Safety system for detecting collision of medical table

Abstract

A system (200) for detecting a collision of a patient support device (18) with an object, ground, or a portion of an operating table, where the system (200) comprises: a patient support device (18) that can be used as a portion of an operating table; a load sensor device having at least one load sensor which outputs a sensor value; a load determination unit that determines a load from the sensor value, the load comprising a load acting on the load sensor device or a load acting on the patient support device (18); and a detection unit which, during the downward movement of the patient support device (18) or of at least one section of the patient support device (18), detects a possible collision of the patient support device (18) with the object, the ground or a part of the operating table when the load determined by the load determination unit is below a predetermined first threshold value.

Description

[0001] This application claims the priority of German patent application 10 2022115 287.1 filed in the German Patent and Trademark Office on June 20, 2022. The disclosure content of German patent application 10 2022 115 287.1 is hereby incorporated into the disclosure content of the present application. Technical Field

[0002] The present disclosure relates to a medical and surgical table in which a table top and / or a section of a table top is movable. In particular, this relates to a system that can detect collisions of the table. For example, the table top may collide with an object during its downward movement or a section of the table top may collide with the base of the table while descending. Background Art

[0003] Operating tables are used, for example, to support patients during surgical operations. Due to the flexibility in assembling the operating table, the number of accessories and the different possibilities for positioning the patient that the operating table offers, nurses and doctors must take into account several important aspects in order to be able to use the operating table correctly. For example, the accessories used and their configuration should be adapted to the weight of the patient. In addition, the patient support device on which the patient is located should only be moved, turned or tilted within permissible limits. When adjusting the operating table, it should be ensured that the patient is properly fastened and does not fall off or slide off the operating table. In addition, when adjusting the operating table, care should be taken that the operating table does not collide with external objects, such as a C-arm.

[0004] The operating table is usually covered with a cover during surgery. When the patient support device is electrically adjusted in order to position the patient, the patient support device can easily collide with surrounding objects. The operating table itself or also the cover located on the operating table can impair the field of vision of the user adjusting the operating table. This can cause collisions with objects that are not in the user's field of view. Collisions can also occur due to carelessness of the user.

[0005] The patient support device of the operating table can have replaceable, detachably connectable segments. Usually, some or all of the replaceable segments are movable. By using different replaceable segments, a single operating table can be reconfigured in different ways for different patients and medical procedures. In addition, the individual segments or the entire patient support device can be adjusted in different ways. For example, the individual segments or the entire patient support device can be tilted or flipped or moved in the longitudinal direction or vertical direction. When adjusting the individual segments or the entire patient support device, it may happen that the segments or the patient support device collide with other parts of the operating table, such as the base of the operating table. In addition, the patient support surface or its segments may also collide with the ground on which the operating table stands.

[0006] The collision of the patient support device with external objects, the ground or other parts of the operating table may damage expensive equipment items. In addition, due to the collision, people may be injured, for example, body parts may be clamped.

[0007] The collision that occurs should be detected and the movement of the patient support device should be stopped quickly in order to limit the force or pressure at the collision point. Thus, damage to external devices, to personnel and to the operating table itself can be avoided as much as possible.

[0008] Document US10646191 B2 discloses a collision avoidance system and method for a bed that can be used in medical applications. The system includes a load sensor that measures the load caused by supporting a bed surface with and / or without a load on the bed surface, and outputs corresponding load data. In addition, a collector is provided, which communicates with the load sensor and collects the load data output by each load sensor. An evaluation processor is connected to the collector and determines whether the collected load data gradually increases or decreases within a preset time period, wherein the gradual increase or decrease of the collected pressure data within the preset time period indicates that the bed surface collides with an object. The system also includes a control device that controls the bed surface so that when the evaluation processor determines that the detected load data gradually increases or decreases within a preset time period, the bed surface stops moving. US10646191B2 does not disclose a collision detection system, which detects a possible collision between the patient support device and the object when the load determined by the load determination unit is lower than a preset threshold value during the downward movement of the patient support device or at least one section of the patient support device. US 10646191 B2 also does not teach a system that temporarily stops the collision detection function as a reaction to a sudden weight increase. Summary of the invention

[0009] The object of the present disclosure is to provide a system which is advantageously designed for detecting a possible collision of a patient support device with an object.

[0010] Additionally, the system may be implemented to stop movement of the patient support device when a collision is detected.

[0011] According to a first aspect of the disclosure, a system is proposed, which is designed to detect a collision of a patient support device with an object, a floor, or a part of an operating table. The system may include a patient support device, a load sensor arrangement including at least one load sensor, and a detection unit.

[0012] The patient support device can be used as part of an operating table and can be used to support a patient. In some embodiments, the patient support device can be a surgical patient support device on which the patient is supported during a surgical operation. In addition, the patient support device can be used to fasten accessories. The patient support device can be modularly constructed and have a main support surface section, which can be expanded by coupling a number of auxiliary support surface sections. The main support surface section and the auxiliary support surface section can have mechanical connecting elements, by means of which the main support surface section and the auxiliary support surface section can be detachably connected. The auxiliary support surface section can be, for example, a leg section, a foot section or a head section. In addition, the auxiliary support surface section can also be an extension or an intermediate section, which is, for example, inserted between the main support surface section and the head section. Sliding rails or lateral rails can be arranged on the sides of the main support surface section and the auxiliary support surface section. Accessories can be detachably fastened to the sliding rails or lateral rails.

[0013] In some embodiments, the patient support device can be fixedly connected to the column of the operating table. The operating table can be movable. The support or base of the operating table can have wheels or rollers, by which the operating table can travel on the ground. Alternatively, the support or base can be fixedly anchored to the ground.

[0014] In some embodiments, the patient support device can be designed so that it can be detachably connected to a movable surgical patient transporter and a column of an operating table. Before the surgical operation, the patient support device can be mounted on the patient transporter. The patient can be brought to the operating table by means of the patient transporter. There, the patient support device can be fastened to the operating table column and disconnected from the patient transporter. While the patient support device is mounted on the patient transporter, most of the preparations for the surgical operation can be carried out. For example, the patient support device can be assembled from individual sections and accessories and the patient can be prepared for the surgical operation. Only when the preparations are completed can the patient support device be fastened to the operating table column.

[0015] The load sensor device can have one or more load sensors. When only the load is to be determined, a single load sensor can be sufficient. However, the load sensor device can also contain multiple load sensors, such as two, two or more, three, three or more, or four load sensors, or also include other load sensors. This is particularly meaningful when the center of gravity of the load is also to be determined in addition to the load. When using a 6D force measurement sensor, the center of gravity can also be calculated based on the single load sensor. At least one load sensor can output a sensor value, from which the load acting on the load sensor device can be determined and in addition the load acting on the patient support device can also be determined. The load acting on the load sensor device can especially include all external force variables, i.e., forces and moments acting on the load sensor device.

[0016] The load sensors can be, for example, force sensors, in particular weighing cells, which measure the forces acting on the respective sensors. The force sensors can output an electrical signal, for example a voltage, as an output signal, from which the respectively measured force can be derived. It can also be provided that the force sensors output as sensor values ​​the specific magnitude of the force respectively measured by the force sensor, for example in digital form.

[0017] Furthermore, it is conceivable that the load sensor arrangement determines the resulting total force from the sensor values ​​of a plurality of load sensors, wherein the resulting total force results from the individual forces acting on the different force sensors.

[0018] The loads acting on the load sensor device include, for example, loads caused by components of the operating table arranged above the load sensor device and loads caused by the patient supported on the patient support device or other objects located on the patient support device. In addition, a person standing next to the operating table can also cause a load on the patient support device, for example by supporting the person with a hand or another body part on the patient support device. In addition, external forces that occur in different ways can cause loads on the patient support device. Such loads can also be measured by the load sensor device.

[0019] The load sensor device can be arranged in the operating table at different positions. In some designs, the load sensor device can be integrated into the column of the operating table or into the patient support device. In addition, the load sensor device can be arranged at or adjacent to the intersection formed by the column and the patient support device or the support foot (or base). Therefore, the load sensor device can be arranged, for example, between the patient support device and the column. Alternatively, the load sensor device can be arranged, for example, between the column and the support foot.

[0020] In some designs, the load sensor device may be integrated into the patient transporter.

[0021] The load sensor device can be integrated into an operating table or a patient transporter so that all loads flow through the load sensor device or are transmitted through it. In particular, loads caused above the load sensor device can flow through the load sensor device or be transmitted through the load sensor device.

[0022] The load determination unit can be coupled to the load sensor device and obtain sensor values ​​output by one or more load sensors. Based on the sensor values, the load determination unit can determine the load and, if desired, the center of gravity of the load in a preset coordinate system. The load can include a load acting on the load sensor device or a load acting on the patient support device. The load can be given by the load determination unit, for example, in the form of weight, especially in kilograms, or in the form of force, especially gravity, for example in Newtons. In some designs, the load determined by the load determination unit can be the load acting on the load sensor device or the load acting on the patient support device or the total load of the operating table or the total load of the patient transporter on which the patient support device is mounted. The center of gravity of the load can be given relative to a defined point of the patient support device or the operating table. In addition, the center of gravity of the load can also be given in a coordinate system that may not be related to the patient support device or the operating table, but the origin of the coordinate system is fixed at an external point, for example, a defined point in the operating room. The absolute position of the center of gravity of the load can thus be given.

[0023] The load acting on the load sensor device can also be referred to as the measurement load. The measurement load corresponds to the load generated by all persons, objects and forces on the operating table or the patient transporter above the load sensor. The measurement load corresponds to the load value measured by the load sensor device.

[0024] The load acting on the patient support device can be called effective load and corresponds to the following load, which is caused by components and personnel and external forces that are not associated with the patient support device or the operating table or the patient transporter and acts on the patient support device. The components associated with the patient support device can be the following components, which are identified by means of a detection system, such as a support surface segment or a support surface section and / or other accessories. The influence of the components associated with the patient support device or the operating table or the patient transporter is not taken into account in the effective load. Only the remaining components, that is, the components that are not associated with the patient support device or the operating table or the patient transporter contribute to the effective load. This can be, for example, an accessory that is not identified by the detection system, or it can be other objects placed on the patient support device. In addition, the patient on the patient support device contributes to the effective load. In addition, all forces acting on the patient support device from the outside contribute to the effective load, which are, for example, applied to the patient support device by personnel and / or objects outside the patient support device.

[0025] When the patient support device is mounted to a column of an operating table or a patient transporter, the total load of the operating table or patient transporter can also be determined. The total load of the operating table or patient transporter is the load resulting from the measured load and the load caused by components associated with the operating table or patient transporter and located below the load sensor device. Thus, the total load takes into account the load of components that are located below the load sensor device and cannot be measured by the load sensor device and thus do not contribute to the measured load. Thus, the total load is the load resulting from the entire operating table or patient transporter, the patient, components associated with the operating table or patient transporter, components not associated with the operating table or patient transporter and other external forces.

[0026] The detection unit can be coupled to the load determination unit and can receive the variables determined by the load determination unit, namely the load and, if necessary, the center of gravity of the load. The detection unit can detect a possible collision of the patient support device with an object, the ground or a part of an operating table during the downward movement of the patient support device or at least one section of the patient support device. Such a collision causes a reduction in the load determined by the load determination unit. The detection unit detects a possible or potential collision of the patient support device with an object, the ground or a part of an operating table during the downward movement of the patient support device or at least one section of the patient support device when the load determined by the load determination unit is below a predefined first threshold value.

[0027] The collisions detected by the detection unit, as described herein, also include collisions of accessories fastened to the patient support device with objects, the ground or parts of the operating table. For example, accessories can be fastened to the sliding rails or lateral rails and collide with other objects when the patient support device moves downward. Such collisions cause a load reduction determined by the load determination unit.

[0028] When a possible collision is detected, the movement of the patient support device can be stopped quickly and the forces or pressures at the collision point can be limited. Damage to external devices, personnel and the operating table itself can thus be avoided as much as possible. The faster the movement of the patient support device is stopped, the greater the pressure at the collision point can be limited.

[0029] The downward movement of the patient support device or a section of the patient support device is a movement in which at least a part or section of the patient support device moves downward, i.e. in the direction of the ground on which the operating table stands. The downward movement can be carried out in different ways. For example, the patient support device can be tilted or turned over. The tilt (English: trend) of the patient support device is also called Trendelenburg tilt, in which the patient is supported so that the patient's head is located at the bottom and the patient's pelvis is higher up. In the reverse Trendelenburg tilt, the patient's head is supported at a high position and the pelvis is lower down. Turning (English: tilt) means that the patient support device is tilted to the side. The tilting or turning of the patient support device is carried out around one or more hinges. The part of the patient support device located on one side of the one or more hinges moves downward here, while the part located on the other side of the hinge can move upward.

[0030] The patient support device can be tilted or turned as a whole. It is also possible that only one or more sections of the patient support device are moved downwards, for example by adjusting, in particular tilting or turning, one or more sections. For example, the leg section of the patient support device can be tilted downwards.

[0031] In addition, the patient support device can be moved downward as a whole by means of the lifting column. As long as the tilting or tilting is not carried out at the same time, the tilt angle and the tilting angle of the patient support device are maintained during the downward movement.

[0032] During the downward movement of the patient support device or a section of the patient support device, a collision with an object may occur. The object may be, for example, an object located below the patient support device. Furthermore, the patient support device may collide with the ground on which the operating table is located. Furthermore, the patient support device may collide with other parts of the operating table. For example, tilting of the entire patient support device or only a section, such as a leg section, may result in the patient support device or the section colliding with the foot of the operating table.

[0033] As described, the detection unit can monitor the load determined by the load determination unit and detect when the load falls below a preset first threshold value when the patient support device or at least one section of the patient support device moves downward. A collision of the patient support device or a part thereof causes such a load reduction. However, the load reduction can also have other causes. For example, an object can be removed from the patient support device during the downward movement. This can also cause a load reduction. Therefore, it can only be inferred from the load reduction that a collision may have occurred.

[0034] The preset first threshold value may refer to a reference value. In some designs, the reference value may be a load determined by the load determination unit shortly before the downward movement begins. The first threshold value may be defined such that it is smaller than the reference value and has a preset distance from the reference value. The value of the first threshold value or the distance between the first threshold value and the reference value is a magnitude for the sensitivity of the collision detection. The smaller the distance between the first threshold value and the reference value, the higher the sensitivity of the collision detection. The larger the distance between the first threshold value and the reference value, the more load reduction is required in order to trigger the collision detection. Therefore, the larger the distance between the first threshold value and the reference value, the more pressure is generated at the collision point or the more force acts on the collision point. The opposite applies, the smaller the distance between the first threshold value and the reference value, the greater the probability of an erroneous collision detection.

[0035] The system described herein can also optionally be designed to detect a possible collision of the patient support device with an object, the floor or a part of the operating table not only when the patient support device or at least one section of the patient support device is moved downward, but also when the patient support device or at least one section of the patient support device is moved upward. Such a detection during the upward movement can be performed, for example, by the described detection unit or a further detection unit.

[0036] The load determination unit and / or the detection unit can be integrated into the operating table or the patient transporter or can be located outside the operating table or the patient transporter. For example, the load determination unit and / or the detection unit can be integrated into a computing unit that is located outside the operating table or the patient transporter and is connected to the operating table or the patient transporter, for example via radio or fixed laying cables.

[0037] If an additional load is applied to the patient support device during the downward movement, for example due to a person being supported on the patient support device or an object being placed on the patient support device or being fastened to the patient support device, the load determined by the load determination unit increases. In addition, impacts can be applied to the patient support device from above. This can cause the load to oscillate, so that it falls below the first threshold value, although no collision has occurred. In order to avoid such false detections or to reduce their probability, in some embodiments the detection unit can be designed such that after the load determined by the load determination unit exceeds a preset second threshold value, the detection unit briefly does not indicate a possible collision or briefly interrupts collision detection.

[0038] The second threshold value may be greater than the first threshold value. The second threshold value may be defined such that it is greater than a reference value and has a preset distance from the reference value, wherein the reference value is the load determined by the load determination unit shortly before the start of the downward movement. In some designs, the distance between the first threshold value and the reference value may be the same or approximately the same as the distance between the second threshold value and the reference value. It may also be provided that the distance between the first threshold value and the reference value and the distance between the second threshold value and the reference value differ in value by no more than 10%, 20%, or 30%.

[0039] After the load determined by the load determination unit exceeds the second threshold, the detection unit may not indicate a possible collision for a certain time in order to inhibit erroneous collision detection. The time may be referred to as a "snooze time" and has a preset duration, for example, a duration in the range of 0.5 seconds to 10 seconds or longer.

[0040] In some embodiments, a false collision detection can be avoided in that a third threshold value is predefined, which is lower than the first threshold value. After the load determined by the load determination unit exceeds a predefined second threshold value, the collision detection can be terminated. The second threshold value can be designed as described above. The detection unit only briefly detects a possible collision when the load determined by the load determination unit is below the third threshold value. Since the third threshold value is lower than the first threshold value, the load reduction must be greater in order to detect a possible collision. As a result, false collision detection can be avoided in the time window after the first threshold value is exceeded, but a collision that actually occurred can be detected.

[0041] The time window in which the detection unit detects a possible collision only when the third threshold value is fallen below can have a predefined duration, for example a duration in the range of 0.5 seconds to 10 seconds or longer.

[0042] In some embodiments, a first threshold value, a second threshold value, and / or a third threshold value are respectively preset individually for at least a portion of an axis and / or for the lowering of the patient support device by means of a lifting column, wherein the patient support device or at least a section of the patient support device can be tilted or turned during the downward movement about the axis. Thus, for each hinge or a portion of hinges that causes the tilting or turning of the patient support device or the section, one or more of the three different threshold values ​​can be preset. In particular, the sensitivity of the collision detection can thereby be set individually for each hinge or a portion of hinges.

[0043] The load determination unit can determine different loads in relation to the inclination and / or the turning of the patient support device. In some embodiments, one or more or all threshold values ​​in the group of the first, second and third threshold values ​​can be variable. For example, the corresponding threshold value can be related to the inclination angle and / or the turning angle of the patient support device or at least one section of the patient support device. Thereby, a dependency of the load determined by the load determination unit on the inclination angle and / or the turning angle can be at least partially compensated. The corresponding threshold value can be related to the adjustment or position of one or more hinges. When the position of one or more hinges changes continuously during the downward movement, the threshold value can also be changed continuously.

[0044] In some embodiments, the distance between the first threshold value and the load determined by the load determination unit shortly before the start of the downward movement is approximately the same in value as the distance between the second threshold value and the load determined before the start of the downward movement. If the threshold values ​​are variable, the first threshold value and the second threshold value can be adjusted in the same way during the downward movement so that the distance between them is always the same.

[0045] As described above, the load determined shortly before the start of the downward movement can be used as a reference value, in particular the reference value to which the first and second thresholds refer. Alternatively, the output of a very slow sliding mean filter on the load determined by the load determination unit can also be used as a reference value.

[0046] In some embodiments, the detection unit can monitor the load determined by the load determination unit during the downward movement and set the first threshold value and / or the second threshold value such that the distance between the first threshold value and the load determined by the load determination unit and / or the distance between the second threshold value and the load determined by the load determination unit is constant or at least approximately constant during the downward movement. In other words, the detection unit can track the threshold value of the load that changes during the downward movement. However, this should only involve a slight change in the threshold value, whereby an actual collision can be detected.

[0047] As described above, during the downward movement of the patient support device or at least one section of the patient support device, the detection unit detects a possible collision of the patient support device with an object, the ground or a part of the operating table when the load determined by the load determination unit is below a preset first threshold value. The fact that the load is below the first threshold value does not necessarily indicate that a collision has occurred. The below the first threshold value may also occur for other reasons. Therefore, the detection unit can be designed so that it takes into account further conditions in addition to the conditions mentioned so that it can decide whether a possible collision has occurred. In the following, additional conditions for a possible collision of the patient support device with an object, the ground or a part of the operating table are proposed. The additional conditions can be combined with each other in any form. It is also conceivable that only one of the conditions mentioned below is taken into account for the detection of a possible collision.

[0048] In addition to the load, the load determination unit can in some embodiments additionally determine the center of gravity of the load based on the sensor values. When the patient support device moves without a collision, the center of gravity of the load changes slowly and in a predictable manner with respect to the axis of movement, the direction of movement and the speed of movement. In the event of a collision, the center of gravity changes suddenly relative to this, in particular about one or more axes. Therefore, as an additional condition for a possible collision of the patient support device with an object, the ground or a part of the operating table, the detection unit can determine whether the center of gravity of the load determined by the load determination unit changes suddenly during the downward movement of the patient support device or at least one section of the patient support device. A sudden change can be detected, for example, when the center of gravity of the load changes by at least one preset value, for example by at least 3 cm, 5 cm, 10 cm, 15 cm or 20 cm, within a preset time period, for example within a time period of less than 2 s or 1 s or 0.5 s or 0.3 s or 0.1 s.

[0049] Since the load center of gravity changes continuously during the movement of the patient support device, it may be challenging to detect sudden changes in the center of gravity caused by a collision.

[0050] Furthermore, the sudden change of the center of gravity during a collision is largely dependent on the current center of gravity position and the collision location. The greater the distance between the center of gravity and the collision location, the greater or better the influence on the center of gravity position can be detected. The most unfavorable situation is a collision with an object at the current center of gravity position. In this case, the sudden change of the center of gravity is relatively small.

[0051] Furthermore, the heavier the patient, the smaller the sudden change in center of gravity during a collision.

[0052] The factors mentioned above can be considered when setting the detection threshold.

[0053] In some embodiments, the detection unit can determine the force caused by a possible collision and acting on the patient support device and / or the position where the patient support device may collide with an object, the ground or a part of the operating table. During the collision, the collision force should increase and the collision position should remain approximately constant. Therefore, the detection unit can determine as an additional condition for the possible collision of the patient support device with an object, the ground or a part of the operating table: during the possible collision, the force caused by the possible collision increases and / or the collision position is approximately constant. If this is the case, the detection unit can confirm that a possible collision has occurred. It can be proposed that the collision position is considered to be approximately constant when it changes by no more than 5 cm, 10 cm, 20 cm or 30 cm during the collision, for example.

[0054] Observation of the impact force and / or impact location is particularly useful to differentiate between an impact and a malfunction of a load sensor or other input into a load determination algorithm. When the impact location is not constant, an increase in the impact force may be attributed to a malfunction rather than to an impact.

[0055] In some designs, the detection unit can determine the force and / or collision position caused by a possible collision based on the load determined by the load determination unit and / or the center of gravity of the load determined by the load determination unit and / or changes in sensor values ​​output by at least a portion of the load sensors during a possible collision.

[0056] In some embodiments, the load sensor device can have a plurality of load sensors which output sensor values. At least a part of a possible movement of the patient support device or at least a section of the patient support device about different axes and / or by means of a lifting column can each be associated with a selection of load sensors. During a movement of the patient support device or at least a section of the patient support device, the detection unit can analyze the forces acting on the load sensors associated with the movement.

[0057] For example, an operating table may have a plurality of hinges. Each of the hinges may be associated with a specific load sensor in the set of load sensors. When the patient support device or at least one section is moved by means of one of the hinges, the detection unit may analyze the forces acting on the load sensor associated with the hinge.

[0058] As an additional condition for a possible collision of the patient support device with an object, the ground or a part of the operating table, the detection unit can determine whether the analyzed forces fall below a predefined force threshold value during a possible collision. If all analyzed forces or a plurality of analyzed forces or at least one of the analyzed forces falls below the force threshold value, the detection unit can infer from this that a possible collision exists. However, a significant reduction in force should not be caused by a movement of the patient support device.

[0059] Furthermore, the detection unit can determine, as an additional condition for a possible collision of the patient support device with an object, the ground and a part of the operating table, whether the time derivative of the analyzed force falls below a preset fourth threshold value during a possible collision. The fourth threshold value can be selected such that it reflects a strong negative slope of the force. If the analyzed force derivative falls below the fourth threshold value, the detection unit can confirm that a possible collision exists.

[0060] In some embodiments, the load sensor device can have a plurality of load sensors which output sensor values.

[0061] In some embodiments, a plurality of load sensors may be arranged in a single common plane. In some embodiments, the load sensors may be arranged symmetrically.

[0062] In some embodiments, the load sensor device can be disposed between at least two parts of the operating table that are substantially immovable relative to each other.

[0063] In some embodiments, the load sensors of the load sensor device can be arranged parallel to each other and in a mirrored manner. For example, the load sensor device can have four force sensors or weighing cells in total. This embodiment has the advantages of increased accuracy and reliability.

[0064] In some embodiments, a plurality of or all load sensors of the load sensor device may be arranged mirror-symmetrically about a first imaginary axis and mirror-symmetrically about a second imaginary axis. The first axis and the second axis may be oriented orthogonally to each other. For example, the first axis may extend parallel to a main axis of the patient support device, while the second axis extends perpendicular to the main axis but parallel to the patient support device. The load sensor device may be arranged between the patient support device and the operating table column.

[0065] In some designs, the load sensors can be arranged in a grid pattern or mesh. For example, the load sensors can be arranged in a 2×2 grid. The load sensors can be arranged in a grid arrangement with 2 to 4 load sensors in each dimension, for example.

[0066] The load sensors arranged in mirror-symmetrical manner can be oriented in the same direction. In particular, the load sensors arranged in mirror-symmetrical manner can be oriented parallel to one another. The load sensors can each have a main axis, wherein the main axes are oriented parallel to one another.

[0067] In some designs, the load sensors of the load sensor assembly can be structurally identical.

[0068] In some designs, the load sensor has an elongated shape. For example, the load sensor can be a rectangular body.

[0069] In some embodiments, the detection unit can generate a collision signal indicating that the operating table is in a safety-critical state when the detection unit detects a possible collision of the patient support device with an object, the ground, or a part of the operating table.

[0070] Furthermore, an acoustic and / or optical warning signal can be generated. Furthermore, a textual warning signal can be generated, which can be displayed to a user, for example, on a remote control of the operating table. Furthermore, the movement of the patient support device and / or the operating table can be restricted. For example, the extension and / or tilting and / or turning of the patient support device and / or the movement of the operating table can be slowed down or stopped. Furthermore, at least one function of the patient support device and / or the operating table can be blocked.

[0071] When the detection unit once again determines that the patient support device and / or the operating table is in a safe state, the measures taken can be reduced or cancelled.

[0072] In some designs, the patient support device may be part of an operating table. The operating table may include a base or legs and a column and the load sensor device may be disposed in the column.

[0073] In some embodiments, the detection unit can detect a possible collision when the load determined by the load determination unit decreases by at least one collision threshold value during the downward movement of the patient support device or at least one section of the patient support device. The load directly before the start of the downward movement can be used as a reference value for the collision threshold value. The at least one collision threshold value can be selected, for example, such that it corresponds to the first threshold value described above. That is, when the load determined by the load determination unit decreases by at least one collision threshold value, the load is simultaneously below the first threshold value.

[0074] In some designs, the system may set a collision threshold based on one or more of the following variables: the position of the patient support device, the angle of the patient support device, the hinge angle of a hinge within the patient support device, the translational position and / or tilted position and / or flipped position of the patient support device, and the current movement pattern of the patient support device.

[0075] In some embodiments, when the load determined by the load determination unit increases by at least one error warning trigger value during the downward movement of the patient support device or at least one section of the patient support device, the system can temporarily ignore all possible collisions caused by the reduction in the load determined by the load determination unit.

[0076] In some embodiments, the detection unit can compare the load determined by the load determination unit when the patient support device is stationary with the load determined by the load determination unit when the patient support device is subsequently moved downward. An indication of a possible collision can be a smaller load measured when the patient support device is subsequently moved downward. In addition, a load that is less than at least a threshold value when the patient support device is moved downward can indicate a possible collision.

[0077] In some embodiments, the detection unit may be configured only to detect a collision between the patient support device and an object, the ground, or a portion of the operating table below the patient support device during a downward movement of the patient support device or at least one section of the patient support device. In addition, the system may also include other separate collision detection units, which, for example, detect collisions when the patient support device or at least one section of the patient support device moves upward and / or sideways.

[0078] According to a second aspect of the present disclosure, a method for detecting a collision of a patient support device with an object, a ground or a part of an operating table is provided. The patient support device can be used as a part of an operating table and can in particular be a surgical patient support device. A load sensor device having at least one load sensor that outputs a sensor value can be provided. A load can be determined based on the sensor value, wherein the load includes a load acting on the load sensor device or a load acting on the patient support device. During a downward movement of the patient support device or at least one section of the patient support device, a possible collision of the patient support device with an object, a ground or a part of an operating table can be detected when a certain load is below a preset first threshold value.

[0079] The method according to the second aspect can have all embodiments described in this disclosure in conjunction with the system according to the first aspect.

[0080] The present disclosure also includes electronic instructions and / or circuits for controlling an operating table, as well as a remote control device, display, and user interface for use with an operating table. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Below, exemplary embodiments of the present disclosure are described in detail with reference to the accompanying drawings, which show:

[0082] Figure 1 shows a schematic side view of an operating table according to the present disclosure together with a patient positioned on a patient support device of the operating table;

[0083] Figure 2 A schematic diagram showing the system architecture of a system according to the present disclosure;

[0084] Figure 3 A schematic diagram showing a surgical table according to the present disclosure for illustrating measured load, effective load and total load;

[0085] FIG. 4A to FIG. 4C Schematic diagrams showing different embodiments of an operating table according to the present disclosure having a load sensor arrangement in different positions;

[0086] FIG. 5A to FIG. 5DSchematic diagrams showing different embodiments of an operating table according to the present disclosure, the operating table having force sensors arranged in parallel and in a mirror-symmetrical manner;

[0087] Fig. 6A and Figure 6B A schematic diagram for illustrating the forces acting on the force sensor is shown;

[0088] Fig. 7A and Figure 7B shows a schematic diagram for illustrating the reduction of the transverse forces due to the symmetrical arrangement of the force sensors;

[0089] Figure 8 A schematic diagram is shown for illustrating the determination of a gravity vector when a patient support device is tilted;

[0090] Fig. 9A and Fig. 9B A schematic diagram showing a system according to the present disclosure before and during a collision of a patient support device with an object;

[0091] Fig. 10A and Fig. 10B showing a schematic diagram of a system according to the present disclosure having an external load applied to a patient support device during downward movement;

[0092] Fig.11 A schematic diagram showing load vibration caused by an external load;

[0093] Fig.12 an exemplary diagram showing an inclination angle of a patient support device and a load determined by a load determination unit;

[0094] Fig.13 A schematic diagram showing a method according to the present disclosure for detecting a collision of a patient support device with an object;

[0095] Fig.14A and Fig. 14B A schematic diagram showing a system according to the present disclosure showing the center of gravity of a load before and during a collision of a patient support device with an object;

[0096] Fig.15 A schematic diagram of a system according to the present disclosure is shown for illustrating the determination of collision force and collision location;

[0097] Fig.16 A schematic diagram showing a system according to the present disclosure for illustrating the association of specific load sensors with various hinges of an operating table; and

[0098] FIG. 17A to FIG. 17C Schematic diagrams showing different application scenarios of the system according to the present disclosure. DETAILED DESCRIPTION

[0099] In the following description, exemplary embodiments of the present disclosure are described with reference to the accompanying drawings, which are not necessarily to scale but merely schematically illustrate the corresponding features.

[0100] It should be noted that the features and components described below can be combined with each other, regardless of whether they are described in conjunction with a single embodiment. The combination of features in the respective embodiments serves only to illustrate the basic design and function of the claimed device.

[0101] In the figures, identical or similar elements are provided with the same reference symbols wherever this is expedient.

[0102] Figure 1 A mobile operating table 10 is schematically shown, which can be used to support a patient 12 during a surgical operation and for transporting the patient. The mobile operating table 10 comprises, from bottom to top: a foot or base 14 for parking the operating table 10 on the ground; a vertically arranged operating table column 16 including the foot 14; and a patient support device 18 fastened to the upper end of the operating table column 16. The patient support device 18 can be fixedly connected to the operating table column 16 or alternatively can be detachably fastened to the operating table column 16.

[0103] The patient support device 18 is modular and is used to support the patient 12. The patient support device 18 comprises a main support surface section 20 connected to the operating table column 16, which can be expanded as desired by coupling a number of auxiliary support surface sections. The patient support device 18 can be implemented as a table top of a surgical table or operating table 10. Figure 1 In the embodiment, a leg section 22 , a shoulder section 24 and a head section 26 are coupled to the bearing surface main section 20 as bearing surface auxiliary sections.

[0104] The patient support device 18 of the operating table 10 can be placed at a suitable height and can be tilted and turned depending on the type of surgical procedure to be performed.

[0105] The operating table column 16 is designed to be height-adjustable and has an internal mechanism for setting the height of the patient support 18 of the operating table 10. The mechanism is arranged in a housing 28 which protects the components from contamination.

[0106] The foot 14 has two sections 30, 32 of different lengths. Section 30 is a short section that is associated with the foot end of the leg section 22, i.e., with the end of the patient support device 18 on which the foot of the patient 12 to be treated lies. Section 32 is a long section that is associated with the head section 26 of the patient support device 18.

[0107] Furthermore, the support foot 14 has wheels or rollers, by means of which the operating table 10 can move on the ground. Alternatively, the support foot 14 can be fixedly anchored at the ground.

[0108] Lateral rails 34 are arranged on both sides of the patient support device 18. Accessories can be releasably fastened to the lateral rails 34.

[0109] For better illustration, Figure 1 A Cartesian coordinate system XYZ is drawn in. The X-axis and the Y-axis are horizontal axes, the Z-axis is a vertical axis. The X-axis extends along the supporting surface subsections 22, 24, 26 arranged side by side.

[0110] Figure 2 The system architecture of the system 100 according to the present disclosure is schematically shown. The system 100 is a system according to the first aspect of the present disclosure and can be operated by means of the method according to the second aspect.

[0111] System 100 is not limited to Figure 1 The operating table 10 shown in FIG. 1 also has a load sensor device 102, a load determination unit 104, a safety unit 106, a monitoring and calibration unit 108, a data storage device 110, and further components 112 of the operating table system 100. In addition, the safety unit 106 includes a detection unit 113, an anti-tilt unit 114, and an overload protection unit 115.

[0112] The load sensor device 102 includes one or more load sensors and is designed to measure at least one variable from which the load acting on the load sensor device 102 can be determined. In this case, the load sensors are force sensors, which each measure the force acting on the corresponding sensor. The sensor value or force value measured by the individual force sensors is output by the load sensor device 102 as a signal 120 in digital form. In addition, the load sensor device 102 includes the electronic components required for the operation of the force sensors.

[0113] The load determination unit 104 receives the signal 120 with the measured sensor values ​​or force values ​​and determines therefrom the load and in particular the center of gravity of the load. As load, the load determination unit 104 can determine a measured load, a useful load and / or a total load.

[0114] In order to be able to appropriately process and analyze the force values ​​provided, the load determination unit 104 requires some data on the geometry and mass or weight of the operating table 10 and the accessories. These data are stored in a data memory 110 and are provided to the load determination unit 104 by means of a signal 122. In particular, information about the mass and center of gravity of the individual components and accessories of the operating table 10 can be extracted from these data. The data memory 110 can be expanded via a communication module of the operating table 10.

[0115] The load determination unit 104 generates a signal 124 as an output signal, which contains information about the specific load and the center of gravity of the load. This information is transmitted both to the safety unit 106 and to the monitoring and calibration unit 108 .

[0116] All available data, including the load, center of gravity and position data of the operating table 10 and the accessories recognized by the operating table 10, are analyzed in the safety unit 106. The safety unit 106 decides whether the operating table 10 is safe or whether it is in a dangerous situation. The safety unit 106 generates a safety signal 126, which indicates whether the operating table 10 is in a safety-critical state.

[0117] Depending on the difficulty of the identified situation, the algorithm reacts accordingly. The operating table 10 can, for example, only issue a warning or stop the movement. The warning can be issued via an acoustic or optical signal through the operating table 10 or in text form via the remote control. The measures can vary from slowing down the movement speed through stopping the movement to blocking some functions and continue until a state is reached in which the operating table 10 is safe again.

[0118] It may be provided that the safety function can be deactivated by the user at any time and the movement of the operating table 10 can be continued at his own risk.

[0119] The detection unit 113 is a subunit of the safety unit 106 and receives the load and the load center of gravity determined by the load determination unit 104. During the downward movement of the patient support device 18 or at least one section of the patient support device 18, the detection unit 113 detects a possible collision of the patient support device 18 with an object, the ground or a part of the operating table 10. The detection unit 113 generates a collision signal 128, which indicates whether a possible collision has occurred. The collision signal 128 is a safety signal of the safety unit 106.

[0120] The anti-tilt unit 114 and the overload protection unit 115 are further subunits of the safety unit 106. The anti-tilt unit 114 generates an anti-tilt protection signal 130 as a function of the total load and / or the center of gravity of the total load, which indicates whether there is a risk of tipping over of the operating table 10. The overload protection unit 115 generates an overload protection signal 132 as a function of the payload and / or the center of gravity of the payload, which indicates whether there is a risk of overloading the operating table 10 and / or at least one component of the operating table 10. Alternatively, the overload protection unit 115 uses the measured load or the total load and / or the center of gravity of one of the loads to generate the overload protection signal 132. The anti-tilt protection signal 130 and the overload protection signal 132 are safety signals of the safety unit 106.

[0121] If the foot 14 has wheels or rollers and is instead fixedly connected to the ground, the anti-tilt unit 114 can be deactivated or not implemented in the safety unit 106 .

[0122] Since the system 100 is to reliably detect critical situations, the system 100 also has a monitoring and calibration unit 108. This software module checks the plausibility of the measured values ​​and detects whether the system is operating incorrectly or whether a calibration or tare determination of the system 100 is required. The monitoring and calibration unit 108 generates corresponding output signals 134, 136, which are transmitted to the load determination unit 104 or the component 112 of the operating table 10.

[0123] Components 112 of operating table 10 continuously generate position data, data for setting individual components, and information about accessories recognized by operating table 10 . These data are made available to system 100 by means of signal 138 .

[0124] Figure 3 The schematic diagram illustrates different loads that the load determination unit 104 can determine based on the data provided by the load sensor unit 102. Figure 3 In the embodiment of the present invention, the measured load, the effective load and the total load are denoted by reference numerals 140, 142 and 144. For each of these loads, the load determination unit 104 can determine the position of the center of gravity of the associated load.

[0125] The measured load is the load acting on the load sensor device 102. The measured load corresponds to the load generated above the load sensor by all persons, objects and forces acting on the operating table 10. The measured load corresponds to the load value measured by the load sensor device 102.

[0126] The effective load corresponds to the load caused by components and persons and external forces not associated with the patient support device 18 or the operating table 10 and acting on the patient support device 18 or the operating table. The influence of components associated with the patient support device 18 and recognized accessories is not taken into account in the effective load. Only the remaining components of the patient support device, that is, components not associated with the patient support device 18, contribute to the effective load. This can be, for example, accessories that are not recognized by the operating table 10. In addition, the patient located on the patient support device 18 contributes to the effective load. In addition, all forces acting on the patient support device 18 from the outside, such as those applied to the patient support device 18 by persons and / or objects located outside the operating table 10, contribute to the effective load. The effective load is essentially a measured load without the influence of known objects such as tabletop parts, recognized accessories, etc.

[0127] The total load is the load derived from the measured load and the load caused by components associated with the operating table 10 and located below the load sensor device 102. Therefore, the total load takes into account the load of components that are located below the load sensor device 102 and cannot be measured by the load sensor device 102 and thus do not contribute to the measured load. Therefore, the total load is the load derived from the entire operating table 10, the patient, components associated with the operating table 10, components not associated with the operating table 10, and other external forces.

[0128] FIG. 4A to FIG. 4C Different embodiments of an operating table 10 according to the present disclosure are schematically illustrated.

[0129] In the operating table 10, a load sensor device 102 with a plurality of load sensors is arranged between at least two parts of the operating table 10. In particular, the at least two parts are substantially immovable relative to one another. In the present embodiment, when the patient support device 18 is adjusted during operation of the operating table 10, for example when the patient support device 18 is tilted and / or tilted and / or longitudinally and / or laterally adjusted, the at least two parts are substantially immovable relative to one another, i.e. they remain substantially in the same position relative to one another. This applies not only to the spacing between the at least two parts but also to one or more angles that the at least two parts enclose with one another.

[0130] The load sensor device 102 is preferably integrated into the operating table 10 so that the entire load above the load sensor flows through or is transferred therethrough.

[0131] The load sensor device 102 can be disposed at various locations in the operating table 10. Figure 4A In the embodiment shown in FIG. 1 , the load sensor device 102 is disposed between the support leg 14 and the operating table column 16, and Figure 4B The load sensor device 102 is integrated into the operating table column 16. Figure 4C In FIG. 1 , the load sensor assembly 102 is adjacent to the interface between the patient support device 18 and the operating table column 16 .

[0132] Figure 5A The operating table 10 is shown with a load sensor arrangement 102 arranged between the patient support device 18 and the operating table column 16. The load sensor arrangement 102 comprises four structurally identical force sensors 1a, 1b, 2a and 2b, which are arranged parallel to one another and in a mirror-image manner. Figure 5B and Figure 5C Two different variants with regard to the placement of the force sensors 1 a , 1 b , 2 a , 2 b are illustrated in FIG. Figure 5B and Figure 5C The load sensor device 102 is shown along Figure 5ATop view of line AA drawn in .

[0133] For orienting the force sensors 1a, 1b, 2a, 2c, a first axis 150 and a second axis 152 are provided which are perpendicular to one another. The first axis 150 extends parallel to the main axis of the patient support device 18, while the second axis 152 extends perpendicularly thereto but parallel to the patient support device 18.

[0134] The force sensors 1a, 1b, 2a, 2c each have a main axis, which is located at Figure 5B is oriented parallel to the first axis 150. Figure 5C , the main axes of the force sensors 1a, 1b, 2a, 2b are oriented parallel to the second axis 152. In addition, the force sensors 1a, 1b, 2a, 2b are arranged in pairs in a mirror-symmetrical manner about the axes 150, 152, respectively. The pairs (1a, 1b), (1a, 2a), (1b, 2b) and (2a, 2b) respectively form mirror-symmetrical force sensor pairs. In some embodiments, the force sensors 1a, 1b, 2a, 2b are arranged in a 2×2 grid as shown. In some embodiments, the grid arrangement has at least two force sensors 1a, 1b, 2a, 2b on each side. In some embodiments, the force sensors 1a, 1b, 2a, 2b are all located in a single common plane in which the first axis 150 and the second axis 152 are arranged.

[0135] The force sensor can also be used with Figure 5B and Figure 5C In the sensor device 102, a plurality of exemplary alternative arrangements of the force sensor in the sensor device 102 are provided in different ways. Figure 5D Shown in.

[0136] In Figure 5B or Figure 5C Taking the sensor device 102 shown in FIG. 1 as an example, the measured load can be calculated by adding all the forces measured by sensors 1a, 1b, 2a, 2b. The corresponding center of gravity can be calculated with the help of the torque compensation equation given below and in Fig. 6A and Figure 6B Calculated using the forces shown in . Fig. 6A shows a cross-sectional view along the x-axis and Figure 6B A cross-sectional view along the y-axis is shown. The torque compensation equation can be applied in both directions so that the x- and y-components of the center of gravity can be determined:

[0137] F L =F 1a +F 2a +F 1b +F 2b (1)

[0138]

[0139] In equations (1) to (3), F L is the gravitational force generated by the patient. Force F 1a 、F 1b 、F 2a and F 2b is the force measured by sensors 1a, 1b, 2a, 2b. Parameters a and b are the distances between the sensors in the x-direction or y-direction. CG and Y CG is the x-coordinate or y-coordinate of the center of gravity of the load caused by the patient.

[0140] By adding or subtracting the corresponding weights of the operating table 10 and its center of gravity values ​​stored in the data memory 110 , the effective load and the total load and their corresponding center of gravity values ​​can be calculated.

[0141] Sensors 1a, 1b, 2a, 2b Figure 5B and Figure 5C The proposed arrangement makes the system relative to the lateral force F r is robust. Due to the symmetrical arrangement, the lateral force F r is offset, as in Fig. 7A and Figure 7B As shown in .

[0142] The compensation of lateral forces also allows the described system to reliably measure forces and center of gravity when the patient support device 18 is in an inclined position. Figure 8 The gravity vector F is shown L How can it be divided into two components. One component is transverse to the force sensor and cancels out due to the effects explained above. The second component F M It runs perpendicularly to the main surface of the force sensor or the patient support device 18 and is reliably measured. When the inclination angle α of the patient support device 18 is known, the actual load above the sensor and its center of gravity can be calculated.

[0143] Fig. 9A and Fig. 9B The operating table system 200 according to the present disclosure is schematically shown. Figure 2 The elements of the operating table system 100 are schematically shown in FIG. Fig. 9A and Fig. 9B Not shown.

[0144] Fig. 9A The patient support device 18 is shown in a non-moving state, while Fig. 9BIn the embodiment of the present invention, a reverse Trendelenburg tilt is performed, wherein the foot section of the patient support device 18 moves downward. During the downward movement, the patient support device 18 collides with an object 210 arranged below the patient support device 18 .

[0145] The collision causes a load F determined by the load determination unit 104. L Reduce. Fig. 9A and Fig. 9B The load F is drawn in L The vector whose vector length gives the load F determined by the load determination unit 104 L The size of the load F 碰撞 is transferred to the collision location, whereby the load F measured by the load determination unit 104 L Furthermore, the collision causes a sudden change in the load center of gravity calculated by the load determination unit 104. 空闲 And measure the moving load center of gravity COG after the collision 碰撞 .

[0146] The detection unit 113 is coupled to the load determination unit 104 and receives the variables determined by the load determination unit 104, in particular the measured load F L The load F determined by the load determination unit 104 in a stationary state L corresponds to the weight of the patient or the gravitational force caused by the patient. During the downward movement of the patient support device 18 or a section of the patient support device 18, when the load F determined by the load determination unit 104 L Below the preset first threshold L 碰撞 , the detection unit 113 detects a possible collision of the patient support device 18 with an object, the ground on which the operating table 10 stands, or a part of the operating table 10. L <L 碰撞 When a possible collision is detected, the movement of the patient support device 18 is stopped quickly to limit the force or pressure at the collision point.

[0147] exist Fig. 10A and Fig. 10B During the downward movement, the external load F 外部 is applied to the patient support device 18. Fig. 10A In the embodiment, the patient support device 18 is in a rest position and the load F is measured by the load determination unit 104. L .exist Fig. 10B In the process, the foot section of the patient support device 18 moves downward and additionally applies the external load F 外部is applied to the patient support device 18, for example by a person supporting himself on the patient support device 18. When the external load F 外部 When removed during the downward movement, the load F determined by the load determination unit 104 L The resulting vibrations can lead to false collision warnings, since the load F may be affected by the load vibrations even though no collision has occurred. L may drop below the threshold L 碰撞 .

[0148] Fig.11 Load vibrations are shown, which are caused by external loads, for example impacts from above on the patient support device 18. Fig.11 In the graph shown in FIG. 1 , the load F determined by the load determination unit 104 is plotted with respect to time t. L . Load F L For example, it can be given as a weight in kilograms or as a gravity in Newtons.

[0149] According to the load F L The curve of , which is shown as a dotted line, shows that during the downward movement, an external load is applied to the patient support device 18 . The removal of the external load causes a load oscillation.

[0150] In the rest state of the patient support device 18, ie before the start of the downward movement, the load determination unit 104 determines a rest load, the level of which serves as a reference value. The load determined by the load determination unit 104 directly before the start of the downward movement is referred to as L 空闲 .

[0151] Threshold L 碰撞 Less than the load L determined directly before the start of the downward movement 空闲 And has a load L 空闲 The predetermined spacing. Threshold L 碰撞 With load L 空闲 The distance corresponds to the collision threshold. L Reduced to below the threshold L 碰撞 When the load F L From the load L 空闲 When the collision threshold is reduced by at least the collision threshold, the detection unit 113 detects a possible collision.

[0152] In order to prevent erroneous collision detection caused by load vibration, the second threshold L is preset. 警告 , the second threshold is greater than the load L 空闲 And in Fig.11 The value of the threshold L 碰撞 Same distance load L 空闲 The threshold L警告 With load L 空闲 The spacing can also be related to the threshold L 碰撞 With load L 空闲 The spacing is different. Threshold L 碰撞 With load L 空闲 The distance between them can be called the collision threshold and is Fig.11 Indicated by b.

[0153] Once the load F determined by the load determination unit 104 L Exceeding the threshold L 警告 , the detection unit 113 is deactivated for a preset period of time. During the period of time, the detection unit 113 does not output a collision warning in order to prevent erroneous collision detection. Fig.11 In the example shown, the load F L At time t 1 After the threshold L 警告 .

[0154] Alternatively, it can be provided that the detection unit 113 is under load F L Exceeding the threshold L 警告 Thereafter, a collision is detected only under predetermined conditions. For this purpose, a third threshold value L is preset. 小睡 , the third threshold is less than the threshold L 碰撞 For the activation threshold L 小睡 The premise is that the load F L Exceeding the threshold L 警告 At the next time t 小睡 During this period, only when the load F L Below the threshold L 小睡 A possible collision is detected only when

[0155] Duration t 小睡 has a preset length, and once the load F L Exceeding the threshold L 警告 , that is, at time point t 1 Alternatively, at load F L The threshold L has been exceeded before 警告 Afterwards, when the load F L After load value L 空闲 Time, duration t 小睡 This ensures that the activation time t is only activated when load vibration occurs. 小睡 The situation described in Fig.11 Shown in.

[0156] Threshold L 小睡 The maximum load L 最大 Determine that the maximum load exceeds the threshold value L 警告 After reaching the load FL Threshold L 小睡 With maximum load L 最大 The spacing can be, for example, the maximum load L 最大 With load value L 空闲 At least twice the spacing. Fig.11 Medium, maximum load L 最大 With load value L 空闲 The spacing is represented by a. Therefore, the threshold L 小睡 With maximum load L 最大 The spacing can be at least 2a.

[0157] The reason for the distance 2a is that in the event of an impact from above on the patient support device 18, the load F L First the load a rises, then the impact rebounds like a wave and the load F is measured. L Reduce to below the original load value L 空闲 Due to attenuation, at the maximum load value L 最大 The "rebound" below is less than 2a. The "rebound" should not be detected as a collision. However, if the "rebound" is greater than 2a (from the maximum load value L 最大 ), then this can be detected as a possible collision.

[0158] exist Fig.12 In the example, the inclination angle of the patient support device 18 is expressed in degrees / 100 and the load F determined by the load determination unit 104 is expressed in degrees / 100. L Plotted in kg / 10 versus time t. Fig.12 It is shown that the measured load F L As the inclination angle changes, the actual load on the patient support device 18 remains unchanged. In order to avoid false collision detection, the threshold value L 碰撞 and L 警告 can be correlated with the inclination angle and / or the tilt angle of the patient support device 18. As a result, the measured load F can be at least partially compensated. L Dependence on tilt angle and / or flip angle.

[0159] Fig.13 A flow chart 300 is shown, which illustrates a method for detecting a collision of the patient support device 18 with an object, the ground or a part of the operating table 10 . The method is executed by the detection unit 113 .

[0160] After the start, it is checked in decision step 301 whether 10 ms have elapsed. Therefore, the method starts from the beginning every 10 ms.

[0161] In step 302, the detection unit 113 obtains the measured load F L and the load center of gravity COG of the load determination unit 104 .

[0162] In decision step 303 , it is checked whether the patient support device 18 or at least a section of the patient support device 18 has moved in any way.

[0163] If the result of decision step 303 is "No", the current load value F L In step 304, the load value L 空闲 The method returns to decision step 301. If the result is "yes", it is checked in decision step 305 whether the current load F L Whether the threshold L is reached or exceeded 警告 .

[0164] At the current load F L Reach or exceed the threshold L 警告 , the snooze / nap time is activated for a preset duration in step 306. During the time, the detection unit 113 does not detect a possible collision. After the snooze / nap time has elapsed, the method returns to decision step 301.

[0165] At the current load F L The threshold L is not reached or exceeded 警告 , it is checked in step 307 whether the patient support device 18 or at least one section of the patient support device 18 has moved downwards. If this is not the case, the method returns to decision step 301.

[0166] As long as the downward movement has been confirmed, it is checked in decision step 308 whether the current load F L Does it satisfy the inequality F? L <L 碰撞 , especially L 碰撞 =L 空闲 If this is the case, the movement of the patient support device 18 or a section thereof is stopped in step 309 and the collision location is determined in step 310 . The method then returns to decision step 301 .

[0167] Fig.14A and Fig. 14B and Fig. 9A and Fig. 9B Similarly, a sudden change in the load center of gravity calculated by the load determination unit 104 is shown, which is caused by the collision of the patient support device 18 with the object 210 during the downward movement. 空闲 And measure the moving load center of gravity COG after the collision 碰撞 .

[0168] As an additional condition for a possible collision, the detection unit 113 can determine whether the load center of gravity determined by the load determination unit 104 changes suddenly during the downward movement of the patient support device 18 or a section of the patient support device 18 .

[0169] Fig.15 The diagram illustrates the determination of the impact force and impact position. Before the impact, the gravity force F caused by the patient is measured by the load determination unit 104. g As load F L,空闲 . Measured load center of gravity COG before collision 空闲 Equal to the patient's load center of gravity C g :

[0170] F L,空闲 =F g (4)

[0171] COG 空闲 =C g (5)

[0172] The collision causes the C The force F acting on the patient support device 18 C The load determination unit 104 measures the following load F during a collision: L,碰撞 and the following load center of gravity COG 碰撞 :

[0173] F L,碰撞 =F g -F c (6)

[0174]

[0175] Equations (6) and (7) can be transformed as follows:

[0176] F c =F g -F L,碰撞 (8)

[0177]

[0178] During the collision, the force F c Raised and impacted position C c is approximately constant. In this case, a collision can be detected. When the collision position C c When it is not constant, the collision force F c The increase in F can be attributed to the fault rather than to the collision. c There may also be no collision when it is reduced or kept constant.

[0179] Fig.16The embodiment of the load sensor device 102 with four load sensors 401, 402, 403, 404 is shown. Each hinge by which the patient support device 18 or a section of the patient support device 18 can be moved is associated with one or more load sensors 401, 402, 403, 404. The associated sensor is most affected in the corresponding movement. By way of example, the association of a hinge that causes a movement of the patient support device 18 or a section thereof in a specific direction with a specific sensor of the load sensors 401, 402, 403, 404 is shown in the following Table 1.

[0180] Hinge direction Associated load cell Right rear down 402 Left rear down 401 Right Leg down 403 Left leg down 404 Flip left 401，404 Flip To the right 402，403 tilt normal 403，404 tilt on the contrary 401，402 Travel up / down down 401，402，403，404

[0181] Table 1

[0182] Depending on the form of movement, the detection unit 113 monitors the load sensor(s) associated with the hinge performing the movement. The detection unit 113 analyses the forces acting on the monitored load sensors.

[0183] If the analyzed force decreases significantly, the detection unit 113 can infer from this that a possible collision has occurred. However, a significant decrease in force should not be caused by a movement of the patient positioning device 18 .

[0184] Furthermore, the detection unit 113 can check whether the time derivative of the force analyzed during a possible collision is below a preset fourth threshold value. If the time derivative of the force analyzed is below the fourth threshold value, the detection unit determines that a possible collision exists.

[0185] FIG. 17A to FIG. 17C Different application scenarios of the operating table system according to the present disclosure are shown.

[0186] exist Fig.17A In FIG. 1 , the load F determined by the load determination unit 104 is plotted with respect to time t. L Before starting the downward movement, a load F of 90 kg has been determined. L Threshold L 碰撞 and L 警告 It has been determined that L 碰撞 Lower than L 空闲 (=90kg)15kg, that is, the collision threshold b, and L 警告 Higher than L 空闲 10kg.

[0187] From the load F L It can be concluded from the time variation curve that when the load F L When the load F increases or decreases stepwise or monotonically, the detection unit 113 does not detect the collision. L At time point t 1 Below the threshold L 碰撞A possible collision is detected only when

[0188] exist Fig. 17B Medium, load F L At time point t 2 Exceeding the threshold L 警告 Next, the detection unit 113 ignores the load F for a certain period of time. L , which is symbolically represented by area 410. During this time period, detection unit 113 does not determine a possible collision.

[0189] exist Fig. 17C In the figure, the patient support device 18 is arranged from the left in the longitudinal direction (see Fig. 17C left side of the figure) to the right (see Fig. 17C The load sensor device 102 has four load sensors 401, 402, 403, 404, wherein the load sensors 401, 402 are arranged on the left side of the operating table 10 and the load sensors 403, 404 are arranged on the right side of the operating table 10.

[0190] When the patient support device 18 is initially adjusted, the patient support device 18 is located on the left side of the operating table column 16. In this case, the large force or load F L,401,402 The load is applied to the load sensors 401, 402 arranged on the left side, and only a small force or load F L,403,404 The load is applied to the load sensors 403, 404 arranged on the right side, as can be seen from the Fig. 17C The further the patient support device 18 moves to the right, the greater the load F L,401,402 becomes smaller and the load F L,403,404 However, the total load F L Keep stable and do not cause collision detection.

[0191] Exemplary embodiments and variations consistent with the present disclosure are described in the following list of points and options:

[0192] Point 1: A system (100, 200) for detecting a collision of a patient support device (18) with an object, a floor, or a portion of an operating table (10), wherein the system (100, 200) comprises:

[0193] A patient support device (18), in particular a surgical patient support device (18), which can be used as part of an operating table (10);

[0194] A load sensor device (102), the load sensor device having at least one load sensor (401, 402, 403, 404), the load sensor outputting a sensor value;

[0195] a load determination unit (104) that determines a load based on the sensor value, wherein the load includes a load acting on the load sensor device (102) or a load acting on the patient support device (18); and

[0196] A detection unit (113) detects a possible collision of the patient support device (18) with an object, the ground or a part of an operating table (10) during a downward movement of the patient support device (18) or at least one section of the patient support device (18) when the load determined by the load determination unit (104) is below a preset first threshold value.

[0197] Point 2: The system (100, 200) according to point 1, wherein after the load determined by the load determination unit (104) exceeds a preset second threshold value, the detection unit (113) temporarily does not indicate a possible collision.

[0198] Point 3: A system (100, 200) according to Point 1, wherein, after the load determined by the load determination unit (104) exceeds a preset second threshold, when the load determined by the load determination unit (104) is lower than a preset third threshold, the detection unit (113) briefly detects a possible collision, wherein the third threshold is smaller than the first threshold.

[0199] Point 4: A system (100, 200) according to any of the above points, wherein a first threshold value and / or a second threshold value and / or a third threshold value are individually preset for at least a portion of an axis and / or for the lowering of the patient support device (18) by means of a lifting column (16), wherein the patient support device (18) or at least a section of the patient support device (18) can be tilted or turned around the axis during the downward movement.

[0200] Point 5: A system (100, 200) according to any of the above points, wherein the first threshold value and / or the second threshold value and / or the third threshold value are respectively variable and are related to the tilt angle and / or the flip angle of the patient support device (18) or at least one section of the patient support device (18).

[0201] Point 6: A system (100, 200) according to any of the above points, wherein the first threshold distance from the load determined by the load determination unit (104) before starting the downward movement is approximately the same in value as the second threshold distance from the load determined before starting the downward movement.

[0202] Point 7: A system (100, 200) according to any of the above points, wherein the detection unit (113) sets the first threshold and / or the second threshold so that the distance between the first threshold and the load during the downward movement and / or the distance between the second threshold and the load during the downward movement is approximately constant.

[0203] Point 8: The system (100, 200) according to any of the above points, wherein the load determination unit (104) additionally determines the center of gravity of the load based on the sensor value; and

[0204] As an additional condition for a possible collision of the patient support device (18) with an object, the ground or a part of an operating table (10), the detection unit (113) determines whether the center of gravity of the load determined by the load determination unit (104) changes suddenly during the downward movement of the patient support device (18) or at least one section of the patient support device (18).

[0205] Point 9: A system (100, 200) according to any of the above points, wherein the detection unit (113) determines the forces caused by a possible collision and acting on the patient support device (18) and / or the position where the patient support device (18) may collide with an object, the ground or a part of the operating table (10); and

[0206] As an additional condition for a possible collision of the patient support device (18) with an object, the ground or a part of the operating table (10), the detection unit (113) determines that during a possible collision,

[0207] Whether the forces caused by a possible collision increase and / or whether the collision position is approximately constant.

[0208] Point 10: A system (100, 200) according to Point 9, wherein the detection unit (113) determines the force and / or collision position caused by a possible collision based on the load determined by the load determination unit (104) and / or the load center of gravity determined by the load determination unit (104) and / or changes in sensor values ​​output by at least a part of the load sensors (401, 402, 403, 404) during a possible collision.

[0209] Point 11: The system (100, 200) according to any one of the above points, wherein the load sensor device (102) has a plurality of load sensors (401, 402, 403, 404), and the load sensors output sensor values;

[0210] at least a part of the possible movement of the patient support device (18) or at least a section of the patient support device (18) about different axes and / or by means of a lifting column (16) is respectively associated with a selection of load sensors (401, 402, 403, 404); and

[0211] The detection unit (113) analyzes, during a movement of the patient support device (18) or at least one section of the patient support device (18), load sensors (401,

[0212] 402, 403, 404).

[0213] Point 12: A system (100, 200) according to point 11, wherein as an additional condition for a possible collision of the patient support device (18) with an object, the ground or a part of an operating table, the detection unit (113) determines whether the analyzed force is below a preset force threshold during a possible collision.

[0214] Point 13: A system (100, 200) according to point 11 or 12, wherein as an additional condition for a possible collision of the patient support device (18) with an object, the ground or a part of the operating table (10), the detection unit (113) determines whether the derivative of the analyzed force is below a fourth threshold value during a possible collision.

[0215] Point 14: The system (100, 200) according to any of the above points, wherein the load sensor device (102) has a plurality of load sensors (401, 402, 403, 404), the load sensors output sensor values, and the load sensors (401, 402, 403, 404) have at least one of the following features:

[0216] The load sensors (401, 402, 403, 404) are arranged in a single common plane;

[0217] The load sensors (401, 402, 403, 404) are arranged in a grid form;

[0218] The load sensor (401, 402, 403, 404) has an elongated shape;

[0219] The load sensors (401, 402, 403, 404) are arranged mirror-symmetrically about a first axis and mirror-symmetrically about a second axis oriented orthogonal to the first axis; and

[0220] The load sensors (401, 402, 403, 404) are arranged between at least two parts of the operating table (10) that are substantially immovable relative to each other.

[0221] Point 15: A system (100, 200) according to any of the above points, wherein the detection unit (113) generates a collision signal after detecting a possible collision between the patient support device (18) and an object, the ground or a part of the operating table (10), so that the collision signal indicates a safety-critical state of the operating table (10), generates an acoustic and / or optical warning signal and / or a text-based warning signal, and / or slows down or stops the movement of the patient support device (18) and / or the operating table (10), and / or blocks at least one function of the patient support device (18) and / or the operating table (10).

[0222] Point 16: A system (100, 200) according to any of the above points, wherein the patient support device (18) is part of an operating table (10), and the operating table (10) further includes a base (14) and a column (16), and wherein the load sensor device (102) is arranged in the column (16).

[0223] Point 17: A system (100, 200) according to any of the above points, wherein the detection unit (113) detects a possible collision when the load determined by the load determination unit (104) decreases by at least one collision threshold during downward movement of the patient support device (18) or at least one section of the patient support device (18).

[0224] Point 18: A system (100, 200) according to any of the above points, wherein the detection unit (113) detects a possible collision when the load determined by the load determination unit (104) reduces at least one collision threshold during the downward movement of the patient support device (18) or at least one section of the patient support device (18), and wherein the system (100, 200) sets the collision threshold based on one or more of the following variables: the position of the patient support device (18), the angle of the patient support device (18), the hinge angle of a hinge in the patient support device (18), the moved position and / or the tilted position and / or the flipped position of the patient support device (18) and the current movement mode of the patient support device (18).

[0225] Point 19: A system (100, 200) according to any of the above points, wherein when the load determined by the load determination unit (104) increases at least one error warning trigger value, in particular during downward movement of the patient support device (18) or at least one section of the patient support device (18), the system (100, 200) temporarily ignores all possible collisions due to the reduction in the load determined by the load determination unit (104).

[0226] Point 20: A system (100, 200) according to any of the above points, wherein the detection unit (113) compares the load determined by the load determination unit (104) when the patient support device (18) is stationary with the load determined by the load determination unit (104) when the patient support device (18) subsequently moves downward, in particular wherein when the patient support device (18) subsequently moves downward, a smaller load indicates a possible collision, in particular wherein when the patient support device (18) moves downward, a load that is smaller than at least one collision threshold indicates a possible collision.

[0227] Point 21: A system (100, 200) according to any of the above points, wherein the detection unit (113) is only configured to detect a collision between the patient support device (18) and an object, the ground or a part of the operating table (10) located below the patient support device (18) during the downward movement of the patient support device (18) or at least one section of the patient support device (18); and

[0228] The system (100, 200) in particular also comprises at least one further separate collision detection unit.

[0229] Point 22: A method for detecting a collision of a patient support device (18) with an object, a floor, or a portion of an operating table (10), wherein:

[0230] The patient support device (18) can be used as part of an operating table (10) and is in particular a surgical patient support device (18);

[0231] Providing a load sensor device (102), the load sensor device having at least one load sensor (401, 402, 403, 404), the load sensor outputting a sensor value;

[0232] determining a load based on the sensor value, wherein the load includes a load acting on the load sensor device (102) or a load acting on the patient support device (18); and

[0233] During a downward movement of a patient support device (18) or at least a section of a patient support device (18), a possible collision of the patient support device (18) with an object, the ground or a part of an operating table (10) is detected when the determined load falls below a predefined first threshold value.

Claims

1. A system (100, 200) for detecting a collision of a patient support device (18) with an object, a floor, or a portion of an operating table (10), wherein the system (100, 200) comprises: A patient support device (18), in particular a surgical patient support device (18), which can be used as part of an operating table (10); A load sensor device (102), the load sensor device having at least one load sensor (401, 402, 403, 404), the load sensor outputting a sensor value; a load determination unit (104) for determining a load based on the sensor value, wherein the load comprises a load acting on the load sensor device (102) or a load acting on the patient support apparatus (18); and A detection unit (113) detects a possible collision of the patient support device (18) with an object, the ground or a part of the operating table (10) during a downward movement of the patient support device (18) or at least a section of the patient support device (18) when the load determined by the load determination unit (104) is below a preset first threshold value.

2. The system (100, 200) according to claim 1, Therein, after the load determined by the load determination unit (104) exceeds a predefined second threshold value, the detection unit (113) briefly, in particular within a range of 0.5 seconds to 10 seconds, does not indicate a possible collision.

3. The system (100, 200) according to claim 1, in, After the load determined by the load determination unit (104) exceeds a preset second threshold value, when the load determined by the load determination unit (104) is lower than a preset third threshold value, the detection unit (113) briefly detects a possible collision, in particular in a range of 0.5 seconds to 10 seconds, wherein the third threshold value is smaller than the first threshold value.

4. The system (100, 200) according to any one of the preceding claims, The first threshold value and / or the second threshold value and / or the third threshold value are respectively predefined individually for at least a portion of an axis and / or for the lowering of the patient support device (18) by means of a lifting column (16), wherein the patient support device (18) or at least a section of the patient support device (18) can be tilted or tilted about the axis during the downward movement.

5. The system (100, 200) according to any one of the preceding claims, The first threshold value and / or the second threshold value and / or the third threshold value are each variable and are dependent on an inclination angle and / or a tilt angle of the patient support device (18) or at least one section of the patient support device (18).

6. The system (100, 200) according to any one of the preceding claims, The first threshold value is approximately the same value as the distance between the first threshold value and the load determined by the load determination unit (104) before the downward movement begins.

7. The system (100, 200) according to any one of the preceding claims, The detection unit (113) sets the first threshold value and / or the second threshold value so that the distance between the first threshold value and the load during the downward movement and / or the distance between the second threshold value and the load during the downward movement is approximately constant.

8. The system (100, 200) according to any one of the preceding claims, wherein The load determination unit (104) additionally determines the center of gravity of the load based on the sensor value; and As an additional condition for a possible collision of the patient support device (18) with an object, the ground or a part of an operating table (10), the detection unit (113) determines whether the center of gravity of the load determined by the load determination unit (104) changes abruptly during a downward movement of the patient support device (18) or at least one section of the patient support device (18).

9. The system (100, 200) according to any one of the preceding claims, wherein The detection unit (113) determines forces caused by a possible collision and acting on the patient support device (18) and / or a position where the patient support device (18) may collide with an object, the ground or a part of the operating table (10); and As an additional condition for a possible collision of the patient support device (18) with an object, the floor or a part of an operating table (10), the detection unit (113) determines whether the forces caused by the possible collision increase during the possible collision and / or whether the collision position is approximately constant.

10. The system (100, 200) according to claim 9, The detection unit (113) determines the force and / or collision position caused by a possible collision based on the load determined by the load determination unit (104) and / or the load center of gravity determined by the load determination unit (104) and / or the changes in sensor values ​​output by at least a part of the load sensors (401, 402, 403, 404) during the possible collision.

11. The system (100, 200) according to any one of the preceding claims, wherein The load sensor device (102) has a plurality of load sensors (401, 402, 403, 404), and the load sensors output sensor values; at least a part of the possible movement of the patient support device (18) or at least a section of the patient support device (18) about different axes and / or by means of a lifting column (16) is respectively associated with a selection of the load sensors (401, 402, 403, 404); and The detection unit (113) analyzes, during a movement of the patient support device (18) or of at least a section of the patient support device (18), forces acting on load sensors (401, 402, 403, 404) associated with the movement.

12. The system (100, 200) according to claim 11, As an additional condition for a possible collision of the patient support device (18) with an object, the floor or a part of an operating table (10), the detection unit (113) determines whether the analyzed force falls below a predefined force threshold value during a possible collision.

13. The system (100, 200) according to claim 11 or 12, As an additional condition for a possible collision of the patient support device (18) with an object, the floor or a part of an operating table (10), the detection unit (113) determines whether the analyzed force derivative falls below a fourth threshold value during a possible collision.

14. The system (100, 200) according to any one of the preceding claims, The load sensor device (102) has a plurality of load sensors (401, 402, 403, 404), the load sensors output sensor values, and the load sensors (401, 402, 403, 404) have at least one of the following features: The load sensors (401, 402, 403, 404) are arranged in a single common plane; The load sensors (401, 402, 403, 404) are arranged in a grid form; The load sensor (401, 402, 403, 404) has an elongated shape; The load sensors (401, 402, 403, 404) are arranged mirror-symmetrically about a first axis and mirror-symmetrically about a second axis oriented orthogonal to the first axis; and The load sensors (401, 402, 403, 404) are arranged between at least two parts of the operating table (10) that are substantially immovable relative to each other.

15. The system (100, 200) according to any one of the preceding claims, The detection unit (113) generates a collision signal after detecting a possible collision of the patient support device (18) with an object, the ground or a part of the operating table (10), so that the collision signal indicates a safety-critical state of the operating table (10), generates an acoustic and / or optical warning signal and / or a text-based warning signal, and / or slows down or stops the movement of the patient support device (18) and / or the operating table (10), and / or blocks at least one function of the patient support device (18) and / or the operating table (10).

16. The system (100, 200) according to any one of the preceding claims, The patient support device (18) is part of the operating table (10), and the operating table (10) further comprises a base (14) and a column (16), and wherein the load sensor device (102) is arranged in the column (16).

17. The system (100, 200) according to any one of the preceding claims, The detection unit (113) detects a possible collision when the load determined by the load determination unit (104) decreases by at least one collision threshold value during a downward movement of the patient support device (18) or at least one section of the patient support device (18).

18. The system (100, 200) according to any one of the preceding claims, The detection unit (113) detects a possible collision when the load determined by the load determination unit (104) reduces at least one collision threshold value during a downward movement of the patient support device (18) or at least one section of the patient support device (18), and wherein the system (100, 200) sets the collision threshold value based on one or more of the following variables: the position of the patient support device (18), the angle of the patient support device (18), the hinge angle of a hinge in the patient support device (18), the displacement position and / or the tilting position and / or the tilting position of the patient support device (18) and the current movement mode of the patient support device (18).

19. The system (100, 200) according to any one of the preceding claims, When the load determined by the load determination unit (104) increases by at least one error warning trigger value, in particular during a downward movement of the patient support device (18) or at least one section of the patient support device (18), the system (100, 200) temporarily ignores all possible collisions due to the reduction in the load determined by the load determination unit (104).

20. The system (100, 200) according to any one of the preceding claims, The detection unit (113) compares a load determined by the load determination unit (104) when the patient support device (18) is stationary with a load determined by the load determination unit (104) when the patient support device (18) subsequently moves downward, wherein a smaller load when the patient support device (18) subsequently moves downward indicates a possible collision, and wherein a load that is less than at least a collision threshold when the patient support device (18) moves downward indicates a possible collision.

21. The system (100, 200) according to any one of the preceding claims, wherein the detection unit (113) is configured only for detecting a collision between the patient support device (18) and an object, the ground or a part of an operating table (10) below the patient support device (18) during a downward movement of the patient support device (18) or at least a section of the patient support device (18); and The system (100, 200) in particular also comprises at least one further separate collision detection unit.

22. A method for detecting a collision of a patient support device (18) with an object, a floor or a portion of an operating table (10), wherein: The patient support device (18) can be used as part of an operating table (10) and is in particular a surgical patient support device (18); Providing a load sensor device (102), the load sensor device having at least one load sensor (401, 402, 403, 404), the load sensor outputting a sensor value; determining a load based on the sensor value, wherein the load includes a load acting on the load sensor device (102) or a load acting on the patient support device (18); and During a downward movement of the patient support device (18) or at least a section of the patient support device (18), a possible collision of the patient support device (18) with an object, the ground or a part of an operating table (10) is detected when the determined load falls below a predefined first threshold value.

Images