Dutch horticulturalist exploits motion control technology to automate materials handling
30 November 2006
While EEU’s engineers are familiar with working with all kinds of plant, in the Netherlands that plant can often have leaves! Holland, famous as it is for its horticultural industry, probably boasts more nurseries than anywhere and many of them have sophisticated handling equipment. Sluiter Ellwoodii is a tree grower that has benefited from EEU’s control engineering expertise. Based in Opheusden, in the Netherlands the company grows various types of conifers both under glass and outside in the huge facility.
As part of the process, containers are at various times transported either to a cut line or to a washing machine using overhead cranes. The unusual aspect of the configuration however, is that two cranes share a single track. Clearly, this gives the possibility of collisions and hence, there is a controller on each crane that must communicate continuously with the main controller on the ground. The system uses Ethernet protocol with infrared communications. In this way the position of each crane is always known and if there is a risk of collision, one of the cranes automatically stops.
The controls and the software for the cranes were designed and installed by EEU using Yaskawa MP2300 machine controllers. These intelligent, flexible and easy to use modular motion controllers are capable of controlling up to 48 axes over a fieldbus. The unit can give analogue, communication or pulse outputs, giving speed control, torque control and position control facilities across servo, stepper and open and closed loop inverter drive applications.
The MP2300 can also operate multiple axes with complete synchronisation and, because motion and sequence control are both executed in the same unit, motion control is handled with ease. The programming for the controllers was created using Yaskawa’s own software running in Windows. The communications capability of the MP2300 controllers enables them to interchange signals across a single network throughout the whole nursery.
Various modules can be fitted within a single rack to provide the ultimate machine control for any given application. These flexible modules enable the connection of different types of motors to be used with other vendor’s controllers.
The Sluiter Ellwoodii system has been maintained by EEU over a running period of four years without a failure (With MP920). According to Piet Toonstra, EEU’s engineer on the project, the customer cannot believe the reliability.
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