Name: modeling and experimental analysis of the single-shaft coaxial motor-pump assembly in electrohydrostatic actuators
Uploaded: 2022-06-13T14:00:00
Description: Watch this Scientific Journal Video about Modeling and Experimental Analysis of the Single-Shaft Coaxial Motor-Pump Assembly in Electrohydrostatic Actuators at JoVE.com

This work was supported by Chinese Civil Aircraft Project [No. MJ-2017-S49] and China Postdoctoral Science Foundation [No.2021M700331].

1. Simulation of pump flow characteristics
<ol>
	<li>Build the simulation model of the motor-pump assembly. Open the AMESim simulation platform and enter the SKETCH mode.
	<ol>
		<li>Build the simulation model for a single piston according to the kinematic mathematic model and the distribution curve (Figure 3). Encapsulate the single-piston model as a super component (Figure 4). 
		NOTE: The main kinemati...

<ol>
	<li>Yu, B., Wu, S., Jiao, Z., Shang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-objective+optimization+design+of+an+electrohydrostatic+actuator+based+on+a+particle+swarm+optimization+algorithm+and+an+analytic+hierarchy+process.">Multi-objective optimization design of an electrohydrostatic actuator based on a particle swarm optimization algorithm and an analytic hierarchy process.</a> Energies. 11 (9), 2426 (2018).</li><li>Chao, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Load-sensing+pump+design+to+reduce+heat+generation+of+electro-hydrostatic+actuator+systems.">Load-sensing pump design to reduce heat generation of electro-hydrostatic actuator systems.</a> Energies. 11 (9), 2266 (2018).</li><li>Zhao, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+research+on+tribological+characteristics+of+TiAlN+coated+valve+plate+in+electro-hydrostatic+actuator+pumps.">Experimental research on tribological characteristics of TiAlN coated valve plate in electro-hydrostatic actuator pumps.</a> Tribology International. 155, 106782 (2021).</li><li>Zhao, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+of+cylinder+block/valve+plate+interface+in+axial+piston+pumps:+Theoretical+models,+experimental+investigations,+and+optimal+design.">Review of cylinder block/valve plate interface in axial piston pumps: Theoretical models, experimental investigations, and optimal design.</a> Chinese Journal of Aeronautics. 34 (1), 111-134 (2021).</li><li>Chao, Q., Zhang, J., Xu, B., Huang, H., Pan, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+high-speed+electro-hydrostatic+actuator+pumps+in+aerospace+applications:+challenges+and+solutions.">A review of high-speed electro-hydrostatic actuator pumps in aerospace applications: challenges and solutions.</a> Journal of Mechanical Design. 141 (5), 050801 (2019).</li><li>Fu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+performance+analysis+of+position-based+impedance+control+for+an+electrohydrostatic+actuation+system.">Design and performance analysis of position-based impedance control for an electrohydrostatic actuation system.</a> Chinese Journal of Aeronautics. 31 (3), 584-596 (2018).</li><li>Alle, N., Hiremath, S. S., Makaram, S., Subramaniam, K., Talukdar, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+on+electro+hydrostatic+actuator+for+flight+control.">Review on electro hydrostatic actuator for flight control.</a> International Journal of Fluid Power. 17 (2), 125-145 (2016).</li><li>Chakraborty, I., Mavris, D. N., Emeneth, M., Schneegans, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+methodology+for+vehicle+and+mission+level+comparison+of+More+Electric+Aircraft+subsystem+solutions:+Application+to+the+flight+control+actuation+system.">A methodology for vehicle and mission level comparison of More Electric Aircraft subsystem solutions: Application to the flight control actuation system.</a> Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering. 229 (6), 1088-1102 (2014).</li><li>Zhang, T., He, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+reliability-based+robust+design+method+for+the+sealing+of+slipper-swash+plate+friction+pair+in+hydraulic+piston+pump.">A reliability-based robust design method for the sealing of slipper-swash plate friction pair in hydraulic piston pump.</a> IEEE Transactions on Reliability. 67 (2), 459-469 (2018).</li><li>Guo, S., Chen, J., Lu, Y., Wang, Y., Dong, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydraulic+piston+pump+in+civil+aircraft:+current+status,+future+directions+and+critical+technologies.">Hydraulic piston pump in civil aircraft: current status, future directions and critical technologies.</a> Chinese Journal of Aeronautics. 33 (1), 16-30 (2020).</li><li>Habibi, S., Goldenberg, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+of+a+new+high-performance+electrohydraulic+actuator.">Design of a new high-performance electrohydraulic actuator.</a> IEEE/ASME Transactions on Mechatronics. 5 (2), 158-164 (1999).</li><li>Xu, B., Hu, M., Zhang, J., Mao, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distribution+characteristics+and+impact+on+pump's+efficiency+of+hydro-mechanical+losses+of+axial+piston+pump+over+wide+operating+ranges.">Distribution characteristics and impact on pump's efficiency of hydro-mechanical losses of axial piston pump over wide operating ranges.</a> Journal of Central South University. 24 (3), 609-624 (2017).</li></ol>

When conducting these experimental steps, it is important to make sure that the pressure measuring points are close enough to the oil port of the pump, which would greatly influence the experimental results. In addition, pay attention to the pressure of the inlet port of the motor-pump assembly to ensure that no cavitation exists, especially at high-speed working conditions.
This method enables a dynamic adjustment of oil supply pressure, realizing an accurate simulation of different working c...

Known as a typically integrated actuator with high power density, the EHA has broad prospects in areas such as aerospace, aviation, construction machinery, and robotics1,2. The EHA mainly consists of a servo motor, pump, cylinder, pressurized reservoir, valve block, mode control valves, module control valves, and sensors, constituting a highly integrated, pump-controlled, closed hydraulic system. The schematic diagram and physical model are shown in Figure 13,4,5,6,7. The motor-pump assembly is the core power and the control component, and it determines the static and dynamic performance of the EHA7.
The conventional motor-pump assembly consists of a separate motor and pump, whose shafts are connected by a shaft coupling8. This structure has significant negative effects on the performance and life of the EHA. First, both the motor and pump will bear a relatively large vibration due to the assembling accuracy, especially at high speed5. Vibration will not only affect the output characteristics of the pump but also accelerate the wear of the friction interfaces in the pump, leading to the failure of the motor-pump assembly9. Second, sealings must be set at the shaft ends of the pump, which cannot fundamentally prevent leakage. Meanwhile, the mechanical efficiency of the motor-pump assembly decreases with increasing friction resistance10. Third, the frequent reversing of the motor-pump assembly will accelerate the wear of the coupling and increase the possibility of fatigue fracture, reducing the system reliability of the EHA11,12.
Thus, a single-shaft coaxial motor-pump assembly within a shared housing was developed to avoid these shortcomings. The structure is shown in Figure 2. A no-coupling design is adopted in this component, which could simultaneously increase the dynamic performance and the lubricating status of the motor and pump. This single-shaft coaxial design ensures the alignment of the two rotors and improves dynamic balance under high-speed conditions. Moreover, shared housing fundamentally eliminates shaft end leakage.
Testing the output characteristics of the EHA motor-pump assembly is of great significance for the optimization and improvement of the EHA performance. However, there are relatively few studies on performance testing of the motor-pump assembly, especially for EHAs. Therefore, we conducted a testing method of combining simulation and experiments. This method is suitable for testing motor-pump assemblies with a wide range of operating conditions, especially EHA pumps.
There are two main challenges: the first is to build an accurate simulation model to analyze the output flow characteristics of the motor-pump and provide assistance for the optimal design of the motor-pump assembly. We have established a simulation model of the motor-pump assembly through hierarchical modeling and realized the simulation analysis of the output flow by changing different parameters. The second is the cavitation of the test element caused by high speed, which is the most important aspect that distinguishes it from ordinary pumps. Therefore, we focused more on the design of the oil supply system when designing the test system to realize the test under various working conditions.
In this protocol, a one-dimensional simulation model was established to simulate the pump flow characteristics initially, judging whether the pump flow characteristics meet the requirements of EHA. Then, the flow characteristics and the overall efficiency were experimentally tested on a dedicated test bench, obtaining the overall efficiency map that cannot be accurately simulated by simulation. Lastly, the pump flow characteristics were compared with the experimental results to verify the accuracy of the simulation results. Meanwhile, the overall efficiency map was obtained to evaluate the performance of the single-shaft coaxial motor-pump assembly.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>AmeSim simulation platform</td>
			<td>Siemens</td>
			<td>Amesim 16</td>
			<td></td>
		</tr>
		<tr>
			<td>DAQ card</td>
			<td>Advantech</td>
			<td>PCI1710</td>
			<td></td>
		</tr>
		<tr>
			<td>Flowmeter</td>
			<td>KRACHT</td>
			<td>VC0.04E1RS, 0.02-4 L/min</td>
			<td></td>
		</tr>
		<tr>
			<td>Flowmeter</td>
			<td>KRACHT</td>
			<td>VC0.4E1RS, 0.2-40 L/min</td>
			<td></td>
		</tr>
		<tr>
			<td>Industrial Computer</td>
			<td>Advantech</td>
			<td>610H</td>
			<td></td>
		</tr>
		<tr>
			<td>Oil supply motor</td>
			<td>Siemens</td>
			<td>1TL0001-1BB23-3JA5</td>
			<td></td>
		</tr>
		<tr>
			<td>Oil supply pump</td>
			<td>Kangbaishi</td>
			<td>P222RF01DT</td>
			<td></td>
		</tr>
		<tr>
			<td>OriginPro</td>
			<td>OriginLab Corporation</td>
			<td>OriginPro 2021 (64-bit) 9.8.0.200</td>
			<td></td>
		</tr>
		<tr>
			<td>Pressure sensor</td>
			<td>Feejoy</td>
			<td>PI131G(0-5 MPA)F4MCAH5C</td>
			<td></td>
		</tr>
		<tr>
			<td>Proportional relief valve</td>
			<td>Huade hydraulic</td>
			<td>DBE10-30B/50YV</td>
			<td></td>
		</tr>
		<tr>
			<td>Proportional relief valve</td>
			<td>Huade hydraulic</td>
			<td>DBE10-30B/315YV</td>
			<td></td>
		</tr>
		<tr>
			<td>Spindle motor</td>
			<td>HAOZHI</td>
			<td>DGZX-18020 / 22A2-KFHWVJLS</td>
			<td>Max speed: 18,000 rpm;&#160; Power: 22 kW</td>
		</tr>
		<tr>
			<td>Temperature sensor</td>
			<td>Feejoy</td>
			<td>TI-A42M1A180/30+F1</td>
			<td></td>
		</tr>
	</tbody>
</table>

modeling and experimental analysis of the single-shaft coaxial motor-pump assembly in electrohydrostatic actuators

An electrohydrostatic actuator (EHA) can be the most promising alternative compared with the traditional hydraulic servo actuators for its high power density, ease of maintenance, and reliability. As the core power unit that determines the performance and service life of the EHA, the motor-pump assembly should simultaneously possess a wide speed/pressure range and a high dynamic response.
This paper presents a method to test the performance of the motor-pump assembly through simulation and experimentation. The flow output characteristics were defined through simulation and analysis of the assembly at the beginning of the experiment, leading to the conclusion of whether the pump could meet the requirements of the EHA. A series of performance tests were conducted on the motor-pump assembly via a pump test bench in the speed range of 1,450-9,000 rpm and the pressure range of 1-30 MPa.
We tested the overall efficiency of the motor-pump assembly under various working conditions after confirming the consistency between the test results of the flow output characteristics with the simulation results. The results showed that the assembly has higher overall efficiency when working at 4,500-7,000 rpm under the pressure of 10-25 MPa and at 2,000-2,500 rpm under 5-15 MPa. Overall, this method can be utilized for determining in advance whether the motor-pump assembly meets the requirements of EHA. Moreover, this paper proposes a rapid test method of the motor-pump assembly in various working conditions, which could assist in predicting EHA performance.

The simulation result of the discharge flow (Figure 10A) indicated that the discharge flow decreased slightly with the increase in load pressure when the speed was constant. Furthermore, the output flow rate increased linearly with increasing speed when the pressure is constant, judging from the same belt width. To directly evaluate the performance of the motor-pump assembly under different working conditions, we plotted its volumetric efficiency diagram (Figure 11A</str...

Watch this Scientific Journal Video about Modeling and Experimental Analysis of the Single-Shaft Coaxial Motor-Pump Assembly in Electrohydrostatic Actuators at JoVE.com

Modeling and Experimental Analysis of the Single-Shaft Coaxial Motor-Pump Assembly in Electrohydrostatic Actuators

We built a simulation model to evaluate pump flow characteristics and performance of the single-shaft coaxial motor-pump assembly in electrohydrostatic actuators and investigate the overall efficiency in a wide set of working conditions of the motor-pump assembly experimentally.

An electrohydrostatic actuator (EHA) can be the most promising alternative compared with the traditional hydraulic servo actuators for its high power ...

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