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The complexity of algorithms implemented in digital systems grows. Methods are developed for most effective use of both hardware resources and energy. For engineers the problem of hardware resources optimization in design of control units is still an important issue. The standard way of implementing the control unit as a finite-state machine (FSM) is not satisfactory as it consumes considerable amounts of field-programmable gate arrays (FPGA) resources. This paper is devoted to the design of a Moore FSM in FPGA structure using look-up tables and embedded memory blocks (EMB) elements. The problem background is discussed. The method of the design of Moore FSM logic circuits with EMB based on splitting the set of logical conditions and the encoding of logical conditions is presented. Examples of design and research results are given.

This Letter displays, via the numerical simulation of a real digital filter, that a finite-state machine may behave in a near-chaotic way even when its corresponding infinite-state machine does not exhibit chaotic behavior.

Lower-limb exoskeletons are an effective means to provide paraplegic and hemiplegic individuals with the ability to walk upright. A lot of studies about lower-limb exoskeletons have been developed to assist the impaired populations. However, the existing devices are still too technically complex and expensive for practicality. In this paper, a compact lower-limb exoskeleton for walking assistance is developed, in which a steel-cable actuator is specially designed. In order to accomplish the different tasks presented to gait generation, a control method with multiple stages is employed. In this approach, four basic states and seven intended motions are designed for the finite-state machine. In addition, the reference trajectories of these intended motions are presented and fitted by a modified first-order polynomial-fitting method. Preliminary motion tests of the exoskeleton with three healthy subjects are performed. The results verify the effectiveness of the system design and the gait-generation approach proposed in this paper. The overall exoskeleton system is compact and the corresponding operations are convenient and reliable.

Exchanging simulation models is currently of utmost importance. To improve interoperability between suppliers and original equipment manufacturers (OEMs), the functional mock-up interface (FMI) is exchanged in a standard format called functional mock-up unit (FMU). Since its first release, many simulation tools took the initiative to support FMI. However, since then, there have been many complaints stating that exchanging models via FMI does not work as stable as expected. The reason usually turned out to be the implementation of tool vendors that sometimes fail to comply with the standard fully. This paper introduces a methodology for testing FMI compliance of importing simulation tools using a set of reference FMUs. The standard defines the implementation of FMI functions calling sequence in a state machine. Therefore, conformance testing (also called fault detection) from automata theory is utilized to produce reference FMUs based on the FMI state-machine.