Automatic control device for tractor mounted tools

DETAILED DESCRIPTION A principal object of the present invention is to monitor the position of a tractor mounted tool by utilizing a sensor device that detects the position of the tool and generates a variable output signal which is a function of the instantaneous position of the tool.
The output signal may be used to control the position of the tool or to indicate its relative position.
Another object of the present invention is to provide an automatic control device which may be programmed to change the angular attitude of a tool at a preselected elevation by monitoring the elevation and angular attitude of the tool with sensor devices that change in relative potential depending on the instantaneous elevation and attitude of the tool and comparing the output potentials of the sensor devices with the output potential from pre-programmed angular and elevation selector devices.
A further object is to provide a control device which monitors the voltage drop across a variable resistance in a sensor device that is directly proportional to the position of the tool and to compare the relative voltage from the sensor device with a reference voltage of a preselected setting on a selector device.
The two voltages are of inverse polarity and are compared across a null detector such that a command signal is generated when the voltages are substantially matched and thus indicates that the tool is at the preselected position.
Yet another object is to provide such a control device wherein the change in resistance is made in consecutive incremental steps such that consecutive tool positions are sharply delineated.