Blog Post

Incorporating Ergonomics into HMI Design

Sarah Landry

According to the International Ergonomics Association“Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data, and other methods to design in order to optimize human well-being and overall system performance.”

ProSys has implemented many ergonomic principles into its design of Interface Dynamics, which is its human-machine interface (HMI) library that supports process-operator interface goals for process displays, historical trends and data, operations data and control system data. Because operator awareness and performance are vital to plant safety and efficiency, interfaces must be designed to optimize operator-interface interaction. Many design aspects must be considered in order to minimize eye strain, fatigue, headaches and other physiological impacts associated with frequent computer interface use, and also to increase the overall system performance of the plant.

Human Well-Being

Color

ProSys incorporates standard colors for display backgrounds, and objects are optimized for reduced eye strain. For alarm indications, standardized high-intensity colors stand out from the display and immediately catch the attention of the operator. Color blindness must be considered when designing an interface. In addition to color, standard alarm symbols (with corresponding alarm colors) appear during an alarm. Symbols and colors blink when unacknowledged by the operator and once acknowledged, remain steadily visible throughout the duration of the alarm. In the design process, applying filters for color-deficient vision can be used to visualize how colors appear to those with deuteranopia (insensitivity to green), protanopia (insensitivity to red) and tritanopia (insensitivity to blue). Incorporating this tool into display design can be used to determine if any colors need to be adjusted in order to support those affected with color blindness.

Clarity

Presenting important process information without cluttering the screen with unnecessary detail is imperative. Displays should clearly present information such that the operator can quickly access important details without having to search. Dominating the screen area with superfluous information can create a higher frequency of searching, which in turn can cause eye fatigue, headaches, confusion and ultimately a reduction in operator efficiency. ProSys assesses which pieces of process information are necessary to display and then uses its Interface Dynamics elements to represent that information in a clear and consistent format.

Consistency

Interfaces should be as consistent as possible in order to increase recognition, decrease confusion and decrease search time. ProSys incorporates consistent display layouts, standardized shapes and colors and common interface elements in order to allow for easier interpretation of processes and process readings. This ensures that the operator does not spend extra time searching, processing and trying to distinguish between various elements while navigating through and between displays.

Overall System Performance

ProSys also implements human factors principles into its design in order to optimize overall system performance. Ease-of-use and intuitive elements equally contribute to a successful interface and can aid in reducing operator training time. Context menus (available on all points with a simple right-click) provide standard functions for all points, along with point-specific functions based on point type. The menu bar provides easy, standardized access to all functions on all displays, and rolls away on mouse-hover. Values can be entered by a simple select element-type value-press enter method, or by “Select Point” or PMK keys. These aspects reduce required operator clicks and/or keystrokes and improve response time. Colors and shapes on a display convey information in an intuitive manner. ProSys uses standard representative shapes to display elements of a process, which have the ability to change colors based on real-time process information. For example, dynamic shapes are indicated with a bold outline. Closed pumps and valves appear dark gray, and open pumps and valves will change to the same color as the line. Clear and consistent displays also contribute to overall system performance, reducing search time and increasing response efficiency.

ProSys uses the principles of human factors in every aspect of its design process. The well-being of the plant and its operators, combined with the overall efficiency of the system, contribute to a successful and productive process.