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Wearable, Soft Robotic Exoskeleton Gloves

The New Dexterity / Open Bionics wearable, affordable, soft exogloves are bionic devices for rehabilitation and human augmentation.

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Body-Powered Exoskeleton Glove Video: https://www.youtube.com/watch?v=sHJ_ZJMQ4vw

Hybrid, Motorized Exoskeleton Glove Video: https://www.youtube.com/watch?v=uHxYOOTGwWw

Robotic Hand exoskeletons have become a popular technological solution for assisting people that suffer from neurological conditions and for enhancing the capabilities of healthy individuals.This class of devices ranges from rigid and complex structures to soft, lightweight, wearable gloves. Despite the progress in the field, most existing devices do not provide the same dexterity as the healthy human hand. This project focuses on a new class of affordable, lightweight, robust, easy-to-operate exoskeleton gloves that can be developed with off-the-shelf materials and rapid prototyping techniques.

According to the World Health Organization (WHO), in many countries, less than 15% of people who require assistive devices and technologies have access to them [1]. Impairment of hand function is one of the most common consequences of neurological and musculoskeletal diseases such as arthritis, Cerebral Palsy, Parkinson's Disease, and stroke [2]. In order to accelerate the rehabilitation process of impaired people, it is important to execute repetitive movements and to try to perform daily tasks [3]. Many robotic devices have been developed to assist patients with limited mobility of the hand during physical therapy or to augment the capabilities of able bodied users [4]. In this project, we propose two compact, wearable, and lightweight assistive exoskeleton gloves for grasping capabilities enhancement. The first device uses a body-powered mechanism while the second device is an underactuated, motorized solution. 

A Body Powered Exoskeleton Glove

The body-powered exo-glove was designed to enhance the grasping capabilities of the user, providing easiness and intuitiveness of operation, with long autonomy, low maintenance, and low cost. The device consists of four different parts: the differential module, the soft glove, the tendon tensioning and adjustment mechanism, and the harness.

The body-powered mechanism allows the transmission of forces from the upper body (e.g., the shoulders) to the index, middle, and thumb fingers through the tendon routing system. Simple body movements can increase the tension of the tendon, actuating the soft exo-glove. 

A Hybrid, Motorized Exoskeleton Glove with Variable Stiffness Joints, Abduction Capabilities, and a Telescopic Extra Thumb

The hybrid exoskeleton glove is a more sophisticated device that is composed of two main systems: the soft exoskeleton glove and the control box. The soft glove system of the device is composed of a thin, high sensibility glove, a tendon-driven system that consists of six artificial tendons, a pneumatic system that consists of four soft actuators.

The operation of the device is straightforward. Using the smartphone app, the user selects the mode desired to control the exoskeleton glove. The user can combine the motions (e.g., full grasp with abducted fingers or tripod grasp with the extra thumb inflated). A flex sensor can be selected to trigger the desired motion when a set bending angle is reached. The information is transmitted to a microcontroller through Bluetooth communication. Then, the microcontroller activates the chosen actuators that are connected to the glove.

The hybrid exoskeleton glove is modular and each of the glove features can be used independently. The abduction chambers, the extra thumb, and the jamming structures can be adapted or removed according to the user's needs.

Designs, Electronics, and Code

All the exoskeleton glove designs, electronics, and code can be found at the following URLs: 

https://github.com/newdexterity/Body-Powered-Exoskeleton-Glove

https://github.com/newdexterity/Hybrid-Exoskeleton-Glove

References

[1] W. H. Organizationet al., “Guidelines for training personnel indeveloping countries for prosthetics and orthotics services,” 2005.

[2] C.-Y. Chu and R. M. Patterson, “Soft robotic devices for hand rehabil-itation and assistance: a narrative review,”Journal of neuroengineeringand rehabilitation, vol. 15, no. 1, p. 9, 2018.

[3] P. S. Lum, C. G. Burgar, P. C. Shor, M. Majmundar, and M. Van derLoos, “Robot-assisted movement training compared with conventionaltherapy techniques for the rehabilitation of upper-limb motor functionafter stroke,”Archives of physical medicine and rehabilitation, vol. 83,no. 7, pp. 952–959, 2002.

[4] P. Maciejasz, J. Eschweiler, K. Gerlach-Hahn, A. Jansen-Troy, andS. Leonhardt, “A survey on robotic devices for upper limb rehabilita-tion,”Journal of neuroengineering and rehabilitation,...

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Bill of Materials - Body Powered Exoglove Glove.PDF

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  • Results: Body Powered Exoskeleton Glove

    New Dexterity07/06/2020 at 00:21 0 comments

    The experiment focused on wearing the devices to evaluate the grasping performance for different everyday objects. The goal of these tests was to verify if the subject was capable of executing different grasping tasks and handle the objects as a healthy individual. When the device is locked in a position of grasping, it is possible to grasp and retain the object without difficulties due to the constant force applied by the differential in the body-powered device. In order to evaluate the amount of force exerted by the devices, two different grasping types were used: the pinch grasp and the power grasp. A Biopac MP36 data acquisition unit (Biopac Systems, Inc., Goleta, California) was used with the SS25LA dynamometer to measure the forces exerted in each scenario. The maximum force obtained for the pinch grasp and power grasp configurations were 8.2 N and 11.6 N, respectively. These pinch and power grasp forces are enough to execute most of the activities of daily living.

    The video below demonstrates the operation of the Body Powered Exoskeleton Glove:

  • Results: Hybrid, Motorized Exoskeleton Glove

    New Dexterity07/06/2020 at 00:17 0 comments

    The second experiment focused on measuring the maximum forces that the device can apply to grasp objects. In this experiment, a Biopac MP36 data acquisition unit (Biopac Systems, Inc., USA) was used with the SS25LA dynamometer to measure the forces exerted during pinch and power grasps. EMG sensors were connected to the forearm of the subject to monitor the muscle activity and guarantee that the subject was not exerting any kind of involuntary forces while grasping the dynamometer. During the experiment, the forearm was placed on the table surface to keep the hand still, and the system was actuated until the torque limit of the motors was reached (3.8 N.m). Six trials were recorded and the maximum force obtained was 19.5 N for power grasps and 12.4 N for pinch grasps. The required force to grasp objects during ADLs does not exceed 15 N, and the pinch forces required to execute most of the daily life tasks are lower than 10.5 N. Thus, the proposed soft robotic glove can exert enough force to stably grasp everyday life objects.

    The video below demonstrates the operation of the Hybrid, Motorized Exoskeleton Glove:

  • Description: Hybrid, Motorized Exoskeleton Glove

    Lucas Gerez07/01/2020 at 23:55 0 comments

    A Hybrid, Motorized Exoskeleton Glove with Variable Stiffness Joints, Abduction Capabilities, and a Telescopic Extra Thumb

    The proposed device is composed of two main systems: the soft exoskeleton glove and the control unit. The control unit is composed of five Dynamixel XM430-W350-T motors, two mini 12V air pumps, one 12V vacuum pump, three solenoid valves, a microcontroller (Robotis OpenCM9.04), and a small circuit to control the air pumps. All six tendons are connected to the pulleys of the motors and run though polyurethane tubes that are used for tendon routing from the control box to the soft glove. The ring and pinky fingers are connected to the same motor since these fingers have a supplementary role during object grasping. 

    The soft glove system of the proposed device is composed of a thin, high sensibility glove, a tendon-driven system that consists of six artificial tendons, a pneumatic system that consists of four soft actuators, and five laminar jamming structures. Five plastic tendon termination structures are stitched onto the fingertips of the glove. Soft anchor points have been added in the glove structure for rerouting the tendon, offering better sensibility of the grasped objects than the rigid anchor points. The tendon-driven system has a tendon connected to each of the fingertip structures and an extra tendon that is connected to the thumb's interphalangeal joint region so as to allow for the execution of the thumb's opposition motion. 

    A tendon-driven solution for the thumb abduction / opposition was chosen over a soft actuator based solution, in order to avoid the obstruction of the region between the index and the thumb, as many different grasps types require the object to be positioned in-between the thumb and the index metacarpophalangeal joints (in the human hand purlicue area). The tendons used in the exoskeleton glove are made out of a low friction braided fiber of high-performance UHMWPE (Ultra-High Molecular Weight Polyethylene) and can withstand forces up to 500 N. The soft actuators are used for two different purposes, to allow for the execution of the abduction / adduction motion of the fingers and to increase grasp stability by activating a telescopic extra thumb that provides grasp support. Three pneumatic chambers have been developed with a "V" shape, and they have been fixed in the region in between the fingers to facilitate the execution of the abduction motion of the fingers. The soft actuator was designed to provide active assistance on finger abduction and passive on finger adduction, once the human hand is naturally adducted. 

    The soft actuators that have been designed are described in the following subsections. At the back of each digit, laminar jamming structures are attached to control the force required to close the digits, to maintain the fingers steady in a desired configuration, and to perform passive extension of the fingers keeping the hand in its natural, zero effort position. The laminar jamming structures can achieve multiple stiffnesses by applying a pressure gradient into the system and relying on the friction between the layers. A single vacuum pump is used to jam the layers of all fingers, enabling variable joint stiffness. A flex sensor was placed at the index finger region and is used to trigger a desired function of the exoskeleton glove when a set bending angle is achieved. 

    The operation of the device is straightforward. Using the smartphone app, the user selects the mode desired to control the exoskeleton glove. The user can combine the motions (e.g., full grasp with abducted fingers or tripod grasp with the extra thumb inflated). A flex sensor can be selected to trigger the desired motion when a set bending angle is reached. The information is transmitted to a microcontroller through Bluetooth communication. Then, the microcontroller activates the chosen actuators that are connected to the glove.

  • Description: Body-Powered Exoskeleton Glove

    Lucas Gerez07/01/2020 at 23:53 0 comments

    A Body Powered Exoskeleton Glove

    The body-powered exo-glove was designed to enhance the grasping capabilities of the user, providing easiness and intuitiveness of operation, with long autonomy, low maintenance, and low cost. The device consists of four different parts: the differential module, the soft glove, the tendon tensioning and adjustment mechanism, and the harness (see Figure below).

    The differential module is a solution for tendon tensioning and even distribution of the grasping forces for the participating fingers. The particular differential mechanism can also be applied to different underactuated prosthetic and orthotic systems. Differentials based on the whiffletree mechanism are widely used in underactuated robot hands. The differential is divided into three different parts: the ratchet clutch, the linear ratchet, and the spring loaded whiffletree mechanism. The ratchet clutch mechanism consists of a ratchet-pulley block for tendon wrapping, a pawl that blocks the rotation of the ratchet in one direction and an elastic element that acts as a spring and pushes the pawl against the ratchet teeth, constraining its motion in the other direction. This mechanism allows a fine and precise adjustment of the tendon length (with a precision of 0.87 mm). The purpose of using this mechanism is to adjust the length of multiple tendons that are routed through the tendon routing tubes and reach the glove. In order to keep the tendon tensioned for a long time, a linear ratchet was used. This mechanism guarantees that the tendon is locked in one position until the mechanism is used again. This mechanism consists of several "V" shape teeth arranged on a row, a lever, a rail, a base, and two springs. The rail is fixed to the differential module through screws and the base can slide on the rail guaranteeing that the motion of the base always happens on a single axis. When the upper cable is pulled, the lever is pushed by a spring against the teeth until the system reaches the desired position. Then, the lever slides into one of the "V" shape teeth locking the mechanism and keeping the tension constant. When the system is re-engaged, the lever is pulled again to the channel and a spring that connects the base to the differential module walls pulls the base until the lever reaches its lowest position and the tendon returns to its initial tension. When the upper cable is pulled again the cycle is reinitialized. The ability to keep the tendons tensioned for long periods of time is of paramount importance for underactuated and body-powered systems, since in other tendon-driven, motorized solutions (e.g., fully-actuated systems) the dedicated motors can adjust the tensioning of the tendons and hold the load while the grasping and manipulation of the objects take place.

    The body-powered mechanism allows the transmission of forces from the upper body (e.g., the shoulders) to the index, middle, and thumb fingers through the tendon routing system. Simple body movements can increase the tension of the tendon, actuating the soft exo-glove. The differential mechanism is used to evenly distribute the forces to the fingers. In order to operate the device, this cable must be accurately tensioned and for this purpose, a tension adjustment mechanism was designed. The mechanism consists of a base where the parts are connected, a lever, a pulley with rectangular teeth, a cover and a retractable reel. After wearing the mechanism, the user presses a lever and the cable on the reel (separate from the tendon) rotates the pulley in the counterclockwise direction wrapping the actuation tendon around it and tensioning it. The plastic cover guarantees that the cable does not slip out of the pulley channel.

    The proposed harness was chosen for the body-powered device because it is comfortable and helps to keep the shoulders aligned. When the right arm or the shoulders move transmitting forces to the main cable, the differential is pulled and the artificial...

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  • Assembly Guide: Hybrid, Motorized Exoskeleton Glove

    Lucas Gerez07/01/2020 at 23:44 0 comments

    The motorized exoskeleton glove consists of three different main parts:

    • Control Unit
    • Robotic Glove
    • Smartphone Interface App

    Control Unit Preparation

    In order to prepare the control unit you will require the following parts. The 3D printed parts are represented by the white parts. The wiring diagram for the electronics are described in the Build Instructions section of this project.


    Robotic Glove Preparation

    The preparation procedure of the robotic glove is similar to the soft glove of the body-powered exoskeleton glove (video below). The fabrication processes of the abduction chambers and the inflatable extra thumb are described in the Build Instructions section of this project. Once the 3D printed parts are stitched on the glove, the soft parts (abduction chambers, jamming structures and the inflatable extra thumb) can be glued (with superglue) on the glove in the positions showed in the picture below.


    Smartphone Interface App Preparation

    In order to control the motorized exoskeleton glove you need to follow the steps below:

    1. Upload the Arduino code to the OpenCM microcontroller (Available in the GitHub repository).
    2. Download the Arduino bluetooth controller app.
    3. Connect your phone to the Bluetooth module and set up the desired commands according to the Arduino code.

  • Assembly Guide: Body-powered Exoskeleton Glove

    Lucas Gerez07/01/2020 at 23:42 0 comments

    The body-powered exoskeleton glove consists of four different main parts: 

    • The differential module
    • The soft glove
    • The tendon tensioning and adjustment mechanism
    • The harness

    In order to build the body-powered exoskeleton glove, the differential module, the soft glove, and the tendon tensioning and adjustment mechanism must be assembled. 

    Differential Module Preparation

    In order to prepare the differential module you will require the following parts. The 3D printed parts are represented by the white parts. The video shows the assembly procedure of the differential module.


    Tendon Tensioning and Adjustment Mechanism Preparation

    In order to prepare the tendon tensioning and adjustment mechanism you will require the following parts. The 3D printed parts are represented by the white parts. The video shows the assembly procedure of the tendon tensioning and adjustment mechanism


    Soft Glove Preparation

    In order to prepare the soft glove you will require the following parts. The 3D printed parts are represented by the white parts. The video shows the assembly procedure of the soft glove.


    Device Assembly

    The video below shows the assembly and testing procedure of the body-exoskeleton glove.

  • Introduction and Motivation

    New Dexterity06/29/2020 at 08:08 0 comments

    The human hand is one of the most complex structures of the human body and Nature’s most versatile and dexterous end-effector. Roboticists have always been inspired by the human hand, and they constantly seek new ways of transferring the human skills to robotic platforms, enabling them to execute complex everyday life tasks that require increased dexterity (e.g., grasping and manipulating objects
    or physically interacting with the environment surrounding them) [1]. According to [2], a small set of representative grasp types accounts for more than 80% of the grasp configurations needed during activities of daily living. The grasps used for such activities include the cylindrical, spherical, tridigital, tip
    (precision grasp), and lateral grasp [3]. All these grasps can be executed with the thumb, index and middle fingers that are the most important ones, while the ring and pinky fingers appear to
    have a supplementary role [4]. Such outcomes have been used for the development of simplified robotic devices, that offer lightweight and affordable solutions without compromising their overall efficiency [5].

    Several studies have focused on the force exertion capabilities of the human hand demonstrating that a healthy individual can generate a maximum grip force that ranges from 300 N to 450 N [6]–[8]. In particular, in [8] the authors conducted experiments to measure the human hand and finger forces in
    different situations and obtained a mean value of 54 N for pinch grasp forces and 43 N for distal fingerpad forces exerted on flat surfaces. However, most of the activities of daily living, do not require the high contact and grasp forces that humans are capable of exerting. According to [9], the necessary forces to manipulate objects found on activities of daily living do not exceed 10 - 15 N.

    The importance of the role of the hand is quite evident in cases of people that suffer from paralysis or stroke. These patients lose some of the capabilities of their hands (e.g., have weaker grasps) and this loss has a tremendous impact on their lives and in some cases on their independence. Over the last
    decades, the field of exoskeletons, exosuits and in general assistive devices has witnessed an explosive growth. Many wearable, assistive devices have been designed to increase the capabilities of the human hand and to provide assistance to their users to execute activities of daily living (ADLs) or to
    regain some of the lost dexterity [10], [11]. These wearable devices can be actuated in different ways (e.g., through cables, linkages, hydraulic systems, and inflatable structures) and can
    have different stiffness, from completely soft to totally rigid.

    In [12], the authors propose a rigid hand exoskeleton that weighs 1.1 kg and can exert a continuous force of 5 N through linkages and motors connected to the hand. In [5], a tendon driven soft robotic exo-glove is proposed, that can generate a pinch force of 20 N and a wrap grasp force of 40 N using a
    battery powered actuation unit that weighs more than 1.5 kg. In [13], the authors present a tendon-driven robotic glove that can apply a maximum grip force of 15 N using a backpack weighing approximately 6 kg. In [14], the authors propose the SEM Glove, a tendon-based assistive glove that can exert up to 4 N in the fingertips using a battery which lasts approximately one day and costs more than 4,000 USD. In [15], the authors present the SSRG glove, a robotic glove used in space suits that employs linear actuators that pull synthetic tendons to increase the grip strength by more than 60 N. In [16], the authors propose an exo-glove that achieves an increase of about 8 N of the distal tip force using a belt pack with a
    battery and a hydraulic system that weighs 3.3 kg and can run for two hours. In [17],...

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View all 7 project logs

  • 1
    3D Printed Parts

    Download and 3D print the STL files from the following GITHUB repositories:

  • 2
    Exoskeleton Controller Circuit

    Connect the cables according to the schematic below. The components required are the following:

    • 2 Mini Air Pumps
    • 2 Solenoid Valves
    • 1 Vacuum Pump
    • 5 Mosfet transistors
    • 5 Resistors (2.2k Ohms)
    • 1 Resistor (10k Ohms)
    • 1 Flex Sensor
    • 1 OpenCM 9.04 Microcontroller
    • 1 Arduino Bluetooth Module (HC-05)
    • 5 Dynamixel XM430-W350-T motors
    • 1 Power distribution board (Robotis SMPS2Dynamixel)
  • 3
    Pneumatic Extra-thumb

    The soft telescopic, extra thumb actuator is based on a urethane rubber (Smooth-On Vytaflex 40) structure designed for grasping assistance during the execution of ADLs. The foldable structure was designed in such a way that it does not influence grasps that do not require an extra thumb due to its small thickness and telescopic behaviour. The rounded shape of the actuator was chosen so as to maximize the size of the objects that could be grasped by employing the actuator. The actuator operates at a pressure of 20 kPa, weighs 18 g, is 10 mm thick, and 80 mm long. 

    The manufacturing process of the inflatable thumb involves the following three molding steps: 

    1. The foldable part of the actuator is fabricated using two molds.
    2. The base layer is fabricated using a third mold, with the base layer being 1.5mm thick and 2 mm smaller than the foldable part in all directions so that they can be molded together.
    3. After both parts are cured, a fourth mold is used to combine the upper part and the base layer part, filling the remaining gaps between the two parts and bonding them together. This technique avoids leakages and deformations in the actuator. Although having a thick elastomer base, a fabric layer can be added to the base to restrict the extension of the actuator along the base axis.

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