Motion detecting system for use in a safety system for power equipment

A woodworking machine comprising:

• a cutter;
• a motor adapted to drive the cutter;
• a detection system adapted to detect a dangerous condition between a user and the cutter;
• a reaction system adapted to perform a specified action to mitigate the dangerous condition upon detection of the dangerous condition by the detection system;
• and
• a control system adapted to determine whether the cutter is moving by detecting back emf produced by the motor as the motor coasts down after power has been removed from the motor, and further adapted to deactivate the detection and/or reaction system if the cutter is not moving.

A woodworking machine comprising:

• a cutter;
• a motor adapted to drive the cutter;
• a detection system adapted to detect a dangerous condition between a user and the cutter;
• a reaction system adapted to perform a specified action to mitigate the dangerous condition upon detection of the dangerous condition by the detection system;
• and
• control means for detecting back emf produced by the motor as the motor coasts down after power has been removed from the motor, and for triggering the reaction system only if a dangerous condition is detected when a predetermined level of back emf is also detected.