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.

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.

On Integration of Additive Manufacturing During the Design and Development of a Rehabilitation Robot: A Case Study

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Kaci E. Madden ◽  
Ashish D. Deshpande
Keyword(s):  
Additive Manufacturing ◽  
Neurological Disorders ◽  
Development Process ◽  
Mechanical Design ◽  
Rehabilitation Robotics ◽  
Critical Design ◽  
Rehabilitation Robots ◽  
Time Optimization ◽  
Hand Exoskeleton

The field of rehabilitation robotics has emerged to address the growing desire to improve therapy modalities after neurological disorders, such as a stroke. For rehabilitation robots to be successful as clinical devices, a number of mechanical design challenges must be addressed, including ergonomic interactions, weight and size minimization, and cost–time optimization. We present additive manufacturing (AM) as a compelling solution to these challenges by demonstrating how the integration of AM into the development process of a hand exoskeleton leads to critical design improvements and substantially reduces prototyping cost and time.

scholarly journals Control Strategies and Artificial Intelligence in Rehabilitation Robotics

AI Magazine ◽  
2015 ◽  
Vol 36 (4) ◽  
pp. 23-33 ◽  
Author(s):  
Domen Novak ◽  
Robert Riener
Keyword(s):  
Artificial Intelligence ◽  
Control Strategies ◽  
Rehabilitation Robotics ◽  
Control Algorithms ◽  
Assistive Robots ◽  
Socially Assistive Robots ◽  
Rehabilitation Robots ◽  
Exercise Adaptation ◽  
Dominant Paradigm ◽  
Do So

Rehabilitation robots physically support and guide a patient's limb during motor therapy, but require sophisticated control algorithms and artificial intelligence to do so. This article provides an overview of the state of the art in this area. It begins with the dominant paradigm of assistive control, from impedance-based cooperative controller through electromyography and intention estimation. It then covers challenge-based algorithms, which provide more difficult and complex tasks for the patient to perform through resistive control and error augmentation. Furthermore, it describes exercise adaptation algorithms that change the overall exercise intensity based on the patient's performance or physiological responses, as well as socially assistive robots that provide only verbal and visual guidance. The article concludes with a discussion of the current challenges in rehabilitation robot software: evaluating existing control strategies in a clinical setting as well as increasing the robot's autonomy using entirely new artificial intelligence techniques.

Development of Advanced Mechanical System for 3-D Full-Scale Earthquake Testing Facility

2002 ◽  
Author(s):  
Shintaro Watanabe ◽  
Kazuhiko Maekawa ◽  
Yasuyuki Tanaka ◽  
Akesi Koike ◽  
Yukiharu Yamasaki
Keyword(s):  
Full Scale ◽  
Shaking Table ◽  
Test Facility ◽  
Wave Form ◽  
Low Friction ◽  
3 Dimensional ◽  
Large Size ◽  
Testing Facility ◽  
Ring Seal ◽  
Hyogo Prefecture

The largest 3-dimensional vibration test facility is being constructed in Japan’s Hyogo Prefecture. The objective of this facility is to assist the investigation on the process of the collapsing phenomena of a full-scale structure in an earthquake. This facility has a large size shaking table (15 m × 20 m), with a payload of 12 MN. Actuators are connected to the shaking table via 3-D links. In order to reduce the distortion of accelaration wave form, low friction tribo-elements are employed in the actuators; a hydrostatic bearing for rod supports, a pressure balanced seal for pistons, a floating ring seal for 3-dimensional joints. Since these elements are large and heavily loaded, the deformation of them are relatively large compared to the oil film gap in the elements and make design difficult. The paper exhibits the tribological performance of the actuators and joints.

scholarly journals Interoperability of RehabRobo-Onto

2017 ◽  
Author(s):  
Zeynep Dogmus ◽  
Volkan Patoglu ◽  
Esra Erdem
Keyword(s):  
Developed Countries ◽  
Rehabilitation Robotics ◽  
Physical Rehabilitation ◽  
Disease Ontology ◽  
Permanent Disability ◽  
Knowledge Resources ◽  
Rehabilitation Robots ◽  
Physical Burden ◽  
Neurological Injuries ◽  
The Cost

The leading cause of permanent disability in developed countries is due to neurological injuries, such as stroke. While physical rehabilitation therapy is indispensable for treating neurological disabilities, repetitive and high intensity therapies place high physical burden on the therapist and significantly increase the cost of such treatments. These challenges have led to design and development of various robot-assisted rehabilitation devices. As the number of rehabilitation robots increase, the information about them also increases, but most of the time in unstructured forms (e.g., as text in publications), which make it harder to access the requested knowledge and reason about it. Also, due to interdisciplinary nature of rehabilitation robotics, sometimes requested knowledge requires integration of further knowledge from related disciplines (e.g., physical medicine). Motivated by these challenges, we have designed and developed the first formal rehabilitation robotics ontology, called RehabRobo-Onto, to represent knowledge about rehabilitation robotics in the structured form of OWL. In this abstract, we continue our studies on RehabRobo-Onto by discussing its interoperability with the available knowledge resources, such as Foundational Model of Anatomy (FMA) and Human Disease Ontology (DO), towards personalized physical rehabilitation therapies.

scholarly journals EXPERIENCES ON THE LOW PRESSURE WATER HYDRAULIC SYSTEMS

1999 ◽  
Vol 1999 (4) ◽  
pp. 357-363 ◽  
Author(s):  
Jussi AALTONEN ◽  
Kari KOSKINEN ◽  
Matti VILENIUS ◽  
Pekka KUNTTU
Keyword(s):  
Low Pressure ◽  
Hydraulic Systems ◽  
Pressure Water ◽  
Water Hydraulic

scholarly journals Professionals' Views and Experiences of Using Rehabilitation Robotics With Stroke Survivors: A Mixed Methods Survey

2021 ◽  
Vol 3 ◽  
Author(s):  
Lutong Li ◽  
Sarah Tyson ◽  
Andrew Weightman
Keyword(s):  
Stroke Rehabilitation ◽  
Rehabilitation Robotics ◽  
Ease Of Use ◽  
Online Questionnaire ◽  
Patient Factors ◽  
Rehabilitation Robots ◽  
Home Based ◽  
Functional Software ◽  
And Storage ◽  
Staff Workload

Objective: To understand the reason for low implementation of clinical and home-based rehabilitation robots and their potential.Design: Online questionnaire (November 2020 and February 2021).Subjects: A total of 100 professionals in stroke rehabilitation area were involved (Physiotherapists n = 62, Occupation therapists n = 35).Interventions: Not applicable.Main Measures: Descriptive statistics and thematic content analysis were used to analyze the responses: 1. Participants' details, 2. Professionals' views and experience of using clinical rehabilitation robots, 3. Professionals' expectation and concerns of using home-based rehabilitation robots.Results: Of 100 responses, 37 had experience of rehabilitation robots. Professionals reported that patients enjoyed using them and they increased accessibility, autonomy, and convenience especially when used at home. The main emergent themes were: “aims and objectives for rehabilitation robotics,” “requirements” (functional, software, and safety), “cost,” “patient factors” (contraindications, cautions, and concerns), and “staff issues” (concerns and benefits). The main benefits of rehabilitation robots were that they provided greater choice for therapy, increased the amount/intensity of treatment, and greater motivation to practice. Professionals perceived logistical issues (ease of use, transport, and storage), cost and limited adaptability to patients' needs to be significant barriers to tier use, whilst acknowledging they can reduce staff workload to a certain extent.Conclusion: The main reported benefit of rehabilitation robots were they increased the amount of therapy and practice after stroke. Ease of use and adaptability are the key requirements. High cost and staffing resources were the main barriers.

A New Approach to Sizing Low Pressure Systems

2017 ◽  
Author(s):  
Nathan Keller ◽  
Monika Ivantysynova
Keyword(s):  
Hydraulic System ◽  
Low Pressure ◽  
Hydraulic Systems ◽  
Pressure System ◽  
Hydraulic Unit ◽  
Duty Cycles ◽  
Low Pressure System ◽  
Hydrostatic Transmissions ◽  
Cylinder Flow ◽  
Low Pressure Systems

Closed-circuit hydraulic systems, like hydrostatic transmissions and Displacement Controlled (DC) architecture systems, require an integrated low-pressure system. These low-pressure systems provide several important functions to the hydraulic system. They prevent cavitation, provide cooling flow through the cooler, replenish the hydraulic system with cool oil, assist in the oil filtration process, provide pressure to the hydraulic unit control systems and, in the case of DC systems with differential cylinders, balance the unequal cylinder flow. Traditionally, the sizing of low-pressure systems is accomplished using a static sizing approach. In this approach, a constant efficiency of the hydraulic units is assumed, and the system is operating at a maximum power condition. The result is often an oversized charge pump and accumulator, if one is present. A dynamic sizing method has been developed using MATLAB/Simulink® with high fidelity empirical loss models for hydraulic displacement machines. Using realistic duty cycles for hydraulic systems and measured data, the low-pressure system can be accurately sized. Dynamically sizing low-pressure systems reduce parasitic losses on the prime mover because of smaller pump sizes, thus freeing power to be used elsewhere. Another concept presented in this work is the possibility of isolating the hydraulic unit control pressure supply and the low-pressure system. Realistic examples have been simulated to demonstrate the power savings of dynamically sizing low-pressure systems.

Analytical Modelling of Rolamite Mechanism Made of Shape Memory Alloy for Constant Force Actuators

2015 ◽  
Author(s):  
Andrea Spaggiari ◽  
Eugenio Dragoni
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Metal Strip ◽  
Force Generation ◽  
Constant Force ◽  
Low Friction ◽  
Actuation Force ◽  
Long Stroke ◽  
Force Generator ◽  
Roll Back

This paper analyses the Rolamite architecture exploiting shape memory alloys as power element to obtain a solid state actuator. The Rolamite mechanism was discovered in the late sixties, initially as precision and low friction linear bearing. The most common Rolamite configuration consists of a flexible thin metal strip and two rollers mounted between two fixed parallel guide surfaces. The system can roll back and forth without slipping guided by the plates along its so called sensing axis. The system presents another relevant advantage in addition to low friction coefficient, which is the possibility to provide force generation in a quite simple way. In the original literature works the force was provided thanks to cutouts of various shape in the strip, though this method does not allow the Rolamite to be considered a proper actuator, but only a force generator. In this paper we developed the idea of exploiting the shape memory alloy as Rolamite power element and therefore to use the shape memory effect to change the elastic properties of the strip and to provide the actuation force. The mechanical analyses and the equations where the martensite-austenite transition is modelled in a simplified way, show that this application is feasible, mainly thanks to the initial precurvature of the SMA strip. The discussion of the results highlights some important merits of this architecture such as long stroke, constant force and compactness.

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