US Patent 6840895 Tool side robotic safety interlock

A robotic tool changer with an improved safety interlock includes a master unit, a tool unit, and a coupler movable between coupled and decoupled positions and operative to couple the master and tool units. A circuit for actuating the coupler is associated with the tool unit, for connection to an interlock that closes when the tool is safely parked in a tool stand. The circuit enables the coupler to assume the decoupled position when the master and tool units are coupled and the circuit is closed. The robotic tool changer additionally includes a circuit operative to enable the coupler to assume the decoupled position when the master unit is decoupled from the tool unit.