Mobile Heavy Equipment - High Efficiency Excavator (Test Bed 1)
See video of the excavator test bed being put through its paces at Purdue University's Maha Fluid Power Center.
Prof. Monika Ivantysynova, Purdue University
One of largest sectors using fluid power is the mobile equipment sector. This sector includes heavy machines such as excavators and wheel loaders that are commonly used in industries such as construction, agriculture, mining, and forestry. Fluid power is essential to this type of its inherent high power density. The power requirements in this mobile equipment are large while the equipment size must be as compact as possible for mobility and packaging. The design of these fluid power systems has generally focused on power and productivity giving little thought to the efficiency of the system. In recent years, however, new and stricter emissions regulations and increasing fuel costs have caused the industry to look for more efficient system designs. With this motivation the CCEFP has designated an excavator, one of the most common multi-actuator mobile machines in use, as a test bed for research. The test bed will be used as a platform to demonstrate the significant improvement in the hydraulic system efficiency of heavy mobile machines that could be achieved by integrating advanced system and component designs being studied by researchers throughout the CCEFP.
CCEFP Compact Excavator at Maha Labs, Purdue University
Statement of Test Bed Goals
Since the inception of the Center, the goal of this test bed has been to study new system concepts based on throttle-less actuator technology to demonstrate fuel savings and improved performance for the large sector of construction, agricultural and forestry machinery. The test bed also served to study and demonstrate effective control strategies for complex multi-actuator systems and new human-machine interfaces, such as those which provide haptic feedback.
Dramatic improvements on fuel economy have been predicted and demonstrated on the test bed, through use of displacement-controlled (DC) actuation. Lower waste heat was also predicted after transition to DC actuation, thus maintaining acceptable oil temperatures throughout the excavator hydraulic system. Also, a study for the feasibility utilizing a novel hydraulic hybrid architecture proved that a significant reduction in engine size is possible while equaling or exceeding the performance capability of a machine. Additional fuel savings were predicted for the DC hybrid architecture over the non-hybrid DC architecture.
In this reporting period, the primary question to be answered is what are the technological barriers, solutions and potential for DC actuation and hydraulic hybrid technologies to be successful in improving fuel consumption in multi-actuator mobile machines? Task definition and functional requirements:
- Reduce engine size by 50% of standard excavator
- Maintain standard machine performance
- Improve energy savings over non-hybrid DC excavator
Test Bed’s Role in Support of Strategic Plan
This test bed supports the Center’s goal to achieve a drastic improvement in efficiency of existing fluid power applications and to reduce petroleum consumption and pollution. The test bed is used to demonstrate fuel saving technologies and effective machine power management, especially for large and high power equipment. The demonstrated new actuator technology will open new applications in both large scale heavy duty machinery and robots and in human scaled applications like surgery robots or other portable devices where efficient and compact actuator technology is necessary.
Description and Explanation of Research Approach
Test bed 1, the excavator, has been used primarily to demonstrate potential energy savings of multi-actuator mobile machines through innovative system designs and advanced control strategies. However, the system is also very suitable for demonstrating the capabilities and performance of individual components and systems developed by projects throughout CCEFP.
The core of the test bed will be based upon the theoretical results from project 1A.2 although technologies developed as part of other CCEFP projects will be integrated onto the test bed for demonstration. The contributions are as follows:
- Project 1A.2 (Ivantysynova, Purdue):
- Controls for optimal power management of multi-actuator DC hydraulic system
- Design and installation of novel hybrid hydraulic system and downsizing of excavator engine
- Reduction of hydraulic cooling power due to improved system efficiency
- Design and installation of smart pump with integrated electronic pump controls
- Design and implementation of energy management strategies on hybrid hydraulic excavators
- Design of pump-switching architectures that enhance the capability of multi-actuator machines
- using DC actuation
- Investigation of advanced control strategies enabling pump-switching functionality in DC multi-
- actuator machines
- Investigation of system prognostic schemes for DC hybrid multi-actuator machine systems
- Project 1B.1 (Ivantysynova, Purdue): Development of next generation of highly efficient and smart variable displacement pumps
- Project 1G.1 (Michael, Milwaukee School of Engineering): Testing of energy efficient hydraulic fluids
- Project 3A.1 (Book, Georgia Tech): Tele-operation of the test bed using haptics controls and the Phantom controller
- Project 1E.2 (Cunefare, Georgia Tech): Novel energy-harvesting concept to provide power for pressure sensors
- Project 1E.2 (Lumkes, Purdue): Development of virtual variable displacement pump for the excavator low pressure hydraulic system using high speed on-off valves
- Project 1E.3 (Lumkes, Purdue): Development of a high efficiency, high bandwidth, actively controlled variable displacement pump/motor
- Project 1E.7 (Vacca, Purdue): New generation of variable displacement external gear pumps
- Project 3B.3 (Vacca, Purdue): Novel, adaptive control strategy based on extremum-seeking control for active vibration damping.
Figure 1: Series-Parallel Hybrid DC Excavator System (L) and Detailed System Model (R) used in Simulation