HUMAN SUPERVISORY PERFORMANCE IN FLEXIBLE MANUFACTURING SYSTEMS

The Flexible Manufacturing System (FMS) integrates humans, computers, robots, and computerized machines in order to meet system goals. The objective of the current dissertation is to explore both the optimal allocation of tasks between human supervisor and computers and the optimal number of machines which a supervisor should control in an FMS. As a background to the proposed methodology, the relevant literature pertaining to FMS is reviewed with special emphasis on human-computer communication, multitask performance in FMS in relation to inverted-U theory, attention theory, and human decision capabilities. The hypotheses are proposed that there is an interaction effect between the number of machines and the task allocation level and that there exists an optimal level of number of machines for the operator to monitor. These hypotheses were tested in a statistically balanced experimental design using 30 subjects with three independent variables: number of machines (5 levels--4, 8, 12, 16, or 20 machines), task allocation (2 levels--high or low), and sequence of task presentation (2 levels). Physiological measures (EKG and respiratory rate) and two subjective stress questionnaires were used as indices of the arousal level. The results reveal that the Inverted-U function for response time as a function of machine level was not supported and the allocation level was significant for both performance and subjective stress criteria. These results suggest that in the supervision of FMS the task allocation to the supervisor is critical but that the size of the FMS system (4 to 20 machines), with the allocations studied, has no effect on either stress or performance of the operator in the FMS

The Development of a Training Expert System for TFT-LCD Defects Inspection

At present, the image quality of LCD panels has been determined subjectively by human visual inspection. In fact, the inspectors need to memorize a large number of instructions. The inspection tasks include a series of complicated procedures that increase the workload of the inspectors. This research focuses on the improvement of LCD inspection. The knowledge extracting of inspection data was to analyze association rules through interviewing experienced inspectors. Then the nested IF-THEN inspection rules between defects and test patterns were analyzed by two-dimensional matrix and group technology (GT). In terms of inspection test patterns, the occurring sequence of pattern was rearranged to make inspection tasks more efficient. Furthermore, this study aimed to construct an expert system for LCD defects inspection. According to the results of the experiment and expert evaluation, the expert system was proposed as a training support system to aid the trainees to learn inspection skills more effectively. Therefore, the performance of the inspection training could be improved

Safety Assessment of Different In-Vehicle Interface Designs for Bus Collision Warning Systems

Numerous studies have concluded that collision warning systems (CWSs) help drivers be aware of imminent dangerous situations. Driving safety and ergonomics make designing a CWS a very important task. Many studies have explored the effects of different types of CWS interface designs on driving safety performance. However, most of these studies were for passenger cars, with few studies focusing on buses. This study investigates the effects of four different types of in-vehicle bus CWS interfaces on driver reaction time to front events (i.e., a lead vehicle breaking suddenly) and side events (i.e., a vehicle cutting in too close) using a bus driving simulator. Twenty-nine professional bus drivers participated in the experiment. For both front events and side events, the driving experiment results reveal that driver reaction times are highly correlated with crash occurrence. The four different types of bus CWS interface designs can significantly reduce driver reaction time. Driver response time is the shortest for the interface using a beep and symbol shown on a heads-up display indicating the direction of danger. This study concludes that buses should be equipped with CWSs to protect the safety of bus drivers and passengers