Current hydraulic systems involving multiple actuators and a single hydraulic power supply generally have poor efficiency. Using throttling valves to control multiple actuators requires meeting the highest pressure requirement and the total flow of all of actuators.
When there is a large difference in the pressure requirement of the actuators, fluid throttling results in significant energy losses. The purpose of this project is to implement switch-mode control in a multi-actuator circuit and demonstrate the improvement in efficiency over a traditional hydraulic system with throttling valve control.
To accomplish this task a hydraulic crane arm powered by two actuators was designed and constructed. One actuator provides a pivoting motion utilizing low pressure and high flow, while the other provides a lifting motion utilizing high pressure and low flow.
Using a simple feedback control loop, the crane arm lifts, rotates, and lower a load. After designing and testing the hydraulic crane, the team concluded that high-speed switch technology with multiple actuators is feasible. This new technology, once implemented on a larger scale in realistic applications, will reduce losses in hydraulic systems that depend on multiple actuators to function.
The concept of fluid power has many applications ranging from high precision robotics to critical systems in the vehicles that many rely on every day. The basic purpose of a fluid power circuit is to convert mechanical energy into fluid energy.
Once this conversion is made, the system must deliver the power to where it is needed in the system and convert the fluid energy back into mechanical energy. In many cases, it is possible to achieve the desired end result without any conversion to fluid energy. When the energy needs to be delivered to a location far away from the energy source, however, a complex system of gears, chains, belts, and linkages would be necessary.
This often comes at the expense of the cost, simplicity, and reliability of the system. A typical fluid power circuit is comprised of a hydraulic pump, to convert mechanical energy to fluid energy, a series of hoses to carry the fluid to its required location, and an actuator to convert the fluid energy back into mechanical energy.
The remainder of the system is comprised of simple and generally inexpensive control components, such as valves and accumulators. The chief advantage of fluid power is its ability to deliver substantial amounts of energy to remote locations without the need for cumbersome mechanisms.
Source: Worcester Polytechnic Institute
Author: Patrick Ennis | Peter Forte | Brendan Gove | Christopher Wellington