REAL

Nullspace-based input reconfiguration architecture for over-actuated aerial vehicles

Péni, Tamás and Vanek, Bálint and Lipták, György and Szabó, Zoltán and Bokor, József (2020) Nullspace-based input reconfiguration architecture for over-actuated aerial vehicles. In: Fault Diagnosis and Fault-tolerant Control of Robotic Systems. IET, pp. 235-256. ISBN 978-1-78561-830-7

This is the latest version of this item.

[img] Text
reconf_iet_bookchapter.pdf - Accepted Version
Restricted to Registered users only

Download (3MB)

Abstract

The most stringent requirements for improved reliability and environmental sustain- ability of safety critical flight control systems could only be satisfied with the most advanced fault tolerant control (FTC) techniques [1], [2]. The FTC system is re- quired to detect and identify the failure and then to compensate its effect by recon- figuring the control system [3]. Focus on the environmental impact of the aircraft triggers the need for higher performance flight control systems, which leads to a paradigm shift from robust passive FTC towards active methods relying on switch- ing, gain scheduled or linear parameter-varying (LPV) methods with certifiable al- gorithms [4]. In the past few years a wide variety of FTC design approaches have been proposed [5, 6]. This chapter focuses on the reconfiguration task in the case of actuator failures. The approach considered here is the control input reallocation [7], where the aim is to compensate the actuator failures by reconfiguring the remaining flight control surfaces such that the performance degradation caused by the failure is as small as possible. One possible approach to solve this problem is based on the nullspace (or kernel) of the aircraft dynamics. These algorithms can be applied only if control input redundancy is available in the system [8]. As in aerospace applications this is often the case [9], this approach is a promising method for fault tolerant flight control design. The classical kernel-based algorithms assume constant input direction matrices and thus use static matrix kernels [7], [8]. This concept is extended in [10] and [11] by using dynamic nullspace generators. Though the concept presented in these papers is similar to that is discussed here, the algorithms in [10] and [11] highly depend on the linear time invariant (LTI) framework and thus their extension to the parameter varying case rises several theoretical problems. This chapter proposes a different approach, which is promising for LPV applications as well. The main component of the proposed reconfiguration architecture is the nullspace of the controlled LPV plant model. Although the nullspace of a dynamical system bears significant importance on several other fields of control as well [12],[13],[14] its numerical computation has been solved only partially so far. In [15] an algorithm based on matrix pencils is proposed to compute the dynamic kernel of an LTI system. Although this approach is computationally efficient, it is based on frequency domain formulation, which prevents its extension to LPV systems. In [12] the nullspace of a parameter-dependent, memoryless matrix is addressed in connection with controller design. The paper uses linear-fractional representation (LFR), but it does not con- sider the case of dynamic kernels. Moreover, the method of [12] does not analyse and thus cannot guarantee the well-definedness of the kernel basis, which are also necessary to use the kernel in any further design process. The LFR-Toolbox [16] also provides a method for nullspace computation. The algorithm is similar to the one given in [12] and it can be applied for dynamical systems as well, but it does not work for the general case as it requires certain rank conditions to be satisfied. In this chapter we revise the existing methods and assemble a complete tool for ker- nel computation that can be applied for parameter-dependent matrices and LTI/LPV dynamical systems as well. The chapter is structured as follows, Sections 1.1 and 1.2 are devoted to the numerical computation of the parameter varying nullspace. The proposed actuator reconfiguration architecture is discussed in Section 1.3. The simulation example, using the B-1 aircraft is presented in Section 1.4, while the results derived in the chapter are is concluded in Section 1.5.

Item Type: Book Section
Subjects: T Technology / alkalmazott, műszaki tudományok > T2 Technology (General) / műszaki tudományok általában
Depositing User: Péni Tamás
Date Deposited: 23 Sep 2019 08:05
Last Modified: 23 Sep 2020 09:52
URI: http://real.mtak.hu/id/eprint/100446

Available Versions of this Item

Actions (login required)

Edit Item Edit Item