Longhua Ma

Design and Implementation of a Wireless Sensor Network for Smart Homes

Wireless sensor networks (WSNs) have become indispensable to the realization of smart homes. The objective of this paper is to develop such a WSN that can be used to construct smart home systems. The focus is on the design and implementation of the wireless sensor node and the coordinator based on ZigBee technology. A monitoring system is built by taking advantage of the GPRS network. To support multi-hop communications, an improved routing algorithm based on the Dijkstra algorithm is presented. Preliminary simulations have been conducted to evaluate the performance of the algorithm.

Integrated Design and Implementation of Embedded Control Systems with Scilab

Embedded systems are playing an increasingly important role in control engineering. Despite their popularity, embedded systems are generally subject to resource constraints and it is therefore difficult to build complex control systems on embedded platforms. Traditionally, the design and implementation of control systems are often separated, which causes the development of embedded control systems to be highly time-consuming and costly. To address these problems, this paper presents a low-cost, reusable, reconfigurable platform that enables integrated design and implementation of embedded control systems. To minimize the cost, free and open source software packages such as Linux and Scilab are used. Scilab is ported to the embedded ARM-Linux system. The drivers for interfacing Scilab with several communication protocols including serial, Ethernet, and Modbus are developed. Experiments are conducted to test the developed embedded platform. The use of Scilab enables implementation of complex control algorithms on embedded platforms. With the developed platform, it is possible to perform all phases of the development cycle of embedded control systems in a unified environment, thus facilitating the reduction of development time and cost.

Field Programmable Gate Array Based Parallel Strapdown Algorithm Design for Strapdown Inertial Navigation Systems

A new generalized optimum strapdown algorithm with coning and sculling compensation is presented, in which the position, velocity and attitude updating operations are carried out based on the single-speed structure in which all computations are executed at a single updating rate that is sufficiently high to accurately account for high frequency angular rate and acceleration rectification effects. Different from existing algorithms, the updating rates of the coning and sculling compensations are unrelated with the number of the gyro incremental angle samples and the number of the accelerometer incremental velocity samples. When the output sampling rate of inertial sensors remains constant, this algorithm allows increasing the updating rate of the coning and sculling compensation, yet with more numbers of gyro incremental angle and accelerometer incremental velocity in order to improve the accuracy of system. Then, in order to implement the new strapdown algorithm in a single FPGA chip, the parallelization of the algorithm is designed and its computational complexity is analyzed. The performance of the proposed parallel strapdown algorithm is tested on the Xilinx ISE 12.3 software platform and the FPGA device XC6VLX550T hardware platform on the basis of some fighter data. It is shown that this parallel strapdown algorithm on the FPGA platform can greatly decrease the execution time of algorithm to meet the real-time and high precision requirements of system on the high dynamic environment, relative to the existing implemented on the DSP platform.

Enhanced Energy-Aware Feedback Scheduling of Embedded Control Systems

Dynamic voltage scaling (DVS) is one of the most effective techniques for reducing energy consumption in embedded and real-time systems. However, traditional DVS algorithms have inherent limitations on their capability in energy saving since they rarely take into account the actual application requirements and often exploit fixed timing constraints of real-time tasks. Taking advantage of application adaptation, an enhanced energy-aware feedback scheduling (EEAFS) scheme is proposed, which integrates feedback scheduling with DVS. To achieve further reduction in energy consumption over pure DVS while not jeopardizing the quality of control, the sampling period of each control loop is adapted to its actual control performance, thus exploring flexible timing constraints on control tasks. Extensive simulation results are given to demonstrate the effectiveness of EEAFS under different scenarios. Compared with the optimal pure DVS scheme, EEAFS saves much more energy while yielding comparable control performance.

Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems

There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless control systems closed over WLAN, a cross-layer adaptive feedback scheduling (CLAFS) scheme is developed, which takes advantage of the co-design of control and wireless communications. By exploiting cross-layer design, CLAFS adjusts the sampling periods of control systems at the application layer based on information about deadline miss ratio and transmission rate from the physical layer. Within the framework of feedback scheduling, the control performance is maximized through controlling the deadline miss ratio. Key design parameters of the feedback scheduler are adapted to dynamic changes in the channel condition. An event-driven invocation mechanism for the feedback scheduler is also developed. Simulation results show that the proposed approach is efficient in dealing with channel capacity variations and noise interference, thus providing an enabling technology for control over WLAN.

Net-in-Net: Interaction Modeling for Smart Community Cyber-Physical System

Cyber-physical system (CPS) integrates physics with Internet to provide a timely, confidential and efficient interaction of physical appliances with people. However, as a CPS Application, Smart Home still has difficulties in building a centralized interaction for remote monitoring. The paper presents the interaction model of Smart Community Cyber-Physical System (SCCPS) with the name Net-in-Net. The proposed model interaction is organized as a Wireless Sensor Network with Zigbee and GPRS technologies. Furthermore, B/S and C/S mixed mode is used as the architecture of remote interaction. After that a Cyber Protocol of application layer is proposed. Such model is supposed to provide a smart home interaction of high Security, reliability, stability and timeliness.

A Low-Cost Embedded Controller for Complex Control Systems

The complexity of real-world industrial control systems is growing rapidly. This raises significant challenges for the use of embedded systems in control applications, since embedded platforms are generally resource limited. In this work we develop a Scilab/Scicos based embedded controller on which various control software can be easily modeled, simulated, implemented, and evaluated to meet the ever-expanding requirements of complex industrial control applications. It is built on the Cirrus Logic EP9315 ARM9 systems-on-chip board. With the developed platform, it is possible to design and implement complex embedded control systems that employ advanced control strategies in a rapid and cost-efficient fashion. Thanks to the free and open source nature of the software packages used, the cost of the embedded controller is minimized.

Programming scilab in ARM linux

Scilab is a free and open source alternative to commercial scientific software packages for numerical computations. It provides an open programming environment along with a large number of powerful primitives. To realize the full potential of Scilab in embedded systems, this paper presents programming techniques essential for using Scilab in the ARM Linux environment. The Scilab package that usually runs on general-purpose computers is ported to the embedded Linux platform with an ARM9 processor. The programming of embedded software and hardware drivers using the ported Scilab package is addressed. Examples are given for illustrating the programming techniques. The cost of the embedded platform developed in this work is very low thanks to the free nature of the software packages used. The flexibility of embedded software built on this platform can be maximized since the source code is open.

Performance-Aware Power Management in Embedded Controllers with Multiple-Voltage Processors

The goal of this work is to minimize the energy dissipation of embedded controllers without jeopardizing the quality of control (QoC). Taking advantage of the dynamic voltage scaling (DVS) technology, this paper develops a performance-aware power management scheme for embedded controllers with processors that allow multiple voltage levels. The periods of control tasks are adapted online with respect to the current QoC, thus facilitating additional energy reduction over standard DVS. To avoid the waste of CPU resources as a result of the discrete voltage levels, a resource reclaiming mechanism is employed to maximize the CPU utilization and also to improve the QoC. Simulations are conducted to evaluate the performance of the proposed scheme. Compared with the optimal standard DVS scheme, the proposed scheme is shown to be able to save remarkably more energy while maintaining comparable QoC.

The Innovative Design of Low Cost Embedded Controller for Complex Control Systems

With the availability of ever more powerful and cheaper products, the number of embedded devices deployed in the real world has been far greater than that of the various generalpurpose computers such as desktop PCs. An embedded system is an application-specific computer system that is physically encapsulated by the device it controls. It is generally a part of a larger system and is hidden from end users. There are a few different architectures for embedded processors, such as ARM, PowerPC, x86, MIPS, etc. Some embedded systems have no operating system, while many more run real-time operating systems and complex multithreaded programs. Nowadays embedded systems are used in numerous application areas, for example, aerospace, instrument, industrial control, transportation, military, consumer electronics, and sensor networks. In particular, embedded controllers that implement control functions of various physical processes have become unprecedentedly popular in computer-controlled systems (Wittenmark et al., 2002 ; Xia, F. & Sun, Y.X., 2008). The use of embedded processors has the potential of reducing the size and cost, increasing the reliability, and improving the performance of control systems.