Today’s human-machine interfaces (HMIs) provide the link between sophisticated technology and the human touch required to effectively operate essential systems and applications. By offering intuitive contact between the operator and the process, users can safely operate trains, build cars, produce manufactured goods, or machine critical industrial parts, for example. Performance advancements continue to drive new embedded designs in these arenas, and HMIs are evolving in step. Integrating HMIs with control systems is proving valuable in many embedded sectors, with the fastmoving, global transportation market leading the charge.
Characterized by diversity within systems and applications, transportation solutions range from operator controls to passenger-facing systems. Expectations of service and versatility are on the rise, and designers need to think well beyond merely satisfying longevity, low-power, and extreme processing demands. Applica tions today include a variety of wireless interfaces such as Wi-Fi, GSM/3G, and GPS; resulting designs must function with high electromechanical reliability and a minimum number of system cables. Yet too many individual systems can increase maintenance and its associated costs, and can complicate the process of data acquisition and network control. The challenge for designers is to integrate the functionality of multiple systems in a way that maintains performance and does not sacrifice safety. Transportation Applications
Drive HMI Evolution
Many control systems in transportation environments require a graphical user interface, a challenge compounded by ongoing exposure to shock, vibration, and extreme temperatures. Visual systems are, in fact, vital to train control, with complex displays delivering information and visual feedback about the ongoing operational condition of the line. For example, during a typical trip, an HMI displays route progress and schedule (planned and actual), telemetry information (speed or system status), or a crew warning when approaching speed restrictions or potential hazards, such as a crew working on tracks. In response, a user can change speeds, update the schedule, and make announcements to the passengers.
Reliability and long-term deployment are essential priorities, along with high-performance processing that incorporates any number of real-time data sources. For example, systems that provide passenger information are exposed not only to the elements, but also to a much more rigorous environment of shock and vibration than an interface at a stationary bank kiosk or ticket counter. Ideal systems also provide enhanced graphics and a continuous upgrade path for OEMs — pointing developers toward customized COTS products and platforms, and an increasing focus on converged HMI systems that leverage standards-based technologies.
Meeting Today’s Application Needs with HMIs
While earlier generations of HMIs were effective as the principal point of contact between users and systems, they were considered primarily display technologies. These separate displays or touch screens connected with a USB interface to a central computer, which in turn connected to an I/O box or networked system. Cabling was more extensive and system footprint was expanded with multiple components, establishing a greater number of potential failure points and limiting applications that required more physical space in the cab. Most importantly, these multiple interfaces resulted in more complex implementations, in turn reducing reliability and increasing maintenance and overall cost of ownership.