high gain is introduced to compensate the unknown constant and handle the unknown input-output polynomial growth rate of the system nonlinearities. By applying a novel Lyapunov functional and an extended state observer, the output feedback controller is designed, which can guarantee the global adaptive regulation of closed-loop systems. Finally, a numerical example is provided to illustrate the effectiveness of the theoretical results.

The output feedback stabilization problem is investigated in this paper for nonholonomic systems with stochastic disturbances. The objective is to design global asymptotical stabilization output feedback controllers in probability for systems by using discontinuous control. A switching control strategy based on the output measurement of the first subsystem is employed to achieve almost global asymptotical stabilization in probability. The input‐state scaling technique is introduced for discontinuous feedback and a high gain observer is introduced for states estimate. Thereby, the integrator backstepping technique is applied to the design of the controllers. The output feedback global asymptotical stabilization in probability is realized. An example is given to show the effectiveness of the proposed scheme.Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

This paper investigates the problem of global finite-time stabilization by output feedback for a class of nonholonomic systems in chained form with uncertainties. By using backstepping recursive technique and the homogeneous domination approach, a constructive design procedure for output feedback control is given. Together with a novel switching control strategy, the designed controller renders that the states of closed-loop system are regulated to zero in a finite time. A simulation example is provided to illustrate the effectiveness of the proposed approach.

We study the problem of global state feedback control for a class of time-delay uncertain systems. Under mild regularity conditions on the system nonlinearities involving time delay, a delay-independent, non-smooth dynamic state compensator is constructed by developing a dynamic gain based design method. Using appropriate Lyapunov-Krasovskii functionals, we prove that all the states of the time-delay nonlinear system can be regulated to the origin while maintaining boundedness of the closed-loop system. As a byproduct of this development, adaptive regulation of the same class of nonlinearly parameterized systems with time-delay is also shown to be possible, via a similar Lyapunov-Krasovskii design method. Two examples are presented to validate the effectiveness of the proposed non-smooth feedback controllers.

In this paper, we consider a class of non‐linear systems in which a set of constant parameters is unknown and some state variables are not available for measurement. For such systems we provide a constructive procedure for the solution of the global adaptive tracking problem with dynamic partial state feedback. We illustrate an application of the control strategy to the adaptive non‐linear friction compensation of a DC motor servomechanism. We improve previous results in tow directions: we allow for a subset of the unmeasurable states to enter in a system non‐linearly; we consider systems which are linearly parametrized with respect to a set of unknown constant parameters. Copyright © 2002 John Wiley & Sons, Ltd.

In this paper we consider a class of nonlinear systems in which a set of constant parameters is unknown and some state variables are not available for measurement. For such systems we provide a constructive procedure for the solution of the global adaptive tracking problem with dynamic partial state feedback. We illustrate an application of the control strategy to the adaptive nonlinear friction compensation of a DC motor servomechanism. We improve previous results in two directions: we allow for a subset of the unmeasurable states to enter in the system nonlinearly; we consider systems which are linearly parametrized with respect to a set of unknown constant parameters.

Dynamic Control Technique for Nonholonomic Systems