Human-robot collision predictor for flexible assembly

<p class="Abstract"><span lang="EN-US">The performance of human–robot collaboration can be improved in some assembly tasks when a robot emulates the effective coordination behaviours observed in human teams. However, this close collaboration could cause collisions, resulting in delays in the initial scheduling. Besides the commonly used acoustic or visual signals, vibrations from a mobile device can be used to communicate the intention of a collaborative robot (cobot). In this paper, the communication time of a virtual reality and depth camera-based system is presented in which vibration signals are used to alert the user of a probable collision with a UR5 cobot. Preliminary tests are carried out on human reaction time and network communication time measurements to achieve an initial picture of the collision predictor system’s performance. Experimental tests are also presented in an assembly task with a three-finger gripper that functions as a flexible assembly device.</span></p>

Development of Standards for Production of an Exit Sign Lighting to Minimize Human Reaction Time - Part II: Combination of Graphical Symbol Colours

In emergency situations, exit sign lightings play a role in reducing evacuation time for occupants by providing accurate and prompt information on the correct evacuation direction. In other words, it can be said that the better the recognition of exit sign lighting, the greater the probability of securing the safety of life because the evacuation route information is given to the occupants and eventually the time taken for route selection and movement is shortened. In this study, human reaction time was measured for 27 kinds of graphic symbol color combinations of exit sign lightings in the visible light region, and through this, a graphic symbol color combination that can minimize reaction time to exit sign lightings was derived. As a result, it was found that the color combination of green and white background color, which is currently mainly used in Korea, has the shortest reaction time.

Development of Standards for Production of an Exit Sign Lighting to Minimize Human Reaction Time - Part I: The Minimum Effective Dimensions

Based on National Fire Safety Codes 303 in Korea, the size of an exit sign lighting to be installed is determined according to space use. Accordingly, a small exit sign lighting can be installed in a large area, which causes problems in the visual recognition of the exit sign lighting by occupants and increases the time required for evacuation. Therefore, in this study, human reaction time measurement experimental tests were conducted in a virtual reality environment to analyze the minimum effective dimension of an exit sign lighting. It was found that the minimum effective dimension of emergency exit sign lighting should be set to a length of 255 mm or more on one side of a 1:1 square display surface.

Psychometric test system for measuring cognitive reaction time

For the assessment of human reaction time, a test environment was developed. This system consists of an embedded device with organic light-emitting diode (OLED) displays with push buttons for the combined presentation of visual stimulation and registration of the haptic human reaction. The test leader can define the test sequence with the aid of a graphical user interface (GUI) on a personal computer (PC). The validation of the system was proved by measuring the latency times of the whole system, which are conditioned by the specific hard- and software constellation. Through the investigation of the display’s light radiation by a photodiode and the recorded current consumption, latency times and their variance were specified. In the fastest mode the system can reach an error limit of 60 μs.