Modern vehicles contain an increasing number of electric actuators. Apart from standard actuators which are mainly used for driving comfort, increasing numbers of actuators find their way into the engine compartment, with a direct bearing on the function of the combustion engine. The underlying reason for this? The need to develop clean, efficient and powerful engines.
The Ilmenau-based Steinbeis Transfer Center for Mechatronics develops magnetic actuator systems for a variety of automotive suppliers. To develop functioning test samples quickly, it is essential to have an end-to-end right hardware and software platform. Typical examples of their output are actuators used in air management systems (electric valve controls, air timing valves, electrically driven exhaust gas recirculation valves) or operating material pumps (water pumps, fuel pumps). The actuators concerned are used in systems featuring a high degree of mechanical influence (e.g. valves, pumps or fan wheels), electric actuators (brushless DC motors or solenoid actuator with reciprocating movements and controllable dwell) and control devices.
For each group of functions, the Steinbeis experts created circuit plans which could be reduced easily into a control device using a simple common circuit layout frame. To provide working samples they normally use a 19 inch cassette module. To create prototypes they develop a circuit frame tailored to the specific application before integrating it into the housing of the actuator system. At the heart of each device lies a digital signal controller belonging to the Freescale MC56F83xx and MC56F80xx group of products. These components offer the benefits of a digital signal processor and a micro-controller with a peripheral module optimized for actuation control tasks.
A number of derivates exist with a range of peripheral and storage device options. Programming is carried out in ANSI-C with graphical support in an integrated development environment (CodeWarrior development studio for Freescale DSP56800/E hybrid controllers). As before, software modules can be used in variety of other applications. Development is made more comfortable by linking into PC host systems with a graphical interface. The controller can be designed and put through function prototyping by using tools such as the Matlab/SIMULINK group of products. The team also uses universal control circuit boards and evaluation boards for initial function testing. To network the system, they developed their own CAN protocol.
For developers, the hardware and software platform setup offers a range of benefits. For example, control device development can be incredibly quick and there is much less redesigning. Also, as they use the same tools they quickly accumulate knowledge and can exchange ideas within the team. Further, it is easier to standardize development documentation and sharing information with customers is much more straightforward.
Dr.-Ing. Veit Zöppig
Steinbeis Transfer Center Mechatronics (Ilmenau)
stz144@stw.de