Project 1

Develop a double-acting actuator model using Simscape Multibody and Simscape components. The mechanical system of the cylinder needs to be built using Simscape Multibody library components/blocks, and the hydraulic system needs to be modeled using Simscape library physical components.

When looking for a device to move the load in both directions, double-acting cylinders are useful applications when your machine requires more than one movement. Unlike single-acting cylinders, double-acting cylinders can extend and retract without the need for a spring. Instead of applying pressurized air into one port, double-acting cylinders have two ports where air can enter in and out.

Air enters through one port moving the piston forward and then applies pressurized air into the other port retracting the piston back into the cylinder. Double-acting cylinders are the most widely used pneumatic actuators compared to single-acting cylinders given their ability to extend and retract within a shorter period, thus, becoming more efficient and precise.

Double-acting pneumatic cylinders are mostly used in industrial and robotics industries. They perform tasks such as opening/closing doors and lifting and moving merchandise off conveyor belts. Other uses include medical applications, earth-moving equipment, and space programs.

Advantages of Double Acting Cylinder:

• More control over movement since pressurized air moves both ways
• Faster, stronger, and use less energy
• Offer more design variation: stroke and bore sizes
• Many double-acting pneumatic cylinders are ISO compliant as opposed to single pneumatic cylinders

Disadvantages of Double Acting Cylinder:

• More costly than single pneumatic cylinders
• Requires bigger housing - if used as a feed cylinder it needs to be coupled with another machine system
• In certain situations, air consumption may be calculated at different rates

When comparing single-acting vs double-acting hydraulic cylinders, the most visible difference is the number of couplers or connection ports. A single-acting hydraulic cylinder includes just one port. This is where the hydraulic fluid enters and forces the plunger out in one direction. A double-acting cylinder includes two ports. One for the hydraulic fluid to enter and extend the plunger, and the other for retracting the cylinder.

The plunger in a single-acting hydraulic cylinder extends when hydraulic fluid under high pressure is pumped into the cylinder. When it is time to retract the cylinder, depending upon the cylinder design, the plunger can be retracted using a return spring, by the load, or simply by gravity.

In a double-acting hydraulic cylinder, the plunger retracts when hydraulic fluid is pumped under high pressure into the top port, forcing the plunger back to its original position. This can be done quickly, if required, or very gradually with precise control.

Double-acting hydraulic cylinders can pump hydraulic fluid to both sides of the plunger. Connection ports positioned near both ends allow the piston rod to move both forward and backward. The extra port also allows more control of the plunger during retraction and ensures it always returns to its starting point.

The faster and more predictable retraction of double-acting cylinders makes them the better choice for projects needing repeatable accuracy.

This model shows a moving piston in a cylinder powered by a double-acting hydraulic cylinder. The double-acting actuator model is developed using Simscape Multibody and Simscape components. The mechanical system of the cylinder is built using Simscape Multibody library components and the hydraulic system is modeled using Simscape library physical components.

The Double-Acting Hydraulic Cylinder block contains mechanical and hydraulic subsystems. The mechanical subsystem models the piston and barrel (cylinder) using Simscape Multibody components. A Prismatic Joint block provides the translational degree of freedom needed for piston extension and retraction. The piston's range of motion is constrained using joint limits. The hydraulic subsystem contains two Translational Mechanical Converter blocks from the Isothermal Liquid foundation library in Simscape. These blocks exchange velocity and force information with the prismatic joint via a Translational Multibody Interface block. In addition, both of the converter blocks are configured to accept a physical position signal from the prismatic joint. These connections ensure that the state of the hydraulic chambers in the converter blocks is always consistent with the state of the prismatic joint. Using Double-Acting Hydraulic piston movement is made at both ends of the barrel.