Ethernet-enabled motor drives used in aircraft door simulator

The dynamic control of motion, which is made possible by a high-speed Ethernet Powerlink machine network, is behind a new generation of aircraft door trainer that offers exceptional flexibility to simulate emergency conditions.

The Cabin Emergency Evacuation Trainer (CEET), which is manufactured by EDM, uses Baldor's Ethernet-compatible machine controller, with two servo motor axes to control the operating characteristics of the emergency exit door's hinge and handle. The 100 Mbits/second speed of the Ethernet control network allows EDM to dynamically vary the loading force that each of the two motors applies throughout the door's operational cycle. This gives EDM's airline clients the means to realistically simulate problems ranging from a simple failure of the door's hydraulic actuation, to complex scenarios such as obstructions or damage.

EDM's latest real-time control system is an iteration of an existing design. 'Intelligent' drives - with built-in positioning capability - had been used previously because the integrated nature of the system gave the developers a level of control over drive parameters that is not normally available using traditional analogue interfaces.

Ethernet Powerlink delivers more elegant control

The introduction of drives compatible with the real-time Ethernet Powerlink protocol allowed EDM to create a more elegant control system. A single controller - the NextMove e100 - and software program dynamically manages the position, speed and torque limits on both motor axes, as well as a large array of I/O that controls other simulated aircraft functions such as cabin lighting and indicators.

The engineering development environment for the motion control system, Mint Workbench, was a critical factor for EDM in the selection process, as simulators are almost invariably highly application-specific systems produced in small quantities. Among the key features that interested the development team was easy connectivity of the real-time machine and motion controller with a PC - which runs EDM's graphical aircraft emergency simulation software. This was achieved by means of ActiveX components, bundled as part of Baldor's free developer's toolkit.

The motion and I/O control software is written in Mint, Baldor's high-level machine and motion control language. Another attraction for EDM was the availability of a free multi-tasking kernel. This avoided a lot of programming effort by allowing the code for the standalone motion control axes of the previous simulator to be imported and treated as individual tasks, giving the developers a good starting point for the new system.

Simulated pressure profiles

A major functional addition in this iteration of the design is the ability for the remote controller to dynamically vary each motor's forward and reverse torque limits, based on the angular position of the door and handle. EDM, and its users, exploit this ability to program sophisticated 'pressure profiles', such as stiff doors, and door and handle jams.

"Software represents one of the largest elements of our product costs. The high-level nature of the Mint language helps us to minimise the engineering cycles for new simulator designs," says EDM's systems manager, Alan Nicholson. "Now that the base software is in place, modifying it to emulate different types of aircraft door can be achieved very quickly."

Another important aspect of the development tools for EDM is the advanced diagnostics capability. This gives EDM access to features built into the Ethernet Powerlink hardware, such as data acquisition capabilities, an error log, and a temperature sensor. The user can monitor real-time parameters of the control system, for example, or run test moves - and compare them with ones captured at the time of manufacture using a 'software oscilloscope' tool - to see if any mechanical issues have emerged following commissioning.

As the tools are free-issue, EDM bundles them onto the control PC provided with each simulator. This helps EDM to offer rapid engineering support to airline customers worldwide in the event of a problem, by simply logging into the system over the internet.

The first user of EDM's new generation of simulation technology is a major European airline, which commissioned a cabin trainer for the Airbus A319. Since this order, EDM has completed a door trainer for the inaugural purchaser of the new double-decker Airbus A380.

Brake pedal simulation

EDM is additionally employing the real-time torque control facility of Baldor's Ethernet Powerlink motion control modules to emulate brake pedal action on a vehicle simulator project.

"The sheer speed of Ethernet Powerlink allows EDM to vary torque limits dynamically rather than simply configuring them - a control mechanism that is simply not feasible using a traditional analogue interface, or a general-purpose fieldbus," adds Baldor's David Greensmith. "This new network will allow most machine builders to take a completely fresh look at their control system architecture: our single Ethernet Powerlink controller can handle up to 200 devices on the network for example, including managing up to 16 interpolated axes simultaneously."