In Vortex® Studio Editor, you can now simulate various hydraulics components, such as an actuator, a pump, a divider, a combiner and a transmission using the Hydraulics Systems extensions.

By linking these components together, you can simulate realistic hydraulics systems for a variety of uses, such as simulating the hydraulics systems of an excavator arm.

This page describes the components that make up a hydraulics system, and how they interact with each other.

Pump

A pump generates the power in a hydraulics system, providing a flow of liquid whose pressure and flow are used to activate an actuator.

• Inputs
  • Pump RPM: Revolutions per minute of the pump.
  • Flow Request: Specifies requested flow of liquid in the pump (in m³/s).
  • Pressure Request: Specifies the requested pump pressure (in pascals, N/m²).
  • Max Pressure Factor: Maximum pressure factor used to compute the Corner Flow output. The Corner Flow is the maximum flow at maximum power.
  • Flow Unload Factor: Factor used to smooth the flow of liquid.
• Parameters
  • Activate: Select this box to activate the pump.
  • Max Power: Sets the maximum power of the pump (in watts).

  • Volumetric Efficiency: Value that simulates the volumetric efficiency of the pump. This is the ratio of the actual liquid flow in the pump versus the theoretical flow.

  • Mechanical Efficiency: Value that simulates the mechanical efficiency of the pump. This is the ratio of the pump's theoretical torque versus the actual torque.
  • Max Operating Flow: Specifies the maximum liquid flow of the pump (in m³/s).
  • Min Operating Flow: Specifies the minimum liquid flow of the pump (in m³/s).
  • Max Operating Pressure: Sets the maximum operating pressure of the pump (in pascals, N/m²).
  • Min Operating Pressure: Sets the minimum operating pressure of the pump (in pascals, N/m²).
  • Displacement per Revolution: Specifies the volume displaced per revolution of the pump (in m³).
  • Filter Rise Time Delay: Introduces a time delay (in seconds) used to increase pressure. This is accomplished by using a low-pass filter to achieve the requested pressure.
  • Filter Fall Time Delay: Introduces a time delay (in seconds) used to decrease pressure. This is accomplished by using a low-pass filter to achieve the requested pressure.
  • Pressure Overhead Factor: This value multiplies with Pressure Request as a safety factor. The pressure value used by the low-pass filter to progressively adjust the actual pressure over time is given by: Pressure Request * Pressure Overhead Factor + Pressure Overhead Offset.
  • Pressure Overhead Offset: This value is added to Pressure Request to account for losses in the system. The pressure value used by the low-pass filter to progressively adjust the actual pressure over time is given by: Pressure Request * Pressure Overhead Factor + Pressure Overhead Offset.

Actuator

An actuator is a component of a hydraulics system that moves another component.

The actuator's Constraint parameter specifies a constraint with one degree of freedom (usually a hinge or prismatic) that is activated according to the pressure and flow provided by the pump. These linked constraints have only one controllable coordinate, meaning one degree of freedom and five constrained degrees. The rigid body linked to this constraint moves via the controllable coordinate. The actuator controls the motion of this coordinate, which could be locked in plastic mode or motorized.

The actuator can be directly connected to a pump by flow and pressure, via a connection container, as seen below.

An actuator can be defined by the bore area and rod area. These values are outputs that are computed internally using the Max Operating Pressure of the actuator, and the Max Force of the Extend and Retract valves.

• Inputs
  • Control Input: The value of the control input (e.g., joystick) connected to the actuator. Values range between -1 and 1.
  • Supply Pressure: Sets the supplied pressure (in pascals, N/m²) connected either directly from a pump or indirectly through manifolds.
  • Supply Flow: Sets the supplied flow (in m³/s) connected either directly from a pump or indirectly through manifolds.
  • Area Scale: Specifies a scaling factor to dynamically vary the actuator area, thus changing its maximum force.
  • Lock Mode: Selecting this parameter immediately brakes the parameter.
  • Float Mode: Selecting this option adds the capability of floating or free fall mode for the constraint used by the actuator. The constraint coordinate must be set to Motorized, and Lock Mode must not be selected.
  • Extend Valve Fault and Retract Valve Fault: These sections contain multiplicative factors to control the speed, maximum pressure, relief force, drift force, overspeed force and final force or the actuator's valves. These factors are Speed Factor, Max Pressure Factor, Relief Force Factor, Drift Force Factor, Overspeed Force Factor, Final Force Factor.
• Parameters
  • Activate: Select this parameter to activate the actuator.
  • Drift Valve: Select this parameter to block the pressure when the speed of the associated constraint is moving opposite to the desired direction. Relates to Drift Force.
  • Overspeed Valve: Select this parameter to allow controlling the force when the associated constraint is moving faster than the desired speed. Relates to Overspeed Force.
  • Constraint: Sets the constraint that you want this actuator to control. Use the Browse buttons in this field to select a constraint from the Explorer panel.
  • Max Operating Flow: Maximum flow of the actuator (in m³/s).
  • Max Operating Pressure: Maximum pressure of the actuator (in pascals, N/m²).
  • Gear Ratio: This value models a transmission module placed after the actuator. It scales the output constraint speed and hydraulic force of the actuator according to the following:
    • Hydraulic force output = (Hydraulic Outputs > Coordinate Force) / Gear Ratio
    • Hydraulic speed output = (Constraint Outputs > Current Velocity) * Gear Ratio
  • Speed Ratio: This value reduces the requested flow of the actuator. Acceptable values range from 0 (no flow) and 1 (no change in flow request).
  • Lock Max Force: Specifies the maximum force (in newtons, N) of the constraint coordinate when the constraint is in Lock mode. The minimum force is the negative of this value.
  • Closing Threshold: If Control Input is between +/- this value, the actuator valve is considered closed.
  • Speed Threshold: Below this speed, the actuator will not be considered as moving (in m/s).
  • Pressure Request Rise Filter: Introduces a time delay (in seconds) used to increase pressure. This is accomplished by using a low-pass filter to achieve the requested pressure.
  • Pressure Request Fall Filter: Introduces a time delay (in seconds) used to decrease pressure. This is accomplished by using a low-pass filter to achieve the requested pressure.
    • Max Speed: Maximum speed of the constraint (in m/s).
    • Acceleration: Inverse of time delay to accelerate the constraint (in s^-1).
    • Deceleration: Inverse of time delay to decelerate the constraint (in s^-1).
    • Snubber Distance: Defines the distance that the piston will slow down before it reaches its limit to avoid impact (in meters).
    • Max Force: Maximum force of the valve (in newtons, N). This value is determined by the area of the piston (bore area or rod area) multiplied by Max Operating Pressure.
    • Relief Force: Sets the force used to hold the constraint when Control Input is zero (in newtons, N).
    • Drift Force: Increases the pressure when the associated constraint is moving opposite to the desired direction (in newtons, N). (Only in effect if Drift Valve is selected).
    • Overspeed Force: Increases the pressure when the associated constraint is going faster than the desired velocity. (Only in effect if Overspeed Valve is selected).
      

      Relief Force, Drift Force and Overspeed Force should all be greater Max Force. These forces are used to take over for Max Force when more pressure is required to stop the actuator under their respective circumstances.

Divider Manifold

A divider manifold allows you to split the flow and pressure of a pump to multiple actuators. The flow is divided and distributed to the connected actuators, and the pressure is the same for all of them. The divider outputs its total power.

To use a divider, specify how many actuators will link to it, then connect it to the pump and actuators in a connection container.

• Inputs
  • Pump Supply Pressure: Specifies the input pressure of the attached pump (in pascals, N/m²).
  • Pump Supply Flow: Specifies the input supply of the attached pump (in m³/s).
  • Actuator Pressure Request: Sets the pressure required per actuator (in pascals, N/m²). Each row relates to value specified in the Actuator Count parameter.
  • Actuator Flow Request: Sets the flow required per actuator (in m³/s). Each row relates to value specified in the Actuator Count parameter.
• Parameters
  • Actuator Count: Adjust this value to reflect the number of actuators connected to the divider. New inputs Actuator Pressure Request Pressure, and Actuator Flow Request will appear, with one row for each actuator.

Combiner Manifold

A combiner manifold allows you connect several pumps to provide more power to a single actuator than a single pump can provide. The combiner outputs its total power, factoring in power lost in the combiner.

The combiner's properties allows you to specify the ratio of pumps, controlling in what proportion each pump is used by the combiner.

The example below demonstrates multiple pumps connected to a combiner in a connection container and then output to a single actuator.

• Input
  • Actuator Pressure Request: Sets the pressure required by the connected actuator (in pascals, N/m²).
  • Actuator Flow Request: Sets the flow required by the connected actuator (in m³/s).
  • Pump Supply Pressure: Specifies the input pressure per pump (in pascals, N/m²). Each row relates to the amount of pumps specified in the Pump Count parameter.
  • Pump Supply Flow: Specifies the input supply per pump (in m³/s). Each row relates value specified in the Pump Count parameter.
  • Ratio: Sets the ratios of the pumps connected to the combiner. The sum must equal to 1; if set to zero, to valve is closed. Each row relates to the value specified in the Pump Count parameter.
• Parameters
  • Pump Count: Adjust this value to reflect the number of pumps connected to the combiner. New inputs Pump Supply Pressure, Pump Supply Flow, and Ratio will appear, with one row for each pump.

Transmission

The transmission allows you to transfer power from an engine to several hydraulic pumps. The sample connection container below demonstrates how a transmission connects to a pump that is connected to an actuator.

For each pump, the gear ratio can be specified, allowing the distribution of the RPM to the various pumps. The total torque provided by the transmission is outputted.

For example, the Shaft RPM output of a vehicle can be connected to the Engine RPM input of the transmission. Hydraulics systems can often stall an engine due to the high torque requested in short time interval. When linking an engine to the Hydraulics Systems, it is recommended that you create a speed governor and a ECU (Engine Control Unit) to interact with the engine, via Python Scripting. The Hydraulics Systems can be used in Vehicle Systems, using the engine of the vehicle.

The following example shows a hydraulics system for an excavator.

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• Inputs
  • Engine RPM: Specifies the rotations per minute of the vehicle.
  • Pump Torque: Sets the torque for each pump (in newton meters, N⋅m). The rows in this input relate to the value in the Pump Count parameter.
• Parameters
  • Pump Count: Sets the number of pumps connected to the transmission. Increasing this value adds rows to the Pump Torque input and Gear Ratio parameter.
  • Gear Ratio: Each row in this list corresponds to a pump, as specified in Pump Count. The value in this row scales the value in the corresponding Pump RPM row. A value of 1 means the Pump RPM is unchanged; less than 1 scales down; greater than 1 scales up.