Narrow Aisle designs and manufactures battery powered stacking and order - picking vehicles for use in high storage density warehouses. The company employs 90 people in these tasks, and achieves sales of 6.875 MECU in its main UK and European markets for these products.
The company’s range of products occupies a niche market sector within the general fork lift market, and most of the company’s competitors in its niche sector are larger companies that also specialise in the manufacture of fork lift trucks. The company’s objective in introducing microcontroller technology into the control system for its ‘Combi’ stacking vehicles was to improve its competitive position by reducing costs, improving product reliability, and to reduce the time required to customise a vehicle to meet a particular customer’s specific requirements.
The existing control systems for the stacking vehicles are based upon standard industrial relays, hard wired to particular logic requirements, together with some use of Programmable Logic Controllers. These control systems are bulky, expensive, and difficult and time consuming to install and repair. The use of hard - wired logic results in large numbers of connections, leading to unreliability in operation. This hard wired technology meant that it was difficult to make changes to a system after assembly and solutions to design problems may not be possible at reasonable cost.
This latter factor was a major disadvantage because each Combi vehicle may have its own deviation from a basic control system. These deviations were accommodated by the design department, in producing a relevant design, and by the electrical production department in planning and implementing the system to the bespoke design. The complexity of the basic system meant that both endeavours were prone to error.
The introduction of microcontroller component technology into the control system has resulted in:
- Assembly time reduced by approximately 20%.
- Increased reliability following the great reduction in the number of electrical connections, and safety critical operation due to the use of redundant components..
- Easier fault finding by service engineers, using built in diagnostic indicators.
- Reduced downtime of the vehicle due to 2 and 3.
- The possibility of the introduction of more advanced product features in the future.
The development of the improved control unit was completed within12 months from the start date of February 1997.
The prototype control unit for the improved product cost 32 KECU to develop, and will payback this investment within 8 months. The return on investment for the application experiment is 220%.
Narrow Aisle is now capable of producing further microcontroller product designs. The company’s experience in specifying the minimum set of critical functionality improvements required for the product enabled the product to be developed to budget and timescale estimates, and has produced internal benefits in terms of greater enthusiasm for further technology increments as a result of the improved reliability and reduced manufacturing costs for the prototype products.
The application of microcontroller devices to produce an improved performance over that of a system implemented using PLC units will be of interest to many companies applying PLCs in machinery or process control applications. Specifically, the results of the application experiment would be of interest to any company that currently uses small to medium size programmable logic controllers where safety is important
