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Top1. Introduction
Pneumatic supply is normally powered by compressed air or inert gases. It is widely applied on mechanical control and automation process. It consumes more than billions electricity kWh one year around the world (Shi, et al 2019). However, inappropriate pneumatic pressure may cause irregular action of facilities even danger (Gaudeni, et al 2019; Davidovikj, et al 2018). Also, its power evaluation and measurement methods should be studied further to improve the efficiency of pneumatic system, and their applicability should be validated (Qiu, et al 2016; Chen, et al 2015; Xu, at al 2017). In past ten years (Shi, et al. 2019), many methods were focused on evaluation and measurement of pneumatic system the power. The analysis of energy loss in different pneumatic system and components has been unveiled (Xu, et al. 2014). Accordingly, several energy-saving system or dimensionless optimizations have been developed (Xu, et al. 2014; Yu, et al. 2014; Shi, et al 2014).
The actuator power to machinery can be transmitted and controlled through the pneumatic system. Due to some advantages such as low price and easy maintenance, the pneumatic system has been widely used in industry, becoming a crucial energy consumption source (Shi, et al. 2016; Liu, et al 2009; Mei, et al. 2015; Saadat, et al 2015; Shi, Y. et al 2013). For example, energy consumption of pneumatic system in Europe, USA, and China consumed more than 9% of total industrial power consumption (Radgen, 2006; Senniappan, 2004; Qin, et al 2008). However, improper use of pneumatic system may result in an high inefficiency that can be low as 30% in case of poor management and low efficiency of pneumatic components (Cai, et al 2006; Chen, et al. 2014). To improve the efficiency of pneumatic systems, the methods to accurately measure the compressed air should be well established.
Pneumatic measurement can be specified using three values related to constant-temperature accuracy, i.e. repeatability, hysteresis, and linearity (Frantlović, et al. 2014). However, much like anything else in the physical measurement world, the measurement such as using piezoresistive pressure sensors is subject to changes in environmental conditions. Most importantly, temperature effects tend to be the greatest impact on pressure measurement accuracy. It means that the measurement behavior of the pressure transducer shifts with temperature variation. Accordingly, temperature-related zero offsets and span errors arise in industry.
This paper aims to present a highly accurate pneumatic measurement based on the piezoresistive pressure sensor, particularly suiting extreme temperatures. The proposed system structure is introduced in Section II. The software system is illustrated in Section III. It includes description of the calibration process and HMI design. In Section IV, the experiments covering the design of module circuits, performance evaluation and temperature influence are provided and discussed.