Actuation

This demo shows a muscle actuation based on two air muscle actuators (or McKibben artificial muscles) in antagonistic connection. The air muscle actuators are connected to the opposite sides of a lever. The 4-way directional valve is controlled by an electro-mechanical valve actuator. In the 4-way directional way when the high-pressure path P-A and return line B-T are open, the top air muscle actuator contracts and forces the bottom air muscle actuator on the opposite side to extend. Similarly, as the high-pressure path P-B and return line A-T open, the bottom air muscle actuator starts to contract and forces the top air muscle actuator to extend. The oscillating motions of the muscles are converted into the angular rotation of the output load connected to the mechanical linkage modeled with the slider-cranks.

The actuator consists of a proportional 4-way directional valve driving a double-acting hydraulic cylinder. The cylinder drives a load consisting of a mass, viscous and Coulomb friction, constant force, and a spring. The actuator is powered by a variable-displacement, pressure-compensated pump, driven by a constant velocity motor. Pipelines between the valve, cylinder, pump, and the tank are simulated with the Hydraulic Pipeline blocks.

The use of a 2-way valve in a closed-loop circuit together with a double-acting hydraulic cylinder, fixed orifice, mass, spring, damper, and control blocks.

A closed-circuit hydraulic actuator driven by a variable-speed pump. The actuator is arranged as a closed fluid system with two replenishment valves (check valves) and a spring-loaded accumulator serving as a replenishment reservoir. The pump speed is controlled by the difference between the commanded and measured piston position. The actuator acts against a spring, a damper, and a time-varying load.

Model, parameterize, test, and compare design cases for a counterbalance valve in a boom arm mechanism. A counterbalance valve allows an upstream flow from the back port to the load port through the check valve stage during cylinder rod extension, and it allows a downstream flow from the load port to the back port through the relief valve stage during cylinder rod retraction in the boom arm mechanism. Counterbalance valves help with the load holding, load actuation, speed control, and safety by controlling the piston motion of the booming cylinder. When you run the model, it generates a plot of the booming cylinder position and the forces at the A side and B side of the cylinder piston.

Linearize a Simscape™ hydro-mechanical system model to check stability of an open-loop system around an operating point. This example uses the Simulink Control Design™ Frequency Response Estimator block to perform a frequency response estimation experiment and store the data for later estimation offline.

Perform a sensitivity analysis for tandem primary cylinder model in Simscape™. The example requires the Simulink Design Optimization™ to be installed and licensed to run.

Parameterize and test a tandem primary cylinder starting from a manufacturer’s datasheet. This example uses optimization to determine remaining unknown parameters, given the numerical data extracted from the datasheet. After the model is simulated, it compares the resulting push rod force - brake pressure relationship curve to the curve provided on the manufacturer datasheet. Understanding the behavior of the tandem primary cylinder is important when selecting other braking system components.

A custom hydraulic cylinder model that omits the effect of fluid compressibility in the cylinder chambers. The double-acting cylinder connected to a 4-way valve to model a simple closed-loop actuator.

An actuator that drives a machine tool working unit performing a sequence of three technological operations: coarse drilling, fine drilling, and reaming. The actuator speed is controlled by one of three pressure-compensated flow control valves metering out return flow from the cylinder. The selection of an appropriate flow control is performed by directional valves that are activated by a control unit.

A simplified version of an actuation system consisting of the lift and tilt cylinders. Each cylinder is controlled by an open center, 6-way, 3-position directional valve. The valves are connected in series through their unloading branch such that the system pump is unloaded when both command levers are in neutral position. If either tilt or lift command is applied, the unloading path is closed.

The model consists of a double-acting hydraulic cylinder controlled by an open-center 4-way directional valve and a power unit built of a flow rate source and a pressure-relief valve. The cylinder is loaded with an active force in 10000 N trying to extend the rod. In other words, the cylinder experiences an overriding load while extending. To hold the rod in place while the directional valve is in the neutral position and prevent losing control of the cylinder extension, the counterbalance valve is used. The valve controls the return flow from port A. The valve pilot port P is connected to cylinder port B, thus making it impossible for the cylinder to move until pressure at port B builds up to certain level.

An actuator controlled by a 4-way directional valve and loaded with an overriding load, requiring the use of counterbalance valves to prevent the load from creeping when the directional valve is in the neutral position. In the neutral position, the directional valve connects ports A and B to the reservoir while blocking the pressure port P. The counterbalance valves block flow from returning to the reservoir, thus holding the actuator in place.

An actuator built around a telescopic hydraulic cylinder, which is equipped with three rods interacting with each other through hard stops. The effective areas of the rods are set to 20, 16, and 12 cm^2 respectively, which causes the first rod to move first, followed by the second, and then by the third rod. The actuator is controlled by a 2-position 3-way valve, which connects the actuator chamber to the tank at neutral position. As the control signal is applied to the valve, the actuator chamber is connected to the pump and the actuator starts extending. The rods are retracted by external load when the chamber is connected to the tank. The power unit relief valve is set to 50 bar, and maximum load to be handled by the actuator is 2500 N.

The use of a double-acting hydraulic cylinder. The clamping structure is simulated with the spring and damper installed between the cylinder case and the reference. The cylinder performs forward and return strokes caused by the change of pressures at ports A and B. The cylinder load consists of inertia, viscous friction, and constant opposing load of 400 N.

A hydraulic cylinder equipped with a custom model of snubbers (cushions) on both sides of the cylinder. The snubbers are implemented as two-chamber cushions separated by the cushioning bush as the piston comes close to the end of the stroke. The cushioning provides hydraulic braking as the cylinder reaches the end of its stroke, absorbing some of the kinetic energy of the system before the piston reaches the end stop.

The use of a 3-way valve to control the motion of a hydraulic differential cylinder. The valve connects cylinder port B either to tank or to cylinder chamber A through the fixed orifice. The cylinder extends when its ports are both connected to the pressure source due to difference in piston areas. Orifice B controls the extension speed. The cylinder retracts if chamber B is connected to tank.

An injection molding actuation system. The model contains a set of cartridge valves that control pumps, motors, and cylinders to execute the steps of an injection molding process.

An oscillating hydraulic mechanism that consists of a single-acting hydraulic rotary actuator, winch, flow control valve, two-position electro-hydraulic valve, and power and control units. The mechanism maintains oscillating vertical motion of the weight by raising it to 25 cm and then allowing it to fall. To raise the weight, the electro-hydraulic valve is energized and connects the power unit to the hydraulic actuator inlet. As the weight reaches 25 cm the valve is deenergized, connecting the actuator chamber to tank.

Model, parameterize, and test a pressure control solenoid valve. This example also generates a plot of the relationship between applied solenoid force and the resulting actuator port pressure.

A double-acting actuator with differential cylinders. The pump output is connected to cylinder B of the actuator while cylinder A of the actuator can be connected to either the pump or the reservoir through the 3-way directional valve. When cylinder A is connected to the pump, pressures at both cylinders become equal. Because of the larger effective piston area in cylinder A, the interface force in cylinder A is larger than that of in cylinder B which causes the piston to extend. When cylinder A is connected to the reservoir, the piston starts to retract. The 3-way directional valve is controlled by a sinusoidal signal to achieve repeating reciprocal motion in the actuator.

A typical hydraulic cylinder actuator used to operate friction clutches, brakes and other devices installed on rotating shafts. The key element of the actuator is a piston that moves back and forth under pressure provided through the central drill in the shaft and through channels in the clutch. In the example, the actuator acts against a preloaded spring, which tends to push the piston against the clutch wall.

Model, parameterize and, test a secondary cylinder. Given the numerical data extracted from the datasheet of the single-stage primary cylinder, the unknown parameters of the secondary cylinder are calculated. The model is simulated to generate the plot between the applied force to the single-stage primary cylinder and the pressure developed inside the secondary cylinder.

A sequence circuit that is based on four check valves installed in both pressure and return lines of the second rotary actuator. The cracking pressure of all the valves is set higher than any load pressure of Rotary Actuator 1, but lower than pressure that develops in its chambers at the end of the stroke when Rotary Actuator 1 reaches its hard stop. As a result, the Rotary Actuator 2 starts moving only after the Rotary Actuator 1 completes its stroke.

A model of a two-stage servo-valve with a 4-way, 3-position spool valve in the power stage and a flapper-nozzle amplifier in the pilot stage. The flapper is connected to the armature of a torque motor, which in the example is represented with an ideal translational force source. The servo-valve shown in the example is equipped with the spring feedback between the flapper and the spool of the main valve. To investigate the behavior of such a valve, axial hydraulic forces on all four spool orifices are accounted for in the model by using Spool Orifice Hydraulic Force blocks. The servo-valve controls a simple double-acting cylinder in an open-loop application.

Model, parameterize and test a single-stage primary cylinder starting from manufacturer datasheet information. Given the numerical data extracted from the datasheet, the unknown parameters are calculated. The model is then simulated and the resulting push rod force versus pressure relationship curve is compared with curve provided on the manufacturer datasheet.

A single-acting hydraulic cylinder controlled by an 3-way directional valve. It drives a load consisting of a mass, viscous friction, and preloaded spring. The pump unit is assumed to be powerful enough to maintain constant pressure at the valve inlet.

Model, parameterize and test a tandem primary cylinder starting from manufacturer datasheet information. First, there is a brief discussion on the mathematical modeling of the system. Given the numerical data extracted from the datasheet, optimization is then used to determine remaining unknown parameters. The model is then simulated and the resulting push rod force - brake pressure relationship curve is compared with the curve provided on the manufacturer datasheet. Understanding the behavior of the tandem primary cylinder is an important prerequisite to selection of other braking system components.