Safe and reliable: further development of a field robot

摘要

High levels of reliability and safety are necessary and can be achieved by novel developments within automated perception, diagnosis and decision making and fault tolerant operation. The aim is to add functionality to an existing robot prototype so that it will behave in a safe, reliable and effective manner under unmanned operation. The existing machine system and the proposed operation conditions were assessed by a machine safety consultant to check the compliance of existing legal requirements. Based on legal safety consultancy and a failure modes and effects analysis a redesign of the machine system was completed. The supposed operation is spraying and mowing in semi-public orchards. The machine will be unmanned but not unattended. An operator prepares, checks and starts the machine in the operation area. During machine operation the operator is around and is supposed to complete other working tasks. An additional stereo vision camera and a laser scanner will provide more information about the machine environment to avoid collision with obstacles and improves the machine navigation, this will contribute to reduce the dependency on GPS information. Signal monitoring software was developed to achieve higher levels of reliable and fault tolerant control. An additional safety circuit including bumper switches allow the machine to stop when other collision sensors fail.