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Automatic Transport Systems Need Different Approach

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16.12.2004

The way in which automatic transport systems are currently designed, is out of date. That is one of the conclusions of PhD student Corné Versteegt, who will defend his thesis on 15 December at TU Delft. This is important information for the transport sector, which will become more automated in the future.

An example of transport automation is the future Ondergronds Logistieke Systeem Schiphol (Underground Logistic System Schiphol, or OLS Schiphol), that will connect the airport with the flower auction complex in Aalsmeer and a future rail terminal in Hoofddorp.
The OLS Schiphol will use so-called Automatically Guided Vehicles (AGVs). These are vehicles that do not need a driver. This greatly reduces the cost of labour and also allows the system to be active 24 hours per day.

Automated transport systems potentially have many advantages, but researcher Versteegt also sees a number of shortcomings in current design practice. To much work is done ad hoc, there is too little cooperation and too little early testing. ‘A number of factors contribute to this. This is a relatively new, technically complex and dynamic field, and many different parties are involved; all with their own, conflicting, interests.’

Versteegt has also found that when the choice for an operating system is made, one of two extremes is usually chosen: either a centrally controlled hierarchical system, or a decentralised system, where all ‘power’ is distributed among the separate parts. According to Versteegt, neither strategy is fruitful. Hierarchical structures are clumsy and inflexible and can only be used in small systems. A weakness of decentralised systems is that they are vulnerable and unpredictable in crisis situations.

Versteegt: ‘I argue for a compromise, the so-called holonic approach. In this approach, as much control as possible is decentralised, but central controls can still be used. In crisis situations, for example in case of fire, accidents or delayed planes, the system can be controlled more centrally.’ This approach was successfully implemented in the plans for the OLSS Schiphol. A combination of computer models and physical prototypes was used for testing. ‘Kind of like a child playing trains, but in this case, much larger and more expensive ones.’

Exactly when the OLS Schiphol system is expected is not yet clear. ‘But if it is built, it will make use of an holonic operating system. This approach is slowly growing in popularity. It has already been implemented in other transport systems and in industrial production processes, for example. My research has contributed to the acceptance of the holonic control system approach in the corporate sector.’ The Netherlands is, according to Versteegt, a world leader in the automation of transport systems.

Maarten van der Sanden | Source: alphagalileo
Further information: www.tudelft.nl

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