A method for controlling a hydrostatic drive, which has a driving engine, a hydraulic pump coupled to the driving engine and a hydraulic motor coupled to the hydraulic pump by way of a pressurized hydraulic work line, includes calculating a manipulated variable vector comprising at least one manipulated variable for the hydrostatic drive based on (i) an output torque setpoint value for a torque on a secondary shaft driven by the hydraulic motor, (ii) a rotational speed and torque of the driving engine emerging from a predetermined operating point characteristic for the driving engine, and (iii) volumetric and mechanical losses of at least one adjuster unit comprising the hydraulic pump and the hydraulic motor. The manipulated variable vector is used to control the hydrostatic drive.

A method of controlling a propulsion system of a work or agricultural vehicle, wherein the propulsion system includes a prime mover and a hydraulic transmission including a variable displacement pump configured to be driven in rotation by the prime mover and a variable displacement hydraulic motor, operatively connected to the pump by means of a forward hydraulic line and a return one, the method providing for an ECO operating mode in which the accelerator controls the displacement of the hydraulic pump while the engine is operated at a fixed speed and in which, in said ECO operating mode, there is a step for acquiring a current speed of the vehicle (Step 1) and a limiting step (Step 3) of said displacement of the hydraulic pump when said current speed is lower than a predetermined speed threshold.

A method for controlling the traction of a vehicle hydraulic assistance circuit, including a target pressure is applied, a setpoint pressure and a theoretical value of a parameter are determined, a pressure setpoint is applied to the hydraulic pump, equal to the setpoint pressure, and an actual value is measured in the hydraulic assistance circuit. The actual value measured in the hydraulic assistance circuit is compared to the theoretical value, and if a gap between the actual value and the theoretical value is greater than a threshold value, a step of adjusting the setpoint is carried out in which the pressure setpoint of the hydraulic pump is modified so that it is equal to an actual pressure, to within an adjustment coefficient.

A working machine is provided, which includes a machine body, a prime mover, a pair of traveling devices, a pair of traveling motors to be switched between a first speed and a second speed higher than the first speed, a pair of traveling pumps driven by the prime mover to supply operation fluid to the pair of traveling motors, respectively, a controller configured to automatically shift down the pair of traveling motors from the second speed to the first speed, a mode switch configured for an operator to select an ON position allowing the controller to automatically shift down the first traveling motor from the second speed to the first speed and an OFF position preventing the controller to automatically shift down the first traveling motor from the second speed to the first speed, and a display to display that the operator selects the ON position of the mode switch.

A drum drive system includes a controller configured to control a prime mover, a variable displacement pump, and a variable displacement motor of the vehicle to provide a target drum speed for a drum of the vehicle. To provide the target drum speed, the controller having programmed instructions to (i) initially operate the variable displacement motor at a maximum motor displacement and operate the variable displacement pump at a pump displacement that provides the target drum speed without needing to actively manipulate a prime mover speed of the prime mover, (ii) increase the pump displacement and decrease a motor displacement without needing to actively manipulate the prime mover speed while still providing the target drum speed, and (iii) increase the prime mover speed if necessary to maintain the target drum speed in response to the pump displacement reaching a maximum pump displacement and the motor displacement reaching a minimum motor displacement.

An electronic begin of regulation (EBOR) control system and method is disclosed for a hydraulic motor of a machine having an engine for producing power and a track system for moving. The EBOR system includes a flow source, variable displacement motor, pressure sensor and control unit. The operator sets a pressure setpoint. The flow source generates flow in a loop with the motor. The pressure sensor senses loop working pressure. The control unit adjusts motor displacement based on comparisons between the pressure setpoint and sensed loop working pressure. The flow source can be bidirectional, and different pressure sensors can be used depending on the direction. The pressure setpoint can be varied during operation, and the control unit can adjust the displacement of the motor based on comparisons between the latest pressure setpoint and the loop working pressure sensed by the appropriate pressure sensor.

A drum drive system includes a control system configured to control a prime mover, a variable displacement pump mechanically coupled to the prime mover, and a variable displacement motor fluidly coupled to the variable displacement pump. The control system has programmed instructions to operate the prime mover, the variable displacement motor, and the variable displacement pump to drive a drum of the vehicle; acquire pressure data indicative of a pressure of a fluid flowing between the variable displacement pump and the variable displacement motor; and in response to the pressure of the fluid being below a threshold pressure and while maintaining a drum speed of the drum: increase a pump displacement of the variable displacement pump, reduce a speed of the prime mover, and reduce a motor displacement of the variable displacement motor.

Methods and systems for controlling a hydromechanical transmission are proposed. In one example, a control method for a hydrostatic unit of a hydromechanical variable transmission (HVT) is presented, comprising controlling the hydrostatic unit via a feedforward control architecture including a non-linear, multi-coefficient model, wherein the hydrostatic unit comprises a hydrostatic pump and a hydrostatic motor and a desired differential pressure of the hydrostatic unit or a desired hydraulic pump displacement may be used as inputs for the model, where the model's output is a pressure difference for a pump control piston coupled to a swash plate of the hydrostatic unit. Use of the non-linear model permits the hydrostatic unit to be controlled based on load, speed, and/or torque, thereby increasing the adaptability of the control system.

A system, apparatus and method providing a predictive maintenance system for a vehicle comprising a hydrostatic transmission. Sensors are installed on a vehicle to monitor various operating characteristics of a hydrostatic transmission. The sensors generate raw sensor data that is received by an onboard edge processing unit that applies the signals to a neural network model to derive predictions of potential future mechanical failures of the hydrostatic transmission. The inferences and raw sensor data may be sent to a remote data center via a personal communication device associated with the vehicle, to further train the neural network model.

A swash plate angle for a hydrostatic power unit of a continuously variable hydromechanical transmission is determined using a feedforward compensation term, to reduce reliance on closed loop control. The feedforward term is based on knowledge of the hydrostatic power unit determined as a function of knowledge of certain parameters, including, but not limited to, hydrostatic power unit pressure, swash plate angle, desired hydrostatic power unit ratio, and pump speed.