WO2017106924A1

WO2017106924A1 - Tactile medical examination simulator

Info

Publication number: WO2017106924A1
Application number: PCT/AU2016/051277
Authority: WO
Inventors: Ben Patrick HORAN; Helen FORBES; Diane Joan PHILLIPS; Tracey Katherine BUCKNALL; Catherine NAGLE
Original assignee: Deakin University
Priority date: 2015-12-23
Filing date: 2016-12-22
Publication date: 2017-06-29

Abstract

A simulator apparatus for simulating a response to a tactile medical examination, comprising a housing; an aperture formed in the housing; a membrane accessible via the aperture and comprising a first surface and a second surface, the first surface being touch accessible by a user; a linear electro-mechanical actuator located within the housing; a head attached to an end of the linear electro-mechanical actuator; and a controller for driving the linear electro-mechanical actuator so as to cause an outer surface of the head to apply a linear force to the second surface of the membrane and thereby simulate movement of a body part to the user when the first surface of the membrane is palpated.

Description

TACTILE MEDICAL EXAMINATION SIMULATOR

FIELD OF THE INVENTION

[0001] The present invention relates generally to an apparatus for simulating a response to a tactile medical examination. Embodiments of the invention are suitable for use in simulating a response to a tactile medical examination of a patient's abdomen or throat, but it will be appreciated that the invention is also applicable to apparatus for simulating a response to a tactile examination of a variety of different regions or parts of the animal or human body.

BACKGROUND OF THE INVENTION

[0002] Many medical procedures require the tactile examination of a patient. For example, midwives are required to perform a tactile examination of pregnant women to assess uterine contractions during the first stage of labour for frequency, duration and intensity. Some uterine contractions are difficult to detect and midwifery students are often provided with limited opportunities to work with experienced midwives and/or real patients in labour to be taught how to conduct such tactile examinations and become familiar with various types of uterine contractions. Novice midwives commonly perform tactile examination of pregnant women without a sufficient foreknowledge of the frequency, duration and intensity of uterine contractions to safely determine when the delivery is proceeding well or when medical intervention is required.

[0003] In order to address this issue, training simulators have been proposed in order to provide an artificial learning environment for training midwives and other medical professionals. One such system uses a series of fluid-filled bladders which are selectively inflated and deflated. However, in such an arrangement, the dynamic fluid properties as well as the behaviour of the bladders themselves need to be taken into consideration when attempting to control or generate a particular stimulation. Moreover, it is not possible to determine whether a person is actually touching one of the bladders, and to do so would require a complex set of sensors. Moreover, localised stimulations are not possible to generate in such systems since the entirety of the bladder is inflated or deflated. The use of bladders also makes variations in the frequency, intensity and scope of stimulations difficult or impossible to generate.

[0004] There remains a need to provide a simulator apparatus for simulating a response to a tactile medical examination that is accurate, can simulate a range of stimulations likely to be experienced by a medical practitioner during tactile examination of a patient or animal, and is simple to manufacture, assemble and maintain.

[0005] It would also be desirable to provide a simulator apparatus for simulating a response to tactile medical examination that ameliorates or overcomes one or more disadvantages or inconveniences of known stimulator apparatus.

SUMMARY OF THE INVENTION

[0006] One aspect of the invention provides a simulator apparatus for simulating a response to tactile medical examination, comprising: a housing; an aperture formed in the housing; a membrane accessible via the aperture and comprising a first surface and a second surface, the first surface being touch accessible to a user; a linear electromechanical actuator located within the housing; a head attached to an end of the linear electromechanical actuator; and a controller for driving the linear electromechanical actuator so as to cause an outer surface of the head to apply a linear force to the second surface of the membrane and thereby simulate movement of a body part to the user when the first surface of the membrane is palpated.

[0007] In one or more embodiments, the simulator apparatus further includes an actuator feedback mechanism for providing a feedback signal indicative of actuator position to the controller. In such an arrangement, the controller may be configured to vary the linear force applied to the second surface of the membrane in response to the actuator position feedback signal.

[0008] In one or more embodiments, the linear electromechanical actuator generates linear motion from a motor acting to rotate a shaft, and the feedback mechanism includes an encoder. [0009] In one or more embodiments, the outer surface of the head which contacts the second surface of the membrane has an ellipsoid shape. [0010] In one or more embodiments, the simulator apparatus further includes a mechanism to vary the angle of incidence of the linear electromechanical actuator and/or contact position of the head on the second surface of the membrane. In such an arrangement, the ellipsoid shape may be configured to maximise contact of the head on the second surface of the membrane over a desired range of angles of incidence.

[0011] In one or more embodiments, the simulator apparatus may further comprise a virtual reality apparatus for replicating the environment in which the medical examination is conducted. [0012] In one or more embodiments, the housing is in the form of at least part of a human or animal body.

[0013] The housing may be in the form of at least part of a human torso. In such arrangements, the housing may be in the form of at least part of a female torso, and the aperture may be in a region corresponding to the abdomen. [0014] In one or more embodiments, the membrane covers the aperture.

[0015] In one or more embodiments, the housing is in the form of at least part of a human head. In this case, the aperture may be in a region corresponding to a human mouth.

[0016] For example, the membrane may be in the form a tube having a form corresponding to a human throat, the tube having an inner and an outer surface, wherein the first surface of the membrane is the interior surface of the tube and is accessible by the user.

[0017] In one or more embodiments, the controller may be configured to cause the linear electromechanical actuator to simulate any one or more of burst contractions, a heartbeat, throat contractions during intubation or other internal body organ movement.

[0018] In one or more embodiments, the controller may be configured to cause the linear actuator to vary the intensity and/or duration of the force applied to the membrane. [0019] In one or more embodiments, the controller comprises a processor and a memory device for storing a series of instructions to cause the processor to operate the stimulator apparatus.

[0020] In one or more embodiments, the membrane is held in tension by the head attached to an end of the linear electro-mechanical actuator.

[0021] In one or more embodiments, the membrane maintains a form when tension is removed

[0022] In one or more embodiments, the membrane is deformable when touched to provide passive feedback to the user.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Features and advantages of the present invention will become apparent from the following description of embodiments thereof, provided by way of example only, with reference to the accompanying drawings in which: [0024] Figure 1 depicts one embodiment of a simulator apparatus according to the present invention;

[0025] Figure 2 is a schematic diagram of various electrical and mechanical components of the simulator apparatus depicted in Figure 1 ;

[0026] Figures 3 and 4 are representations of imagery displayed to a user of the simulator apparatus depicted in Figures 1 and 2;

[0027] Figures 5 and 6 depict interaction between a first embodiment of a head attached to an end of a linear electromechanical actuator and a membrane forming part of the simulator apparatus depicted in Figures 1 and 2;

[0028] Figure 7 depicts interaction in-between a second embodiment of a head attached to an end of a linear electromechanical actuator and a membrane forming part of the simulator apparatus depicted in Figures 1 and 2;

[0029] Figures 8 to 10 depicts various embodiments of cartesian coordinates defining variations of an ellipsoid shape applied to the head used in the simulator apparatus of Figures 1 and 2 to apply a force to the membrane forming part of that same simulator apparatus; [0030] Figure 1 1 is a torque-current characteristic of DC motor forming part of the simulator apparatus depicted in Figures 1 and 2;

[0031] Figure12depicts the differences between tensile and compressive properties of the membrane forming part of the simulator apparatus depicted in Figures 1 and 2;

[0032] Figure 13 depicts another embodiment of a simulator apparatus in which a multiple degree of freedom linear electro-mechanical actuator is employed; and

[0033] Figures 14 to 16 depict a further embodiment of the invention suitable for use in intubation training.

DETAILED DESCRIPTION OF EMBODIMENTS

[0034] Referring now to Figure 1 , there is shown generally a simulator apparatus 10 for simulating a response to a tactile medical examination. In this instance, the simulator apparatus is used to provide visual, tactile and auditory interaction for teaching midwifery students to assess uterine contractions during the first stage of labour for frequency, duration and intensity. Using the simulator apparatus 10, educators and trainers are able to provide an accurate, repeatable and realistic experience to midwifery students.

[0035] It is to be appreciated that the invention is suitable for use in a wide range of applications in which a response to a tactile medical examination of a human or animal body or part thereof is to be simulated. For example, the present invention may be adapted to simulate the response of a heartbeat or other internal body organ movement to a tactile medical examination.

[0036] The simulator apparatus 10 includes a housing 12 having the form of a female torso. The housing 12 includes a central portion 14 having a rounded form intended to approximate the shape of a pregnant woman's abdomen. The housing 12 further includes breast portions 20 and 22.

[0037] The housing 12 provides a rigid static three-dimensional surface which can be used to align the physical world of a user in front of them with a virtual world projected by means of a virtual reality headset 28. By aligning the three-dimensional surface of the housing 12 with the virtual world presented by the virtual reality headset 28, the user can feel parts of a patient which are not dynamically actuated thereby adding increased realism and allowing the user to locate an aperture 30 formed in the housing 12 for tactile medical examination. In this example, the aperture 30 is positioned just below a sternum region of the torso. The aperture 30 is covered by a membrane 32 which provides an outer surface that is touch accessible to the user.

[0038] Various electrical and mechanical elements of the simulator apparatus 10 are depicted in Figure 2, notably including a linear electromechanical actuator 50 located within the housing 12 and a head 52 attached to an end of the linear electromechanical actuator 50. A controller 54 acts to drive the linear electromechanical actuator 50 so as to cause an outer surface of the head 52 to apply a linear force to an inner surface of the membrane 32 and thereby simulating birthing contractions to the user when an outer surface of the membrane 32 is palpated.

[0039] The linear electromechanical actuator 50 operates by conversion of rotary motion into linear motion. In this exemplary embodiment, the linear electro- mechanical actuator 50 is realised by means of a linear motor including a rotary electric motor 55 mechanically connected to rotate a lever arm 56 which in turn pushes a shaft 57 to provide the linear motion. The lever arm 56 has a fixed radius which impacts the conversion of torque provided by the rotary electric motor to force. The force transmitted by the shaft 57 is determined as Torque = Force x Radius where x represents the cross product. The shaft 57 as driven by the lever arm, and is constrained by a motion constraint mechanism 58 to acts in a specified direction.

[0040] It will be appreciated that various other embodiments of linear motors, for example using linear magnetic tracks rather than rotary motion, can be used. Similarly, in other embodiments, the linear electromechanical actuator can be realised by a rotary electric motor coupled to a lever or other simple mechanical mechanism to convert rotary to linear motion.

[0041] A shaft coupled encoder 62 or similar position measurement device acts to monitor the rotary position of the motor 55 and provide an output signal indicative of the actuator position. Accordingly, by controlling operation of the electric motor 55, the linear electromechanical actuator 50 causes the head attached to the shaft 57 to be driven towards the membrane 32, or to be retracted from the membrane 32, so as it to apply or remove a linear force to the inner surface of that membrane. [0042] In embodiments in which the linear electro-mechanical actuator does not involve the use of a rotary electric motor, a linear encoder or other similar means can be used to provide a feedback signal indicative of actuator position to the controller 54. [0043] In the exemplary embodiment shown in Figure 2, the angle of incidence of the linear electromechanical actuator 50 in relation to the membrane 32 can be varied by operation of a stepper motor 64 coupled to the linear electromechanical actuator 50 by means of a knuckle joint 66 or like coupling mechanism. By operation of the stepper motor 64, it is possible to vary the angle of incidence of the linear electromechanical actuator on the membrane 32 and/or the contact position of the head 52 on the inner surface of the membrane 32. Variations in angle of incidence and head contact position are reference 52' and 52".

[0044] The controller 54 includes computing apparatus 68, which in turn includes a processor 70, main memory 72, display interface 74 and communications interface 76 all coupled to a communications infrastructure 78. The main memory 72 acts to store a series of instructions to cause the processor 70 to operate the simulator apparatus 10 in the manner described herein. The display interface 74 forwards graphics, text and other data from the communications infrastructure 78 for supply to the display of the virtual reality headset 28. The communications interface 76 allows software and data to be transferred between the computing apparatus 68 and external devices. Software and data transfer via the communications interface 76 are transmitted to and from computing apparatus 76 along a communications path 80.

[0045] The electric motor 55, which forms part of the linear electromechanical actuator 50, is driven by a motor driver 84, whilst the positioning motor 64 is driven by a motor driver 82. The communications infrastructure 78 enables the interconnection of and transmission of data and control signals between the motor drivers 82 and 84, the processor 70, main memory 72, display interface 74 and communications interface 76.

[0046] The series of instructions stored in the main memory 72 also causes the processor 70 to generate a virtual reality environment for transmission to and display on the virtual reality headset 28. Exemplary images 90 and 92 representative of the virtual reality environment displayed to the user via the headset 28 are shown in Figures 3 and 4. [0047] The simulator apparatus 10 also includes a motion tracker 34, placed in this example above the sternum and between the breasts of the abdomen-shaped central portion 14 of the housing 12, for tracking movement of the user's hand and providing a corresponding input signal to computing apparatus 68. The computing apparatus 68 causes generation of a representation 94 of the user's hand in the virtual reality environment viewed by the user on the virtual reality headset 28 when the hand is not in contact with the haptic area. Because the headset 28 blocks view of the real environment this hand tracking and visualisation function assists the user in physically navigating around the housing 12. A suitable motion controller is the Leap Motion Controller manufactured by Leap Motion, Inc.

[0048] The non-deformable upper surface of the head 52 contacts the second surface of the membrane 32 to generate a continuous haptically active surface. The combination of the curved surface of the head 52 with the membrane 32 results in a continuous surface of variable stiffness requiring only a single degree of freedom force to be applied by the linear electromechanical actuator 50. Figure 5 depicts application of such a single degree of freedom force in the direction indicated by the arrow referenced in "F" from a first position 100 in which the head 52 does not make contact with the membrane 32 to a position 102 in which the membrane 32 is deformed. [0049] The effectiveness of the head 52 in generating desired simulations for a given angle of incidence Θ is related to dimensions a, b and c defining the shape of the head 52.

[0050] Where the geometry of the upper surface of the head 52 enables a large enough deviation of the angle of incidence from perpendicular to the membrane 32, the electromechanical actuator 50 is able to service a large membrane surface area 32. In this way, use of the positioning motor 64 in conjunction with operation of the electric motor 55 to advance the head 52 towards and apply a force on the membrane 32 enables a localised force to be applied to a desired area of the membrane 32. Exemplary contact positions 104, 106 and 108 of the head 52 on the membrane 32 are displayed in Figure 6.

[0051] An advantage of using a combination of a linear electromechanical actuator and a membrane in a manner described above is that the membrane 32 deals with lateral forces so that lateral forces do not need to be dealt with by the haptic device. By way of explanation, in the case where there was no membrane, the user would place their hands on the head 52. Because it is only providing a single dimension force (which is good in that it is achievable cheaply and robust), a force can only be provided in that direction. If the electro-mechanical actuator was facing directly upwards, in the Z-direction, a force can be provided to the user's hand when they push down in that direction. Because there are no actuators to push in the X or Y directions, haptic/force feedback cannot be provided in those two dimensions.

[0052] By having the membrane 32, forces cannot be controlled in the X and Y directions directly but through choice of the membrane, a particular response will be generated when the user exerts a force in those directions. Referring to Figure 1 1 (a), the properties of the chosen membrane in the X and Y directions (i.e. tension on the material), these will give the user a particular tactile impression. While these forces in the X and Y directions are not controlled by the actuator, selection of the properties for a particular application will suffice because the primary area of consideration is palpation in the Z direction. Selection of the material properties gives those forces, across the entire area of the membrane 32 and the linear electro-mechanical actuator and head need only provide force in the Z direction only in one area of the membrane 32. This can be achieved cheaply and effectively by the above-described arrangements. [0053] In some instances, it is desirable for the head 52 to make contact with the membrane 32 over a large surface area. In order for this to be achieved, regard must be had to the desired deviation of angle of incidence of the linear electromechanical actuator 50 upon the membrane 32. Where a larger range of angles of incidence is required, then dimensions a, b and c defining the ellipsoid shape of the head 52 should be similar to each other, so that the head has a spherical shape 120 as depicted in Figure 7, and a similar surface area contact is made by the head 52 on the membrane 32 regardless of the angle of incidence, such as the angles of incidence 122, 124 or 126 depicted.

[0054] Where only a small deviation of angle of incidence from perpendicular is anticipated, then the shape of the ellipsoid head can be "flattened" to provide more contact area if necessary. Depending on the required contact area, the overall size of the head 52 can therefore be reduced. [0055] By way of explanation, the geometry of the upper surface of the head 52 which contacts the membrane 32 is a preferably a suitable ellipsoid which acts to transmit force from the linear electromechanical actuator 50 in a manner which distributes the force over the largest possible contact area of the membrane 32 whilst avoiding an obvious "bump" in the resulting membrane outer surface as well as allowing desired variation in the angle of incidence of the linear electromechanical actuator 50 upon the membrane 32.

[0056] Provision of such a curved upper surface of the head 52 making contact with the membrane 32 allows the following things: i. a solid or non-deformable ellipsoid upper surface distributes force over a larger area so that the presence of a discreet head bearing against the membrane is less apparent to a person performing a tactile examination of the membrane 32;

ii. there are no sharp edges that would otherwise damage the surface of the membrane; and

iii. the curvature of the ellipsoid means that different angles of incidence can be achieved by the electromechanical actuator and head and the force transferred to the membrane.

[0057] The ellipsoid upper surface in a Cartesian coordinate system can be defined by three dimensions a, b, and c and given by: x 2 2 2

y z

— + -— I = 1

a² b² c²

Graphical depiction three different and exemplary head geometries 130, 132 and 133 are shown in Figure 8. Figure 8 (a) shows the case where a = b = c is a spheroid, Figure 8 (b) shows the case where a=b but c is half the value giving an oblate (disc shaped) ellipsoid, and Figure 8 (c) shows the case where b=c but a is twice the value giving a prolate (football shaped) ellipsoid.

[0058] The magnitudes of a, b and c defining the size of the ellipsoid surface, can be scaled to form different size contact surfaces as required for a particular application. As discussed above the values of the parameters relative to one another impacts the curvature of the surface and thus the operation and effectiveness of the invention. [0059] Assuming that the linear electro-mechanical actuator 50 which provides the force does so in the direction defined as the Cartesian z-axis, if the upper ellipsoid surface of the head 52 is not selected correctly then the effectiveness of the curved surface in distributing the force is compromised. If c is much larger than both a and b, and the force is applied in the z-direction, it will approach becoming a tip which will be detrimental to (i-iii) above. Figure 9 shows an exemplary head geometry 140 where c is four times larger than a and b. If c is much larger than a but not b, or b but not a, it will approach becoming a blade as shown by the exemplary head geometry 150 in Figure 10 which will be detrimental to (i-iii) above. [0060] The use of a curved ellipsoid surface to make contact with the elastic skin allows different angles of incidence of the linear electro-mechanical actuator/head pair with the membrane. This provides the following benefits: i. different mounting configurations such as for compactness, or other; and ii. the linear electro-mechanical actuator/head pair to move around to access a larger membrane.

[0061] The use of a linear electromechanical actuator provides a simple and low cost method to apply the forces without the need for a force sensor. This is achieved based on the Torque-Force characteristic of a DC motor. Through controlling the current directly, or by varying the voltage (through the ohmic characteristics of the DC motor), the applied torque can be controlled in open loop. An example Current-Torque profile 160 is shown in Figure 10. By monitoring the motor's position, by means of the shaft coupled encoder 62 or other similar position measurement device as described above, it is possible to determine if contact (external force) has been made to the surface. [0062] The membrane should ideally be comprised of one or more layers in order to provide the following mechanical properties: iii. have tensile properties (elasticity/stiffness) as shown in Figure 1 1 (a), suitable to the appropriate application such that when pushed against by the ellipsoid head the whole area feels similarly stiff, not just the area where contact is made with the surface of the head.

iv. the single or multiple layers having suitable compressive properties, as shown in Figure 1 1 (b), to suit the requirements of the particular application. [0063] The size of the membrane should ideally be large enough that it at least covers the area of contact with the ellipsoid head.

[0064] It will be appreciated from the foregoing that the simulator apparatus 10 comprises a realistic three-dimensional visual environment and haptic feedback system of the abdomen of a pre-natal patient. The simulator apparatus 10 enables training midwives to be presented with an accurate an immersive virtual environment where many parameters can be changed such as the hospital room, patient behaviour, sounds and distractions, and also enables training midwives to physically feel, using their hand, realistic intra-partum contractions where the contraction intensity and duration can be altered by the computing apparatus 68.

[0065] The membrane 32 is preferably elastic so that after removal of a force applied by the linear electro-mechanical actuator, it returns to its original form.

[0066] In one or more embodiments, the membrane 32 may simply be a surface/skin held in tension. However, in other embodiments, the membrane 32 may have a form or shape to which it returns, making it well suited to many applications, such as having the contour of the human abdomen. In these embodiments, a relatively thick membrane (e.g. 7 - 10 mm) may be used, and the rigidity of the membrane selected distributes force across the surface in a relatively even manner. The choice of the material used to form the membrane 32 can be varied to change the compression of the surface by providing different degrees of compliance.

[0067] Whilst the linear electro-mechanical actuator depicted in Figure 1 is relatively simple device, it will be appreciated that other mechanisms exist to generate the desired linear motion, Figure 13 depicts an example in which three axes, three- degrees-of-freedom haptic device 170 is used, such as the Novint Falcon gaming joystick which includes three actuators acting in unison to provide a desired linear haptic force.

[0068] Although the above described embodiments relate to a training apparatus to simulate a response to a tactile medical examination of a patient's abdomen during birthing, it will be appreciated that the invention is also applicable to apparatus for simulating a response to a tactile examination of a variety of different regions or parts of the animal or human body. [0069] Intubation trainers currently use a rubber or similar model where the geometry of the model represents that of a toddler. This however does account for changing the diameter of the throat and other relevant passages due to swelling etc. Figures 14 to 16 depict another embodiment of the invention in which a housing 180 is in the form of at least part of a human head, and an aperture 182 formed in the housing 180 is in a region corresponding to a human mouth.

[0070] In this embodiment, a membrane 184 is in the form a tube having a form corresponding to a human throat. The membrane/tube 184 has an inner surface 186 and an outer surface 188. The outer surface 188 of the membrane/tube 184 is accessible by the head 52 attached to an end of the linear electromechanical actuator 50, whereas the inner surface 186 is touch accessible by a user using an intubator 190 to place an intubation tube 192 in and through the membrane/tube 184. In this way, the head 52 pushes against the outer surface 188 to simulate a throat with both varying openness and force during intubation. [0071] The head 52 pushing against the outer surface 188 of the membrane/tube 184 provides (a) a simple mechanism for reducing the diameter of the opening and (b) increases the coefficient of friction between the rubber passage material and the tube being inserted.

[0072] Further applications in which the present invention can be used include intrapartum contractions, Cardiopulmonary Resuscitation (CPR) training and any other applications where palpation of a body region is required.

[0073] For example, current CPR trainers use a spring to provide the resistance to the user. There are limitations with this including the spring resistance cannot be easily adjusted. The resistance will rebound (which can be reduced with damping), but the rebound is not controllable. The present invention naturally lends itself to CPR training where the force can be easily controlled to cater for a range of forces, such as several kg of downward force for an infant, versus 10's of kgs for a full grown adult.

[0074] Those skilled in the art will appreciate that there may be many variations and modifications of the configuration described herein which are in the scope of the present invention.

Claims

The claims defining the invention are as follows:

1 . A simulator apparatus for simulating a response to a tactile medical examination, comprising:

a housing;

an aperture formed in the housing;

a membrane accessible via the aperture and comprising a first surface and a second surface, the first surface being touch accessible by a user;

a linear electro-mechanical actuator located within the housing;

a head attached to an end of the linear electro-mechanical actuator; and a controller for driving the linear electro-mechanical actuator so as to cause an outer surface of the head to apply a linear force to the second surface of the membrane and thereby simulate movement of a body part to the user when the first surface of the membrane is palpated.

2. A simulator apparatus according to claim 1 , and further including

an actuator feedback mechanism for providing a feedback signal indicative of actuator position to the controller.

3. A simulator apparatus according to claim 2, wherein the controller is configured to vary the linear force applied to the second surface of the membrane in response to the actuator position feedback signal.

4. A simulator apparatus according to either one of claims 2 or 3, wherein the linear electro-mechanical actuator generates linear motion from a motor acting to rotate a shaft, and wherein the feedback mechanism includes an encoder.

5. A simulator apparatus according to any one of the preceding claims, wherein the outer surface of the head which contacts the second surface of membrane has an ellipsoid shape.

6. A simulator apparatus according to any one of the preceding claims, and further including a mechanism to vary the angle of incidence of the linear electro-mechanical actuator and/or contact position of the head on the second surface of the membrane.

7. A simulator apparatus according to claim 6 when dependant on claim 5, wherein the ellipsoid shape is configured to maximise contact of the head on the second surface of the membrane over a desired range of angles of incidence.

8. A simulator apparatus according to any one of the preceding claim, and further comprising:

a virtual reality apparatus for replicating the environment in which the medical examination is conducted.

9. A simulator apparatus according to any one of the preceding claims, wherein the housing is in the form of at least part of a human or animal body.

10. A simulator apparatus according to claim 9, wherein the housing is in the form of at least part of a human torso.

1 1 . A simulator apparatus according to claim 10, wherein the housing is in the form of at least part of a female torso, and wherein the aperture is in a region corresponding to an abdomen.

12. A simulator apparatus according to any of the preceding claims, wherein a membrane covers the aperture.

13. A simulator apparatus according to claim 9, wherein the housing is in the form of at least part of a human head.

14. A simulator apparatus according to claim 13, wherein the aperture is in a region corresponding to a human mouth.

15. A simulator apparatus according to claim 14, wherein the membrane is in the form of a tube having a form corresponding to a human throat, the tube having an inner and an outer surface, wherein the first surface of the membrane is the interior surface of the tube and is accessible by the user.

16. A simulator apparatus according to any one of the preceding claims, wherein the controller is configured to cause the linear electro-mechanical actuator to simulate any one or more of birth contractions, a heartbeat, throat contractions during intubation or other internal body organ movement.

17. A simulator apparatus according to any one of the preceding claims, wherein the controller is configured to cause the linear actuator to vary the intensity and/or duration of the force applied to the membrane.

18. A simulator apparatus according to any one of the preceding claims, wherein the controller comprises a processor and a memory device for storing a series of instructions to cause the processor to operate the simulator apparatus.

19. A simulator apparatus according to any one of the preceding claims, wherein the membrane is held in tension by the head attached to an end of the linear electromechanical actuator.

20. A simulator apparatus according to any one of the preceding claims, wherein the membrane maintains a form when tension is removed

21 . A simulator apparatus according to any one of the preceding claims, wherein the membrane is deformable when touched to provide passive feedback to the user.