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In agriculture, a large variability of objects in a range of sizes and shapes is found, leading to problems in size grading. For example, for a low-cost product such as potatoes, the predominantly used mechanical size-determining systems have errors of up to 30% and can cause damage, but they are cheap and have a throughput up to 20 tonnes per hour. Alternatives which can guarantee an improvement in accuracy and a financial gain for the companies are required. In this paper methods for the determination of volume and axis measurements using a simple ring sensor system are described. A modified co-ordinate system and the segmentation of the area between the ring and the object are used. The volume determination is independent of the direction of presentation of the objects. For the determination of axes, the objects must be presented in the longitudinal direction to allow the use of simple 2D algorithms. The accuracy of the system depends both on the number of transmitters and receivers placed on the ring and on its diameter. A small ring sensor system was developed, which can scan 3D objects in real time (36 000 potatoes, 3.6 tonnes per hour) with an accuracy of better than 5% for a volume larger than 100 cm 3 .

Results show that with the nerve stimulator set at 2.5 mA (pulsed at a frequency of 2 Hz), peripheral nerves are stimulated if they lie within 5 mm of the wires. Should a distal muscle twitch occur, wires should be repositioned so that equivalent stimulation produces no twitch. The technique was used during Ilizarov frame application in ten patients, with only a single occurrence of distal muscle twitches in a lower-leg frame. Following repositioning of the Ilizarov wire in this case, no further twitches were observed, indicating that no Ilizarov wire was inserted close to peripheral nerves. No neurologic impairment was present postoperatively.

To produce consistent products, graded to predetermined size and inspected for disease and defects such as bruising and common scab is important for the final quality presented to the consumer. A project funded by the British Potato Council, the Ministry of Agriculture Fisheries and Food (MAFF), and R J Herbert Engineering (a British manufacturer) is aimed at developing spectrophotometnc methods of disease detection previously investigated by SAC through to commercialisation.At The Scottish Agricultural College (SAC ) work has shown that diseases such as gangrene, soft rot and common scab present uniquely different wavelength patterns or spectra. This was also found to be the case for bruising, which could be detected to a depth of 4 mm.The linking of spectrocopy and video camera technology to create two dimensional images in several wavebands ( visible to near infrared) has formed the basis of a multispectral camera which will allow the capture of images of produce. Associated hardware and software allows discrimination between the different categories to be carried out in real time using sets of individual pixels from each image. Two modules will be integrated into the system, one for disease and surface defects and the other to detect sub-surface defects. This will allow the manufacturer to offer a variable degree of sophistication on the commercial machine which could be tailored to the users requirements.High throughput and the ability to distinguish between type and severity of disease is a pre-requisite for the final system. The final operating speed will be between 2and 10 potatoes per second (3 to 8 Tonnes per hour).A range of defects on other vegetables and fruits have been studied and results have been equally encouraging. It is therefore envisaged that the same technology could be applied to sorting of other produce.1.