Retaining device for an instrument

Abstract

The invention relates to a retaining device for an instrument, comprising at least one joint having at least two parts that can be moved relative to each other and at least one drive unit associated with the joint. The drive unit is designed to move the joint by driving at least one of the parts of the joint that can be moved relative to each other. The retaining device also comprises a securing device, which has a locking mechanism associated with the joint and a release unit that can be activated, wherein the locking mechanism interacts with the release unit in such a way that the locking mechanism holds the joint in a locked position as long as the release unit is not activated. The securing device is designed to permit a motion of the joint out of the particular locked position within a specified range of motion even if the release unit is not activated. The invention further relates to a corresponding securing device for a retaining device and to an operating method for said securing device.

Claims

1. A retaining device for an instrument, comprising: at least one joint, the at least one joint including at least two parts which are movable relative to one another; at least one drive unit assigned to the at least one joint; and a securing mechanism including: a lock assigned to the at least one joint and a release unit adapted to be selectively activated, the lock being configured to hold the at least one joint in a locking position when the release unit is not activated, the at least one drive unit being configured to move the at least one joint by driving at least one of the at least two parts of the joint, wherein the securing mechanism is configured to permit a movement of the at least one joint out of the locking position within a predetermined range of movement even when the release unit is not activated to enable vibration damping, wherein if the release unit is not activated and the lock has been disengaged, the securing mechanism limits the movement of the at least one joint to the predetermined range of movement, and wherein if the movement of the at least one joint departs from the predetermined range of movement, the securing mechanism activates the lock.

2. The retaining device according to claim 1, further comprising: a mechanism for active vibration damping configured to output to the at least one drive unit a balancing signal, wherein the at least one drive unit moves the at least one joint in such a manner that vibrations of the retaining device can be balanced out.

3. The retaining device according to claim 1, wherein the lock includes at least one stop surface and at least one counter-stop surface, configured to interact in order to hold the at least one joint in the locking position.

4. The retaining device according to claim 3, wherein: the lock includes a brake with a movable part which is coupled with the at least one driven part of the at least one joint, and the at least one stop surface of the lock is arranged on the movable part of the brake and the at least one counter-stop surface is arranged on the at least one driven part of the at least one joint.

5. The retaining device according to claim 4, wherein the brake is an electromagnetic brake.

6. The retaining device according to claim 3, wherein the lock includes a stop on which the at least one stop surface is formed and which can engage with a recess having at least two counter-stop surfaces for locking movement of the at least one joint in two opposite directions of motion.

7. The retaining device according to claim 6, wherein the stop is configured to be movable back and forth between a first position, in which it locks the movement of the at least one joint, and a second position, in which it permits the movement of the at least one joint.

8. The retaining device according to claim 6, wherein the stop is a stop pin.

9. The retaining device according to claim 3, wherein a clearance is provided between the at least one stop surface and the at least one counter-stop surface of the lock in a direction of motion of the at least one joint.

10. The retaining device according to claim 3, wherein at least one elastic intermediate element is provided between the at least one stop surface and the at least one counter-stop surface of the lock in a direction of motion of the at least one joint.

11. The retaining device according to claim 1, further comprising: a monitoring appliance configured to monitor whether the at least one joint is being moved within the predetermined range of movement and to transmit feedback concerning the movement of the at least one joint to the securing mechanism.

12. The retaining device according to claim 11, wherein the securing mechanism is configured to permit an activation of the lock on the basis of the feedback of the monitoring appliance.

13. The retaining device according to claim 11, wherein the monitoring appliance includes at least one sensor for monitoring the movement of the at least one joint.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in the following in exemplary manner on the basis of the accompanying schematic Figures. Shown are:

(2) FIG. 1 a schematic side view of a retaining device according to the invention,

(3) FIG. 2 a schematic, partially sectioned side view of a swivel joint of a retaining device according to the invention according to FIG. 1,

(4) FIGS. 3a-e schematic detailed views of the lock mechanism according to FIG. 2, wherein these views show different positions and embodiments of the lock mechanism in perspective representation,

(5) FIGS. 4a and 4b schematic, partially sectioned side views of the lock mechanism according to detail A of FIG. 2,

(6) FIG. 5 a schematic, partially sectioned side view of a brake of a retaining device according to the invention according to FIG. 1,

(7) FIG. 6 a schematic detailed view of the coupling of the brake according to FIG. 5 with a part of the joint of the retaining device according to the invention, and

(8) FIG. 7 a flow chart that describes the procedures within a securing mechanism of the retaining device according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) In FIG. 1 an embodiment, represented in greatly simplified form, of a retaining device according to the invention is shown in side view. The retaining device is denoted generally by reference symbol 10. The device 10 includes an instrument 12, for example, as illustrated, a microscope or suchlike, which is connected to the retaining device 10. In the embodiment represented in FIG. 1 the retaining device 10 is arranged on the floor B of a room. Alternatively, however, the retaining device 10 could also, of course, have been fitted to the side walls or to a ceiling wall of a room.

(10) The retaining device 10 which is represented is constructed in the form of a so-called stand which exhibits several rigid elements 16, 18, 20 (hereinafter designated as arms) which are connected to one another by means of several swivel joints 14. Accordingly, arms 16 and 18 are connected to one another so as to be movable relative to one another by means of swivel joint 14.sub.1, and arms 20 and 18 by means of swivel joint 14.sub.2. At the free end of the retaining device 10 an instrument receptacle 22 is fitted, which in turn is connected to arm 20 via a swivel joint 14.sub.3. Depending on the type and design of the retaining device 10, in this way the instrument 12 can be moved about several axes which may be arranged parallel or transversely to one another. As an alternative to the retaining device 10 shown, the present invention also encompasses, of course, retaining devices that include one or more sliding joints instead of, or in addition to, a swivel joint. Arbitrary joint combinations with variably many and variably designed joints are possible in this connection.

(11) The following remarks on the mode of operation and configuration of swivel joint 14.sub.1 apply likewise to swivel joints 14.sub.2 and 14.sub.3.

(12) Assigned to the individual swivel joints 14 of the retaining device 10 are drive units (not represented), for example in the form of an electric motor or suchlike, which serve to drive at least one of the movable parts of the swivel joint 14 and in this way to move it relative to the other part. Accordingly, as shown in FIG. 2, arm 18 is moved relative to arm 16 by a drive shaft 18a connected to arm 18, exhibiting at its free end an interface 18b via which it can be connected to the drive unit in such a manner that the drive shaft 18a together with arm 18, driven by the drive unit, can move about an axis of rotation D.

(13) In the embodiment shown in FIG. 2 the drive shaft 18a extends through a through-bore of arm 16, in which connection the shaft 18a may be supported in low-friction manner within the through-bore (not represented). The configuration of the swivel joint 14 represented in FIG. 2 is, however, only exemplary; accordingly, the linkage 18b to a drive unit may also be configured at a different place and in a completely different way, such as, for example, with a drive shaft of the drive unit engaging with arm 18, with a drive unit engaging on the outer contour of arm 18 and suchlike.

(14) Ordinarily in the case of a retaining device, such as the retaining device 10 according to the invention, the drive or the drive unit is provided at each swivel joint 14. Said drive unit may serve to balance out a load torque that is generated in the respective swivel joint 14, caused by the dead weight of the instrument 12 fitted to the retaining device 10 and of the individual elements of the retaining device. For instance, at swivel joint 14.sub.1 a load torque is generated that results from the weight forces of all the elements connected to arm 18 (inclusive of the instrument 12), and from the associated lever arm.

(15) In order to be able to guarantee a manual handling (manual positioning) of the instrument 12 that is as simple as possible, the drive units in the respective swivel joints 14 serve to balance out the respective load torque by an equally large counter-moment, so that in the case of a manual movement of the instrument 12 in the working space of the retaining device 10 the latter can be moved by an operator in virtually weightless manner, and inertias are also compensated (active compensation). In any case, the friction forces arising in the swivel joints 14, which (with lock disengaged) are slight and depending on the configuration of the retaining device likewise canas can also inertias arisingbe compensated by the drive unit (active compensation), have to be overcome by the operator who would like to move the instrument 12 freely. Alternatively, the retaining device according to the invention may, however, also display in each joint a mechanical full or partial compensation of load torques arising.

(16) As can likewise be discerned in FIG. 2, swivel joint 14.sub.1 (just like swivel joints 14.sub.2 and 14.sub.3) exhibits in addition a lock, for example in the form of a stop pin 26, which serves to couple with one another the parts of swivel joint 14.sub.1 that are movable relative to one another, in order in this way to block a rotational motion of swivel joint 14.sub.1. With the aid of the lock the retaining device 10 can retain the desired position after completion of the positioning. As an alternative to a positive coupling, shown in FIG. 2, of the parts 16, 18 of swivel joint 14.sub.1 which are movable relative to one another, a non-positive coupling is also conceivable, as explained below. In addition, it is equally possible to arrange the lock between the drive unit and the part 16 of swivel joint 14.sub.1 which is not driven by a drive unit, or between the driven part 18 of swivel joint 14.sub.1 and an immovable part of the retaining device 10, in order to couple these elements with one another.

(17) A release unit 24 arranged on the instrument 12 forms, together with the lock, a so-called securing mechanism which serves to protect people located in the working space of the retaining device 10 against unintentional movements of the retaining device 10. Accordingly, the retaining device 10 can only be moved freely within its entire working space when the release unit 24 has been activated, whereby in its activated state it interacts with the lock in such a manner that the latter releases the swivel joint 14. As soon as the release unit 24 is not activated, such a free mobility of the retaining device 10 in its working space is no longer to be possible, for safety reasons.

(18) The release unit 24 may include a handle, a push-button, a joystick or any other type of input unit which the user can actuate or activate in order to express the fact that he/she would like to move the retaining device 10.

(19) By reason of its structure, the retaining device 10 according to the invention also offers, besides the manual mobility described above, the possibility to be moved automatically by means of a controller. In principle, a control unit, which is not represented, generates, for example for the purpose of building up a counter-torque in the respective swivel joint 14, a control signal which has the effect that the drive unit drives as desired at least one of the parts of the swivel joint 14 that are movable relative to one another, and in this way moves the swivel joint 14. Once the release unit 24 has been activated, the retaining device 10 may, however, also be moved into a desired position by means of the same control unit or an additional control unit, by the control unit controlling the corresponding drives of the swivel joints 14 (remote-controlled operation).

(20) Moreover, the retaining device 10 is configured in such a manner that vibrations arising, for example due to a post-oscillation of the retaining device 10 after a positioning movement has to taken place (manually or automatically) or due to room vibrations which are transmitted to the retaining device 10, for example via the floor B, are damped. This is obtained via a mechanism for active vibration damping (not represented), which uses the drive units of the driven swivel joints 14 for the purpose of vibration damping. To this end, the mechanism for active vibration damping emits to the respective drive unit a balancing signal (where appropriate, superimposed on the control signal) which has the effect that the drive unit moves the swivel joint 14 in such a way that vibrations of the retaining device 10 are compensated. Ordinarily, such a balancing signal is configured in such a manner that it brings about a periodic movement of the swivel joint 14 (exciter vibration) corresponding to the active vibration, whereby by virtue of a phase shift of the exciter vibration relative to the active vibration the active vibration and the exciter vibration cancel each other out.

(21) In order that such an active vibration damping is still possible even when the retaining device is not freely movable in the working space but is to remain in a retaining position, the securing mechanism is set up to permit a movement of the swivel joint 14 out of the respective locking position within a predetermined angular range if the release unit 24 has not been activated.

(22) In a first configuration variant, the securing mechanism, as shown in FIGS. 2 to 4b, includes a lock with at least one stop pin 26 (in FIGS. 4a and b, two stop pins 26 are shown), the outer circumferential surface of which forms a stop surface 26a. As represented in FIGS. 4a and 4b, each stop pin 26 can be moved back and forth between a first position, in which it locks the movement of the swivel joint 14, and a second position, in which it permits the movement of the swivel joint. Each stop pin 26 is received in its first position in a recess 28 (in FIGS. 4a and b, two recesses 28 are shown) which exhibits counter-stop surfaces 28a and 28b. Each stop pin 26 may be arranged on the part 18 of swivel joint 14.sub.1 driven by the drive unit or on the non-driven part 16 of swivel joint 14.sub.1, in which case the recesses 28, which provide the counter-stop surfaces 28a and 28b, are arranged on the respective other part of swivel joint 14.sub.1.

(23) The mechanism that is shown for moving the stop pins 26 back and forth comprises, according to FIGS. 4a and 4b, a magnet M and also a spring F. The spring F is received in the interior of the stop pin 26 and biases the latter in such a manner that it is located in the first locking position if the spring F is relaxed. This is also indicated by the arrow F.sub.spring in FIG. 4a. Of course, other possible arrangements of the spring F are conceivable.

(24) The magnet M (which is intended to represent schematically a source of magnetic attractive force of any type whatever) serves to relocate the stop pin 26 into the second position thereof (cf. FIG. 4b), in which it permits the movement of the swivel joint 14. For this purpose, a magnetic force, symbolised by the arrow F.sub.magnet as shown in FIG. 4b, acts on the stop pin 26, as a result of which the spring F is biased. In the case of the magnet M it is a question not of a permanent magnet but rather of a magnet that is capable of being electrically activated, for example in the form of a coil or suchlike. If the magnet M does not have current applied to it, no magnetic force F.sub.magnet acts on the stop pin 26, so that the latter is moved back again into its first position as a result of the spring force F.sub.spring of the biased spring F (cf. FIG. 4a).

(25) The mechanism that is shown for moving the stop is purely exemplary and may, for example, be replaced by reversal of action or by using other elements for the introduction of force.

(26) In FIGS. 3a to 3c a possible configuration of the receptacles 28 with the counter-stop surfaces 28a and 28b is shown, in which a stop pin 26 is received in different positions relative to the counter-stop surfaces 28a, 28b. Accordingly, the recess 28 is configured, as clearly perceptible, in such a manner that a clearance is provided between the stop surface 26a of the stop pin 26 and the counter-stop surface 28a or 28b in the direction of motion of the swivel joint 14 (indicated by the arrow R), so that a slight movement of swivel joint 14.sub.1 within a predetermined angular range is possible even when the lock has been activated.

(27) In order to be able to enable a lock of the swivel joint 14 in, as far as possible, any conceivable position, it is necessary to provide a plurality of recesses 28 with corresponding counter-stop surfaces 28a, 28b and also at least two stop pins 26, which are arranged relative to one another and with respect to the counter-stop surfaces 28a, 28b with angular offset (relative to the axis of rotation D) in such a manner that at least one of the stop pins 26 is always capable of engaging with a recess 28, even if the other stop pin is blocked by a counter-stop surface 28b (cf. FIG. 3d).

(28) Moreover, the configuration of the stop pin 26 in the form of a circular cylinder according to FIGS. 2 to 4b and the configuration of the recess according to FIGS. 3a to e are purely exemplary. Accordingly, in an alternative embodiment, for example with conical or sawtooth-shaped stops and corresponding recess surfaces, an unwanted blocking of the movement of the stop pin 26 out of the second position into its first position can be very largely avoided by means of a counter-stop surface 28b (as shown in FIG. 3d).

(29) In addition, instead of, or in combination with, the clearance, discussed above, in the direction R of motion of swivel joint 14.sub.1 it is possible to provide an elastic intermediate element E between the stop surface of the stop and the counter-stop surface 28a, 28b (as shown in FIG. 3e), which permits a further movement of swivel joint 14.sub.1 even when the stop is already bearing against the elastic intermediate element E (cf. FIG. 3e).

(30) The elastic intermediate element E may be arranged either on the counter-stop surface 28a, 28b or on the stop surface 26a. For example, it is conceivable to provide the stop pin 26 or a stop of whatever type with an encasement consisting of an elastic material, for example rubber.

(31) An alternative, non-positive type of lock may include a brake 30 (cf. FIGS. 5 and 6) which couples with one another either the parts 16, 18 of the swivel joint 14 which are movable relative to one another or the drive unit with an immovable part, for example the arm that is not driven by the drive unit (in FIG. 2, arm 16). An example of such a brake 30 is a so-called electromagnetic closed-circuit brake which exhibits a brake disc 32 held under preload, which presses against a corresponding brake stop surface 34 and in this way establishes the force-fit. For this purpose a spring F with a thrust washer 36 presses the brake disc 32 against the corresponding brake stop surface 34. Only when an electrical voltage is applied to the closed-circuit brake is the thrust washer 36 moved by magnetic forces (which are generated by a coil-carrier 38 supplied with current) away from the brake stop surface 34 and contrary to a biasing force F.sub.spring of the spring F, so that an axial spacing arises between the brake stop surface 34 and the brake disc 32 of the closed-circuit brake. In this position the force-fit is annulled and the previously braked parts can be moved freely relative to one another.

(32) The advantage of such a closed-circuit brake consists, in particular, in the fact that in the event of a possible power failure the brake is automatically activated and in this way the retaining device can be prevented from moving in undesirable manner as a result of its dead weight. A further advantage of a non-positive configuration of the locksuch as, for example, in the form of a brakeconsists in the fact that the parts that are movable relative to one another can still be moved, if necessary by overcoming the friction forces of the closed-circuit brake that has been engaged, even when the lock is active, making it possible, in the event of a system failure, to move the retaining device manually out of a position of potential danger.

(33) In the case of the brake 30 shown in FIGS. 5 and 6 the brake disc 32 is coupled with the driven part 18 of swivel joint 14.sub.1, whereas the brake stop surface 34 may, for example, be rigidly connected to the further part 16 of swivel joint 14.sub.1 or to an immovable part of the retaining device 10. The coupling of the brake disc 32 with the driven part 18 is effected via a splined-shaft-like gearing 38a on the outer peripheral surface of a drive shaft 18a of the driven part 18 with a substantially corresponding gearing 40a on the inner peripheral surface of a central recess 40 of the brake disc 32. Each tooth of gearing 38a exhibits two lateral flanks 42a, 42b which form the stop surfaces of the lock according to the invention, whereby the substantially corresponding recesses on gearing 40a each exhibit two flanks 44a, 44b which form the counter-stop surfaces of the lock according to the invention. Between each stop surface and each corresponding counter-stop surface a clearance and/or an elastic element E (in FIG. 6 only one is represented in exemplary manner) is provided in the direction of motion R of part 18, as also explained above in connection with the stop pin 26 with reference to FIGS. 3a to 3c and 3e. The elastic element E serves in this case for the self-centering of the brake disc 32 relative to the drive shaft 18a of the driven part 18, which is linked via the interlocking gearings 38a and 40a.

(34) Finally, in FIG. 7 a flow chart is shown which represents in exemplary manner the mode of operation of the securing mechanism of a retaining device 10 according to the invention. In this embodiment, in addition to or as an alternative to the configuration of the lock shown in FIGS. 2 to 6, a software-based control of the securing mechanism is provided.

(35) In a step S100 a controller of the securing mechanism checks whether the release unit 24 has been activated. For this purpose, use may be made, for example, of a conventional push-button switch or sensor of any type, which is arranged on a holding grip, integrated into a push-button or arranged on a different type of input unit and which permits the intention of a user to move the retaining device 10 to be discerned. Upon activation and/or deactivation of the release unit 24, for example by pressure on the corresponding push-button, this push-button switch or sensor emits a signal to the controller of the securing mechanism. If the controller of the securing mechanism receives, in a step S101, the signal that the release unit 24 has been activated, it outputs to the lock a disengage signal, by virtue of which the lock is disengaged (step S102). A prerequisite for this is, of course, that the lock is capable of being controlled, in whatever manner, by the controller. Such a control is possible, for example, in the embodiment shown in FIGS. 4a and 4b, wherein for the purpose of disengaging the lock the magnet M has current applied to it, moving the stop pin 26 into its second position (disengaging position).

(36) After this, in step S103 the retaining device is freely movable manually or automatically within the entire working space of the retaining device 10. If the release unit 24 is deactivated after completion of the desired movement of the retaining device 10, that is to say, if the securing mechanism receives, in a step S110, the signal that the release unit 24 has not been activated, then, in a step S120 it likewise transmits the signal for disengaging the lock (as described above under step S102), but additionally activates, in a step S130, a monitoring appliance (not represented) which monitors the movement of the at least one swivel joint 14 of the retaining device 10. The following remarks are made with reference to a swivel joint 14 but also apply, of course, given a corresponding configuration of the retaining device, to several swivel joints, such as the swivel joints 14.sub.1, 14.sub.2, and 14.sub.3 of the retaining device 10, or to one or more sliding joints.

(37) The monitoring appliance according to the present invention may use, for example, an internal or external sensor system, that is to say, for example, angle sensors by way of internal sensors of the swivel joint 14 (or displacement-measuring sensors for a sliding joint) or external sensors of a navigation sensor system (not represented) etc., in order to obtain a precise indication of the position in which the swivel joint 14 is located (ACTUAL position) and by what angle (or displacement for the sliding joint) the joint 14 has, where appropriate, moved out of the respective locking position (angle of motion or motion displacement).

(38) For this purpose, the monitoring appliance can, for example, store that position of the joint 14 as locking position in which the joint 14 was located at the time at which the securing mechanism received the signal that the release unit 24 has not been activated (step S110). Starting from this locking position, the monitoring appliance can then check whether the joint 14 is being moved out of this locking position within a predetermined range of movement. For this purpose, the monitoring appliance can, for example on the basis of the locking position and the predetermined range of movement, calculate a SET position and can compare the latter with the ACTUAL position or can compare the angle of motion (or motion displacement), ascertained on the basis of the ACTUAL position, with an angle (or displacement) characterizing the SET position (step S140).

(39) In this connection, the predetermined angle or displacement or the range of movement can be adjusted or altered by an operator, depending on the application, or may comprise a fixed safety value. If in the course of a comparison of the ACTUAL position of the joint, or of the angle of motion of the swivel joint 14 (or motion displacement of the sliding joint) with respect to a SET position or the predetermined angle (displacement), the monitoring appliance comes to the conclusion that the joint 14 is being moved within the predetermined range of movement (step S150), it transmits a positive feedback to the securing mechanism (step S160).

(40) A check is then again made as to whether the release unit 24 has been activated (step S100), and in the case of a release unit 24 that is still deactivated the lock remains disengaged (step S120) and the monitoring appliance activated (step S130). If, however, the monitoring appliance recognizes in a step S140 that the movement of the joint 14 threatens to depart from the predetermined range of movement (step S141), it transmits a negative feedback to the securing mechanism (step S142). The latter then causes, in a step S143, a blocking of the joint 14 by outputting a corresponding signal to the lock. In addition, an error handling (S144) is initiated, within the scope of which a check is made as to why the joint 14 is moving beyond the predetermined range of movement (S144).

(41) The mode of operation of the securing mechanism described in FIG. 7 can, of course, be combined with the mechanical configuration of the lock according to FIGS. 2 to 6, whereby, where appropriate, the clearance between the stop surface and the counter-stop surface of the lock is chosen in such a manner that a blocking arises only when the predetermined range of movement for a movement of the joint has been exceeded. In this case the structural configuration serves as an additional safeguard in case the control of the securing mechanism should fail.

(42) The retaining device according to the invention enables, by virtue of its configuration, in particular by virtue of the configuration of the securing mechanism, that, on the one hand, the securing mechanism of the retaining device can continue to ensure the protection of a person located within the working space of the retaining device, and that, on the other hand, also in a retaining position of the retaining device an active vibration damping can take place by utilizing the drive units, which are already present, of the joints.