In this paper, we propose a hardware design for an effective real time indoor localization system for staff working in high-risk manufacturing areas. Because of the special requirements of our system, the chirp spread spectrum (CSS) is the most suitable indoor localization technology. The details of the new localization system are described. The system involves several anchors, tags, and a gateway, all of which use the nanoLOC TRX transceiver (NA5TR1) RF chip (Nanotron Co., Germany), which is based on the CSS technology. To validate the effectiveness of our system, both ranging and localization tests were carried out. The difference between the ranging accuracy indoors and outdoors was small. The localization system can position indoor mobile staff precisely, enabling the establishment of an emergency rescue mechanism.

Application of terrain-vehicle mechanics for determination and prediction of mobility performance of autonomous wheeled mobile robot (AWMR) in rough terrain is a new research area currently receiving much attention for both terrestrial and planetary missions due to its significant role in design, evaluation, optimization, and motion control of AWMRs. In this paper, decoupled closed form terramechanics considering important wheel-terrain parameters is applied to model and predict traction. Numerical analysis of traction performance in terms of drawbar pull, tractive efficiency, and driving torque is carried out for wheels of different radii, widths, and lug heights, under different wheel slips. Effects of normal forces on wheels are analyzed. Results presented in figures are discussed and used to draw some conclusions. Furthermore, a multiobjective optimization (MOO) method for achieving optimal mobility is presented. The MOO problem is formulated based on five independent variables including wheel radius r, width b, lug height h, wheel slip s, and wheel rotation angle θ with three objectives to maximize drawbar pull and tractive efficiency while minimizing the dynamic traction ratio. Genetic algorithm in MATLAB is used to obtain optimized wheel design and traction control parameters such as drawbar pull, tractive efficiency, and dynamic traction ratio required for good mobility performance. Comparison of MOO results with experimental results shows a good agreement. A method to apply the MOO results for online traction and mobility prediction and control is discussed.

This paper describes a coded cooperative multiple-input multiple-output (MIMO) scheme, where structured low-density parity-check (LDPC) codes belonging to a family of repeat-accumulate (RA) codes are employed. The outage probability of the scheme over Rayleigh fading channels is deduced. In an unknown channel state information (CSI) scenario, adaptive transversal filters based on a spatio-temporal recursive least squares (ST-RLS) algorithm are adopted in the destination to realize receive diversity gain. Also, a joint ‘Min-Sum’ iterative decoding is effectively carried out in the destination. Such a decoding algorithm agrees with the bilayer Tanner graph that can be used to fully characterize two distinct structured LDPC codes employed by the source and relay. Simulation results verify the effectiveness of the adopted filter in the coded cooperative MIMO scheme. Theoretical analysis and numerical simulations show that the LDPC coded cooperative MIMO scheme can well combine cooperation diversity, multi-receive diversity, and channel coding gains, and clearly outperforms coded noncooperation schemes under the same conditions.

The error patterns of a wireless channel can be represented by a binary sequence of ones (burst) and zeros (run), which is referred to as a trace. Recent surveys have shown that the run length distribution of a wireless channel is an intrinsically heavy-tailed distribution. Analytical models to characterize such features have to deal with the trade-off between complexity and accuracy. In this paper, we use an independent but not identically distributed (inid) stochastic process to characterize such channel behavior and show how to parameterize the inid bit error model on the basis of a trace. The proposed model has merely two parameters both having intuitive meanings and can be easily figured out from a trace. Compared with chaotic maps, the inid bit error model is simple for practical use but can still be deprived from heavy-tailed distribution in theory. Simulation results demonstrate that the inid model can match the trace, but with fewer parameters. We then propose an improvement on the inid model to capture the ‘bursty’ nature of channel errors, described by burst length distribution. Our theoretical analysis is supported by an experimental evaluation.

Parallel operation of distributed generation is an important topic for microgrids, which can provide a highly reliable electric supply service and good power quality to end customers when the utility is unavailable. However, there is a well-known limitation: the power sharing accuracy between distributed generators in a parallel operation. Frequency and voltage droop is a well-established control method for improving power sharing performance. In this method, the active and reactive power calculations are used to adjust the frequency and amplitude of the output voltage. This paper describes the digital implementation of a droop method, and analyzes the influence of power calculation on droop method performance. According to the analysis, the performance of droop control in a digital control system is limited by the accuracy and speed of the power calculation method. We propose an improved power calculation method based on p-q theory to improve the performance of the droop control method, and we compare our new method with two traditional power calculation methods. Finally, simulation results and experimental results from a three single-phase 1-kW-inverter system are presented, which validate the performance of our proposed method.

This paper presents the design principles and fabrication techniques for simultaneously forming non-coplanar resonant beams and crab-leg supporting beams of dual-axis bulk micromachined resonant accelerometers by masked-maskless combined anisotropic etching. Four resonant beams are located at the surface of a silicon substrate, whereas the gravity centre of a proof mass lies within the neutral plane of four crab-leg supporting beams on the same substrate. Compared with early reported mechanical structures, the simple structure not only eliminates the bending moments caused by in-plane acceleration, and thereby avoiding the rotation of the proof mass, but also providing sufficiently small rigidity to X and Y axes accelerations, potentially leading to a large sensitivity for measuring the in-plane acceleration.