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Most servo control systems generally adopt incremental optical encoders for speed detection when considering cost and performance requirements. For a fixed sampling period, this kind of encoder along with the generally used so-called M method, may degrade the response or even cause the system to become unstable in a low-speed operating region because of the resulting speed detection delay. In this article, a reference model improves low-speed responses; parameter identification by recursive least square error algorithm overcomes the problem of parameter variations and an adaptive proportional-integral control strategy based on the parameter identification results further justifies the proposed method. A digital signal processor based permanent magnet synchronous motor drive will be used to carry out the experimental results, which show the effectiveness of the proposed method.

Considering the performance and cost, the position and wide-range speed control of a servo control system generally adopted an incremental encoder. The so-called M method, based on averaged calculation of encoder pulses, generally results in detection lag during speed estimation. It would be much worse when the interval between the pulses is wider than the sampling time at low motor speeds. As a result, the detection delay time may make the speed control system unstable. In the paper, instead of using a disturbance torque observer, a reference model via proportional-integral-derivative (PID) control is proposed to approach the instantaneous motor speed and improve the low-speed control performance. A digital signal processor (DSP)-based industrial brushless motor drive will present the experimental results, which show the improved resolution and the effectiveness of the proposed method.

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The application of modern technologies into on-site construction safety management has been proved that be successful. BIM technology which has been studied and developed for adopting widely in the construction industry is promised to bring significant improvements in construction safety management. The article reviewed the application of BIM in the management of construction safety, detailed for each safety work activity. Suggestions for selecting BIM tools in the management of construction safety are also listed. Lastly, the article poses some obstacles while applying BIM to construction safety management in Vietnam.

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