GB2263179A

GB2263179A - Touch simulator

Info

Publication number: GB2263179A
Application number: GB9200667A
Authority: GB
Inventors: Karen Tina Carr; Rupert David England
Original assignee: British Aerospace PLC
Current assignee: BAE Systems PLC
Priority date: 1992-01-04
Filing date: 1992-01-04
Publication date: 1993-07-14
Anticipated expiration: 2012-01-04
Also published as: GB2263179B; GB9200667D0

Abstract

The 'feel' of an object 8 in a virtual reality device is simulated by adjusting the flexibility of a tubular element 1 extending across a joint between two parts of the operator's body eg a finger when relative motion between the two parts reaches a set level eg during a gripping action. The flexibility of the tubular element 1 is reduced by increasing the pressure of fluid in the element eg electro-rheologically to oppose further movement of the fingers thus simulating gripping an object. <IMAGE>

Description

APPARATUS FOR SELECTIVELY CONTROLLING MOVEMENT This invention relates to apparatus for selectively controlling movement of a first portion of an operator's body relative to a second portion thereof joined thereto at an intervening joint and particularly, but not exclusively, is concerned with an interactive glove device provided with such apparatus.

Computer systems are known which mimic reality such as in flight simulators used for training aircraft pilots. As an extension of such computer technology it is also known to provide computer systems which generate artificial images and for these artificial images to form what is known as "virtual reality" perceived by an operator either wearing a helmet provided with means whereby the images are positioned in front of the operator's eyes, or looking into a large format television or projection screen.

In such virtual reality systems the operator is able to interact with the artificial reality images for example by moving, pointing and grasping objects within the artificial image environment. Movement within the artificial image environment is usually triggered by means of sensors attached to the operator in any convenient manner such as by means of sensors sensing the position of the operator's head and body and by means of sensors provided on an interactive glove device worn by the operator and used to give command control signals to control various operations within the artificial image environment. For example pointing a finger of the glove device in any direction can cause seeming movement of the operator in that direction within the artificial image environment. Closing the fist can cause this movement to cease.

Within this artificial image environment, the so called virtual reality, it is possible for an operator wearing an interactive glove device to simulate the grasping and picking up of an object perceived as an image within the artificial image environment. Control of this grasping and lifting movement within conventional systems is imprecise as it is very easy for the operator to close the hand through the object perceived in image form in the artificial image environment. Additionally it is difficult to provide any tactual sensation normally encountered in reality when a hand makes contact with an object.

Attempts have been made to simulate the tactual sensation within an artificial image environment by means of piezoelectric crystals in the glove device which vibrate when activated by an electric current to give a sensation approximating to the sensation experienced on contact in the real world. This is not a satisfactory solution as it can only give some indication of contact and not of the actual sensation of grasping an object. It is still possible with this proposal for the hand to be closed through the perceived artificial image object and there is thus still a need for apparatus which can provide a more realistic effect of actually grasping an object with reduced tendency for the grasping movement to pass through the perceived artificial image.

According to a first embodiment of the present invention there is provided apparatus for selectively controlling movement of a first portion of an operator's body relative to a second portion thereof joined thereto at an intervening joint, which apparatus includes a control member, made at least partially of flexible material, locatable to bridge the joint between the first and second body portions and operable, selectively, on movement of one of said portions relative to the other said portions about the joint to a predetermined position variably to modify the flexibility of the control member so as to increase or decrease movability of said one of said portions relative to the other.

Preferably the control member is of elongated, hollow, tube-like construction and is connectible to a source of fluid, gas and! our liquid under pressure.

Conveniently the control member is connectible to a source of air under pressure and is made of material which is substantially impermeable to air.

Advantageously the apparatus includes a source of air under pressure in the form of a bladder in fluid flow connection with the control member via an openable and closable valve.

Preferably the control member is connectible to a source of electro-rheological fluid and is provided with electrodes such that the rigidity of the fluid in the control member can be varied between a flexible state and a relatively rigid state by application of a voltage across the electrodes.

According to a further embodiment of the present invention there is provided an interactive glove device to be worn by an operator including at least one apparatus as hereinbefore described, in which the control member is positioned, when the glove device is worn, to bridge at least one digit joint of the operator.

Preferably the control member is positioned on a digit of the glove device or forms part of a digit of the glove device so as to be located externally or internally across said at least one digit joint when the glove device is worn by the operator.

Conveniently the control member is dimensioned to cover at least two joints of a digit.

Advantageously the glove device includes a plurality of apparatuses as hereinbefore described wherein the control members are provided one for each digit finger and thumb digit.

Preferably additional control members are provided for the palm andlor back areas of the glove device.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which; Figure 1 is a plan view from above in diagrammatic form of an interactive glove device according to one aspect of the present invention incorporating apparatus according to a further aspect of the present invention, Figure 2 is a view similar to that of Figure 1 of a further embodiment of the present invention, Figure 3 is a schematic sketch view in perspective of an interactive glove device according to the present invention as worn by an operator reaching out to grasp an object or image of an object, and Figure 4 is a view of the Figure 3 glove device showing the operator grasping an object or image thereof.

Apparatus according to the present invention for selectively controlling movement of a first portion of an operator's body relative to a second portion thereof joined thereto at an intervening joint is suitable for use with any jointed part of a human body. However, for the sake of convenience it will be described in more detail in respect of a human hand for controlling movement of all or part of a digit thereof relative to the palm or immediately adjoining part of the digit such as a finger or thumb.

Basically the apparatus includes a control member 1 made at least partially of flexible material and conveniently of elongated, hollow, tube like construction as illustrated. This control member 1 is locatable to bridge the joint between first and second body portions such as between the first and second joints of a finger. The control member 1 is operable, selectively, on movement of one of the portions relative to the other portion about the joint to a predetermined position variably to modify the flexibility of the control member 1 so as to increase or decrease movability of said one of said portions relative to the other.

The control member 1 is connectible to a source of gas andjor liquid under pressure such as a bladder 2 as shown in figure 2, for containing air. To this end the control member 1 is made of flexible material which is substantially impermeable to gas such as air andlor liquid. Suitable materials are plastics, polythene or substantially impermeable fabrics. The pressure in the control member 1 can be varied by means of more or less pressure on the control bladder 2 for example by means of compression members 3 operable to exert more or less pressure on the bladder to therebetween as can be seen in Figure 2. To assist control of the pressure in the control member 1 the bladder 2 is in fluid flow connection with the control member 1 via an openable and closable valve as shown in Figure 1.

Hence by providing more or less air under pressure into the interior of the control member 1 it is possible to modify the flexibility thereof so as to increase or decrease resistance to bending thereof.

As aforesaid the apparatus of the present invention can be used primarily to impart a degree of tactual feel to an operator in an artificial image environment or virtual reality system.

Tactual perception or feel includes tactile, kinaesthetic and haptic perception. For example if the operator in the artificial image environment attempts to kick the image of an object there would be no sensation of contact without a tactual feedback and hence the image of the foot would pass through the image of the object being kicked with consequent reduction in the reality perceived. To provide a degree of tactual feedback an apparatus according to the present invention could be applied across the knee joint or ankle joint of the operator and operated to provide increased rigidity to movement of the operator's leg or ankle at the perceived point of contact between the artificial image of the foot and artificial image of the object being kicked.

Control of the actual point of operation of the apparatus of the present invention can be in any conventional manner such as by means of conventional fibre optic sensors monitoring the positioning of the operator's body parts. As the apparatus of the present invention is, in its preferred form, basically a fluid pressure operated apparatus there will be no electro magnetic or electro static interference signals generated, as could be generated in a conventional proposed piezoelectric technique which would affect the wiring, addressing and signal processing aspects of a conventional sensing, measuring or processing system.

As aforesaid a primary employment for the apparatus of the invention is as part of a an interactive glove device to be worn by an operator of the artificial image environment. In the embodiment of Figure 1 the glove device 5 has a plurality of the control members 1, one for each digit of the glove device. Each control member 5 has an individual openable and closable valve 4 which are linked together for connection at 6 to a source of fluid under pressure such as the bladder 2 shown in Figure 2. In the Figure 2 embodiment the basic difference is that as well as one control member 1 for each digit of the glove 5 device further control members 7 are provided to cover the palm or back portion of the glove device 5 for reasons which will be hereinafter described.

Each control member 1 can cover only one joint in a digit of the hand of an operator when wearing the glove device 5 and for the avoidance of doubt the knuckle joint is considered to be, for the purposes of this description and invention, as a joint between two portions of a body of the operator. Each control member 1 may cover more than one joint when the glove device is worn and to this end may extend completely along the digit as shown in Figures 1 and 2. Of course it is to be understood that there may be more than one such control member for each digit so as to provide individual control of each joint if necessary.

Each control member 1 may be positioned on the digit of a glove device or form part of a digit of the glove device so as to be located externally or internally across at least one digit joint when the glove device 5 is worn by the operator. In the illustrated embodiments of Figures 1, 2, 3 and 4 the control members 1 are located on the glove device so as to lie externally of the hand joints, that is on the side thereof facing away from the closing direction. However, alternatively the control members 1 could be located internally of the glove device so as to lie across the inside of each joint of the operator when wearing the glove device 5, that is so as to lie on the side of the joint facing in the closing direction of the hand.

In operation a glove device 5 provided with apparatus of the present invention and having the control members 1 and 7 externally of the hand joints operates as follows. With the control members in an unpressurized condition the tube like construction thereof is in a relatively flattened position as shown in Figure 3. In this position the control members 1 do not offer any resistance to finger flexion.As the hand approaches and attempts to grasp the image 8 of an object perceived by the operator in the artificial image environment portrayed visually before the operator's eyes preferably in a helmet worn by the operator, sensors such as flexible fibre optic sensors carried by each digit of the glove device andlor a Polhemus 3-body tracker mounted on the glove device 5 sense the position of the operator's hand relative to the object image 8 and at the moment of apparent contact therebetween pressurise the control members 1 by actuating the bladder 2 and opening the valves 4.

Thus as the fingers grasp the object image 8 the pressure in the control members 1 increases the resistance of the control members to further bending and thereby increases the resistance to any further finger flexion which simulates actual contact between the operator's hand and an object so that further flexion of the fingers which would ordinarily result in the fingers passing through the object image 8 is reduced or prevented. In this position the valves 4 are closed and prevent depressurising of the control members 1. Movement of the hand and glove device 5 such that the grip on the object image 8 is relinquished is sensed by the position sensors on the glove device and used to release pressure in the control members 1 to free the digits of the glove device and thereby the fingers for flexion once more. The Figure 4 illustration corresponds to the grasping position in which the control members 1 are pressurised and thereby inflated so as to prevent or reduce further flexion of the fingers in the glove device in a closing direction. The actuation of the glove device should take place relatively quickly as if the actuation response is delayed longer than about 200 to 250 milliseconds the delayed tactual feedback may hinder rather than assist virtual reality interaction performance.

Although one valve 4 for each control member 1 has been illustrated it is of course possible to have all the control members 1 acting from a single openable and closable valve 4 if desired. Additionally it is possible to increase the contact sensation by means of providing additional control members 7 in the form of pads in the glove device palm or back area as illustrated in Figure 2. These operate in conjunction with the control members 1 and are pressurised at the same time and in the same way so as to increase the resistance to bending of the glove device 5 when an object image 8 is encountered.

The degree of pressure imparted to the control members 1 is chosen such as not to result in a spring back of the flexed fingers in the closed position of Figure 4 but merely sufficient as to prevent or reduce further flexion thereof in the closing direction. The use of liquid instead of a gaseous medium such as air for pressurising the control members 1 reduces any potential spring back effect due to the relative incompressibility of the liquid such as water or oil.

Alternatively the medium utilised for pressuring the control members 1 may be an electro-rheological fluid which can be activated by electrode energising. Thus in one state the electro-rheological fluid is flexible allowing the control member 1 to bend to accompany finger flexion whereas in its second state a voltage applied across electrodes in the fluid changes it to a rigid condition thereby preventing or resisting further flexion of the fingers. Of course as in the illustrated embodiments one such apparatus could be provided for each joint of the operator's hand for control individually by independent voltage sources.

Although in the foregoing the apparatus of the present invention has been described in terms of use of pressure in the control members 1 to resist further flexion it is of course possible for the apparatus to be used in the opposite sense in which pressure is initially present in the control members 1 to prevent flexion and removed therefrom to permit flexion for example to correspond to restrainment of a hand in the artificial image environment and consequent release of such restrainment.

Claims

1. Apparatus for selectively controlling movement of a first portion of an operator's body relative to a second portion thereof joined thereto at an intervening joint, which apparatus includes a control member, made at least partially of flexible material, locatable to bridge the joint between the first and second body portions and operable, selectively, on movement of one of said portions relative to the other of said portions about the joint to a predetermined position variably to modify the flexibility of the control member to increase or decrease movability of said one of said portions relative to the other.

2. Apparatus according to claim 1, in which the control member is of elongated, hollow, tube-like construction and is connectible to a source of fluid, gas andlor liquid under pressure.

3. Apparatus according to claim 2, in which the control member is connectible to a source of air under pressure and is made of material which is substantially impermeable to air.

4. Apparatus according to claim 3 including a source of air under pressure in the form of a bladder in fluid flow connection with the control member via an openable and closable valve.

5. Apparatus according to claim 2, wherein the control member is connectible to a source of electro-rheological fluid and is provided with electrodes such that the rigidity of the fluid in the control member can be varied between a flexible state and a relatively rigid state by application of a voltage across the electrodes.

6. Apparatus for selectively controlling movement of a first portion of an operator's body relative to a second portion thereof joined thereto at an intervening joint, substantially as hereinbefore described with reference to Figure 1, Figure 2 or Figures 3 and 4 of the accompanying drawings.

7. An interactive glove device to be worn by an operator including at least one apparatus according to any one of claims 1 to 6, in which the control member is positioned, when the glove device is worn, to bridge at least one digit joint of the operator.

8. An interactive glove device according to claim 7, wherein the control member is positioned on a digit of the glove device or forms part of a digit of the glove device so as to be located externally or internally across said at least one digit joint when the glove device is worn by the operator.

9. An interactive glove device according to claim 8, wherein the control member is dimensioned to cover at least two joints of a digit.

10. An interactive glove device according to any one of claims 7 to 9, including a plurality of apparatuses according to any one of claims 1 to 6, wherein control members are provided one for each finger digit and thumb digit.

11. An interactive glove device according to claim 10, wherein additional control members are provided for the palm and/or back areas of the glove.

12. An interactive glove device to be worn by an operator, substantially as hereinbefore described and as illustrated in Figure 1, Figure 2 or Figures 3 and 4 of the accompanying drawings.