Abstract:
The present invention relates to a device ( 100 ) in a simulation system for simulating an interventional operation. The device ( 100 ) is arranged to receive a number of real instruments, preferably at least two. The device ( 100 ) comprises a number of moveable carriages ( 16 A- 16 C) corresponding to the number of the real instruments. The device ( 100 ) further comprises a track ( 20 ) and an interconnecting member ( 26 ). The interconnecting member ( 26 ) interconnects the carriages ( 16 A- 16 C) serially. Each carriage ( 16 A- 16 C) is provided with an opening for enabling reception of the instruments. Each carriage ( 16 A- 16 C) further comprises members to receive and lock at least one instrument, and members for receiving a movement from the instrument and generating a force, fed back to the instrument with respect to a simulation characteristic.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to a device in a simulation system for simulating an interventional operation and most preferably endovascular operations.  
       BACKGROUND OF THE INVENTION  
       [0002]     Principles of adult education, tenets of experiential learning, and theories addressing the development of expertise have all underscored the critical role experience plays in the learning process.  
         [0003]     State-of-the-art simulations can be successfully included in contemporary surgical and medical education to offer trainees and practicing physicians the requisite learning experiences based on these educational underpinnings. All learners can be offered opportunities to acquire the essential skills and to achieve specified competency levels based on standardized learning experiences. Simulations can be used to facilitate learning through the evaluation of performance and provision of immediate, individualized, and detailed feedback. Simulations offer controlled settings that allow repetition until the defined performance levels are achieved, decrease stress levels of learners, increase the confidence levels of learners, and increase safety in real settings by assuring the achievement of technical competence prior to work on patients.  
         [0004]     Practicing physicians can improve their skills and can learn new procedures emerging as a result of advances in science and technology through educational interventions involving the use of simulations. In addition, the use of simulations can help address practical issues, such as the demands on faculty time, by providing trainees the opportunities for independent learning and practice. The current emphasis on accountability and on assurance of the quality of health care may also be addressed through the use of such simulations and data on outcomes can be used to assure the public of the competence of physicians.  
         [0005]     Simulations should be considered an essential part of every contemporary educational program that addresses technical skills development. They can be used to ensure effective teaching and learning, to provide valid and reliable means of assessment of the skills of learners, to yield information on specific weaknesses that require improvement, and to create individual profiles of the technical ability of learners. In order to achieve the desired results, specific curricula should be developed based on principles of adult education, experiential learning, and effective feedback. Such simulations may also be used in programs of continuing professional education and certification.  
         [0006]     The initial investment of resources needed for the development and acquisition of simulations and for the creation of training programs that incorporate them effectively in educational models is readily offset by the numerous advantages resulting from expeditious performance of procedures in the operating room, enhancement of patient safety, and decrease in the faculty time needed to teach learners various technical skills. Such simulations may also be used to assess the effectiveness of educational efforts and even to select individuals for training. Thus, the simulations have the potential to make a major impact on programs of surgical and medical education of the future.  
         [0007]     As a result of the rapid developments within the computer technique, simulations, especially for the purpose of surgical and medical education, have improved considerably. However, the presently known apparatus and methods do not allow a full range simulation of different instruments used and methods.  
         [0008]     U.S. Pat. No. 6,106,301 discloses an interventional radiology interface apparatus and method interfaces peripherals in the form of mock medical instruments to a medical procedure simulation system to enable performance of a medical procedure on a virtual patient. The Interface apparatus includes a guide wire, catheter and sheath, an injection syringe, an inflation syringe and a foot switch to realistically simulate the instruments utilized during an actual medical procedure. A user manipulates guide wire, catheter and sheath peripherals to traverse an arterial network toward a simulated blockage shown on the medical procedure simulation system display. The foot switch controls the display to provide a fluoroscope image showing the position of the guide wire, catheter, sheath and blockage within the arterial network. The injection syringe may be manipulated to simulate injections of contrast fluid or other pharmaceutical substances through the catheter or sheath into the virtual patient. When a guide wire is positioned past the simulated blockage within the arterial network, the catheter is exchanged for a balloon-tipped angioplasty catheter, and the inflation syringe is manipulated to simulate inflation of the balloon to reduce the blockage. In addition, the interface apparatus may apply force feedback to the guide wire and catheter to simulate forces encountered by these instruments during an actual medical procedure. The interface apparatus measures peripheral manipulation and transfers these measurements via a processor to the medical procedure simulation system to enable simulation of the medical procedure.  
         [0009]     U.S. Pat. No. 6,267,599 discloses a system for producing highly realistic, real-time simulated operating condition for interactive training of persons to perform minimally invasive surgical procedures involving implements that are inserted and manipulated through small incisions in the patient. The virtual environment for this training system includes a housing with small opening. An implement simulating a surgical implement is inserted into the opening and manipulated relative to the housing. A movement guide and sensor assembly monitors the location of the implement relative to the housing and provides data about the implement&#39;s location and orientation within the housing.  
         [0010]     The reported data is interpolated by a computer processor, which utilizes a database of information representing a patient&#39;s internal landscape to create a computer model of the internal landscape of the patient. With reference to this computer model, the processor controls the occurrence of force feedback opposing the motion of the implement. A two-dimensional image representing the implement, as it would appear within the patient is generated by a processor-controlled video imaging system based on the computer model of the patient&#39;s internal landscape. This computer image of the implement is then merged with a video image loop of a patient&#39;s internal landscape as it appears through a heartbeat and breathing cycle, and the merged image is displayed on a video display.  
         [0011]     The combined elements of real-time visual representation and interactive tactile force feedback provide a virtual training simulation with all elements of actual operation conditions, minus a live patient. The system according to the invention described in U.S. Pat. No. 6,267,599 cannot be used for simulating several instruments simultaneously and in real time.  
         [0012]     WO 99/39317 describes an interface device for handling several instruments through the same interface for simulating instrumental movement and rotation in a medical procedure simulation system. This system uses specially manufactured mock instruments that fit into the interface device and the instruments will be engaged and locked by carriage assemblies prepared to receive their specific respective instrument type. The solution with mock instruments and special order of insertion makes this system unrealistic and complex for the user, since the user needs to know the configuration of the carriage assemblies and the correct insertion order according to this configuration.  
       SUMMARY OF THE INVENTION  
       [0013]     One object according to the best embodiment of the present invention is to provide an interface device for simulation of interventional operations and most preferably endovascular operations, which allows simultaneous simulation of different instruments. The device of the preferred embodiment of the invention provides more accurate control.  
         [0014]     Other advantages according to the best embodiments include: 
        The user can work with at least three independent instruments at the same time.     Real instruments can be used.     Through a better feedback system a more realistic feeling is obtained.     instruments can be inserted and withdrawn as in real operations, without special interaction or control from the user.        
 
         [0019]     For these reasons, the initially mentioned device is arranged to receive a number of real instruments, preferably at least two real instruments. The device comprises: a number of moveable carriages corresponding to the number of the real instruments, a track, and an interconnecting member. The interconnecting member interconnects the carriages serially. Each carriage is provided with an opening for enabling reception of the instruments. Each carriage further comprises members to receive and lock at least one instrument. Each carriage further comprises members for receiving a movement from the instrument and generating a force, fed back to the instrument with respect to a simulation characteristic.  
         [0020]     In one preferred embodiment of the invention, the opening is provided within the interconnecting member.  
         [0021]     In another preferred embodiment, the interconnecting member is a telescopic pipe, allowing insertion of nested instruments.  
         [0022]     In a further preferred embodiment each carriage comprises a detecting arrangement for detecting the type of the instrument inserted through the interconnecting member, which simplifies the handling of the instrument.  
         [0023]     In yet a further preferred embodiment, the device is connected to a control unit to measure the movement of the carriages and control the movement by means of a speed control loop and a position control loop, to provide accurate feedback.  
         [0024]     In one preferred embodiment, the carriages are arranged to move along the track.  
         [0025]     In a further preferred embodiment, the carriage has an actual position and a simulated position. The actual carriage position determines the simulated carriage position from a scale table.  
         [0026]     In another preferred embodiment, the carriage is connected through a transmission for driving along the track. The carriage is provided with a crank block, which is arranged in a torque wheel. The crank block is provided with a mating surface, which is pressed towards a collet that grips the instrument wire, in a nested manner.  
         [0027]     In another preferred embodiment, the force between a suspended plate and a chassis. The chassis is arranged on the carriage, is gauged by means of a force sensor.  
         [0028]     In another preferred embodiment, the carriage is provided with a detecting member, which detects presence of an instrument in the carriage.  
         [0029]     In a further preferred embodiment, the detecting member is arranged to detect the type of each instrument.  
         [0030]     In another preferred embodiment, the instruments are categorized into the types with respect to at least one of the following characteristics: thickness, color, structure, material, identity and/or bar code.  
         [0031]     In yet another preferred embodiment, the detecting member is an optical sensor.  
         [0032]     In yet another preferred embodiment, a first interconnecting member is arranged between the opening and the first carriage. A second interconnecting member is arranged between the first carriage and the second carriage. A third interconnecting member is arranged between the second carriage and the third carriage.  
         [0033]     In another preferred embodiment, the device comprises a processing unit for measuring a longitudinal movement and a movement of rotation of the instrument.  
         [0034]     In another preferred embodiment, the device comprises a processing unit, which provides force feedback in the longitudinal direction and in the direction of rotation, of the instrument.  
         [0035]     Most preferably, the instruments are real instruments, with one simulated end. This allows testing different commonly available instruments.  
         [0036]     In yet another preferred embodiment, the device comprises a locking member, for clamping an instrument. The locking member is attached to a central wall. The locking member may comprise a member for applying a torque.  
         [0037]     In yet another preferred embodiment, the crank block is provided inside a torque wheel. The crank block moves in a longitudinal direction and is fixed in the direction of rotation, relatively to the torque wheel.  
         [0038]     The invention also relates to a method of simulating an interventional operation by means of a device in a simulation system is used. The device is arranged to receive a number of instruments, preferably at least two instruments. The device comprises a number of moveable carriages corresponding to the number of the instruments, a track and an interconnecting member. The method comprises the steps of inserting a number of instruments into the device, receiving the instruments by each carriage, which are interconnected serially, by receiving and locking at least one instrument. Each carriage further comprises members for receiving a movement from the instrument and generating a force fed back to the instrument with respect to a simulation characteristic.  
         [0039]     According to one aspect of the invention, a simulator system, preferably an interventional procedure simulator system is provided. The simulator system comprises at least a first and a second displaceable member and a control system. The control system comprises: a first controller (F 1 (s)), controlling the speed of the first displaceable member ( 16 A- 16 C) towards a set value (CDV). The control system further comprises a second controller (F 2 (s)), for combining an error in a position (CAP) and a speed of the second, previous displaceable member (PCAV) to a set speed for the first member. The second controller (F 2 ) controls CDV=C 1 *(CAP−PCAP)+C 2 *PCAV, wherein C 1  and C 2  are constants.  
         [0040]     According to another aspect of the invention, a simulator system, preferably an interventional procedure simulator system is provided. The simulator system comprises an arrangement for receiving an instrument to be simulated. The arrangement comprises identification means for identifying the instrument.  
         [0041]     In yet another preferred embodiment, the arrangement for detecting an instrument, comprise at least one IR diode and at least one IR phototransistor.  
         [0042]     In one preferred embodiment the identification means consists of at least one of thickness, color, structure, material of the instrument, identity and/or bar code.  
         [0043]     According to another aspect of the invention a simulator system, preferably an interventional procedure simulator system is provided. The simulator system comprises members to receive and lock an instrument to be simulated, and a control unit comprising a force sensor. The control unit controls towards a demand force value, DF. A force that a user experiences in the instrument is measured with the force sensor and a signal from the force sensor is fed back in a force feedback control loop towards a set force.  
         [0044]     According to another aspect of the invention a simulator system, preferably an interventional procedure simulator system, an arrangement for generating a resistance in a simulated instrument is provided. The arrangement comprises a control unit and a force sensor. The arrangement further comprises a force feedback control loop for controlling an actuator device for driving an instrument receiver member in a direction. The arrangement further comprises an inner force control loop. The force sensor is arranged for measuring the resistance. A signal from the force sensor is fed back in the inner force control loop that controls, with a loop-amplification, K, provided by the control unit, towards a set force value, SF, provided by the control unit and the inner force control loop controlling the actuator.  
         [0045]     In one preferred embodiment, the control unit controls the loop amplification, K, to achieve a resistance.  
         [0046]     In one preferred embodiment, the control unit controls the set force, SF, to achieve a resistance.  
         [0047]     According to another aspect of the invention a simulator system, preferably an interventional procedure simulator system is provided. The simulator system comprises an arrangement for generating a resistance in a simulated instrument. The simulator system further comprises an arrangement for receiving and fixing a part of an instrument in a device for measuring instrument movement and feeding back a force to the instrument. The arrangement comprises a member for clamping the instrument. The arrangement comprises a crank block, which is arranged in a torque wheel, the crank block is movable in a longitudinal direction inside the torque wheel. The crank block is provided with a mating surface, which is pressed towards a collet that grips the instrument part. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0048]     In the following the inventions will be described in a non-limiting way with reference to the best embodiment of the invention, in conjunction with enclosed drawings, in which:  
         [0049]      FIG. 1  shows a general overview of the device according to the present invention, when used,  
         [0050]      FIG. 2  shows a sectional view of the device,  
         [0051]      FIG. 3  shows the carriages schematically,  
         [0052]      FIG. 4  shows a sectional view of a carriage,  
         [0053]      FIG. 5  shows a lateral view of a carriage,  
         [0054]      FIG. 6  shows a front view of the optic sensor,  
         [0055]      FIG. 7  shows a lateral view of the locking member,  
         [0056]      FIG. 8  shows a block diagram of the control system,  
         [0057]      FIG. 9  shows a block diagram of the passive force feedback loop, and  
         [0058]      FIG. 10  shows a block diagram of the active force feedback loop. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0059]     In the following, the best embodiment of the invention and some modifications thereof, will be described in detail and with reference to the enclosed drawings. Some examples of other possible embodiments will also be described.  
         [0060]     The interface device  100  according to the best embodiment of the present invention, as shown in  FIG. 3 , comprises: 
        Processing units  10  arranged on corresponding Printed Card Boards, PCBs.     A communication unit  12 .     A power supply  14 .     At least three carriages  16 A- 16 C. Each carriage  16  having the same technical features. The carriages  16 A- 16 C are arranged to lock different types of instruments, which is described later on.     Motors and transmission  18  for driving the carriages  16 A- 16 C.     A track  20  on which the carriages  16 A- 16 C can move. In this embodiment it is a common track, but in other embodiments it can for example be three tracks in parallel or the like.     An opening  22  provided with entry pipes  24 .     Interconnecting members  26 , in form of telescopic pipes  26 A- 26 C, see  FIG. 2 .     A cover  28 .     A control unit  30 , in form of software in a PC.        
 
         [0071]     Each carriage  16 A- 16 C comprises:  
         [0072]     A chassis  32  provided with wheels  34 . In other embodiments the chassis can be provided with runners, slide bushings or the like. The chassis  32  is attached to a transmission  18 , preferably a gear belt transmission, through a connector pin for driving along the track  20 . In other embodiments chain transmission, wire transmission or pneumatic cylinder transmission can be used. A suspended plate  38  is attached to the chassis  32  through a spring suspension. One of the springs is a sensor, in form of a load cell, which measures the force between the suspended plate  38  and the chassis  32 . This sensor is henceforth called the force sensor  40 . A substantially, centrally provide wall  42 , is arranged on the suspended plate  38 , see  FIG. 4  and  FIG. 5 .  
         [0073]     The function of each carriage  16 A- 16 C is to detect when an instrument has passed through the carriage, by means of a detecting member  48 , determine the type of the instrument and if a decision is made from the control unit  30 , to lock the instrument. The locking mechanism, further described later on, is activated by the locking member  44  to provide a locking.  
         [0074]     Connections for the interconnecting member  26  are arranged at the opening  22  and the outlet  46 . In the best embodiment of the present invention the interconnecting members are in form of telescopic pipes, but can also be in form of elastic pipes or the like, for example made of rubber or non-rigid plastic. The interconnecting members  26  make it possible to operate with three interacting nested instruments. The interconnecting members  26  moves between the carriages  16 , see  FIG. 2 . The first interconnecting member  26 A, is arranged between the opening  22  and the first carriage  16 A, the second interconnecting member  26 B is arranged between the first carriage  16 A and the second carriage  16 B and the third interconnecting member  26 C is arranged between the second carriage  16 B and the third carriage  16 C.  
         [0075]     The detecting member  48 , in form of an optical sensor, detects presence of an instrument in the carriage  16 . The optical sensor  48  can furthermore determine which type the instrument belongs to. The instruments are categorized into said types according to thickness, and/or other identity signs, for example color, structure and/or material of the instrument. In another embodiment the instruments can be provided with bar codes and the detecting member can be arranged with a bar-code reader. The detecting member  48  is arranged at the outlet  46  and comprises an IR diode  104  and an IR phototransistor  106 , which are arranged at each sides of the tool passage  108 , see  FIG. 6 , through which the instruments passes. The light travels from the IR diode  104  to the IR phototransistor  106  through the light channel  110 . The IR diode  104  emits IR light through voltage supply and current limiting with a resistance. The light is led via the light channel  110  to the IR phototransistor  106 , which is more or less permeable for current, depending on how much light that reaches it. When there is no instrument in the tool passage  108 , a maximal amount of light reaches the IR phototransistor  106 . When an instrument is present in the light channel  110 , it blocks the light flow to the IR phototransistor  106  and hence less light reaches it. The more light that reaches the IR phototransistor  106 , the more current the IR phototransistor  106  let through and the higher the voltage over the resistance gets. An A/D transducer measures that voltage and the measurement test result is sent to the control unit  30 .  
         [0076]     The locking member  44  is arranged to clamp up an instrument, and is attached in the central wall  42 . The same locking member  44  can provide a torque on an instrument, such that it provides force-feedback to the instrument in the direction of rotation.  
         [0077]     Subsequent to the detection and locking of the instrument/instruments is/are, the carriage  16  follows the users movement of the instrument. This is done by means of the transmission  18  and the control electronic, and is so controlled that a demand force is obtained from the control unit  30 . The force-feedback is further described later on.  
         [0078]      FIG. 7  shows the locking member  44  according to the best embodiment of the present invention. A central unit  50  with a torque wheel  52  is attached to the central wall  42  by means of a bearing, for example a ball bearing or a roller bearing. The torque wheel  52  is provided with a gear ring  54 . A torque motor  56  with a motor hub  58  and a torque motor gear wheel  60 , is arranged to drive the torque wheel  52 . A lock wheel  62 , is attached to the torque wheel  52  through a bearing, for example a ball bearing, roller bearing, needle bearing or a polymer bush. Further, a lock motor  64 , with motor hub  66  and lock motor gear wheel  68 , is arranged to drive the lock wheel  62 . The locking member  44  further comprises a collet  70 , which grips the instrument, and a collet seat  72 , in which the collet  70  is arranged.  
         [0079]     A crank block  74 , which is arranged inside the torque wheel  52 , can move in a longitudinal direction, but is fixed in the direction of rotation, relatively the torque wheel  52 . Said crank block  74  is provided with wings. The wings run in a guide track, which is arranged in the torque wheel  52 . The crank block  74  is provided with a mating surface, which is pressed towards the collet  70  that grips the instrument wire. Instead of the crank block  74  other chucking principles can be used.  
         [0080]     The locking member  44  further comprises an inner, lock wheel  62 , which is attached through bearings, for example ball bearings, needle bearings or the like, to the outer, torque wheel  52 . The torque wheel  52  and the lock wheel  62 , respectively, are provided with gear rings  54 . The lock wheel  62  rotates inside the torque wheel  52  and is provided with a thread. The thread affects the crank block  74 , which is fixed in the direction of rotation in the torque wheel  52 , but runs freely in longitudinal direction. The collet  70  is provided at the back edge of the lock wheel  62 . The entire central unit  50  is arranged with two openings  22  in the center, through which the instrument can pass.  
         [0081]     Two motors, the torque motor  56  and the lock motor  64 , are fixed to the central wall  42 . The motor axis are provided with motor gear wheels  60 ,  68 , which goes against the gear rings  54  of the torque motor  56  and the lock motor  64 .  
         [0082]     In the initiation sequence of the interface device, the carriages  16  are positioned closely in a row and towards the instrument entrance side. The user inserts an instrument or a tool in the entry pipe  24 , through the first interconnecting member  26 A, into the first carriage  16 A and through its central unit  50  and out though its outlet  46  there the detecting member, in form of e.g. an optical sensor  48  detects the instrument&#39;s presence and type. The control unit  30  decides from the detected instrument type, whether to lock the instrument or not. If the first carriage  16 A does not lock the instrument, the instrument passes through the first carriage  16 A and out into the second interconnecting member  26 B and further towards the second carriage  16 B.  
         [0083]     If the first carriage  16 A locks the instrument, the locking sequence starts. Thus, the torque wheel  52  is fixed through the torque motor  56 . After that the lock wheel  62  is rotated by means of the lock motor  64 , so that the crank block  74  is pressed towards the collet  70 , which clamps around the instrument. The locking member  44  and the suspended plate  38  are consequently fixed to the instrument.  
         [0084]     After the locking sequence follows the force and torque control. A force controller control, with high frequency from the force sensor  40 , the position of the chassis  32  so that a given set force is maintained in the force sensor  40 . The force is transferred to the instrument. The user feels this set force in the instrument, which gives force-feedback in the longitudinal direction. The torque control sets out a set torque, by means of the torque motor  56 , which causes force-feedback in the direction of rotation. The set force and set torque are determined from the simulation. Information about the position of the instruments in the longitudinal direction and in the direction of rotation is send continuously to the simulation unit  90 .  
         [0085]     If the user withdraws the instrument, so that the carriage  16  passes its initial position, the unlocking sequence starts. The unlocking sequence is carried out in a reversed order as the locking sequence. After the unlocking sequence, the instrument runs freely in the carriage  16 .  
         [0086]     All the carriages  16 A- 16 C operate in the same way. An unlocked carriage follows the nearest previous carriage&#39;s movements in a longitudinal direction along the track  20 . To make the movement of the carriage flexible and reduce the control error, an inner, speed control loop  86  and an outer, position control loop  88  are used. The purpose of the speed control loop  86  is to control the speed of the carriages  16  with respect to each other. The purpose of the position control loop  88  is to keep the distance of the carriage  16  to previous carriage  16  constant.  
         [0087]     The block diagram of  FIG. 8  shows the control system G(s). The system G(s) represents one of the carriages ( 16 A- 16 C) driven by its longitudinal motor. F 1 (s) is a controller, which controls the speed of the carriage towards a set value, Carriage Demand Velocity, CDV. F 1  is placed in one of the processor units  10  in the carriage  16 . F 1  gives a motor force to the longitudinal motor of the carriage  16 .  
         [0088]     F 2 (s) is a controller, which is placed in the control unit  30 , that is, in the PC. F 2  combines the error in position, (Demand position-Carriage Actual Position, CAP) and the speed of previous carriage  16 , (Previous Carriage Actual Velocity, PCAV) to a set speed for the carriage  16 . 
 
 F 2 controls CDV= C 1*(CAP−PCAP)+ C 2*PCAV 
 
         [0089]     wherein:  
         [0090]     CDV=Carriage Demand Velocity  
         [0091]     CA=Carriage Actual Position  
         [0092]     PCAP=Previous Carriage Actual Position  
         [0093]     PCAV=Previous Carriage Actual Velocity  
         [0094]     C 1  and C 2  are constants  
         [0095]     When the carriage  16  has locked an instrument or a tool, the control unit  30  controls towards a demand force value, DF. If the chosen demand force value for example is zero, the carriage  16  will be controlled so that the user experiences zero force in the instrument. If the user for example passes through a stenosis in a vessel, in the simulation, the user will feel a resistance in the instrument and then a desired demand force value is set to that resistance. To accomplish this, the force sensor  40  and the force feedback control loop  102  controls the longitudinal motor. The longitudinal motor drives the carriages  16 A- 16 C along the track  20 . The force that the user experience in the instrument is measured with the force sensor  40 . The signal from the force sensor  40  is fed back in a control loop towards a set force, SF. This force feedback control loop  102  is shown in  FIG. 9 .  
         [0096]     There are two types of force feedback that can be used “passive force feedback” and “active force feedback”.  
         [0097]     The control unit  30  sets the set force value, SF to the controller to be zero (SF=0). It determines the amplification in the inner, force control loop  112  (not the set force!) depending on the set force, SF, that is, the resistance that the simulation want the user to experience. This results in that the frictions in the system G(s) is compensated in a varying extent, determined from the loop amplification.  
         [0098]     Example: With high amplification the user experience zero force. With low amplification, the user experience high resistance. In this way the friction will be what the user experience as resistance and a “passive force-feedback” is accomplished, see  FIG. 9 .  
         [0099]     Thus is: 
 
 K=C 1*(1 −C 2*DF) 
 
         [0100]     wherein:  
         [0101]     K=Loop amplification, F 3 (s)  
         [0102]     DF=Demand Force,  
         [0103]     C 1  and C 2  are constants.  
         [0104]     To provide an “active force feedback” the Demand Force, DF/Set Force value, SF, must be controlled. In this case it is the longitudinal motor, which causes the resistance, see  FIG. 10 .  
         [0105]     The user inserts the instrument for the endovascular operation, for example catheters, balloons, wires and the like, through the entry pipe  24  in the opening  22 . The instrument is led through the interconnecting member  26  into the carriages  16 A- 16 C, which carriages  16 A- 16 C detects the instruments and grab hold of the instrument to be able to measure the movement of the instrument and give feedback to that movement.  
         [0106]     The interface device with associated control unit  30  has the following function: 
        Measure the movement of at least three separate nested instruments. These instruments are real, with one modification, soft and curved points are cut off. The measured movement consists of the longitudinal direction and the direction of rotation of the instrument point.     Measure a pedal position, depressed and released.     Measure the flow from a contrast syringe.     Measure the pressure from a pressure pump for balloon blasting.     Send measured values to the simulation unit  90 .     Receive forces and torque on the instruments respectively from the simulation unit  90 .     Give force-feedback in longitudinal direction and the direction of rotation of the instruments according to received forces and torques.     Measure the signal from a special instrument.        
 
         [0115]     A control program for a system and the device is described in a parallel application, entitled “AN INTERVENTIONAL SIMULATOR CONTROL SYSTEM” (SE 0203567-3) by the same applicant and incorporation herein through reference.  
         [0116]     The present invention has now been described by means of the best embodiment and modifications thereof. However the invention is not limited to the illustrated embodiments, but variants and other modifications are also possible within the scoop of the claims. It is also possible to connect several devices to one or several PC&#39;s for simulating one simultaneous interventional procedure.  
       REFERENCE SIGNS  
       [0000]    
       
          processor unit  10   
          communication unit  12   
          power supply  14   
          carriage  16   
          first, second, third  16 A- 16 C  
          transmission  18   
          track  20   
          opening  22   
          entry pipe  24   
          interconnecting members  26   
          first, second, third  26 A- 26 C  
          cover  28   
          control unit  30   
          chassis  32   
          wheel  34   
          suspended plate  38   
          force sensor  40   
          central wall  42   
          locking member  44   
          outlet  46   
          detecting member  48   
          central unit  50   
          torque wheel  52   
          gear ring  54   
          torque motor  56   
          torque motor hub  58   
          torque motor gear wheel  60   
          lock wheel  62   
          lock motor  64   
          lock motor hub  66   
          lock motor gear wheel  68   
          collet  70   
          collet seat  72   
          crank block  74   
          speed control loop  86   
          position control loop  88   
          simulation unit  90   
          device  100   
          force feedback control loop  102   
          IR diode  104   
          IR phototransistor  106   
          tool passage  108   
          light channel  110   
          Inner force control loop  112