WO2016198602A1

WO2016198602A1 - Haptic feedback system for rehabilitation purposes

Info

Publication number: WO2016198602A1
Application number: PCT/EP2016/063300
Authority: WO
Inventors: Ernst Jan BOS; Reinier Ansgar HILL
Original assignee: Hapticore Holding BV
Current assignee: Hapticore Holding BV
Priority date: 2015-06-12
Filing date: 2016-06-10
Publication date: 2016-12-15
Anticipated expiration: 2017-12-12

Abstract

The present invention describes a haptic feedback system comprising a container enclosing a Magneto-Rheological Fluid (MRF), or a ferrofluid,and a solenoid,or enclosing only vacuum,wherein in the case of a MRF or ferrofluid this responds to a magnetic field created by the solenoid, said haptic feedback system also comprising a glove or sock with one or more sensors, a feedback system involving a software algorithm, and a computer unit with a display screen.

Description

HAPTIC FEEDBACK SYSTEM FOR REHABILITATION PURPOSES

Field of the invention

The present invention relates to a haptic feedback system intended for rehabilitation, such as hand rehabilitation, or other application such as e.g. simulation and/or training or robotic control, for instance in surgery, or in medical or therapeutic diagnostics.

Technical Background

There are known haptic feedback systems intended for hand

rehabilitation. For instance in US 5,693,004 there is described a controllable fluid device for rehabilitation of an injured or weakened complex appendages such as the hands and feet. The controllable fluid device includes a reservoir which contains a sufficient amount of controllable fluid such as a Magneto- rheological fluid. Furthermore, in the article Electromagnetic Modeling and Design of Haptic Interface Prototypes Based on Magnetorheological Fluids (Rizzo et al.) there is described the design and implementation of innovative haptic interfaces based on Magnetorheological fluids (MRFs). In the article there is disclosed 2-D and quasi-3-D MRF-based devices capable of suitably energizing fluids with a magnetic field in order to build shapes that can be directly felt and explored by hand. This article, and other similar are further disclosed below.

One aim of the present invention is to provide an improved haptic feedback system intended for rehabilitation, such as hand or foot

rehabilitation.

Summary of the invention

The latter stated purpose above is achieved by a haptic feedback system comprising a container enclosing a Magneto-Rheological Fluid (MRF), or a ferrofluid, and a solenoid, or enclosing only vacuum, wherein in the case of a MRF or ferrofluid this responds to a magnetic field created by the solenoid, said haptic feedback system also comprising a glove or sock with one or more sensors, a feedback system involving a software algorithm, and a computer unit with a display screen. When being compared with the documents disclosed above there are some important basic differences. In the article Electromagnetic Modeling and Design of Haptic Interface Prototypes Based on Magnetorheological Fluids (Rizzo et al.) the idea is to create an object inside of the MRF liquid by applying a directed magnetic field. According to the present invention, however, the system and method is directed to solidifying the MRF or ferrofluid liquid and use the visual interface to create the illusion of an object. This approach is very simple and viable in comparison to the methods disclosed in the documents above. Since the visual stimulus is leading, a very convincing haptic feedback can be created. The viscosity of the liquid is a known factor at various current settings, so the force applied by the fingers can be calculated in a very precise manner. This is of great importance for one primary application of the present invention, namely hand rehabilitation and diagnostics.

According to one specific embodiment, the container encloses a

Magneto-Rheological Fluid (MRF) or a ferrofluid and a solenoid. A MRF is different from a ferrofluid as the latter has smaller particles. MR fluid particles are primarily on the micrometre-scale and are too dense for Brownian motion to keep them suspended (in the lower density carrier fluid). Ferrofluid particles, however, are primarily nanoparticles that are suspended by

Brownian motion and generally will not settle under normal conditions.

Moreover, it should be noted that all types of MRFs or ferrofluids are possible according to the present invention. As an example, dimorphic

magnetorheological fluids, which e.g. are mixture of particles and nanowires, are totally possible to use according to the present invention.

It should further be said that the present invention also embodies only using vacuum in the container. This is also possible according to the present invention to provide a glove or sock of which the size is possible to alter only by use of a negative pressure or the vacuum.

The approach according to the present invention, regardless of involving MRF or ferrofluid, or only vacuum, is further developed below.

There are reports etc. which disclose the use of MRFs. Some examples are: "Electromagetic Modeling and Design of Haptic Interface Prototypes Based on Magnetorheological Fluids", IEEE Transactions on Magnetics, September 2007, vol. 43, no 9, pages 3586-3599 (Rizzo et al.), "Advanced modelling and preliminary psychophysical experiments for a freehand haptic device", Intelligent Robots and Systems IEEE/RSJ International Conference, October 2006, pages 1558-1563 (Sgambelluri et al.), "A

Permanent-Magnet Exciter for Magneto-Rheological Fluid-Based Haptic Interfaces", IEEE Transactions on Magnetics, April 2013, vol. 49, no 4, pages 1390-1401 (Rizzo et al.), and "A force feedback glove based on

Magnetorheological Fluid: Preliminary design issues" (Cassar et al.),

Proceedings of the Mediterranean Electrotechnical Conference - MELECON, April 2010, pages 618-623. All these articles refer to a system operating by selectively diverting magnetic fields to create physical objects. For instances, from "Electromagetic Modeling and Design of Haptic Interface Prototypes Based on Magnetorheological Fluids", IEEE Transactions on Magnetics, September 2007, vol. 43, no 9, pages 3586-3599, this is stated and clear from the expression of "We developed 2-D and quasi-3-D MRF-based devices capable of suitably energizing fluids with a magnetic field in order to build shapes that can be directly felt and explored by hand. We obtained this effect by properly creating a distribution of a magnetic field over time and space inducing the fluid to assume a desired shape and compliance." The present invention, however, is directed to using the speed of the sensor feedback system to create virtual objects based on coordinates, not on their actual shape. As such, the present invention is not directed to building actual shapes but instead solidifying the complete liquid when e.g. the hand reaches the specific coordinates of a virtual object. This is a very clear difference when comparing the present invention with the articles disclosed above. Brief description of the drawing

In fig. 1 there is shown one embodiment according to the present invention. As may be seen, the system according to the present invention comprises a container enclosing a Magneto-Rheological Fluid (MRF), or ferrofluid, and a solenoid with a coil. The glove has several position sensors. In this case a virtual sphere is also shown. Moreover, some other specific units according to this embodiment are also shown in fig. 1. Specific embodiments of the invention

Below, some specific embodiments of the present invention are disclosed and discussed.

According to one embodiment of the present invention, the container comprises a membrane which by means of force affects the resulting vacuum. By applying an outward force to the membrane this allows the user to adjust the size of the glove (or sock) by means of the resulting vacuum, allowing easy entry and a snug fit. As understood from above, the container is of course open in the end intended for the user to enter with his or her hand in the glove. The glove is an integrated part of the container and as such forms a closed system. The vacuum is applied to this closed system by expanding a membrane enlarging the glove. The user enters the glove and the vacuum can be reduced for optimal fit. This approach can also be used to measure the volume of the hand.

As understood from above, the system according to the present invention comprises a glove when intended for hand rehabilitation. When intended for other type of rehabilitation then this specific unit may be of another type adjusted to fit the body part of the user intended to be inserted. For instance, when using the system for foot/ankle rehabilitation, then a sock may be used instead of a glove.

In relation to the above description it may further be said that the position of the glove (or sock) and as such the hand (or foot) of the user is the input to the system of the present invention. This is in general an important aspect of the methodology according to the present invention.

According to one embodiment of the present invention, vacuum is used and the glove entry is on one side of the system. According to yet another embodiment, the system comprises a cylinder possible to access on both sides, which enables to train the left hand and the right hand separately in one and the same unit. By compressing one glove, the other may be deflated and vice versa.

Moreover, according to one specific embodiment of the present invention the size of the glove or sock is possible to alter. Furthermore, according to yet another specific embodiment of the present invention, the container encloses vacuum, and wherein the vacuum enables to change the size of the glove or sock. A system according to the present invention which only comprises a container enclosing vacuum, i.e. no MRF or ferrofluid, and also comprising the feedback data system may function as a very simple alternative for some specific applications. In this case, the system may in fact also be without sensors, in its most simple embodiment. Such alternatives according to the present invention, which are totally vacuum-directed, may be of special interest for patients having joint movement restrictions, paralysis or swollen hands.

According to yet another specific embodiment, the one or more sensors are multiple gyroscopes, flexsensors, pressure sensors, force sensors, stretch sensors, hall sensors, or accelerometers. Fact is that any type of sensor capable of position/movement/pressure sensing is possible to use according to the present invention. For instance multiple gyroscopes per finger installed on the glove relay attitude gives information back to the controller. An integrated predictive hand movement algorithm translates angles to a very accurate model of the hand, which is then displayed on the display screen of the system. Another example according to the present invention is to use pressure sensor(s) in diagnostics / therapeutics to determine the maximum hand strength.

Moreover, the device according to the present invention either uses a separate sensor glove or sensors integrated in the glove that is part of the device.

According to one embodiment of the present invention, the haptic feedback system has means for introducing a virtual object to the computer system, which virtual object then is displayed on the screen. According to yet another specific embodiment of the present invention, the virtual object on the screen corresponds to coordinates in the container.

According to another specific embodiment of the present invention, the tactile feedback is based on the input of sensor data from a device controlled with the system according to the invention.

Also the properties of the MRF or ferrofluid may vary according to the present invention. According to one specific embodiment of the present invention, the viscosity of the MRF is proportionate to the electrical current put through the solenoid.

Furthermore, the haptic feedback system may be mobile, e.g. by the container being arranged on a frame with wheels. For hand rehabilitation purposes this may facilitate for the user.

Moreover, the present invention is also related to a method involving the haptic feedback system. According to one embodiment there is disclosed a method for performing a haptic feedback operation in a haptic feedback system according to the present invention, said method comprising

introducing an object to the computer system, which object then is displayed on the screen; reaching the coordinates in the container that corresponds to the object displayed on the screen with the glove or sock, which operation allows for an electrical current to be applied to the solenoid which in turn solidifies the MRF immediately. This method gives the user the perception of actually grasping the object.

According to one embodiment of the present invention there is provided a method for performing a haptic feedback operation in a haptic feedback system according to the invention, said method comprising introducing an object to the computer system based on sensor input of a controlled device, which input is then translated to coordinates in the container that corresponds to the real life, and which operation allows for an electrical current to be applied to the solenoid which in turn solidifies the MRF or ferrofluid.

According to one specific embodiment, the electrical current is cut when the grip on the coordinates is let go by a user operating the glove or sock, which renders the MRF or ferrofluid to become liquid again immediately so that a hand, foot or other insertable body part of the user inserted in the MRF or ferrofluid can move freely again.

Moreover, it should also be mentioned that all methods according to the present invention also applies to a system according to the present invention when only vacuum is applied to the container.

Furthermore, the present invention is also related to use of a system according to the invention. As mentioned above, one possible use is for hand rehabilitation or for foot/ankle rehabilitation. Other possible uses according to the present invention are e.g. diagnostics, robotics control, microsurgery, (surgery-) simulation (virtual surgery), gaming, bomb dismantling, in the sex industry or for art works etc. To give some further examples, the present invention also finds use in simultaneous stimulation with for example electrical muscle stimulation (EMS/NMES) and in diagnostics including electromyogram (EMG).

Moreover, the device according to the present invention may be equipped with other specific features of interest for some applications.

According to one specific embodiment, the system is arranged with active cooling which allows the temperature of the liquid to be controlled, which provides an optimal environment to practice for e.g. rheumatoid arthritis patients.

Furthermore, a vibration sensation can be created in the liquid at various frequencies to provide feedback. This may also be used for

therapeutic applications such as sensory threshold detection of nerve conditions and desensibilisation of hypersensitive patients.

Claims

1. Haptic feedback system comprising a container enclosing a Magneto- Rheological Fluid (MRF), or a ferrofluid, and a solenoid, or enclosing only vacuum, wherein in the case of a MRF or ferrofluid this responds to a magnetic field created by the solenoid, said haptic feedback system also comprising a glove or sock with one or more sensors, a feedback system involving a software algorithm, and a computer unit with a display screen.

2. Haptic feedback system according to claim 1 , wherein the container encloses a Magneto-Rheological Fluid (MRF) or a ferrofluid and a solenoid.

3. Haptic feedback system according to claim 1 or 2, wherein the container comprises a membrane which by means of force affects the resulting vacuum.

4. Haptic feedback system according to any of claims 1 -3, wherein the size of the glove or sock is possible to alter.

5. Haptic feedback system according to claim 1 , wherein the container encloses vacuum, and wherein the vacuum enables to change the size of the glove or sock.

6. Haptic feedback system according to any of claims 1 -5, wherein the one or more sensors are multiple gyroscopes, flexsensors, hall sensors, pressure sensors, force sensors, magnetometers, stretch sensors or accelerometers.

7. Haptic feedback system according to any of claims 1 -6, wherein the haptic feedback system has means for introducing an object to the computer system, which object then is displayed on the screen.

8. Haptic feedback system according to claim 7, wherein the object on the screen corresponds to coordinates in the container.

9. Haptic feedback system according to claim 7 or 8, wherein the object is virtual.

10. Haptic feedback system according to any of claim 1 -5, wherein tactile feedback is based on the input of sensor data from a device controlled with the system according to the invention

11. Haptic feedback system according to any of claims 1 -10, wherein the viscosity of the MRF or ferrofluid is proportionate to the electrical current put through the solenoid.

12. Haptic feedback system according to any of claims 1 -10, wherein the haptic feedback system is mobile.

13. Method for performing a haptic feedback operation in a haptic feedback system according to any of claims 1 -12, said method comprising introducing a virtual object to the computer system, which virtual object then is displayed on the screen; reaching the coordinates in the container that corresponds to the virtual object displayed on the screen with the glove or sock, which operation allows for an electrical current to be applied to the solenoid which in turn solidifies the MRF or ferrofluid.

14. Method for performing a haptic feedback operation in a haptic feedback system according to any of claims 1 -12, said method comprising introducing an object to the computer system based on sensor input of a controlled device, which input is then translated to coordinates in the container that corresponds to the real life, and which operation allows for an electrical current to be applied to the solenoid which in turn solidifies the MRF or ferrofluid.

15. Method according to claim 13 or 14, wherein the electrical current is cut when the grip on the coordinates is let go by a user operating the glove or sock, which renders the MRF or ferrofluid to become liquid again so that a hand, foot or other insertable body part of the user inserted in the MRF or ferrofluid can move freely again.