Research Article Noise in Load Cell Signal in an Automatic Weighing System Based on a Belt Conveyor Kyoo Nam Choi Department of Information and Telecommunication Engineering, Incheon National University, Incheon 22012, Republic of Korea Correspondence should be addressed to Kyoo Nam Choi; knchoi@inu.ac.kr Received 23 April 2017; Revised 23 June 2017; Accepted 12 July 2017; Published 8 August 2017 Academic Editor: Stephane Evoy Copyright © 2017 Kyoo Nam Choi. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Noise in load cell signal in an automatic weighing system based on a belt conveyor has been examined experimentally in time and frequency domains to enhance signal quality. Te noise frequency spectrum showed nonlinearly increasing multiple resonance peaks as speed increased. Te noise reduction process using noise reduction algorithm, by sharply rejecting peak noise frequency component and aferward forming optimum pulse width ratio through flter slope control using selective switching of 6 LPF stages, was used for enhanced accuracy. Te efectiveness of proposed method, controlling both cutof frequency and slope of LPF, was evaluated by feeding 50 g test mass, and this noise reduction process showed better noise fltering with enhanced accuracy than fxed cutof frequency control method. Te ratio of top to bottom pulse width showed that LPF cutof frequency above 5 Hz had the ratio above 50% up to 80 m/min speed range. 1. Introduction Te conveyor belt is widely used, for sensing application, to measure continuously the physical parameters of an object in many felds [1]. Te vision sensors are used for tracking and identifying an object moving on a conveyor belt [2– 4], and range sensors are used for volume measurement [5]. Te automatic weighing and sorting system is used in food and pharmaceutical industry where continuous and precise mass measurement of small objects is required [6, 7]. Te belt conveyor is used for automatic weighing to continuously feed products under measurement [8–12]. However the horizontal and rotational movements of belt conveyor eventually cause vibration [13], and these behave as noise source to the output of load cell sensor [14, 15]. High signal-to-noise ratio (SNR) is needed to improve accuracy and resolution of weighing machine; thus noise reduction is essential process [16–19]. Te electric motor, AC induction or BLDC motor, is used to actuate belt conveyor [20–22], which has diferent vibration characteristics. Also other individual components of belt conveyor, such as bearing, belt, and roller, with accompa- nying vibration, transfer noise to load cell sensor [23]. Te way to reduce the vibration noise of belt conveyor has been investigated [24, 25], and the method to locate the fault point in belt conveyor has been attempted by analyzing audible signal from belt conveyor [26, 27]. Also the investigation to driving motor to reduce the noise was conducted [28]. Te work to improve accuracy through modeling has been performed for weighing machine adapting belt conveyor [29]. Further eforts to enhance continuous measurement accuracy for high speed mass measurement have been performed [30, 31]. In respect of analysis method, the algorithm adapting frequency analysis [32, 33] or digital flter [34] was attempted. In this paper, the noise in load cell signal in an automatic weighing system based on a belt conveyor is analyzed, and the method to reduce the noise component in load cell sensor is investigated. 2. Vibration Noise Analysis Noise,   (, ), from belt conveyor contains not only the operating vibration but also the environment noise, as shown in (1). Te environment noise,   (, ), has the characteris- tics of either white noise or nonstationary process; however the operating vibration,   (, ), has the characteristics of wide sense stationary process. Tese noises from individual components of belt conveyor can be analyzed in time domain and frequency domains. Te objective of this study is to Hindawi Journal of Sensors Volume 2017, Article ID 1524782, 9 pages https://doi.org/10.1155/2017/1524782