Success Story:
Industrial truck industry
High-precision and safe manoeuvres in high-bay warehouses thanks to inductive guidance
When industrial trucks are used in the logistics sector, efficiency and safety are paramount. This is why we at INRO Elektrotechnik addressed these issues many years ago. With an inductive vehicle guidance system developed by us, precise and fast driving in warehouses and narrow aisles of high-bay warehouses has been significantly simplified. This increases handling performance as well as safety for personnel.
With conventional mechanical guidance, the industrial truck is guided between two steel profiles bolted to the floor.
The inductive guided vehicle follows a guide wire laid in the ground. If the vehicle deviates from the specified lane, automatic equalisation steering takes place.
The driver is therefore only responsible for the speed and for lifting and lowering the load.
The inductive guidance of industrial trucks in the logistics sector is a combination of various components:
IFG: Inductive guide generator
WGA: Wire Guidance Antenna
Conducting wire made of copper: 6 mm diameter and laid approx. 2 cm deep in the ground, up to 1,000 m long
- Efficient use of space:
The space required for travel paths is minimised to the millimetre, leaving more space for storage racks. - Increased handling performance:
The speed for travelling as well as for lifting and lowering the load can be significantly increased. - Discharge:
Driving personnel are supported and driving manoeuvres are simplified. - Protection:
Operational safety is significantly increased.
The project
in detail
The customer's requirement for the product was to replace the large number of inductive guide generators used from different suppliers with a compact product with defined properties and an optimised scope of services.
The centrepiece of the newly developed system is the inductive guide generator (IFG) mounted on the hall wall. Up to four independent copper conductors lead from it into the floor, where they determine the lane. Each guide wire can have a maximum length of 1,000 metres. As soon as current flows through the IFG at a constant frequency into the guide wire in the ground, an electromagnetic field with a defined frequency is generated.
The IFG has infinitely variable digital frequency and current adjustment as well as four outputs with different frequency and current settings. An additional enable signal can be switched via an external input. The IFG is capable of self-diagnosis and automatic adjustment on conductor loops.
The frequency of the IFG is recognised by the second system component, the WGA (Wire Guidance Antenna). Two of these WGAs are installed in the customer's vehicle as standard (front and rear, each centred near the floor).
The customer requirement for the WGA was to develop an inductive guidance sensor that measures the distance to the wire over the largest possible range with the maximum possible accuracy and triggering and fulfils the requirements of functional safety.
For this purpose, the WGA has a dual-channel capability that enables functional safety use. Five cross coils ensure that various evaluation algorithms are calculated and the absolute distance is also automatically learnt.
After manual tracking onto the guide wire - for example in a narrow-aisle warehouse - any deviation from the specified route is immediately recognised and corrected. Automatic equalisation steering then takes place. The person at the wheel is therefore only responsible for the speed and for lifting and lowering the load and can concentrate on this. The safety distance of 125 mm between the vehicle and the racking is therefore constant and guaranteed at any speed.
The combination of maintaining the lane with millimetre precision and speeds of up to 12 km/h makes the system particularly efficient, fast and safe compared to other logistics systems. Companies can optimise their handling performance in the warehouse, save time and therefore work more efficiently and with a greater focus on turnover.
IF generator
The IF generator (IFG) is a signal generator specially developed for inductive guided vehicles. It allows alternating current signals of constant amplitude and frequency to be impressed into the conductive wires laid in the floor.
The IF generator enables:
- The direct connection of up to four guide wires
- Simultaneous connection of up to three different AC signals in a single conducting wire
- The stepless adjustment of any frequency/current combination between 2 ... < 9 kHz and 25 ... 100 mA via a PC using a serial RS232 cable
- The controlled switching on and off of the AC signals for stationary personal protection systems, programmable via four control inputs
Conclusion
High storage density and limited space combined with high goods turnover are a real challenge in logistics. In a narrow-aisle warehouse, the aisle width is only around 1.50 to 1.80 metres, while the lifting height can be up to 18 metres. However, these difficulties can be overcome with an assistance system such as the IFG inductive guide generator. Precise to the millimetre, efficient, fast and safe - the IFG system from INRO Elektrotechnik is a real success story.
