A Monitoring System to Reduce Shoulder Injury Among Construction Workers

As the work force ages and workers retirement age increases, the number of workers suffering from Work-related Musculoskeletal Disorders (WMSDs) has increased. In a recent study, the U.S Bureau of Labor reported that 6.9% of all WMSDs affected shoulders. Electricians, carpenters, and related construction crafts appear to experience higher incidence of these injuries due the nature of their work that require them often to use Awkward shoulder postures. This research aims to develop a new monitoring system that measure the amount of time workers spend in awkward shoulder postures to help decrease the prevalence of cumulative shoulder injuries and to reduce the number of cases of shoulder WMSDs among construction workers. The monitoring system was designed and a feasibility study was conduct to compare the monitoring system with a state of the art motion tracking system. Overall the monitoring system was able to count the time spent in awkward posture as a discrete state sensor and it can be implemented in the field. However, results showed that the monitoring system in its current configuration require some future work for it to produce quantitatively precise results that can be used in the fields of biomechanics, robotics, and ergonomics

Use of Kinematics to Minimize Construction Workers' Risk of Musculoskeletal Injury

Construction work requires more repetitive and highly physical effort than, for example, office work. Despite technological advancements in construction, the human factor is still an essential part of the industry. Hence, the need to maintain a healthy work environment is a shared interest between workers and industry. This thesis addresses the problem of cumulative injuries among construction workers, with emphasis on masons, and examines ways to improve safety and productivity simultaneously. Vision-based motion capture and sensor-based joint angle measurement techniques were tested against a state-of-the-art Optotrak system. Results show that the overall error in joint angle measurements was 10 deg for vision-based approaches compared to 3 deg for optical encoders. Moreover, a noninvasive fatigue detection method was developed by applying time-delay embedding and phase-space warping (PSW) techniques to a single joint angle, exerted force, and electromyography (EMG) data. Results indicate that the method can detect a slowly changing variable, fatigue in a limb, from a single kinematic signal, limb exerted force, or its EMG signals. Furthermore, twenty one masons distributed in four experience categories, ranging from novice to expert, took part in a study to evaluate safety and productivity in masonry work using inertial measurement units (IMUs). The study hypothesized that masons adopt safer and more productive work techniques with experience and that these techniques can be identified and used to train novice workers. Results indicate that journeymen appear to develop more productive and safer work techniques compared to other groups. On the other hand, the three-years experience group was found to sustain the highest joint compression forces and moments. Results also show that a clear distinction exists between expert and inexpert mason motion patterns. Support Vector Machine (SVM) classifiers were able to identify these differences with an accuracy of %92.04 in 13 seconds using a linear kernel. The thesis findings justify exploration of sensor fusion techniques to combine direct and indirect motion capture systems. The findings also suggest that PSW can be used in applications such as rehabilitation to access information about patient status hidden in the full-chain kinematics using a single kinematic signal. Finally, findings show the potential for training apprentices to excel in all three aspects: proficiency, productivity, and ergonomic safety by following the example of experts

Bedsores Management: Efficiency Simulation of a New Mattress Design

Bedsores, also known as pressure ulcers, are wounds caused by the applied external force (pressure) on body segments, thereby preventing blood supply from delivering the required elements to the skin tissue. Missing elements hinder the skin’s ability to maintain its health. It poses a significant threat to patients that have limited mobility. A new patented mattress design and alternative suggested designs aimed to reduce pressure are investigated in this paper for their performance in decreasing pressure. A simulation using Ansys finite element analysis (FEA) is carried out for comparison. Three-dimensional models are designed and tested in the simulation for a mattress and human anthropometric segments (Torso and Hip). All designs are carried out in solidworks. Results show that the original design can redistribute the pressure and decrease it up to 17% less than the normal mattress. The original design shows better ability to decrease the absolute amount of pressure on the body. However, increasing the surface area of the movable parts results in less pressure applied to the body parts. Thus, this work suggests changing the surface area of the cubes from 25 to 100 cm2