Low-Friction Antagonist Hydraulic Transmission Using Long-Stroke Rolling Diaphragm Cylinders

2017 ◽  
Author(s):  
Saeed Hashemi ◽  
Steven Sobojinski ◽  
William K. Durfee
Keyword(s):  
Dynamic Performance ◽  
Step Response ◽  
Hydraulic Systems ◽  
Axial Motion ◽  
Low Friction ◽  
Stroke Length ◽  
Wearable Robots ◽  
Hydraulic Cylinders ◽  
Long Stroke ◽  
Volume Efficiency

Hydraulic cylinders are the most common actuators for small, passive hydraulic systems. Friction and leakage of the actuators are the most crucial factors for force and volume efficiency. Development of a frictionless and leak-free cylinder would enable implementation of a passive human body controlled device. Due to the limitation of short stroke length in commercial rolling diaphragm (RD) cylinders, a novel fabric-elastomer long-stroke rolling diaphragm (LSRD) cylinder was developed, evaluated, and compared to the commercial rolling diaphragm, O-ring, and gap seal cylinders. The LSRD cylinder has low friction, zero leakage, and can operate at up to 700 kPa (100 psi). The performance of the LSRD cylinders was evaluated using an antagonist hydraulic transmission benchtop device. Axial motion of the LSRD cylinders was converted to a rotary motion on the input and output shafts using timing belts and pulleys. Two LSRD cylinders were engaged on each shaft and two lever arms were used to control the transmission device. A rotation of 90 degrees was achieved using LSRD cylinders with 1.5-inch stroke length. Friction, stiffness, tracking, impulse response, and step response tests were performed at 70, 170, and 275 kPa (10, 25, and 40 psi) preload pressures to evaluate the transmission device and LSRD cylinder dynamic performance. The results demonstrated that at least 275 kPa preload pressure is needed to have a satisfactory performance. The passive antagonist hydraulic transmission can be used in applications such as wearable robots and telepresence devices.

scholarly journals Low Friction, Long-Stroke Rolling Diaphragm Cylinder for Passive Hydraulic Rehabilitation Robots

2017 ◽  
Author(s):  
Saeed Hashemi ◽  
William K. Durfee
Keyword(s):  
Low Pressure ◽  
Rehabilitation Robotics ◽  
Woven Fabric ◽  
Hydraulic Systems ◽  
Low Friction ◽  
Stroke Length ◽  
Hydraulic Actuators ◽  
Rehabilitation Robots ◽  
Ring Seal ◽  
Long Stroke

Hydraulic actuators are commonly used in mechanical systems, and actuator efficiency is one of the most important factors in these systems [1]. The energy loss to overcome friction force makes the actuator less efficient. Wearable rehabilitation robotics is one of the applications of hydraulic actuators. Hydraulic cylinders deliver the power extracted from the external resources and/or less stroke-affected limbs to the more stroke-affected limbs (Fig. 1). O-ring seal, rolling diaphragm, and gap seal cylinders are three common technologies that have been used in different hydraulic systems for years. O-ring seal actuators use an O-ring seal between the piston and cylinder. Rolling diaphragm actuators have a diaphragm between the cylinder and piston which rolls back and forth. In gap seal cylinders, there is a gap between the piston and cylinder. Since it is a tradeoff between leakage and friction, leakage between the two chambers in these cylinders is tolerated to reduce friction (Fig. 2). One study examined low friction cylinders in a low pressure hydraulic transmission [2]. In this study, rolling diaphragm cylinders were used in the transmission, but the restriction on stroke length of these cylinders is a problem that needs to be solved. Commercial rolling diaphragms are manufactured using compression molding of a sheet rubber and woven fabric [2], a manufacturing method that limits the stroke length to no more than the bore of the cylinder. Rolling diaphragm cylinders with the higher stroke-to-bore ratios could multiply the work per cycle of the system [2]. Furthermore, there are limitations of using short stroke length rolling diaphragm cylinders [3] [4]. A more thorough friction evaluation of various cylinder technologies is needed to determine which technology has the lowest friction and is most appropriate for low pressure hydraulic systems like rehabilitation robots. Developing a low friction, leakage-free cylinder without stroke limitations is needed for small hydraulics. Using an experimental test, we measured the resistance forces in three types of cylinders: O-ring, gap seal, and rolling diaphragm. The cylinders were tested at low-pressure and with mineral oil to determine the lowest friction cylinder technology. The same friction test was performed in a novel, long-stroke, rolling diaphragm cylinder (LSRD) to compare it in two different thicknesses with commercial actuators.

Investigation on the Characteristics of a New Structure Brake Distribution Valve

2021 ◽  
Author(s):  
Yuqi Wang ◽  
Xinhui Liu ◽  
Jinshi Chen ◽  
Yafang Han
Keyword(s):  
Lightweight Design ◽  
Dynamic Performance ◽  
Tracking Error ◽  
Model Verification ◽  
Step Response ◽  
Hydraulic Systems ◽  
Control Precision ◽  
Valve Structure ◽  
New Type ◽  
Conventional Structure

Abstract Brake distribution valve is an important part of aircraft hydraulic systems. TO realize the integra-tion and lightweight design of conventional structure valves, this paper proposed a new type brake distribution valve that uses new structure of pressure reducing unit, overflow unit and embedded shuttle valve instead of the conventional valve structure. The new structure de-creases the weight and volume of the valve; reduces the influence of non-work zone and damping on valve performance; improves the control precision and dynamic performance of the brake distribution valve. Both of numerical simulation and model verification experiments of the entire valve demonstrate that the dynamic performance of the new type valve has been significantly improved on the premise of ensuring linear characteristics. The results of simula-tion show that the response time of the new structure valve is 33% shorter than that of the conventional structure valve in case of step response simulation; in case of sinusoidal re-sponse simulation, the tracking error of the valve reduces by nearly 5%.

scholarly journals Development of a Hydraulic Parallel Link Force Display -Improvement of Manipulability Using a Disturbance Observer and its Application to a Master-slave System-

2003 ◽  
Vol 15 (4) ◽  
pp. 391-397 ◽  
Author(s):  
Shigeki Kudomi ◽  
◽  
Hironao Yamada ◽  
Takayoshi Muto ◽  
Keyword(s):  
Dynamic Performance ◽  
Load Force ◽  
Slave System ◽  
Disturbance Compensation ◽  
Practical Application ◽  
Hydraulic Cylinders ◽  
Six Dof ◽  
Parallel Link ◽  
Hydraulic Manipulator ◽  
Master Slave System

We previously developed a six-DOF parallel link force display that is actuated by six hydraulic cylinders. The manipulability of the display, however, was insufficient at first, because the dynamic performance of each cylinder was not necessarily the same as that of the others. To overcome this problem, in the present study we have applied disturbance compensation to improve manipulability. To demonstrate a practical application of this force display, we have also constituted a master-slave system in which the display is adopted as the master, and the same type of hydraulic manipulator is adopted as the slave. An operator manipulated the system so that the slave touched a flexible object serving as a load. Our experiments confirmed that the system was controlled with relatively good dynamic performance, and that the operator was able to feel the load force sensitively through the force display.

Tribological behaviors of PTFE-based composites filled with bronze microparticles

2019 ◽  
pp. 089270571987520
Author(s):  
Amine Charfi ◽  
Sameh Neili ◽  
Mohamed Kharrat ◽  
Maher Dammak
Keyword(s):  
Wear Behavior ◽  
Normal Load ◽  
Optical Microscope ◽  
Hydraulic Systems ◽  
Friction Behavior ◽  
Excessive Pressure ◽  
Research Article ◽  
Hydraulic Cylinders ◽  
Perfect Contact ◽  
The Subject

This research article deals with commercial polytetrafluoroethylene (PTFE)-based composites filled with 30% of bronze microparticles. This shade is used as guide rings in hydraulic cylinders. After a certain number of slip cycles, seal wear is one of the main causes of leaks in the hydraulic systems. To solve this problem, it is essential to act on the seal materials to increase its lifetime and consequently the lifetime of hydraulic systems. Excessive pressure on the seal causes a significant wear while a light contact causes lubricant leak. For both situations, we have a failure of the system. For this reason, it is necessary to have a perfect contact between the seal and the metal surface and simultaneously with minimal wear. This problem is the subject of our research works. We analyze, in this article, the tribological behavior of a PTFE/bronze composite under dry and lubricated sliding conditions for different frequencies and loads. An alternating linear motion ball/plane tribometer has been used to characterize friction and wear behavior of the material. Micrographic observation of wear track was taken with the optical microscope. The results showed the good friction behavior of material for low values of loads and frequencies and essentially for 33 N of load with 1 Hz frequency or for 81 N as normal load with 0.75 Hz frequency as well as lubrication improve the wear rate of the PTFE/bronze composite. Under lubrication, load and frequency become inversely proportional to friction coefficients.

scholarly journals Influence of Temperature Effect on the Static and Dynamic Performance of Gas-Lubricated Microbearings

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 716
Author(s):  
Liangliang Li ◽  
Zhufeng Liu ◽  
Chongyu Wang ◽  
Yonghui Xie
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Operating Environment ◽  
Low Friction ◽  
Operating Stability ◽  
Comprehensive Performance ◽  
Different Temperatures ◽  
Dynamic Performances ◽  
The Difference

Gas-lubricated microbearings are widely applied in multiple fields due to their advantages of high-speed, low friction level and other features. The operating environment of microbearings is complex, and the difference of temperature has an important influence on their comprehensive performance. In this investigation, FEM (finite element method) is employed to investigate the static, dynamic and limit characteristics of microbearings lubricated by different kinds of gas at different temperatures. The results show that the rise of temperature leads to the decline of equivalent viscosity of gas, which weakens the load capacity of microbearings, and furthermore, affects the operating stability of microbearings. The dynamic performances of microbearings at different temperatures are very different, and the two dynamic limit characteristics are more sensitive to temperature when it changes.

scholarly journals A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 292 ◽  
Author(s):  
Damiano Padovani ◽  
Søren Ketelsen ◽  
Daniel Hagen ◽  
Lasse Schmidt
Keyword(s):  
Energy Efficiency ◽  
Cost Efficiency ◽  
Tracking Error ◽  
Hydraulic Cylinder ◽  
Position Tracking ◽  
Hydraulic Systems ◽  
Practical Applications ◽  
Hydraulic Cylinders ◽  
External Loads ◽  
Boom Crane

Self-contained electro-hydraulic cylinders have the potential to replace both conventional hydraulic systems and the electro-mechanical counterparts enhancing energy efficiency, plug-and-play installation, and reduced maintenance. Current commercial solutions of this technology are limited and typically tailor-made, whereas the research emphasis is primarily on cost efficiency and power applications below five [kW]. Therefore, there is the need of developing more flexible systems adaptable to multiple applications. This research paper offers a contribution in this regard. It presents an electro-hydraulic self-contained single-rod cylinder with passive load-holding capability, sealed tank, capable of recovering energy, and scalable up to about eighty [kW]. The system implementation on a single-boom crane confirms its feasibility: The position tracking error remains well within ±2 [mm], oscillations are limited, and the overall energy efficiency is about 60 [%] during actuation. Concerning the passive load-holding devices, it is shown that both vented and non-vented pilot-operated check valves achieve the desired functioning and can hold the actuator position without consuming energy. Additional observations about the size and the arrangement of the load-holding valves are also provided. In conclusion, this paper demonstrates that the proposed self-contained cylinder can be successfully extended to several practical applications, especially to those characterized by overrunning external loads and the need of securing the actuator position.

Internal leakage identification of hydraulic cylinder based on intrinsic mode functions with random forest

2019 ◽  
Vol 233 (15) ◽  
pp. 5532-5544 ◽  
Author(s):  
Lin Li ◽  
Yixiang Huang ◽  
Jianfeng Tao ◽  
Chengliang Liu
Keyword(s):  
Random Forest ◽  
Hydraulic Cylinder ◽  
Support Vector ◽  
Hydraulic Systems ◽  
Intrinsic Mode Functions ◽  
Random Forest Algorithm ◽  
Mode Decomposition ◽  
Empirical Mode Decomposition Method ◽  
Hydraulic Cylinders ◽  
Experimental Pressure

Monitoring for internal leakage of hydraulic cylinders is vital to maintain the efficiency and safety of hydraulic systems. An intelligent classifier is proposed to automatically evaluate internal leakage levels based on the newly extracted features and random forest algorithm. The inlet and outlet pressures as well as the pressure differences of two chambers are chosen as the monitoring parameters for leakage identification. The empirical mode decomposition method is used to decompose the raw pressure signals into a series of intrinsic mode functions to obtain the essence in experimental signals. Then, the features extracted from intrinsic mode functions in terms of statistical analysis are formed the input vector to train the leakage detector. The classifier based on random forest is established to categorize internal leakage into proper levels. The accuracy of the internal leakage evaluator is verified by the experimental pressure signals. Moreover, an internal leakage evaluator is established based on the support vector machine algorithm, in which the wavelet transform is applied for feature extraction. The accuracy and efficiency of different classifiers are compared based on leakage experiments. The results show that the classifier trained by the intrinsic mode function features in terms of random forest algorithm may more effectively and accurately identify internal leakage levels of hydraulic cylinders. The leakage evaluator provides probability for online monitoring of the internal leakage of hydraulic cylinders based on the inherent sensors.

Tuning of PID Controller for the Integrating Systems

2014 ◽  
Vol 541-542 ◽  
pp. 1228-1232
Author(s):  
Hong Kai Liao ◽  
Yi Chao Hu ◽  
Jia Luo ◽  
Xi Zhang ◽  
Shi He Chen ◽  
...  
Keyword(s):  
System Identification ◽  
Dynamic Equation ◽  
Physical Meaning ◽  
Pid Controller ◽  
Dynamic Performance ◽  
Setting Time ◽  
Step Response ◽  
Response Information ◽  
Short Setting Time

According to the idea of the system identification, 2-DOF PID based on the desired dynamic equation (DDE-PID) has been improved. The DDE-based PID is applied to the integrating system. This method only needs the step response information of the plant, which is easy to be obtained. According to the physical meaning of parameters, the tuning is also convenient to meet the requirement of the dynamic performance. The simulations show that the method has the low overshoot and the short setting time on the integrating system.

Experimentally Validated Models of O-Ring Seals for Tiny Hydraulic Cylinders

2014 ◽  
Author(s):  
Jicheng Xia ◽  
William K. Durfee
Keyword(s):  
Simulation Models ◽  
Hydraulic Cylinder ◽  
Operating Conditions ◽  
System Level ◽  
Needle Valve ◽  
Hydraulic Systems ◽  
System Level Simulation ◽  
Piston Seal ◽  
Cylinder Piston ◽  
Hydraulic Cylinders

To enable simulation of tiny hydraulic systems, including predicting system efficiency, it is necessary to determine the effect of the hydraulic cylinder piston seal. For tiny cylinders whose bore is less than 10 mm, O-ring seals are convenient. Simplified models for the O-ring were used to describe piston leakage and friction and based on the models, the force and volumetric efficiencies for tiny cylinders were predicted for a range of steady state operating conditions. To validate the models, a test stand was constructed to collect experimental data for 4, 6 and 9 mm bore cylinders, which were in the form of a vertical ram with a single O-ring seal. The ram was fully extended and put under load. A needle valve was then cracked to cause the ram to descend at different speeds. Pressure, load and velocity were recorded and the data used to calculate cylinder efficiencies, which were then compared to model predictions. The model and the experiment showed essentially zero leakage. The experimental force efficiency had good agreement with the model over a range of operating conditions. The study showed that simple O-ring models for tiny hydraulic cylinders suffice for building system level simulation models.

scholarly journals Dynamics Test Research of Bounce of Carrier-Based Aircraft Arresting Hook

2020 ◽  
Vol 10 (24) ◽  
pp. 9033
Author(s):  
Yiming Peng ◽  
Pengpeng Xie ◽  
Xiaohui Wei ◽  
Hong Nie
Keyword(s):  
Test Data ◽  
Dynamic Performance ◽  
Horizontal Velocity ◽  
Test Method ◽  
Velocity Control ◽  
Stroke Length ◽  
Reliable Test ◽  
Test Process ◽  
Sinking Velocity ◽  
Bounce Height

The test of arresting hook bounce is one of the most essential technologies in the design and research of arresting hook. In order to research the dynamic performance of the hook after touchdown and impacting with the deck when the aircraft is arrested, an approach for a certain type of aircraft arresting hook bounce test is proposed in this paper. Solutions to critical technique issues arising in the test process such as aircraft sinking velocity control, aircraft horizontal velocity simulation, and simulation of the performance of the damper are derived and verified by the bounce test of the arresting hook. The bounce height, bounce distance, stroke length of the arresting hook damper after the hook is impacted are measured by the test. The test method proposed can be used for researching the bounce of arresting hook and providing reliable test data for the design of carrier-based aircraft and arresting hook.

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