BACKGROUND

Dual path machines such as windrowers are typically driven on uneven and sometimes muddy surfaces. Without a positively-controlled steered axle, a dual path machine relies on traction to perform both propulsion and steering. Loose gravel and mud can slow the responsiveness of the drive train. If an operator applies too much acceleration or too rapid of steering for the ground conditions at that time, machine motion can be less than expected. In the condition that a machine is brought to a stop in mud, and one of the driven tires becomes stuck, there is a chance that the machine will pivot around the stuck tire. This is possible because rear casters will pivot to allow full range of motion.

Some dual path agricultural machines include hydraulic damping steer-assist systems coupled to their caster wheels. However, these systems only smooth out motion and do not assist in conditions where loss of traction on one tire causes machine motion to not match the steering input. A positively-controlled steered caster can allow a machine to redirect tractive effort to overcome a stuck tire. Current positively-controlled steering systems must be manually engaged and disengaged, which hinders maneuverability in field conditions.

SUMMARY

Embodiments of the invention solve the above-mentioned problems and other problems and provide a distinct advance in the art of control systems for dual path agricultural machines. Specifically, the invention provides a control system that improves stability, responsiveness, and predictability of a dual path agricultural machine.

An embodiment of the control system is configured for use with a windrower having a chassis, an engine compartment, a cab, a drive system, left and right drive wheels, left and right caster wheels, left and right rear-steer mechanisms, a harvesting component, and a number of user drive input mechanisms.

The chassis supports the engine compartment, cab, harvesting component, and drive system and may include a number of frame rails, cross beams, and other structural members. The chassis may also include a number of mounting points for mounting the above components to the chassis.

The engine compartment encloses the engine and other components of the drive system and is mounted on the chassis behind the cab. The engine compartment may include doors and/or removable access panels for servicing the engine.

The cab protects a user (hereinafter “driver”) and the user drive input mechanisms from outside elements and may include an enclosed canopy having a door and several windows or windshields. A seat and other ergonomic features from which the driver may control the dual path agricultural machine may be positioned in the cab.

The drive system powers the drive wheels and the harvesting component and includes an engine and a drive train. The engine may be a gasoline or diesel internal combustion engine or any other suitable power source. The drive train transfers power from the engine to the drive wheels and may include drive shafts, drive belts, gear boxes, hydraulic or pneumatic lines and valves, and the like.

The left and right drive wheels are large driven wheels positioned near a front end of the chassis and are substantially identical to each other. Each drive wheel rotates about a lateral axis and is driven independently from the other drive wheel.

The left and right caster wheels are non-driven wheels spaced behind the drive wheels and are substantially identical to each other. Each caster wheel is configured to swivel about a vertically extending axis in either a free-wheeling mode or a steering mode.

The left and right rear-steer mechanisms selectively actuate the caster wheels and are substantially identical to each other. Each rear-steer mechanism may include a tie rod, a rack-and-pinion mechanism, gears, hydraulic components, pneumatic components, a rotary motor, or any other suitable actuation components. In one embodiment, the rear-steer mechanisms are configured to be selectively engaged with and disengaged from the caster wheels.

The harvesting component cuts and swaths crops into a windrow and may be removably mounted to the front end of the chassis. The harvesting component may be configured to be selectively deactivated and/or disengaged and controlled via user inputs.

The user drive input mechanisms allow the driver to provide user drive inputs and include a steering wheel and a forward-neutral-reverse lever. Alternatively, the drive input mechanisms may include handlebars, an acceleration pedal, a brake pedal, a yoke, a joystick, an analog or virtual control panel, and other inputs. The user drive input mechanisms may also be virtual controls implemented on a display screen of an integrated or an external computing device such as a smartphone, a tablet, or a remote control device.

The control system of the present invention controls the drive system, drive wheels, harvesting component, and rear-steer mechanisms to more accurately effect the driver's commands. An embodiment of the control system comprises a number of input sensors, a number of status sensors, a number of output sensors, and a controller. The control system may be integrated into existing control systems of the dual path agricultural machine or may comprise dedicated hardware and software or even external computing devices such as a smartphone, a tablet, or a remote computing system.

The input sensors interface with the user drive input mechanisms for sensing positions, orientations, or states of the user drive input mechanisms. The input sensors may be switches, electrical resistance sensors, temperature sensors, touch sensors capacitance sensors, position sensors, angle sensors, speed sensors, proximity sensors, Hall-effect sensors, accelerometers, gyroscopes, pressure sensors, time-of-flight sensors, optical sensors, imaging sensors, cameras, and the like.

The status sensors interface with the drive wheels, the caster wheels, the harvesting component, the drive system, the rear-steer mechanisms, and/or the user drive input mechanisms for sensing statuses of the interfaced devices or statuses of the dual path agricultural machine via the interfaced devices. The status sensors may be switches, electrical current sensors, electrical resistance sensors, temperature sensors, capacitance sensors, position sensors, angle sensors, speed sensors, proximity sensors, inductive sensors, Hall-effect sensors, compass, inertial sensors, accelerometers, gyroscopes, pressure sensors, viscosity sensors, composition sensors, fluid flow sensors, acoustic sensors, wave interference sensors, radio receivers, GPS receivers, radar sensors, time-of-flight sensors, optical sensors, imaging sensors, cameras, engine rpm sensors, caster wheel angle sensors, drive wheel differential sensors, and the like.

The output sensors interface with the drive wheels, the caster wheels, the rear-steer mechanisms, the harvesting component, the drive system, and/or the user drive input mechanisms for sensing outputs of the interfaced devices and hence the dual path agricultural machine. The output sensors may be switches, electrical current sensors, electrical resistance sensors, temperature sensors, capacitance sensors, position sensors, angle sensors, speed sensors, proximity sensors, inductive sensors, Hall-effect sensors, compass, inertial sensors, accelerometers, gyroscopes, pressure sensors, viscosity sensors, composition sensors, fluid flow sensors, acoustic sensors, wave interference sensors, radio receivers, GPS receivers, radar sensors, time-of-flight sensors, optical sensors, imaging sensors, cameras, engine rpm sensors, caster wheel angle sensors, drive wheel differential sensors, and the like.

The controller includes computing components such as a processor, memory, power components, and communication components for communicating with the input sensors, status sensors, output sensors, and other components. The controller implements a stability control mode and a selective rear-steer engagement and actuation mode in addition to and/or in conjunction with conventional dual path agricultural machine control modes. Alternatively, the controller may divided into multiple individual processing units that are in one or more separate enclosures. Portions of the control processing may exist within sensors or output devices such as motors, actuators or hydraulic valves, etc.

In the stability control mode, the driver provides a user drive input via the user drive input mechanisms. The user drive input may include several components such as a speed component and a steering component. In some implementations, the user may only specify a path or automated input source.

The input sensors detect the user drive input or the components or source configuration thereof. The input sensors generate a signal representative of the user drive input or configuration and send the signal to the controller.

The controller derives the user drive input from the above signal and generates a first control signal according to the user drive input. The first control signal represents instructions for the drive system to power the drive wheels so that they effect an actual drive output corresponding to the user drive input (and hence the desired drive output). The controller sends the first control signal to the drive system so that the drive wheels effect the actual drive output.

The output sensors detect the actual drive output. The output sensors generate a signal representative of the actual drive output and send the signal to the controller.

The controller receives the signal from the output sensors and determines a difference between the actual drive output and the desired drive output. This difference may include any combination of a difference in wheel speed, drive system speed, dual path agricultural machine location, change of location, heading, or change of heading, inertial state of machine, turning arc, drive wheel differential, caster wheel angle, and the like. For example, the difference may be caused by one or both of the drive wheels slipping on loose gravel.

The controller generates a second control signal based on the difference between the actual drive output and the desired drive output. For example, the second control signal may include instructions to increase wheel speed of the slipping wheel and increase the steering angle. The controller sends the second control signal to the drive system to adjust the actual drive output so as to reduce the difference between the actual drive output and the desired drive output.

The controller generates a third control signal including instructions to actuate one or both of the caster wheels via the rear-steer mechanisms in certain situations. For example, the controller may generate the third control signal for actuating the caster wheels if a ground speed of the dual path agricultural machine is greater than a minimum threshold ground speed, the steering angle is within a range allowed by rear-steer control, the change of steering angle is within a range allowed by rear-steer control, automated steering is enabled or disabled, automated steering is engaging or disengaging, a location of the dual path agricultural machine is within a prescribed area such as within a maximum distance from a road or outside of a maximum distance from a field path end, the dual path agricultural machine is undergoing back-and-forth motion, the dual path agricultural machine is on a lateral incline having an angle greater than a minimum threshold angle, and/or the harvesting component is disengaged.

The controller sends the third control signal to the rear-steer mechanism to actuate the caster wheels so as to further reduce the difference between the actual drive output and the desired drive output. This may be a corrected signal or only asserting the original steering command. In one embodiment, the controller may instruct the rear-steer mechanisms to actuate only one of the caster wheels while the other caster wheel is not actuated or is not engaged by the rear-steer mechanisms.

In the selective rear-steer engagement and actuation mode, one or more of the status sensors determines a status of the dual path agricultural machine. For example, the status may be a ground speed of the dual path agricultural machine, a turn angle of one of the caster wheels, a turn angle of the steering wheel, a location of the dual path agricultural machine according to a GPS receiver, or any other suitable status. The status sensor generates a signal representative of the status and sends the signal to the controller.

The controller compares the status from the one or more sensors against a criterion such as a minimum threshold ground speed. Other criteria may include a maximum threshold ground speed, a minimum or maximum turn angle of the steering wheel or one of the caster wheels, or any other suitable criteria. It may also compare previous values and/or derived values. Hysteresis, smoothing, dampening, or other additional conditioning may be included in the criteria logic.

The controller generates an activation signal for instructing the rear-steer mechanisms to engage positive control of the caster wheels if the status equates to or is within the above criterion or another criterion. The controller sends the activation signal to the rear-steer mechanisms so that the rear-steer mechanisms engage positive control of the caster wheels.

The controller also generates a control signal for instructing the rear-steer mechanisms to actuate the caster wheels if the status equates to or meets the criterion. For example, the controller may generate an actuation a control signal if the ground speed of the dual path agricultural machine is at least the minimum threshold ground speed. The controller sends the control signal to the rear-steer mechanisms so that the rear-steer mechanisms actuate the caster wheels. In some embodiments, the controller may engage positive control of the caster wheels and actuate it to a position that brings one or more of them to within a criterion if another criterion is met.

On the other hand, if the status does not equate to or is not within the criterion and the rear-steer mechanisms are currently activated, the controller generates a deactivation signal and sends the deactivation signal to the rear-steer mechanisms so as to disengage the rear-steer mechanisms from the caster wheels. That is, the caster wheels may be allowed to free-wheel if rear-steer actuation is not needed. Alternatively, the controller may cease actuation of the caster wheels while the rear-steer mechanisms remain engaged with the caster wheels. In some situations, the controller may delay or prediction to any of the criterion, activation, deactivation, or actuation signals.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the current invention will be apparent from the following detailed description of the embodiments and the accompanying drawing figures.

