A warning system for chainsaw personal safety based on capacitive sensing

This paper presents a capacitive proximity sensor that helps to improve the personal safety features of a chainsaw. Even though chainsaws are equipped with safety features such as kickback protection and chain brakes, related accidents reported each year are huge in number. Safety can be enhanced to a high degree, by integrating human proximity sensing features to the chainsaw and hence activating its brake and turn-off the chainsaw automatically in the occurrence of an accident. This paper proposes a capacitive sensor to detect human proximity near the guide bar and chain of a chainsaw. A prototype sensing system has been developed and tested, validating the usefulness of the proposed scheme. The sensor capacitances are measured using a carrier frequency method with synchronous detection technique. The developed system provides information about human proximity at least for every 200 mus and hence enables the control unit to react in realtime. The system successfully distinguishes between proximity of human and wood. The developed system senses human proximity up to 15 cm from the chainsaw.