Posts Tagged glove

[Abstract] DESC glove: Prototyping a novel wearable device for post-stroke hand rehabilitation


The human brain integrates tactile sensory information from the fingertips to efficiently manipulate objects. Sensory impairments due to neurological disorders, e.g. stroke, largely reduce hand dexterity and the ability to perform daily living activities. Several feedback augmentation techniques have been investigated for rehabilitative purposes with promising outcomes. However, they often require the use of unpractical, expensive, or complex devices. In this work we propose the delivery of vibrotactile feedback based on the Discrete Event-driven Sensory feedback Control (DESC) to promote motor learning in post stroke rehabilitation. For this purpose, we prototyped a novel wearable device, namely the DESC glove. It consisted of a soft glove instrumented with PolyVinylidene Fluoride (PVDF) sensors at the fingertips and eccentric-mass vibration actuators to be worn on the forearm. We proceeded with the characterization of the device, which resulted in promising outcomes. The DESC glove was tested with ten healthy participants subsequently in a pick and lift timed task. The effects of augmented vibrotactile feedback were assessed comparing it to a baseline, consisting of wearing the device unpowered. The results of this pilot study showed a decrease in the time necessary to perform the task, a reduction in the time delay from load force to grip force activation and a diminishing of the grip force applied on the object, which led to a lower breakage rate in the intervention condition. These promising outcomes encourage further experiments with stroke survivors to validate the effectiveness of the device to improve hand dexterity and promote stroke rehabilitation.

via DESC glove | TU Delft Repositories

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[WEB PAGE] Wearable-tech glove translates sign language into speech in real time: The device is inexpensive, flexible and highly durable

Date: June 29, 2020

Summary: Bioengineers have designed a glove-like device that can translate American Sign Language into English speech in real time though a smartphone app. The system includes a pair of gloves with thin, stretchable sensors that run the length of each of the five fingers. These sensors, made from electrically conducting yarns, pick up hand motions and finger placements that stand for individual letters, numbers, words and phrases.


UCLA bioengineers have designed a glove-like device that can translate American Sign Language into English speech in real time though a smartphone app. Their research is published in the journal Nature Electronics.

“Our hope is that this opens up an easy way for people who use sign language to communicate directly with non-signers without needing someone else to translate for them,” said Jun Chen, an assistant professor of bioengineering at the UCLA Samueli School of Engineering and the principal investigator on the research. “In addition, we hope it can help more people learn sign language themselves.”

The system includes a pair of gloves with thin, stretchable sensors that run the length of each of the five fingers. These sensors, made from electrically conducting yarns, pick up hand motions and finger placements that stand for individual letters, numbers, words and phrases.

The device then turns the finger movements into electrical signals, which are sent to a dollar-coin-sized circuit board worn on the wrist. The board transmits those signals wirelessly to a smartphone that translates them into spoken words at the rate of about a one word per second.

The researchers also added adhesive sensors to testers’ faces — in between their eyebrows and on one side of their mouths — to capture facial expressions that are a part of American Sign Language.

Previous wearable systems that offered translation from American Sign Language were limited by bulky and heavy device designs or were uncomfortable to wear, Chen said.

The device developed by the UCLA team is made from lightweight and inexpensive but long-lasting, stretchable polymers. The electronic sensors are also very flexible and inexpensive.

In testing the device, the researchers worked with four people who are deaf and use American Sign Language. The wearers repeated each hand gesture 15 times. A custom machine-learning algorithm turned these gestures into the letters, numbers and words they represented. The system recognized 660 signs, including each letter of the alphabet and numbers 0 through 9.

via Wearable-tech glove translates sign language into speech in real time: The device is inexpensive, flexible and highly durable — ScienceDaily

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[VIDEO] Sensory Electrical Stimulation Glove for Hand Rehab After Stroke – SaeboStim Micro Unboxing Video –YouTube

Unbox the SaeboStim Micro with Dr. Scott Thompson. Boost your hand therapy with this electrical stimulation glove that improves function, weakness, and spasticity.

Want to learn more about electrical stimulation? Check out these FREE resources:………

For more information on the SaeboStim Micro:…

Download your FREE Saebo Exercise Guide here:…

Saebo, Inc. is a medical device company primarily engaged in the discovery, development, and commercialization of affordable and novel clinical solutions designed to improve mobility and function in individuals suffering from neurological and orthopedic conditions. With a vast network of Saebo-trained clinicians spanning six continents, Saebo has helped over 500,000 clients around the globe achieve a new level of independence.

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[NEWS] Researchers at the UI create robotic rehabilitation device to help increase range of motion in the wrist

Assistant professors in the University of Iowa College of Engineering have developed a robotic device to help people increase their range of motion in the wrist using artificial muscles to increase flexibility.


Caterina Lamuta (left) and Venanzio Cichella (right) pose for a portrait in front of their home on Saturday, April 25, 2020. Both mechanical engineering professors at the University of Iowa, the couple is a part of the team working to create a new robotic rehabilitation device.

Two mechanical-engineering assistant professors at the University of Iowa have created a robotic device to give people with limb impairment a wider range of motion. Right now, the pair is focused on the upper limbs and their first prototype increases mobility in the wrist.

The researchers, Venanzio Cichella and Caterina Lamuta, worked together to develop a flexible, lightweight device that can be powered with a small battery. Lamuta and her students are designing and developing the device itself and Cichella and his student are developing the controls of the device.

The device fits over the hand and wrist like a glove, and uses artificial muscles made from carbon fibers which are strong and flexible, Lamuta said. The muscles can lift 12,600 times their weight, and a lot of these artificial muscles can be used to reproduce the arrangement of human muscle. A small battery can be used to power the device, she said.

“So, the idea is to use this more flexible artificial muscle as an alternative for noisy and heavy traditional actuators like electrical motors or hydraulic or pneumatic actuators,” Lamuta said.

The current prototype can perform a few degrees of wrist extension and flexion, she said, but the researchers are working to increase the motion capabilities of the device.

The actuators the researchers are using are very inexpensive, Cichella said. This allows them to not only create a device that is portable and cheap, he said, but allows them to put more of the actuators in the device.

Related: UI researchers say people with spinal-cord injuries can exercise muscles by electrical stimulation

With so many actuators, the question eventually became how to move each of them in order to get the desired action or movement, he said.

Cichella is developing robust control algorithms that can be implemented in the device. He and his student are developing theoretical tools that will help find the optimal controls for the device, Cichella said, and the goal is to implement the algorithms on the side of the device.

Amid spread of the novel coronavirus, some orders for supplies to build sensors have been delayed and working from home makes it so they can’t use larger machinery in the labs, Lamuta said, so they’re going to have delays in their work.

“Part of our research takes place in the lab, which now is the living room of our house and our students’ houses, and also on paper and pen, so it (the challenge) spans both for theoretical and experimental,” Cichella said.

Two UI Ph.D. students and a visiting scholar from Italy are helping with the development of the algorithms and prototypes of the device.

Thilina Weerakkody, a Ph.D. student, and Carlo Greco, the visiting scholar, are working with Lamuta to develop the device itself.

Weerakkody, who has a background in biomedical-device development, has worked on the device, which is similar to an exoskeleton hand, to control it with external feedback. Now, he’s in the process of developing external sensors for the device, he said.

The first prototype only had a single degree of freedom for the wrist, he added.

“Now in the second prototype, we’ve developed a 3D-printed prototype, so in this phase we are trying to elicit two freedom instances,” Weerakkody said.

Greco helped design the muscle used in the glove, choosing the dimension and length of the muscles and studying the schematics of the wrist, he said. The glove was initially able to move up and down in one motion, Greco said, but now they are working to improve movement in the other direction.

“Our testing now is done on a 3D-printed hand with a forearm and we can measure the displacement of the angle of rotation,” Greco said. “…[If] a person does a motion on his own hand and our hand [should] do the same motion in the same [amount of] time.”

Calvin Kielas-Jensen, a Ph.D. student, has worked with Cichella to develop the control algorithms for the device. They’re working with a motion-capture system to give them submillimeter accuracy for the positions of the wrist.

With a background in electrical engineering, Kielas-Jensen has helped with the electronics in the device. He is providing feedback for what kind of sensors should be used and what kind of algorithms should be used to read the data, Kielas-Jensen added.

“It’s a rehabilitation device, so there are plenty of rehabilitation doctors that say that it’s really good to have people do something with their hands,” he said. “It’s one thing to give a patient a stress ball to squeeze, but it gets tired — it gets boring.”

via Researchers at the UI create robotic rehabilitation device to help increase range of motion in the wrist – The Daily Iowan

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[Abstract + References] Design of wearable hand rehabilitation glove with soft hoop-reinforced pneumatic actuator


Traditional hand rehabilitation gloves usually use electrical motor as actuator with disadvantages of heaviness, bulkiness and less compliance. Recently, the soft pneumatic actuator is demonstrated to be more suitable for hand rehabilitation compared to motor because of its inherent compliance, flexibility and safety. In order to design a wearable glove in request of hand rehabilitation, a soft hoop-reinforced pneumatic actuator is presented. By analyzing the influence of its section shape and geometrical parameters on bending performance, the preferred structure of actuator is achieved based on finite element method. An improved hoop-reinforced actuator is designed after the fabrication and initial measurement, and its mathematical model is built in order to quickly obtain the bending angle response when pressurized. A series of experiment about bending performance are implemented to validate the agreement between the finite element, mathematical and experimental results, and the performance improvement of hoop-reinforced actuator. In addition, the designed hand rehabilitation glove is tested by measuring its output force and actual wearing experience. The output force can reach 2.5 to 3 N when the pressure is 200 kPa. The research results indicate that the designed glove with hoop-reinforced actuator can meet the requirements of hand rehabilitation and has prospective application in hand rehabilitation.


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via Design of wearable hand rehabilitation glove with soft hoop-reinforced pneumatic actuator | SpringerLink

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[WEB PAGE] Gripping Aid for Small Items Helpful for Fine-Motor Activities

small item aid and palm pad

The Small Items gripping aid, new from UK-based Active Hands, is designed to enable users with reduced hand function or little or no finger strength to grip small items such as toothbrushes, pens, art items, razors, and makeup brushes with ease.

The gripping aid consists of two parts: a neoprene glove and a Velcro-backed palm pad with clamp. Items clamped in the palm pad can be placed into the glove at any angle, making a wide range of activities accessible, according to the company in a media release.

The clamp mechanism can be easily opened and closed to switch between items. Additional palm pads can also be purchased, enabling users to preload commonly used items and simply switch between the palm pads without having to remove the glove each time. In this way, the aids can promote greater autonomy in many aspects of daily living.

brenda small

“Our mission is to help people achieve more active and inclusive lives – giving them independent access to a variety of activities that would be impossible without Active Hands gripping aids. This new product delivers an effective solution to completing fine-motor activities with reduced grip; something our customers have been asking for,” says Active Hands Director Rob Smith, in the release.

For more information, visit Active Hands.

[Source: Active Hands]

via Gripping Aid for Small Items Helpful for Fine-Motor Activities – Rehab Managment

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[WEB PAGE] Carbonhand — Anatomical Concepts (UK)

Remarkable assistive device for weak grip

Is your grip weaker than it should be due to accident, neurological condition or other illness? You can achieve a stronger grip and more power and endurance which you then can use in a very natural way with the Carbonhand.

The Carbonhand is the latest evolution of the original SEM™ Glove (Soft Extra Muscles for You) and is a smart, wearable assistive aid to improve your “grip ability” when this has been weakened by illness or trauma.

The glove mimics the human hand by using artificial tendons, motors and sensors along with some very clever software. This approach is called “mechatronics” by engineers – but what you will care about is the result – a product that can help you can have the power and endurance in your fingers to get back to a more complete life.

Developed and tested by Bioservo Technologies in Sweden, we are providing assessment, support and sales in the UK

Who Should Use it?

The Carbonhand is a medical device designed to be used by any person with a weak grip.  It is important that the user is able to move their fingers into a grip and extend the fingers again otherwise the glove can’t help.  People may suffer from impaired grip strength for countless reasons, such as muscle and nerve damage, muscle diseases, rheumatism and pain. The Carbonhand strengthens the grip and either compensates where power is lacking or adds extra force and endurance.


 The features of the Carbonhand are easily adjusted via an App

The features of the Carbonhand are easily adjusted via an App

Every year another 60,000 UK stroke survivors will find hand and arm problems limiting their activities.  With the total number of UK stroke survivors over 1 millions persons already, this is a challenge for society as a whole, as well as those affected.

When we also consider that Spinal Cord Injury, Peripheral Nerve Injury, Chronic Pain Syndrome and trauma also affect the hands of thousands, isn’t it about time we had efficient and effective aids and rehabilitation tools? And what about conditions like MS, Rheumatoid arthritis and even the effects of ageing that impact so powerfully on quality of life?

The Carbonhand consists of two main parts:

  • Glove : The main purpose of the glove is to apply the forces generated by the motors in the control unit and to provide the control unit with sensory input from touch sensors at the fingertips. The forces are applied by artificial tendons that are sewn into the glove along the length of the fingers.
  • Control unit : The control unit contains a rechargeable battery power source, one motor for each finger which receives extra force and a micro-controller that controls the SEM™ Glove’s functionality.

Who Should Use it?
The Carbonhand is a medical device designed to be used by any person with a weak grip.  People may suffer from impaired grip strength for countless reasons, such as muscle and nerve damage, muscle diseases, rheumatism and pain. The product strengthens the grip and either compensates where power is lacking or adds extra force and endurance.

 Carbonhand - wear it and forget it

Carbonhand – wear it and forget it

Who Can’t Use it?
The main reason that the product would be ineffective is a complete paralysis of the hand. The sensors in the fingers respond to the user’s intention and ability to apply pressure to the object being gripped. If the person can’t use the fingers at all, the device cannot sense the users intention.

How Do I Try it?
We first must assess if the device is suitable for you. If it is, we will be able to adjust the settings so they suit your current grip issues.  You will wear a snugly fitting glove on your affected hand.  The thumb and two fingers have pressure sensors in the tips that are essential to the glove’s function. A cable bundle connects the glove to a control pack that sits, for example, on your belt. Rechargeable batteries deliver around 8 hours use.  Because the sensors in the glove operate based on touch pressure, you can wear another protective glove over the Carbonhand if necessary for, let’s say, a particular work situation.

UK Pricing is based on a Euro exchange rate with a system package of a control unit, appropriate size glove, batteries, battery charger and manual currently costing around £6,000.  As the price will vary with the exchange rate please check with us for accurate price information.


All UK potential clients will be asked to complete the PRE ASSESSMENT Form here

via Carbonhand — Anatomical Concepts (UK)

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[WEB SITE] Soft Robotic Glove

Soft Robotic Glove

A lightweight robotic glove to assist people suffering from loss of hand motor control to restore their ability to grasp objects independently

The majority of patients with partial or total loss of hand motor abilities, including those suffering from debilitating disorders like muscular dystrophy, amyotrophic lateral sclerosis (ALS), and incomplete spinal cord injury, experience greatly reduced quality of life due to their inability to perform many daily activities. Tasks often taken for granted by the able-bodied become frustrating and nearly impossible feats due to reduced gripping strength and motor control of the hand.


The soft robotic glove under development at the Wyss Institute could one day be an assistive device used for grasping objects, which could help patients suffering from muscular dystrophy, amyotrophic lateral sclerosis (ALS), incomplete spinal cord injury, or other hand impairments to regain some daily independence and control of their environment. Credit: Wyss Institute at Harvard University

Visit site for more —>  Soft Robotic Glove

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[Abstract] A soft robotic glove for hand motion assistance


Soft robotic devices have the potential to be widely used in daily lives for their inherent compliance and adaptability, which result in high safety under unexpected situations. System complexity and requirements are much lower, comparing with conventional rigid-bodied robotic devices, which also result in significantly lower costs. This paper presents a robotic glove by utilizing soft artificial muscles providing redundant degrees of freedom (DOFs) to generate both flexion and extension hand motions for daily grasping and manipulation tasks. Different with the existing devices, to minimize the weight applied to the user’s hands, pneumatic soft actuators were located on the fore arm and drive each finger via cable-transmission mechanisms. This actuation mechanism brings extra adaptability, motion smoothness, and user safety to the system. This design makes wearable robotic gloves more light-weight and user-friendly. Both theoretical and experimental analyses were conducted to explore the mechanical properties of pneumatic soft actuators. In addition, the fingertip trajectories were analyzed using Finite Element Methods, and a series of experiments were conducted evaluating both the technical and practical performances of the proposed glove.


I. Introduction

Glove-type wearable robotic devices are developed to assist people with impaired hand functions both in their activities of daily living (ADLs) and in rehabilitation [1]–[12]. Most of such wearable robotic devices generate hand movements with linkage systems actuated by electrical motors which usually are heavy and inconvenient for using. Moreover, because of the human hand variation, most wearable robotic devices require customization in order to fulfill the geometrical fitting requirements between the exoskeleton device and the human hand joints. Approximating the high dexterity of human hands usually requires high complexity in both the mechanical and controller structures of the robotic systems, and hence also results in high costs for most users.

via A soft robotic glove for hand motion assistance – IEEE Conference Publication

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[ARTICLE] Design and Preliminary Feasibility Study of a Soft Robotic Glove for Hand Function Assistance in Stroke Survivors – Full Text

Various robotic exoskeletons have been proposed for hand function assistance during activities of daily living (ADL) of stroke survivors. However, traditional exoskeletons involve the use of complex rigid systems that impede the natural movement of joints, and thus reduce the wearability and cause discomfort to the user. The objective of this paper is to design and evaluate a soft robotic glove that is able to provide hand function assistance using fabric-reinforced soft pneumatic actuators. These actuators are made of silicone rubber which has an elastic modulus similar to human tissues. Thus, they are intrinsically soft and compliant. Upon air pressurization, they are able to support finger range of motion (ROM) and generate the desired actuation of the finger joints. In this work, the soft actuators were characterized in terms of their blocked tip force, normal and frictional grip force outputs. Combining the soft actuators and flexible textile materials, a soft robotic glove was developed for grasping assistance during ADL for stroke survivors. The glove was evaluated on five healthy participants for its assisted ROM and grip strength. Pilot test was performed in two stroke survivors to evaluate the efficacy of the glove in assisting functional grasping activities. Our results demonstrated that the actuators designed in this study could generate desired force output at a low air pressure. The glove had a high kinematic transparency and did not affect the active ROM of the finger joints when it was being worn by the participants. With the assistance of the glove, the participants were able to perform grasping actions with sufficient assisted ROM and grip strength, without any voluntary effort. Additionally, pilot test on stroke survivors demonstrated that the patient’s grasping performance improved with the presence and assistance of the glove. Patient feedback questionnaires also showed high level of patient satisfaction and comfort. In conclusion, this paper has demonstrated the possibility of using soft wearable exoskeletons that are more wearable, lightweight, and suitable to be used on a daily basis for hand function assistance of stroke survivors during activities of daily living.


The ability to perform basic activities of daily living (ADL) impacts a person’s quality of life and independence (Katz, 1983Andersen et al., 2004). However, an individual’s independence to perform ADLs is jeopardized due to hand motor impairments, which can be observed in patients with neurological disorders such as stroke. In order to improve hand motor functions in terms of strength and range of motion (ROM) (Kutner et al., 2010), stroke survivors undergo rehabilitation programs comprising repetitive practice of simulated ADL tasks (Michaelsen et al., 2006). Normally, patients undergo rehabilitation exercises in a specialized rehabilitation center under the guidance of physiotherapists or occupational therapists. However, due to increasing patient population, it is foreseen that there will be a shortage of physiotherapists to assist in the rehabilitative process. Thus, there will be comparatively less therapy time, which will eventually lead to a slower recovery process for the patients. Over the past decade, technological developments in robotics have facilitated the rehabilitative process and have shown potential to assist patients in their daily life (Maciejasz et al., 2014). One example of such a device is the hand exoskeleton, which is secured around the hand to guide and assist the movement of the encompassed joints. However, due to the complexity of the hand, designing a hand exoskeleton remains a challenging task.

Traditional hand exoskeletons involve the use of rigid linkage-based mechanisms. In this kind of mechanism, rigid components, such as linear actuators, rotary motors, racks, and pinions as well as rigid linkages are normally involved (Worsnopp et al., 2007Rotella et al., 2009Martinez et al., 2010). To assist hand movements that have high degrees of freedom (DOFs), traditional exoskeletons can be incorporated with a substantial number of actuators to achieve the requirement. However, this means that their application is limited due to the increasing bulkiness for higher DOFs. Therefore, these devices are normally restricted in clinical settings and not suitable for performing home therapy. Additionally, their rigidity, weight and constraint on the non-actuated DOFs of the joints pose complications. As a result, the level of comfort and safety of patients is reduced. In view of this, there is an apparent need for the development of exoskeletons that may be used in both clinical and home settings. A lightweight and wearable exoskeleton may allow patients to bring back home to continue daily therapy or to serve as an assistive device for the ADLs.

The development of wearable robotic exoskeletons serves to provide an alternative approach toward addressing this need. Instead of using rigid linkage as an interface between the hand and the actuators, wearable exoskeletons typically utilize flexible materials such as fabric (Sasaki et al., 2004Yap et al., 2016a) and polymer (Kang et al., 2016), driven by compliant actuators such as cables (Sangwook et al., 2014Xiloyannis et al., 2016) and soft inflatable actuators (Polygerinos et al., 2015dYap et al., 2016c). Therefore, they are more compliant and lightweight compared to the rigid linkage-based mechanism. Cable-driven based exoskeletons involve the use of cables that are connected to actuators in the form of electrical motors situated away from the hand (Nilsson et al., 2012Ying and Agrawal, 2012Sangwook et al., 2014Varalta et al., 2014). By providing actuations on both dorsal and palmar sides of the hand, bi-directional cable-driven movements are possible (Kang et al., 2016). These cables mimic the capability of the tendons of the human hand and they are able to transmit the required pulling force to induce finger flexion and extension. However, the friction of the cable, derailment of the tendon, and inaccurate routing of the cable due to different hand dimensions can affect the efficiency of force transmission in the system.

On the other hand, examples of the soft inflatable actuators are McKibben type muscles (Feifei et al., 2006Tadano et al., 2010), sheet-like rubber muscles (Sasaki et al., 2004Kadowaki et al., 2011), and soft elastomeric actuators (Polygerinos et al., 2015b,cYap et al., 2015); amongst which, soft elastomeric actuators have drawn increasing research interest due to their high compliance (Martinez et al., 2013). This approach typically embeds pneumatic chamber networks in elastomeric constructs to achieve different desired motions with pressurized air or water (Martinez et al., 2012). Soft elastomeric actuators are highly customizable. They are able to achieve multiple DOFs and complex motions with a single input, such as fluid pressurization. The design of a wearable hand exoskeleton that utilizes soft elastomeric actuators is usually simple and does not require precise routing for actuation, compared to the cable-driven mechanism. Thus, the design reduces the possibility of misalignment and the setup time. These properties allow the development of hand exoskeletons that are more compliant and wearable, with the ability to provide safe human-robot interaction. Additionally, several studies have demonstrated that compactness and ease of use of an assistive device critically affect its user acceptance (Scherer et al., 20052007). Thus, these exoskeletons provide a greater chance of user acceptance.

Table 1 summarizes the-state-of-art of soft robotic assistive glove driven by inflatable actuators. Several pioneer studies on inflatable assistive glove have been conducted by Sasaki et al. (2004)Kadowaki et al. (2011) and Polygerinos et al. (2015a,b,c). Sasaki et al. have developed a pneumatically actuated power assist glove that utilizes sheet-like curved rubber muscle for hand grasping applications. Polygerinos et al. have designed a hydraulically actuated grip glove that utilizes fiber-reinforced elastomeric actuators that can be mechanically programmed to generate complex motion paths similar to the kinematics of the human finger and thumb. Fiber reinforcement has been proved to be an effective method to constrain the undesired radial expansion of the actuators that does not contribute to effective motion during pressurization. However, this method limits the bending capability of the actuators (Figure S1); as a result, higher pressure is needed to achieve desired bending.

Table 1. Hand assistive exoskeletons driven by inflatable actuators.

This paper presents the design and preliminary feasibility study of a soft robotic glove that utilizes fabric-reinforced soft pneumatic actuators. The intended use of the device is to support the functional tasks during ADLs, such as grasping, for stroke survivors. The objectives of this study were to characterize the soft actuators in terms of their force output and to evaluate the performance of the glove with healthy participants and stroke survivors. The glove was evaluated on five healthy participants in order to determine the ROM of individual finger joints and grip strength achieved with the assistance of the glove. Pilot testing with two stroke survivors was conducted to evaluate the feasibility of the glove in providing grasping assistance for ADL tasks. We hypothesized that with the assistance of the glove, the grasping performance of stroke patients improved.

Specific contributions of this work are listed as follows:

(a) Presented fabric-reinforcement as an alternative method to reinforce soft actuators, which enhanced the bending capability and reduced the required operating pressure of the actuators,

(b) Utilized the inherence compliance of soft actuators and allowed the actuators to achieve multiple motions to support ROM of the human fingers,

(c) Integrated elastic fabric with soft actuators to enhance the extension force for finger extension,

(d) Designed and characterized a soft robotic glove using fabric-reinforced soft actuators with the combination of textile materials, and

(e) Conducted pilot tests with stroke survivors to evaluate the feasibility of the glove in providing functional assistance for ADL tasks.

Design Requirements and Rationale

The design requirements of the glove presented in this paper are similar to those presented by Polygerinos et al. (2015a,b,c) in terms of design considerations, force requirements, and control requirements. For design considerations, weight is the most important design criterion when designing a hand exoskeleton. Previous studies have identified the threshold for acceptable weight of device on the hand, which is in the range of 400–500 g (Aubin et al., 2013Gasser and Goldfarb, 2015). Cable-driven, hydraulic, and pneumatic driven mechanisms are found to be suitable options to meet the criteria. To develop a fully portable system for practical use in home setting, reduction in the weight of the glove as well as the control system is required. The total weight of the control system should not exceed 3 kg (Polygerinos et al., 2015a,b,c). In this work, the criteria for the weight of the glove and control system are defined as: (a) the weight of the glove should be <200 g, and (b) the weight of the control system should be <1.5 kg.

Considering the weight requirement, hydraulic systems are not ideal for this application, as the requirement of a water reservoir for hydraulic control systems and actuation of the actuators with pressurized water will add extra weight to the hand. The second consideration is that the hand exoskeleton should allow fast setup time. Therefore, it is preferable for the hand exoskeleton to fit the hand anatomy rapidly without precise joint alignment. Compared to cable-driven mechanisms, soft pneumatic actuators are found to be more suitable as they allow rapid customization to different finger length. Additionally, they do not require precise joint alignment and cable routing for actuation as the attachment of the soft pneumatic actuators on the glove is usually simple. Therefore, in this work, pneumatic mechanisms were selected. Using pneumatic mechanism, Connelly et al. and Thielbar et al. have developed a pneumatically actuated glove, PneuGlove that is able to provide active extension assistance to each finger while allowing the wearer to flex the finger voluntarily (Connelly et al., 2010Thielbar et al., 2014). The device consists of five air bladders on the palmar side of the glove. Inflation of the air bladders due to air pressurization created an extension force that extends the fingers. However, due to the placement of the air bladders on the palmar side, grasping activities such as palmar and pincer grasps were more difficult. Additionally, this device is limited to stroke survivors who are able to flex their fingers voluntarily.

In this work, the soft robotic glove is designed to provide functional grasping assistance for stroke survivors with muscle weakness and impairments in grasping by promoting finger flexion. While the stroke survivors still preserve the ability to modulate grip force within their limited force range, the grip release (i.e., hand opening) is normally prolonged (Lindberg et al., 2012). Therefore, the glove should assist with grip release by allowing passive finger extension via reinforced elastic components, similar to Saeboflex (Farrell et al., 2007) and HandSOME (Brokaw et al., 2011). The elastic components of these devices pull the fingers to the open hand state due to increased tension during finger flexion. Additionally, the glove should generate the grasping force required to manipulate and counteract the weight of the objects of daily living, which are typically below 1.07 kg (Smaby et al., 2004). Additionally, the actuators in the glove should be controlled individually in order to achieve different grasping configurations required in simulated ADL tasks, such as palmar grasp, pincer grasp, and tripod pinch. For the speed of actuation, the glove should reach full grasping motion in <4 s during simulated ADL tasks and rehabilitation training.

For the actuators, we have recently developed a new type of soft fabric-reinforced pneumatic actuator with a corrugated top fabric layer (Yap et al., 2016a) that could minimize the excessive budging and provide better bending capability compared to fiber-reinforced soft actuators developed in previous studies (Polygerinos et al., 2015c,d). This corrugated top fabric layer allows a small initial radial expansion to initiate bending and then constrains further undesired radial expansion (Figure 1). The detailed comparison of the fiber-reinforced actuators and fabric-reinforced actuators can be found in the Supplementary Material.



Figure 1. (A) A fabric-reinforced soft actuators with a corrugated fabric layer and an elastic fabric later [Actuator thickness, T= 12 mm, and length, L = 160 mm (Thumb), 170 mm (Little Finger), 180 mm (Index & Ring Fingers), 185 mm (Middle Finger)]. (B) Upon air pressurization, the corrugated fabric layer unfolds and expands due to the inflation of the embedded pneumatic chamber. Radial budging is constrained when the corrugated fabric layer unfolds fully. The elastic fabric elongates during air pressurization and stores elastic energy. The actuator achieves bending and extending motions at the same time. (C) A bending motion is preferred at the finger joints (II, IV, VI). An extending motion is preferred over the bending motion at the finger segments (I, III, V) and the opisthenar (VII).

Continue —>  Frontiers | Design and Preliminary Feasibility Study of a Soft Robotic Glove for Hand Function Assistance in Stroke Survivors | Neuroscience

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