Defining the operational/functional requirements
The key to an effective HMI System for any passenger rail application is consistent and predictable performance with time-proven controls that are familiar and intuitive to all passengers. Controls need to be clear and easy to understand and use in order to reduce the risk of human error.
How many functions will be controlled by this interface? Typically, these controls have very few, specific functions. What kind of visual, auditory, or tactile feedback will best serve the passenger in the performance of the defined functions?
Degree of input complexity
Input can be as simple as an on/off, emergency stop.
Feedback is critical to operator effectiveness and efficiency. Feedback can be visual, auditory, tactile, or any combination necessary for the application. In some cases, feedback provides confirmation of an action, while in others it adds to the functionality.
Meeting industry best practices is important in the placement of components, the component's surface area, legend size and color, emergency stop consideration, protective switch guards and shields, plus other ergonomic factors. The goal is optimal usability, efficiency, and safety.
The application environment – encompassing both physical location and vertical industry environment – determines HMI System durability requirements. Antivandalism considerations are part of the rail environment and must be considered.
Not only should the HMI System be rugged enough to withstand heavy use, but it should also last for the duration of the equipment lifecycle. Durability and reliability are also key for passenger cars with very long service lives.
Thorough knowledge of technical ergonomic, design, and manufacturing standards is fundamental to HMI System design. As part of the regulations specific to passenger access, the following audio components are required:
Audible warning device, as well as visible LED signal light; Location at each side of the door to alert passengers of closing doors;Audible and visible signals shall activate independently for an adjustable period of 1 to 5 seconds before door close and is initially set at 2.5 seconds;Signal shall be rated for 30 to 95 volts DC with adjustable output of 75 to 95 dB(A);Audible signal must be located at its affected individual door as a steering aid for the blind.
Define the operator
Know your operator – the key to a successful HMI System implementation requires a well-grounded definition and understanding of the operators. The operator in passenger access will be a passive/intuitive user. Commands/functions should be simple with an easy-to comprehend interface. For this type of user, repeatability is also important – information and actions should appear consistently from use to use.
The panel layout should be designed to provide the operator functional groups of related information in a predictable and consistent manner. The panel will incorporate:
- Electromechanical assembly;
- Ergonomic design;
- Vandal-resistant and durable construction;
- LED illumination.
Choosing the Best Control Technologies
Once you have defined HMI functionality, you are ready to investigate control technologies. Each technology has advantages and disadvantages related to the HMI System, equipment, and application.
Many of these technologies are of more importance to operators than passengers, since they are usually found in the operator compartment.
Switches (Pushbutton, rocker, slide, keylock, rotary, etc.)
Pushbutton switches allow the option of illumination to indicate open/close switch status when a quick visual indication is desired.
Rotary-switch and keylock technologies serve best when the application requires position indicators. Keylocks provide an additional layer of security to the application. Rotary switches also can be used for an application requiring multiple positions.