Abstract: A system for controlling a work vehicle is disclosed. The system may include a controller configured to control motion of the work vehicle and an electronic joystick communicatively coupled to the controller. The electronic joystick may be configured to transmit signals to the controller as it is moved between a neutral position and a full stroke position. The joystick may also be configured such that a varying joystick force is required to move the joystick between the neutral and full stroke positions. In addition, a rate of change of the joystick force may be varied as the electronic joystick is moved across a start/stop position defined between the neutral and full stroke positions.

Abstract: A system for controlling a work vehicle is disclosed. The system may include a controller configured to control motion of the work vehicle and an electronic joystick communicatively coupled to the controller. The electronic joystick may be configured to transmit signals to the controller as it is moved between a neutral position and a full stroke position. The joystick may also be configured such that a varying joystick force is required to move the joystick between the neutral and full stroke positions. In addition, a rate of change of the joystick force may be varied as the electronic joystick is moved across a startstop position defined between the neutral and full stroke positions.

Abstract: A method for controlling a hydrostatic drive unit of a work vehicle is disclosed. The method may generally include determining a reference swashplate position of a hydraulic pump of the hydrostatic drive unit, wherein the reference swashplate position is associated with an uncompensated current command, and determining an actual swashplate position of the hydraulic pump, wherein the actual swashplate position differs from the reference swashplate position due to a loading condition of the work vehicle. In addition, the method may include determining a closed-loop current command based at least in part on the actual and reference swashplate positions and generating a modified current command based on at least one of the uncompensated current command or the closed-loop current command.

Abstract: A method for controlling a hydrostatic drive unit of a work vehicle is disclosed. The method may generally include determining a reference swashplate position for a hydraulic pump of the hydrostatic drive unit, wherein the reference swashplate position is associated with an uncompensated current command, and monitoring an actual swashplate position of the hydraulic pump, wherein the actual swashplate position differs from the reference swashplate position due to a loading condition of the work vehicle. In addition, the method may include determining a current compensation based at least in part on the actual and reference swashplate positions and generating a compensated current command by adjusting the uncompensated current command based on the current compensation, wherein the compensated current command is associated with a compensated swashplate position for the hydraulic that differs from the reference swashplate position.

Abstract: The straight tracking control system can use a control method to achieve a desired straight motion of a machine with a dual path electronically controlled hydrostatic transmission. In the control method, the first drive system, e.g., the left or right drive system, pump solenoid current can be modified based on first and second drive system velocity feedback when the machine is commanded to move in a straight line path in the forward or reverse direction. A memory latching concept is used to latch the straight tracking factor at the initiation of and during the turn so the same straight tracking factor is used throughout the turn. The straight tracking factor is unlatched at the completion of a turn after a specific time delay and a new straight tracking factor can be calculated. The straight tracking method also utilizes transmission fluid temperature and utilizes additional fluid reserve in order to maintain straight machine movement.

Abstract: A fluid device includes a variable swashplate adapted for movement between a first position and a second position. A control piston is adapted to selectively move the variable swashplate between the first and second positions. A control valve is in fluid communication with the control piston. The control valve includes a sleeve defining a spool bore, at least one fluid inlet passage in fluid communication with a fluid source and at least one control passage in fluid communication with the control piston. The control fluid passage includes an opening at the spool bore. A spool is disposed in the spool bore of the sleeve. The spool includes a metering surface that selectively communicates fluid between the fluid inlet passage and the control fluid passage. The metering surface has a first end and a second end. The metering surface having a tapered surface disposed between the first and second ends.

Abstract: A fluid device includes a variable swashplate adapted for movement between a first position and a second position. A control piston is adapted to selectively move the variable swashplate between the first and second positions. A control valve is in fluid communication with the control piston. The control valve includes a sleeve defining a spool bore, at least one fluid inlet passage in fluid communication with a fluid source and at least one control passage in fluid communication with the control piston. The control fluid passage includes an opening at the spool bore. A spool is disposed in the spool bore of the sleeve. The spool includes a metering surface that selectively communicates fluid between the fluid inlet passage and the control fluid passage. The metering surface has a first end and a second end. The metering surface having a tapered surface disposed between the first and second ends.