Transactions of the Institute of Measurement and Control

Parsi, B; Bahrami, M; Esfahani, A Monemian; Sany, B Seyedzadeh

doi: 10.1177/0142331213513607pmid: N/A

This paper presents a new low-cost method for calibration of microelectromechanical system accelerometers. A guide way with low friction that can provide a one-directional linear transversal motion is used. For collecting data sets, the accelerometer is moved manually from one reference point to another, and this movement is measured. A function is developed that relates this movement to acceleration. To verify the proposed calibration method, a three-axis table is used to collect data sets and a least-squares algorithm is applied to find the appropriate function. With this low-cost method, the scale factor matrix, the sensitivity matrix, the non-linear scale factor matrix and bias vector are found.

Wang, Ronghao; Xing, Jianchun; Wang, Ping; Yang, Qiliang; Xiang, Zhengrong

doi: 10.1177/0142331213507595pmid: N/A

This paper deals with the problem of state feedback stabilization with finite-time stochastic stability for a class of discrete-time switched stochastic linear systems under asynchronous switching. The attention is focused on designing the feedback controller that guarantees the finite-time stochastic stability of the dynamic system. The finite-time stochastic stability definition of discrete-time switched stochastic systems is introduced. The asynchronous switching idea originates from the fact that switching instants of the controllers lag behind or exceed those of subsystems. On the basis of the average dwell time method and multiple Lyapunov functions approach, a finite-time stochastic stability condition is established. Then, an asynchronously switched controller is designed and the corresponding switching law is derived to guarantee the considered system be finite-time stochastically stable. Two numerical examples are provided to show the effectiveness of the developed results.

Le, Binh Nguyen; Wang, Qing-Guo; Lee, Tong Heng

doi: 10.1177/0142331213511846pmid: N/A

An effective method is presented to compute the loop gain margins exactly for two-input–two-output processes. The stable regions in parameter space are first obtained by determining the stability boundaries and the loop gain margins found within the stable regions. Examples are provided for illustration and comparison with other methods.

Geng, Jie; Sheng, Yongzhi; Liu, Xiangdong

doi: 10.1177/0142331213512367pmid: N/A

In this paper, a time-varying nonsingular terminal sliding mode (T-NTSM) controller is proposed and modified for the rigid robot manipulators with parametric uncertainties and external disturbances. First, in order to eliminate the reaching phase, a novel T-NTSM manifold is proposed by incorporating a piecewise defined function of time into a nonsingular terminal sliding mode manifold. Then a T-NTSM controller is derived from such a sliding surface, by which the robustness is ensured during the entire response of the system, and the convergence time can be chosen in advance. An especially effective method is provided for parameter selection to meet the convergence time requirement. Subsequently, a modified T-NTSM controller is proposed to enhance performance by introducing a time-varying gain in the proposed T-NTSM manifold. The modified controller ensures faster convergence rate and smaller control input amplitude. Finally, the proposed controllers are applied in the control of a two-link manipulator. All of the simulation results demonstrate the effectiveness of the proposed control methods.

Ma, Qian; Lu, Junwei; Xu, Huiling

doi: 10.1177/0142331213513605pmid: N/A

This paper deals with the consensus problems of multi-agent systems with nonlinear dynamics and sampled data information. The control input of each agent is based on the information of its neighbors at discrete sampling instants rather than the whole continuous process. An input delay approach is utilized to transform the sampling data into the time-varying delayed data. A novel time-dependent Lyapunov functional consisting of the continuous term and the discontinuous term is proposed. Tools like matrix theory, algebraic graph theory, relaxed matrix approach, and convex analysis technique are utilized to derive the sufficient conditions. The estimated upper bound of the sampling interval can be obtained by the proposed conditions. Then, the necessary and sufficient conditions for consensus in systems with linear dynamics are presented. It is shown that the consensus conditions depend on the parameters of the sampling interval, spectra of the Laplacian matrix, and coupling strength. The effectiveness of the proposed design method is demonstrated by the simulation examples.

Xia, Hong; Huang, Ting-Zhu; Shao, Jin-Liang; Yu, Jun-Yan

doi: 10.1177/0142331213513606pmid: N/A

This paper investigates a leader-following formation control problem for second-order multi-agent systems with nonuniform time-varying communication delays under directed topologies. We first propose a consensus protocol and give a sufficient condition for second-order consensus of the system. Then, under a framework of multiple leaders, the protocol is applied to the formation control, including time-invariant formation and time-varying formation as well as time-varying formation for trajectory tracking. It is shown that the agents will attain the desired formation under the protocol. Finally, several simulations are conducted to illustrate the effectiveness of our theoretical results.

Zhan, Xi-Sheng; Guan, Zhi-Hong; Zhang, Xian-He; Yuan, Fu-Shun

doi: 10.1177/0142331213515017pmid: N/A

The optimal tracking performance of single-input-single-output networked control systems over limited communication channels is proposed in this paper. The signal-to-noise ratio (SNR) constrained of communication channel is considered. The tracking performance is measured by the energy of the error variance response between the output of the plant and the reference signal. The optimal tracking performance is obtained by applying the H2 square error criterion and the spectral factorization technique. It is shown that the optimal tracking performance is constrained by the non-minimum phase zeros, the unstable poles of a given plant, the power spectral density of a given reference signal, and the SNR of a communication channel. The results obtained in this work explicitly show how the optimal tracking performance is limited by the communication parameters (SNR in this paper). Finally, computer simulations are performed to verify the analytical results.

Tandon, Akshata; Dhawan, Amit

doi: 10.1177/0142331213508805pmid: N/A

This paper addresses the problem of non-fragile robust optimal guaranteed cost control for a class of two-dimensional discrete systems described by the general model with norm-bounded uncertainties. Based on Lyapunov method, a new linear matrix inequality (LMI)-based criterion for the existence of non-fragile state feedback controller is established. Furthermore, a convex optimization problem with LMI constraints is formulated to select a non-fragile robust optimal guaranteed cost controller, which minimizes the upper bound of the closed-loop cost function. The merit of the proposed criterion in aspect of conservativeness over a recently reported criterion is demonstrated with the help of illustrative examples.

Wang, Yen-Po; Tien, Szu-Chi

doi: 10.1177/0142331213516894pmid: N/A

This article demonstrates an iterative approach for precise parallelism and gap control of two platforms. In order to achieve this goal, three linear actuators were used to adjust the posture and distance of one platform with respect to the other. Besides, motion coupling between three actuators was considered and compensated for by a model-based iterative control method. The features of the proposed method are a simple actuating mechanism, efficient sensing architecture, and robust iterative control for permissive modelling uncertainties. Experimental results show that, within 0.3 s, the desired parallelism and gap can be achieved with errors in the sensor resolution level. Therefore, the proposed method is suitable for precise parallelism and gap control of two platforms.

Yu, Xiao; Lin, Xianwu; Lan, Weiyao

doi: 10.1177/0142331213518578pmid: N/A

This paper investigates the design of a composite nonlinear feedback (CNF) control law for an overhead crane servo system to improve the transient performance of both displacement tracking of the trolley and anti-sway of the payload. To address the property of underactuation of the overhead crane system, a novel nonlinear function of the CNF control law is specifically proposed to compromise the tracking performance of the trolley and the anti-sway performance of the payload. The performance improvement in both tracking of the trolley and anti-sway of the payload is illustrated with a complete comparison between the CNF control method and the trajectory planning method, which has been proposed in recent literature. The simulation results show that this well-tuned CNF control law can significantly shorten the settling time of the trolley displacement tracking and reduce the sway of the payload.