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Adaptive Fault-Tolerant Control of Underactuated Ships without Actuator Redundancy
Published in Jiangshuai Huang, Yong-Duan Song, Adaptive and Fault-Tolerant Control of Underactuated Nonlinear Systems, 2017
Jiangshuai Huang, Yong-Duan Song
A system is underactuated if there are a fewer number of independent actuators than the degrees of freedom. In reality, a lot of nonlinear mechanical systems belong to this type. In recent years many novel nonlinear design techniques have been developed for this control problem, mainly based on a time-varying feedback and discontinuous state-feedback control scheme. For surface vessel when the sway force is taken away with only surge force and yaw force, researchers proposed a number of control schemes. In [68], a discontinuous state-feedback control law is proposed using σ-process to exponentially stabilize the underactuated surface vessel to the origin. In [5], a discontinuous time-varying feedback controller for a nonholonomic system and this scheme is applied to an underactuated surface vessel. In [69] some local exponential stabilization results are developed based on a time-varying homogeneous control approach. In [70] an application of this homogeneous system theory to underactuated surface vessel was considered. In [71] some dynamic feedback results of stabilization were developed by transforming the underactuated surface vessel kinematics and dynamics into the so-called skew form. However, in some cases, the sway force of the surface vessel is necessary and it must be used occasionally. Thus it is naturally to consider a universal control scheme for the surface vessel such that when sway force is taken on or off, the control scheme could be applied in both cases.
Zero dynamics analysis and adaptive tracking control of underactuated multibody systems with flexible links
Published in International Journal of Control, 2021
Zehui Mao, Gang Tao, Bin Jiang, Xing-Gang Yan
Underactuated mechanical systems have less control inputs than degrees of freedom, which have the advantages of lighter weight, cheaper cost, and less energy (Lai, Wang, Wu, & Cao, 2016). Underactuation is purposely introduced in some systems, such as aircraft, underwater vehicles, and humanoid robots, for which the control problem has attracted much attention (Huang, Wen, Wang, & Song, 2015; Jafari, Mathis, Mukherjee, & Khalil, 2016; Lai, Zhang, Wang, & Wu, 2017; Wang, Yang, Shen, Shao, & Wang, 2018; Wu, Luo, Zeng, Li, & Zheng, 2016; Zhang & Wu, 2015). However, most of the existing results attempt to stabilise only a subset of the system's degrees of freedom, which reduces the complexity of the control problem associated with underactuated mechanical systems (Pucci, Romano, & Nori, 2015). The stability problem of the left subset that has no concern with the system's degrees of freedom, has not been fully studied. Therefore, the study on the control design and stability problem of the underactuated mechanical systems is of both theoretical challenges and practical importance.
A stable reentry trajectory for flexible manipulators
Published in International Journal of Control, 2021
Underactuated systems possess less input forces/torques than degree-of-freedom. This becomes particularly interesting for inverse dynamics of constrained non-minimum phase systems. This often occurs in fast-lightweight manipulators. In these cases, an unstable internal dynamics is present and control strategies are used in order to bound it. The number of non-actuated degrees-of-freedom increases the complexity of the inverse dynamics problem. A manipulator with one passive joint is underactuated and its internal dynamics motion could be represented by the relative angle of this joint in position and velocity level . Where and are absolute angles of the consecutive bodies. For systems with multiple non-actuated joints, a set of relative angles could be defined as a vector of deformation . This definition can be used for systems with flexible/elastic bodies too, where, theoretically, an infinite number of non-actuated degree-of-freedom is present.
Stabilisation of a relative equilibrium of an underactuated AUV on SE(3)
Published in International Journal of Control, 2019
Autonomous underwater vehicles (AUVs) are now routinely employed in a wide range of military and civilian applications. For instance, oceanographic sampling and data collection were presented by Bellingham and Rajan (2007), and Hollinger et al. (2016). An innovative underwater towed vehicle was used to investigate water resources (Lock, Spiers, Hostetler, Ray, & Wallschläger, 2016). Marine resources exploration and exploitation was presented in Johnsen, Ludvigsen, Sørensen, and Aas (2016). There are multiple control motions to be employed to implement these applications, such as stabilisation, waypoint navigation, path following, trajectory tracking, etc. Relative equilibria of a marine vehicle correspond to trim trajectories, which can save power. In this study, a relative equilibrium of an underactuated AUV in three-dimensional space is investigated on Lie group SE(3), since SE(3) can describe the evolution of a rigid body without singularities or ambiguities and the relative equilibrium can be viewed as a line navigation. An underactuated system means that the number of independent control inputs are less than the system's degree of freedom, which implies dynamic constraints on underactuated directions. Thereafter, it is difficult to deal with.