Design of an Ergonomic Acquisition and Monitoring Framework in Assembly Task Zulfadli Zailan a, Seri Rahayu Kamat b, MuhamadArfauz A Rahman c, Norhidayah Hashim d, Muhammad Eizzat Roselaile e, Mohd Norazlan Abd Razak f Faculty of Manufacturing Engineering, UniversitiTeknikal Malaysia Melaka, Durian Tunggal, 76100 Melaka, Malaysia a m051310029@student.utem.edu.my, b seri@utem.edu.my, c arfauz@utem.edu.my, d m051210004@student.utem.edu.my, e b051010242@student.utem.edu.my, f b051010200@student.utem.edu.my, Keyword: ergonomic, acquisition, monitoring, working posture, working environment, assembly task. Abstract.Optimum working conditions, such as body posture, body movement and working environment, are commonly not directly known to the worker. In fact, the worker current working conditions are rarely provided. Although some may find it unnecessary, a mechanism to provide information on this situation is deemed to be useful. This paper presents a proposed framework for acquiring and monitoring ergonomic parameters. There are six potential useful parameters proposed in this study. The parameters include temperature, light, vibration, body posture, indoor air quality, and noise. In the proposed framework, the capturing device and signal converter are regarded as the main components. The framework is proposed to capture all parameters in the analog signal, and later convert it into the digital signal using the signal converter. At this stage, NI cdaq-9188 is proposed to be used as the signal converter in the framework. The preliminary work of the proposed framework will be developed in the lab, while the implementation will be conducted at the chosen industry. It is hoped that the proposed framework will benefit industry and promote a safe working environment in the industry, especially for assembly tasks. Introduction In 2012, the manufacturing sector has the highest occupational accident in Malaysia, with an estimation of more than 1700 accidents [1]. The study was made through comparing a mining, construction, agriculture and utility sectors. The comparison shows that the manufacturing sector has the most unsafe working environment. According to Vilas et al., workers performance is much related to the safe and optimum working environment [2]. However not all companies are aware of the acceptable safe and optimum working environment for their workers. There are many parameters that may bring harm to the worker. Temperature, lighting, noise, air quality, radiation, pressure, humidity, and dust are examples of the environment parameters [3]. Vibration, body posture, body movement, load carry by body, hand grip during work are examples of the parameter that inflicts harms to a worker s body [4]. This parameter is captured or measured by the sensor separately. Each parameter is captured by a specific sensor. Fig. 1 shows the parameters that are monitored by the proposed framework.
Lamp Noise Machines Room temperature Body posture Worker Vibration Power tool Workstation Lighting intensity Fig. 1 Ergonomic parameters to be monitored Air quality Material waste These parameters give a significant impact to the workers performance and health. Thus, a system to capture these ergonomic parameters need to be developed to keep the workers wellness and safety. Review of Relevant Works Monitoring system is widely used in the medical, agriculture and meteorology fields [5-7]. However, minimal research is currently undertaking in terms of ergonomic and safety. One of the developed systems is used to manually monitor loading and unloading activities by the industrial workers. The system is used to capture the worker s movement while carrying loads [8]. There is also a system used to detect office workers body postures while sitting on a chair. This system is useful for an office worker who spends a lot of time in front of a computer [9]. However, there are no system available to capture other ergonomic parameters like environmental factor, whole body vibration and body posture, specifically for the manufacturing industry.this is very crucial as most activities conducted by the manufacturing workers are considered as rigorously harmful and potentially affect the safety and health of the workers. To overcome this situation, a suitable mechanism to monitor the optimum and safe working environment is deemed critical. An initial step is currently undertaken to create a monitoring framework for all the parameters and discussed in the next section. Proposed framework The initial work starts with the study conducted at the chosen industry. Later a framework is proposed. The proposed framework is divided into a few sections. Fig. 2 shows the components of the proposed monitoring framework.
Parameter Acquisitionsystem Human factor Environmental factor Sensor Camera Fig. 2 Componentof the proposed monitoring system The proposed monitoring framework consists of the following components: Parameters. Parameter is a factor to be measured and monitored by the proposed monitoring system. It is essential to monitor these parameters to prevent from ergonomic and fatigue hazards, thus, ensure safety among workers. The parameters are divided into the environmental factor and human factor. The environmental factor can lead to an ergonomic, safety and health problems like fatigue, discomfort, heat stress and low concentration ability [3]. As shown in Figure 1, room temperature, air quality and lighting intensity, and noise are the environmental factors that are monitored by the proposed monitoring framework. With these elements monitored, workers fatigue and ergonomic hazards can be measured, thus precautions and preventive steps can be taken at an early stage. As for the human, there are many factors that need to be considered which may optimize working conditions. Two factors are chosen to be monitored and measured by the proposed monitoring frameworks, which are body posture and vibration on the workers. Working with the poor body posture comes with bad circumstances. For a short time of period, a poor body posture can make the worker feel discomfort and fatigue. For a long term, poor body posture promotes an ergonomic hazard, especially work-related musculoskeletal disorder (WMSD) [10]. The body postures that need to be monitored are the repetitive movement and body bending. Body bending is proving to be the cause of low back pain [4].The repetitive movement is measured by counting the body movement per hour. The body bending is shown more clearly in two figures: Fig. 3 show the angle of body bending, and Fig. 4 shows directions of body bend, where the references point is the waist. αº DAQ Monitoring tools PC
Fig. 3 angle of the bending Fig. 4 directions of body bend The second human factor is vibration. Vibration usually caused by power tools or machines. An excessive vibration can cause many health problems, like carpal tunnel syndrome (CTD) and handarm vibration (HAV) [3-4]. The vibration that is measured in the proposed monitoring framework is in the human arm and wrist. Once all the parameters are ready, they need to be identified and acquired by means of a tool. The next section elaborates the proposed acquisition system. Acquisition system. The acquisition systems consist of a capturing device and a signal converter. The capturing devices used for the proposed monitoring system are listed in Table 1. Table 1 Proposed device used for capturing ergonomic parameter Ergonomic factor Capturing device Parameter measurement ( unit ) Temperature Temperature sensor Celsius ( Cº ) Air quality Air quality sensor CO² concentration (ppm) Noise Microphone Decibel ( Db ) Lighting Photo sensor Lux ( lx ) Vibration Vibration sensor Frequency ( Hz ) Body posture or movement Camera Direction and Angle degree ( αº) The expected signal that comes out from the capturing devices is in a form of analog signals. Nevertheless, the computer can only read the digital signals. Thus the signal converter is proposed to be used to convert the analog signals to digital signals. A NI cdaq-9188 data acquisition model is proposed to be utilized in this monitoring framework. Once the data is captured, a mechanism for monitoring the data is required. This is discussed in the next section. Monitoring tools. The measurement of the ergonomic factor is shown in a visual form through a monitoring tool. Examples of the displays that can be used are the desktop computer and smart phone. Discussion and future work A preliminary work on capturing all the desired parameters is currently undergoing. All the preliminary work on capturing all the desired parameters is based on the actual assembly task in the industry. In the following phase, a suitable type of sensor is identified. The type of sensor and its specification is further studied and finalized to ensure efficiency and accuracy of the sensors in the actual working environment. For the data acquisition, a system for acquiring and storing the data
will be developed in the future work. Later, the software that displays the data will be developed. The displaying software has to be user friendly and easy to be analyzed by supervisors or workers. Conclusion A framework for acquiring and monitoring ergonomic parameters has been proposed. Through the provision of this research, an optimum working condition such as body posture, body movement and working environment can be provided. A safe and optimum working environment can benefit both the workers and employers. With a good ergonomically designed and safe working place, productivity and performance among workers may be significantly increased. For the employers, a safe and optimum working environment may reduce the possibilities of accidents amongst the workers, which indirectly lessens medical costs needed to pay to the workers due to the hazards occurred at work. The framework is proposed to capture all parameters in the analog signals, and later converted into the digital signals using the signal converter, and eventually hoped to promote a safe and optimum working environment. Worker will be more confident to work with an employer that can provide a safe and optimum working environment. Thus, percentage for an employer to gain an experienced worker is high. Acknowledgments The authors would like to acknowledge the financial support received from the Universiti Teknikal Malaysia Melaka (UTeM) through the short grants scheme PJP/2012/FKP(4C)/S01118. References [1] Information on www.dosh.gov.my/index.php?option=com_content&view= article&id=795:occupational-accident-statistic-2012&catid=458&itemid=695&lang=en [2] David del Rio Vilas, Francesco Longo, Nadia RegoMonteil, General Framework for The Manufacturing Workstation Design Optimization: a combined ergonomic and operational approach, Society for Modeling and Simulation International (2012), 306-329. [3] David L. Goetsch, Occupational Safety and Health for technologist, engineers and manager, sixth ed., Pearson Prentice Hall, New Jersey, 2008 [4] R. S. Bridger, Introduction To Ergonomic, third ed., Taylor & Francis Group, Boca Raton, 2009 [5] Wang Xiaohong, Liu Li, The Design of Remote Medical Monitoring System Based on Sensors and GPRS, International Forum on Information Technology and Application (2009), 516-519 [6] MengJi-hua, Wu Bin g-fang, Li Qiang-zi, A Global Crop Growth Monitoring System Based on Remote Sensing, IEEE International Conference on Geoscience and Remote Sensing Symposium (2006), 2277-2280. [7] Rong-Hua Ma, Yu-Hsiang Wang, Chia-Yen Lee, Wireless Remote Weather Monitoring System Based on MEMS Technologies, Sensors ISSN/EISSN (2011), 2715-2727 [8] Information on htlp:lldx.doi.org/10.4108//cstpervas/veheal TH2010. 8894. [9] Alvaro Uribe-Quevedo, Byron Perez-Gutierrez, Cesar Guerrero-Rincon, Seated tracking for correcting computer work postures, 29th Southern Biomedical Engineering Conference (2013), 169-170 [10] AtiyaAlzuheri, Lee Luong, Ke Xing, Ergonomics Design Measures in Manual Assembly Work, Engineering System Management and Its Application, Second International Conference (2010), 1-6