Height control for agricultural machine

An agricultural machine including in combination:

• a wheel-supported main frame,
• a machine element movable relatively to said main frame, and having an initial position,
• power means on said frame for moving said element up and down relatively to said main frame in small incremental steps, to vary the distance between a portion of said element and ground level,
• distance-determining means mounted on said element for determining the distance between itself and ground level and for generating electrical signals corresponding to such distance,
• a control circuit supported by said frame, receiving said signals and providing "up" pulses and "down" pulses according to whether said distance is decreasing or increasing, said control circuit including
• a monitor-corrector having a counter preset for a predetermined number of enabling "down" pulses and having a pulse input for said "down" pulses, a pulse output, a reset, and output enabling means for enabling said pulse output only when said predetermined number of enabling "down" pulses is applied to said pulse input before the reset is actuated,
• time delay means for actuating said counter reset after a short predetermined time interval,
• a "down" actuator AND gate connected to said control circuit and normally enabled to pass a "down" pulse,
• a "down" actuator switch actuated by said "down" actuator AND gate,
• "down" applying means for applying each "down" pulse to said "down" actuator AND gate, to said pulse input, and to said time delay means to initiate said predetermined time interval,
• an "up" actuator AND gate connected to said control circuit, normally enabled to pass an "up" pulse,
• an "up" actuator switch connected to the output from said "up" actuator AND gate,
• "up" applying means for applying each "up" pulse to said counter reset to enable said counter,
• first and second one-shot multivibrators connected in series to the output from said counter and including a time delay in said second one-shot multivibrator, each said multivibrator having output means,
• override means connected to the output means of said first one-shot multivibrator and to said "up" actuator switch for sending an "up" pulse to said power means upon actuation of said first multivibrator, and
• disabling means connected to said output means of said second one-shot multivibrator and to both said AND gates to disable further actuation of both said "up" actuator AND gate and said "down" actuator AND gate for a predetermined time interval.

A monitor-corrector for a height-control device for a tomato harvester header that is actuated by "up" pulses and "down" pulses from a control circuit, said monitor-corrector acting to pass or block pulses from the control circuit to a pulse-actuated power device that moves the forward end of said header in incremental steps up and down, respectively, through "up" and "down" actuators, including in combination,

• a counter preset for a predetermined number of enabling "down" pulses from said control circuit and having a pulse input for said "down" pulses, a pulse output, a reset, and output enabling means for enabling said pulse output only when said predetermined number of enabling "down" pulses is applied to said pulse input before the reset is actuated,
• time delay means for actuating said counter reset after a short predetermined time interval,
• a "down" actuator AND gate for connection to said control circuit and normally enabled to pass a "down" pulse,
• a "down" actuator switch actuated by said "down" actuator AND gate,
• "down" applying means for applying each "down" signal to said "down" actuator AND gate, to said pulse input, and to said time delay means to initiate said predetermined time interval,
• an "up" actuator AND gate for connection to said control circuit and, normally enabled to pass an up pulse,
• an "up" actuator switch connected to the output from said "up" actuator AND gate,
• "up" applying means for applying each "up" signal to said counter reset to enable said counter,
• first and second one-shot multivibrators connected in series to the output from said counter and including a time delay in said second one-shot multivibrator, each said multivibrator having output means,
• override means connected to the output means of said first one-shot multivibrator and to said "up" actuator switch for sending an "up" pulse to said power means upon actuation of said first one-shot multivibrator, and
• disabling means connected to said output means of said second one-shot multivibrator and to both said AND gates to disable further actuation of both said "up" actuator AND gate and said "down" actuator AND gate for a predetermined time interval.

A monitor-corrector for a height control device for an agricultural machine element, actuated by "up" signals and "down" signals from a control circuit to pass or block signal pulses from the control circuit to a power device that moves said machine element up and down, respectively, through "up" and "down" actuators, including in combination,

• a counter for connection to said control circuit preset for a predetermined number of enabling "down" pulses and having a pulse input for said "down" pulses, a pulse output, a reset, and output enabling means for enabling said pulse output only when said predetermined number of enabling "down" pulses are applied to said pulse input before the reset is actuated,
• time delay means for enabling said counter reset after a short predetermined time interval,
• a "down" actuator AND gate for connection to said control circuit and normally enabled to pass a down pulse,
• a "down" actuator switch actuated by said "down" actuator AND gate,
• "down" applying means for applying each "down" signal to said "down" actuator AND gate, to said pulse input, and to said time delay means to initiate said predetermined time interval,
• an "up" actuator AND gate for connection to said control circuit, normally enabled to pass an "up" pulse,
• an "up" actuator switch connected to the output from said "up" actuator AND gate,
• "up" applying means for applying each "up" signal to said counter reset to enable said counter,
• first and second one-shot multivibrators connected in series to the output from said counter and including a time delay in said second one-shot multivibrator, each said multivibrator having output means,
• override means connected to the output means of said first one-shot multivibrator and to said "up" actuator switch for sending an "up" pulse to said power means upon actuation of said first multivibrator, and
• disabling means connected to said output means of said second one-shot multivibrator and to both said AND gates to disable further actuation of both said "up" actuator AND gate and said "down" actuator AND gate for a predetermined time interval.

A method for controlling the up-and-down movement of a machine element movable relatively to a wheel-supported main frame of an agricultural machine, through power means that move the element up and down relatively to said main frame in small incremental steps, to vary the distance between a portion of said element and ground level, comprising:

• determining the distance between said portion of said element and ground level,
• generating electrical signals corresponding to such distance,
• converting said signals into "up" pulses and "down" pulses according to whether the distance is decreasing or increasing,
• counting the "down" pulses to determine whether a preselected number of consecutive "down" pulses occur, without an "up" pulse between them, within a short predetermined time period thereby indicating a significant change in the slope of the ground level,
• transmitting the pulses, so long as the "down" pulses per said time period are fewer than said preselected number, to said power means for actuating an incremental step up or down of said machine element for each said pulse,
• when and only when said preselected number of "down" pulses occur within said predetermined time period, blocking the transmission of further "down" pulses from passing to said power means, blocking out the transmission of additional "up" and "down" pulses for a set time period, and returning said machine element toward its said initial position.