GB2511338A

GB2511338A - A Dummy Instrument for use in a Simulator

Info

Publication number: GB2511338A
Application number: GB1303600.9A
Authority: GB
Inventors: Elton David Mckenna; Mohammed Afzal
Original assignee: Keymed Medical and Industrial Equipment Ltd
Current assignee: Keymed Medical and Industrial Equipment Ltd
Priority date: 2013-02-28
Filing date: 2013-02-28
Publication date: 2014-09-03
Anticipated expiration: 2033-02-28
Also published as: GB2511338B; GB201303600D0; WO2014132026A1

Abstract

A dummy endoscope system for use in an endoscopy simulator. Angulation control knobs (105) on the control body (101), are attached to a drive mechanism which moves as the knob rotates. Each drive mechanism is attached to a piston (206) which is slidable in a respective cylinder (208). First and second ports (210, 211) in the cylinder are arranged such that increasing pressure at a first or second port exerts a force on the drive mechanism in a first or second direction respectively. Each port (210, 211) is connected to a flexible tube (212) extending along an umbilical (103) and being connected to a pump (214) to supply it with pressurised air. The pressure of air fed to each tube is controlled by endoscopy simulator to vary the pressure on the piston and hence the force felt at the control knobs in accordance with the requirements of the simulator.

Description

A DUMMY INSTRUMENT FOR USE IN A SIMULATOR

The present invention relates to a dummy instrument for use in a simulator. In particular, the present invention relates to a dummy endoscope for use in an endoscopy simulator.

An endoscopy simulator is a system useful in training operators in the use of endoscopes without risking harm to patients. The system consists of a dummy endoscope which mimics, as closely as possible, the look and feel of a real endoscope. The insertion tube of the endoscope is inserted into a housing (whereas a real endoscope would be inserted into a patient body) . Sensors within the housing measures the linear and rotational position of the insertion tube and sensors on the angulation controls sense the orientation of the tip. This is then used to determine the position of the insertion tube in relation to a software model of the colon.

The software model determines a view corresponding to one that the user would see in a real endoscope procedure and displays this on the screen. In addition, the software model is able to determine the interaction between the insertion tube and the wall of a simulated colon based on the position data and calculate the resistive force that would be felt by the user in a real procedure. Within the housing is a force feedback mechanism to provide variable linear and rotational force feedback so that the user experiences realistic forces as they manipulate the insertion tube. This is important as the operator needs to learn how the endoscope will feel in practice.

An early example of an endoscopy simulator is described in GB 2 252 656.

A real endoscope is provided with an angulation control on the endoscope handle. This control takes the form of a pair of coaxial rotatable knobs one for controlling up/down angulation and the other for left/right angulation. Each knob has a cog within the endoscope handle around which a chain passes. The ends of the chain are each connected to a wire which extends to the tip of the insertion tube. Thus, turning one of the handles causes the wire to move (via the cog and chain) and, depending upon the direction of movement, the endoscope tip is caused to bend in an up/down or left/right direction. Thus, by manipulating the angulation controls, the user is able to steer the endoscope through the colon and to execute various other procedures.

If the tip is manipulated such that it encounters the wall of the colon, the user experiences a resistive force on the control knobs and it is important to learn to recognise this as this gives an indication that they are pressing the end of the endoscope against the colon wall. A well designed simulator needs to be able to provide realistic force feedback to the angulation controls to replicate this force.

Examples of attempts to address this problem are disclosed in WO 2003/058583, Wa 2004/015654 and wa 2005/059866. In each case, the approach taken is to use as much as possible of the real endoscope mechanism in order to replicate this force. Thus, the angulation wires which previously extended from the endoscope handle to the tip of the insertion tube are re-routed around a pulley system in the handle and they extend down the umbilical of the endoscope. At the distal end of the umbilical, the up/down wires are connected to a wheel attached to a first motor while the left/right wires are connected to a wheel attached to a second motor. The simulation software is provided with information concerning the linear and rotational insertion position of the endoscope as well as the up/down and left/right position of the angulation tip. This is compared with the software model of the colon to determine the amount of force feedback to be applied to the angulation controls.

This force is then replicated on the two motors which provide a resistance to the movemedt to the wires which the user then feels on the angulation controls.

Whilst this approach has met with some success, it does suffer from a problem. In a real endoscopic procedure, the endoscope is steered along a tortuous path as it travels along the colon. This often results in loops occurring in the insertion tube. Endoscopists are trained to manipulate the handle of the endoscope such that these loops are transferred from the insertion tube to the umbilical. As a result of this, however, the umbilical can often contain multiple loops which have a reasonably tight radius of curvature. This causes a problem for the above described angulation force feedback mechanism. The umbilical contains four wires that it was not designed to contain in a real endoscope. Further, these wires are required to slide relatively to one another as the angulation controls are manipulated. When the umbilical contains a number of loops, the tight radius of curvature of the umbilical increases the frictional force on the wires to such an extent that the user experiences significant resistive forces which are undesirable as they are not generated via the simulation software. The problem could be addressed by sensing the curvature of the umbilical and attempting to estimate the frictidnal force caused by this curvature and to subtract this from any force feedback applied to the angulation controls. However, this met with limited success as the force was difficult to estimate, and it does not deal with the problem that the unwanted frictional force will still be applied even when little or no force feedback force is called for in the simulation.

According to the present invention there is provided a dummy endoscope system for use in an endoscopy simulator, the system comprising a dummy endoscope comprising an insertion tube and an umbilical both extending from a control body, a pair of rotatable angulation control knobs on the control body, each knob being attached to a drive mechanism which moves as the knob rotates, each drive mechanism being attached to a piston which is slidable in a cylinder or to a pair of pistons each which is slidable in a respective cylinder, first and second ports in the cylinder or cylinders arranged such that increasing pressure at a first port exerts a force on the drive mechanism in a first direction and increasing pressure at the second port exerts a force on the drive mechanism in the opposite direction, each port being connected to a flexible tube extending along the umbilical to the distal end and being connected to a pump to supply it with pressurised air, the pressure of. air fed to each tube being arranged to be controlled by control signals from the endoscopy simulator to vary the pressure on the piston and hence the force felt at the control knobs in accordance with the requirements of the simulator.

Thus, rather than having wires which slide extending down the umbilical, the present invention has tubes which contain pressurised air. Whilst there are relatively tight loops in the umbilical which cause the above mentioned problems with friction, the present invention allows the use of flexible tubing which is robust enough that it will not kink where the loops are formed. Further, as the sliding movement is replaced by pneumatic transmission, the frictional problems are avoided.

The pumps could be vacuum pumps which are controlled to provide the required pressure. However, preferably the system further comprises a proportional regulator between the pumps and tubes to control the air supply to the tubes based on control signals from the endoscopy simulator. The use of a proportional regulator ensures that sufficient high pressure air is quickly transmitted to the appropriate port which improves the responsiveness of the system.

With the pair of cylinders, there is a separate cylinder associated with each of the two directions. This would require an air flow diverter in the control body to avoid additional tubes in the umbilical. However, preferably, the cylinder is a double acting cylinder with the drive mechanism, being attached at opposite ends of a common piston and the first and second ports being provided into the double acting cylinder on opposite sides of the piston. This makes for a simpler system and provides more dynamic control as it allows the proportional regulator to increase the pressure on one side of the piston while decreasing the pressure on the opposite side of the piston to improve the response.

The drive mechanism may for example be a rack and pinion arrangement. However it is preferably a belt drive.

This belt drive may be of any suitable form, such as one or more cables or a flat belt. However, preferably, the belt drive is a chain which engages with the cog attached to the control knob. This provides for more reliable transmission of higher forces. In the case of the double acting piston, preferably an auxiliary cog is provided with its axis spaced from the axis of the control knob and the chain drive is wrapped around the pair of cogs.

An example of a dummy endoscope in accordance with the present invention will now be described with reference to the accompany drawings, in which: Fig. 1 is a schematic view of the simulator system incorporating the dummy endoscope; Fig. 2 is a schematic drawing showing the angulation force feedback system; Fig 3 is a schematic drawing showing the physical layout of the dummy endoscope; and Fig. 4 is a schematic diagram of the operation of the proportional reulator * The basic system to which the invention is applicable is shown schematically in Fig. 1. An endoscope 100 consists of a control body 101 with an insertion tube 102 and an umbilical 103 at the distal end of which is a connector 104.

The control body 101 is provided with a pair of concentric angulation control wheels 105 as found on a conventional real endoscope.

The connector 104 connects to a force feedback unit 109. The insertion tube 102 is also inserted into an orifice in the force feedback unit 109. Here, the insertion tube 102 engages with sensors (not shown) which monitor its linear and rotational position and a force feedback mechanism (not shown) to transmit linear and rotational force feedback to the insertion tube as appropriate. A suItable sensing and force feedback arrangement is disclosed in WO 03/050783.

The system is controlled by a controller 106 which interfaces with the force feedback unit 109. The controller 106 also controls the graphical simulation which is displayed on a monitor 107 and also interfaces with a keyboard 108. It will be appreciated that other user interfaces such as a mouse, or touch-sensitive screen may alternatively be used.

It should be noted that the simulation software which calculates the graphical display and also levels of force feedback to be applied to the insertion tube and angulation controller are well known in the art and will not be described here. The improvement provided by the present invention relates to the manner in which the angulation force feedback is to be transmitted to the control wheels and this is described below with reference to Fig. 2.

The endoscope body 101 is designated schematically in Fig. 2. This is connected to the insertion tube 102 and umbilical 103 as described above and as shown in Fig. 3.

Further, it retains the control wheels 105. Each of these control wheels 105 is rotatable together with a cog 203 as shown in Fig. 2. This is the last part of the conventional endoscope which is retained and everything described subsequently is specifically designed for the simulated endoscope.

As mentioned above, there are a pair of concentric angulation wheels 105. The axle of one extends through the centre of the other such that, in practice, there will be a second cog behind the cog 203 illustrated in Fig. 2.

Associated with that cog is a duplicate of the mechanism described below. One of the wheels 105 is associated with the up/down motion of the angulation tip and the other is associated with the left/right motion of the angulation tip.

As both of these operate in the same way, only one is described here. However, it should be borne in mind throughout this description that there are two mechanisms of the kind described at present.

Extending around the cog 203 is a chain 202. An auxiliary cog 203 is provided such that the chain is looped around the two cogs.

Auxiliary cog 201 is simply provided to allow this loop to be formed and is not connected to any other component.

Each of the free ends of the chain 202 is connected to a respective piston rod 204, 205 and these are, in turn, connected to opposite sides of a double-acting piston 206.

This reciprocates within double-acting cylinder 207 which is effectively split into two first 208 and second 209 chambers.* A first port 210 is provided into first chamber 208 and a second port 211 is provided into second chamber 209.

Each port 210, 211 is connected to an air hose in the form of a flexible tube which leads from the port and is routed down the umbilical 103 to the connector 104 at the distal end. As there are two such mechanisms as described above, there will be four air hoses 212 extending down the umbilical. A proportional regulator 213 is connected at the opposite ends of the air hoses. The proportional regulator 213 may be within the connector 104 or within the force feedback unit 105 as necessary. The proportional regulator is supplied with pressurised air from a pump 214 and receives control signals from the controller 106 along lines 215.

The proportional regulator 213 is shown in greater detail in Fig. 4. It has an inlet port 216 which receives air from the pump 214. It also has an exhaust outlet port 217 and an outlet port 218 which leads to one of the air hoses 212. As will be appreciated, four such arrangements shown in Fig. 4 are required, one for each of the tour air hoses 212. Alternatively, two double output regulators, such as the Unilever PRP300-0241-C-2-N could be used. Air flow through the proportional regulator is controlled by a supply valve 219 and an exhaust valve 220. Operation of the two valves is controlled by a control circuit 211 which communicates with the controller 106.

-10 -The inlet of the air supply valve 219 is connected to the inlet port 216 along line 221. Its output is connected via a first branch 222 to the inlet of the exhaust valve 220 and via a second branch 223 the outlet port 218. The outlet of the exhaust valve 220 is connected to the exhaust port 217 along line 224. A pressure sensor 225 senses the pressure of the outlet port 218 and feeds this value to the control circuit 211.

io when the simulation software determines that the air pressure needs to rise, this is communicated from the controller 106 to the control circuit 211. This moves the air supply valve 219 to the open position thereby placing the air supply in communication with the outlet. The 15. pressure detected by the pressure sensor 225 therefore rises until the target value is reached or whereupon the valve 219 is closed. This provides the feedback ioop which rapidly switches the air supply valve 219 in order to maintain the desired pressure. To assist in this, the exhaust valve 220 is also selectively opened to place the outlet port 218 into communication with the exhaust port 212 thereby venting the outlet.

As the user turns the control wheels 105 on the control body 101, the piston 206 will move backwards and forwards within the cylinder 208. when the simulation software detects that the insertion tube has run up against an obstruction, it calculates the force feedback that will be felt on wheel 105. This information is transmitted to the proportional regulator which will increase the pressure in the air hose 212 leading to the appropriate chamber 208, 209 -11 -such that the user experiences the correct level of force feedback.

In normal use of the proportional regulator, the air pressure is varied in order to move a pneumatic piston to a desired location. The present invention is different in that no movement of the piston is carried out by the regulator.

Instead, this is done by the wheels 105. Instead the pressure regulator is present only to regulate the pressure in the cylinder 207 to provide force feedback.

The system could also mimic other common endoscope scenarios. For example, when the insertion tube of a real endoscope is inserted deeply within a patient, the controls generally feel stiffer. This can be replicated by gradually increasing the pressure in the chambers 208, 209 in response to a signal indicating that the insertion tube has been inserted more deeply into the force feedback unit 105.

Claims

-12 - CLAIMS: - 1. A dummy endoscope system for use in an endoscopy simulator, the system comprising a dummy endoscope comprising an insertion tube and an umbilical both extending from a control body, a pair of rotatable angulation control knobs on the control body, each knob being attached to a drive mechanism which moves as the knob rotates, each drive mechanism being attached to a piston which is slidable in a cylinder or to a pair of pistons each which is slidable in a respective cylinder, first and second ports in the cylinder or cylinders arranged such that increasing pressure at a first port exerts a force on the drive mechanism in a first direction and increasing pressure at the second port exerts a force on the drive mechanism in the opposite direction, each port being connected to a flexible tube extending along the umbilical to the distal end and being connected to a pump to supply it with pressurised air, the pressure of air fed to each tube being arranged to be controlled by control signals from the endoscopy simulator to vary the pressure on the piston and hence the force felt at the control knobs in accordance with the requirements of the simulator.
2. A dummy endoscope according to claim 1, wherein the cylinder is a double acting cylinder with the drive mechanism being attached at opposite ends of a common piston and the first and second ports being provided into the double acting cylinder on opposite sides of the piston.
3. A dummy endoscope accordingly to claim 1 or claim 2, wherein the drive mechanism is a belt drive.

-13 -
4. A dummy endoscope according to claim 3, wherein the belt drive is a chain which engages with the cog attached to the control knob.
5 A dummy endoscope according to claims 2 to 4, wherein an auxiliary cog is provided with its axis spaced from the axis of the control knob and the chain drive is wrapped around the pair of cogs.
6. A dummy endoscope according to any of the preceding claims further comprising a proportional regulator between the pumps and tubes to control the air supply to the tubes based on control signals from the endoscopy simulator.