To increase operator safety in robotic working cells, a capacitive sensor for the detection of humans has been developed. The sensor consists of two electrically conducting planes, insulated electrically from the ambient. When the dielectric or conductive conditions in the space between the planes are altered, e.g. a person enters, the sensor will indicate the presence of the person. The strength of the electric field caused by the sensor is kept low by lock-in amplifier technique. In the article the basic detection principle, the sensor electronics and the sensor signal handling are described and some practical experiments are presented.

A diverse number of insects cause damage and loss to crops in the tropics. Timely and appropriate control measures are necessary if crop losses and hardship to both farmers and the population at large are to be avoided.

To many farmers one of the most effective control measures is often the application of insecticides. The efficiency of insect control with insecticides is largely influenced by a judicious choice of the insecticide and the application equipment. There is therefore a need for the development of appropriate and evaluation of new and existing spray application equipment. Developments of some spray equipments since the late 1960s and their efficacy in the field are discussed. The main advantages of ultra-low volume (ULV) over some electrostatic sprayers are the application of a wide range of insecticides and formulations and better penetration to lower plant parts. The main advantages of electrostatic sprayers are the application of insecticides at extremely low volumes and low energy requirements with some sprayers. The advantages of the hydraulic nozzle sprayers are the even deposition of spray over all plant parts, although logistically the system is inefficient compared to the other systems.

All systems contaminate spray operators during spraying but the exact level of contamination will depend on the concentration, droplet size and formulation of the insecticide.