In this paper, we consider a 2-degrees-of-freedom
(DOF) helicopter system subject to input delays and uncertain
system parameters. To address this challenge in control design,
we develop an adaptive predictor-feedback control law. The
control law is designed to compensate for a known delay while
considering the system uncertainty. Stability of the closed-loop
system is established, where tracking is achieved. We demonstrate
the effectiveness of our proposed control approach through
simulations of the helicopter system, where the input delays are
compensated in the control-loop.
This paper investigates the attitude tracking control problem for uncertain nonlinear rigid body systems, where both inputs and states are quantized. It is common in networked control systems that sensor and control signals are quantized before they are transmitted via a communication network. An adaptive backstepping control algorithm is developed for a class of uncertain multiple-input multiple-output (MIMO) systems where a class of sector bounded quantizers is considered. It is shown that all the closed-loop signals are ensured uniformly bounded and tracking is achieved. Further, the tracking errors are shown to converge towards a compact set containing the origin and the set can be made small by the choice of the quantization parameters and the control parameters. For illustration of the proposed control scheme, experiments were conducted on a 2 degrees-of-freedom (DOF) helicopter system.
In this paper the attitude tracking control problem of a 2 degrees-of-freedom helicopter system with network induced constraints is studied. A predictor feedback control law is developed to compensate a known delay in the communication, where the inputs are quantized before transmitted over the network. Stability of the closed-loop system is established, where tracking is achieved with bounded tracking errors due to the network issues. The developed predictor-based controller is experimentally tested on the helicopter system, where we demonstrate that tracking is achieved in presence of both input delay and quantization.
The anti-swing control of offshore cranes presents much more challenges. Most existing controllers for offshore cranes are designed based on linearized dynamics and require the accurate values of the plant parameters. In this paper, an adaptive sliding mode control scheme is investigated for a nonlinear underactuated crane system with unmodeled dynamics. The proposed control method can ensure asymptotic stability and does not need linearization of the complicated nonlinear dynamic equations during controller design and stability analysis. To reduce the communication burden in a network, a uniform quantizer is introduced in the input communication channel. A quantized adaptive sliding mode control scheme is further developed for the underactuated cranes to compensate for the effects of input quantization and uncertain parameters. The proposed controller together with the quantizer ensures the asymptotic stability of the closed-loop system in the sense of signal boundedness and zero stabilization error. Numerical simulations are conducted to illustrate the effectiveness of proposed schemes.
Schlanbusch, Siri Marte & Zhou, Jing
(2021).
Adaptive Backstepping Control of a 2-DOF Helicopter System in the Presence of Quantization.
In Plapper, Peter (Eds.),
2021 IEEE The 9th International Conference on Control, Mechatronics and Automation.
IEEE conference proceedings.
ISSN 9781728137865.Full text in Research Archive
Schlanbusch, Siri Marte; Zhou, Jing & Schlanbusch, Rune
(2021).
Adaptive Backstepping Attitude Control of a Rigid Body with State Quantization,
Proceedings of 60th IEEE Conference on Decision and Control.
IEEE conference proceedings.
ISSN 978-1-7281-1398-2.p. 372–377.
doi: 10.1109/CDC45484.2021.9683579.
Full text in Research ArchiveShow summary
In this paper, the attitude tracking control problem of a rigid body is investigated where the states are quantized. An adaptive backstepping based control scheme is developed and a new approach to stability analysis is developed by constructing a new compensation scheme for the effects of the vector state quantization. It is shown that all closed-loop signals are ensured uniformly bounded and the tracking errors converge to a compact set containing the origin. Experiments on a 2 degrees-of-freedom helicopter system illustrate the proposed control scheme.
Schlanbusch, Siri Marte; Zhou, Jing & Schlanbusch, Rune
(2021).
Adaptive Attitude Control of a Rigid Body with Input and Output Quantization.
IEEE transactions on industrial electronics (1982. Print).
ISSN 0278-0046.
69(8),
p. 8296–8305.
doi: 10.1109/TIE.2021.3105999.
Full text in Research Archive
Schlanbusch, Siri Marte & Zhou, Jing
(2019).
Adaptive Backstepping Control of a 2-DOF Helicopter.
In Herder, J. & HosseinNia, Hassan (Ed.),
Proceedings, 2019 IEEE 7th International Conference on Control, Mechatronics and Automation.
IEEE Press.
ISSN 9781728137865.p. 210–215.
doi: 10.1109/ICCMA46720.2019.8988761.
Full text in Research Archive
Schlanbusch, Siri Marte & Zhou, Jing
(2020).
Adaptive Backstepping Control in the Presence of Quantization: Application to a 2-DOF Helicopter System.
Schlanbusch, Siri Marte & Zhou, Jing
(2023).
Adaptive Control of Systems with Quantization and Time Delays.
University of Agder.
ISSN 978-82-8427-128-6.Full text in Research ArchiveShow summary
This thesis addresses problems relating to tracking control of nonlinear systems in the presence of quantization and time delays. Motivated by the importance in areas such as networked control systems (NCSs) and digital systems, where the use of a communication network in NCS introduces several constraints to the control system, such as the occurrence of quantization and time delays. Quantization and time delays are of both practical and theoretical importance, and the study of systems where these issues arises is thus of great importance. If the system also has parameters that vary or are uncertain, this will make the control problem more complicated. Adaptive control is one tool to handle such system uncertainty.
In this thesis, adaptive backstepping control schemes are proposed to handle uncertainties in the system, and to reduce the effects of quantization. Different control problems are considered where quantization is introduced in the control loop, either at the input, the state or both the input and the state. The quantization introduces difficulties in the controller design and stability analysis due to the limited information and nonlinear characteristics, such as discontinuous phenomena. In the thesis, it is analytically shown how the choice of quantization level affects the tracking performance, and how the stability of the closed-loop system equilibrium can be achieved by choosing proper design parameters. In addition, a predictor feedback control scheme is proposed to compensate for a time delay in the system, where the inputs are quantized at the same time. Experiments on a 2-degrees of freedom (DOF) helicopter system demonstrate the different developed control schemes.