JP2005143961A - Contact alarming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sense the contact by reducing a load which is applied to an objective when a manipulator comes into contact with the objective. <P>SOLUTION: In this contact alarming device 20, an oscillation detecting element 28 - an oscillator 26 - a contact ball 29 are provided by laminating on the distal end of the manipulator 22 as a contact probe 24. A returning loop of (the contact ball 29) - the oscillation detecting element 28 - an amplifier 34 - a phase compensating circuit 36 - a terminal 32 - the oscillator 26 - (the contact ball 29) is formed by cooperating with a contact recognizing section 30. A deviation between a frequency when the contact ball 29 is not in contact with a biological texture 8, and a frequency when the contact ball 29 comes into contact with the biological texture 8 is detected by a frequency deviation detector 38, and an alarming sound generator 42 notifies an operator of the contact state with the biological texture 8 with a sound by a sound generator 52. An alarming signal generator 44 notifies a manipulator operation controlling section 70 of the contact state with the biological texture 8. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a contact notification device, and more particularly to a contact notification device that detects and notifies that a manipulator has touched an object in a system that handles the object by operating a manipulator.

  A manipulator is operated with a living surgery support device or the like, and a part of the living tissue is pressed, grasped, or grasped. Some manipulators are manually operated by an operator, and some robot systems use electronic control. In the operation of these manipulators, while observing the object with a camera or the like, it approaches a desired part and performs various processes. If the manipulator is operated only by observing the target object, it may be difficult to determine when the target object is touched. Therefore, a contact sensor is attached to the manipulator.

  As a general contact sensor, a so-called pressure sensor that applies a certain measurement pressure to an object and detects a reaction force or strain at that time can be used. That is, a bias pressure corresponding to the measurement pressure is applied to the probe in advance, and if the probe contacts the object, the probe is displaced against the bias pressure, so that the displacement can be detected to detect contact with the object. For example, a measuring instrument having a low measuring pressure of about 20 grams can be used. However, some objects may be deformed or broken at such a measurement pressure, and are not suitable for such soft objects or fragile objects.

  Therefore, as a method that does not require measurement pressure, Patent Document 1 discloses that an electrode is attached to a living body, and a current that flows when the contact detection device comes into contact with the living body is detected to detect contact with the living body. Further, Patent Document 2 discloses detecting contact with a living body by comparing a bioelectrical impedance with a reference resistance using a potential detection electrode.

JP 05-123332 A JP 2003-093361 A

  When using a manipulator, it is desirable to be able to operate it as if it were your fingertip or hand. In other words, when the manipulator is brought into contact with the object, the object should not be deformed or altered as much as possible, and it can be seen that the manipulator has come into contact with the object without looking at the measuring instrument. It is preferable to determine the hardness and softness, to grip the soft object with as little force as possible, and to apply the force to the hard object so that it can be firmly gripped.

  In the prior art, a mechanical load such as a measurement pressure and an electrical load such as a current and a voltage are applied, so that there is a risk of deformation, breakage, or alteration depending on an object. In addition, in the method of determining the contact state by the measuring instrument, it is inconvenient because the operator must look at the value of the measuring instrument one by one.

  An object of the present invention is to provide a contact notification device that can detect a contact by further reducing the load applied to the object when the manipulator contacts the object. Another object is to provide a contact notification device capable of notifying the contact state between a manipulator and an object with higher operator convenience. Still another object is to provide a contact notification device capable of outputting the contact state between a manipulator and an object with higher convenience of manipulator operation.

1. Principle of the Invention The inventor of the present invention has devised a phase compensation method (phase shift method) as a method for accurately and quantitatively evaluating the hardness and softness of an object such as a living body (refer to Japanese Patent Laid-Open No. 9-146991). ). The principle of the invention according to the present application is based on the finding that in the process of measuring the hardness of an object by this phase compensation method, contact with the object can be detected with almost no contact pressure required.

  In the phase compensation method, a transducer and a vibration detection sensor are provided at the tip of a probe, and a phase compensation circuit is provided between the amplifier and the transducer in a feedback loop of the transducer-measurement object-vibration detection sensor-amplifier-vibrator, for example. Is provided. Here, the phase compensation circuit has a function of changing the frequency of vibration to zero the phase difference generated between the input waveform to the vibrator and the output waveform from the vibration detection sensor. Then, the frequency of self-oscillation oscillation that occurs by compensating the phase difference to zero in the feedback loop formed by the probe, the amplifier, and the phase compensation circuit is measured, and the frequency when the probe is not pressed against the measurement object, A deviation from the frequency when the probe is pressed against the measurement location of the measurement object is detected, and this is evaluated in relation to the hardness of the measurement object. As described above, the phase compensation method is not an evaluation of a frequency change with a small change amount of the measurement value among the vibration changes caused by pressing the probe to evaluate the hardness of the measurement object. A phase change having a larger change amount is used. Furthermore, the phase difference measurement, which is difficult to measure with high accuracy, is converted into frequency deviation measurement by the function of the phase compensation circuit, thereby enabling quantification with high accuracy. The magnitude of the conversion coefficient for converting the phase difference into the frequency deviation can be determined by setting parameters of the phase compensation circuit.

  In this way, in order to obtain the hardness of the object by the phase compensation method, the probe is pressed against the measurement location, and the frequency deviation obtained by converting the phase difference generated at that time is measured. That is, when the hardness is to be measured, the probe is statically pressed against the measurement location. In the process of conducting such hardness measurement experiments, it was found that a frequency deviation occurred when the probe was moved so as to lightly rub the surface of the measurement object. That is, in the hardness measurement, the frequency deviation generated when the probe is statically pressed against the object is used. However, the frequency deviation occurs even when the probe is dynamically touched to the object.

  Some measurement objects represent frequency deviations that can be sufficiently detected by simply touching them. It has also been found that when the frequency deviation due to touching is small, it is easy to increase the conversion coefficient of (frequency deviation / phase difference) by setting the parameters of the phase compensation circuit to obtain sufficient detection sensitivity.

  In other words, by setting the parameters of the phase compensation circuit appropriately, almost no contact pressure is required, and the contact can be detected with a frequency deviation simply by touching the measurement object or even when the measurement object is rubbed. Can do. Furthermore, when the parameters of the phase compensation circuit are the same, the magnitude of the detected frequency deviation differs depending on whether the measurement object is hard or soft. For example, by setting the parameters of the phase compensation circuit, the frequency deviation when contacting a hard measurement object can be made larger than the frequency deviation when contacting a soft measurement object.

  In this way, by using the phase compensation method, not only the hardness of the measurement point where the measurement object is fixed is quantitatively determined, but also the contact detection with high sensitivity is possible even when the contact is made almost without applying contact pressure. Furthermore, it was found that it is easy to determine whether the measurement object is hard or soft depending on the magnitude of the frequency deviation when touched. Based on this principle, the present invention further informs that the operator during the operation does not have to look at the measuring instrument one by one, so that the operator touches by voice or the like, and adjusts the hardness when touching by the volume of the voice or the like. There is a feature in the device that informs.

2. A contact notification device according to the present invention is a contact notification device that detects that a manipulator has touched an object and outputs the result when operating the manipulator, and is attached to the manipulator and attached to the object. A contact probe element having a vibrator that receives vibration and a vibration detection sensor that detects a reflected wave from an object, an amplifier having an input terminal connected to a signal output terminal of the vibration detection sensor, and an output terminal of the amplifier And a phase compensation circuit for changing a vibration frequency to zero a phase difference generated between an input waveform to the vibrator and an output waveform from the vibration detection sensor. The frequency of self-oscillation oscillation that occurs by compensating the phase difference to zero by the feedback loop formed by the contact probe, amplifier, and phase compensation circuit is measured, and the contact probe contacts the object. A frequency deviation detector that detects a deviation between the frequency when not touching and the frequency when touching, and an output that outputs a notification sound or light when the detected frequency deviation exceeds a predetermined threshold And means.

  In the contact notification device according to the present invention, it is preferable that the output means further changes the display content of the notification sound or the notification light according to the magnitude of the frequency deviation above a predetermined threshold value.

  Further, in the contact notification device according to the present invention, it is preferable that the output means further outputs a notification signal corresponding to the magnitude of the frequency deviation above a predetermined threshold value to the operation unit of the manipulator.

  According to the present invention, the manipulator is provided with a contact probe having a vibrator and a vibration detection sensor, and the contact of the contact probe with the object is detected in the form of a frequency deviation by the phase difference compensation method. Therefore, as described above, contact can be detected with almost no contact pressure applied, so the load applied to the object can be reduced, deformation due to mechanical load, alteration due to electrical load, etc. can be prevented, and contact can be detected. . In addition, since the means for outputting the notification sound is provided, the operator of the manipulator can know the contact without looking at the measuring instrument one by one, and the convenience for the operator can be enhanced. Notification light may be used instead of the notification sound, and notification sound may be used.

  Further, the display content is changed according to the frequency deviation by at least one of the above-described configurations. The display content can be changed by increasing the volume as the frequency deviation increases, making the sound higher in frequency, increasing the amount of light, or making the light blink faster. Since the frequency deviation at the time of contact represents the hardness and softness of the object, the operator operates the manipulator according to the change of this sound, etc. without looking at the measuring instrument. Adaptive processing such as gripping with a small force can be performed.

  In addition, a manipulator notification signal corresponding to the frequency deviation is output by at least one of the above configurations. For example, when the object is soft due to the detected frequency deviation, a signal for limiting the driving force of the manipulator is issued to notify the manipulator operation unit. This can prevent an excessive force from being applied to the object from the electronically driven manipulator. In addition, the manipulator operation unit that has received the notification signal controls the driving force of the manipulator and can automatically perform adaptive control according to the hardness of the object, which improves the convenience of manipulator operation. .

  As described above, according to the contact notification device according to the present invention, it is possible to detect the contact by further reducing the load applied to the object. Further, the contact state can be notified with higher convenience for the operator. Further, the contact state can be output with higher convenience of manipulator operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the operation support device for living tissue will be described as an application of the contact notification device according to the present invention, but it can also be applied to other systems that need to know the contact state when operating the manipulator. . For example, the contact notification device according to the present invention may be applied to a robot gripping system or the like. In addition, the operation target of the manipulator is not limited to the living tissue, and may be another substance. The manipulator is operated electronically via an operation ball, an operation stick, or the like. However, the operator may directly operate the mechanism part of the manipulator directly. Further, the notification sound will be described as means for notifying the operator of the contact information, but other notification means that does not impair the manipulator operability of the operator, such as notification sound or notification light, may be used.

  FIG. 1 is a block diagram of a surgery support system 10 to which a contact notification device 20 according to an embodiment is applied. Although not a component of the surgery support system 10, FIG. 1 also shows an operating table 6 and a living tissue 8 in an open state placed thereon.

  The surgery support system 10 includes a contact notification device 20, a camera 60 provided on the operating table 6, a display 62 that displays a state captured by the camera 60, and a manipulator operation control unit that controls the operation of the manipulator 22. 70.

  The contact notification device 20 cooperates with a part of a manipulator 22 that performs a treatment such as grasping the biological tissue 8, a contact probe 24 provided at the tip of the manipulator 22, and the contact probe 24. A contact determination unit 30 that determines contact with living tissue and outputs the contact information, an output conversion unit 40 that converts the received contact information into an audio signal, and the like, and a headphone 50 are provided.

  FIG. 2 is a detailed block diagram of the contact notification device 20. In FIG. 2, a contact probe 24 is attached to the tip of one side of a pair of manipulator movable pieces 23a and 23b having a bowl shape in the manipulator 22, and the manipulator 22 is in contact with the living tissue 8 that is the object. It is a composite part having a function as a sensor unit to detect. The contact probe 24 is laminated in the order of the manipulator movable piece 23a-vibration detecting element 28-vibrator 26-contact ball 29 so as to face the inner end of the manipulator movable piece 23a, that is, the other manipulator movable piece 23b. Provided. Each lamination can be performed by adhesion or the like, for example.

  The vibrator 26 is a vibrating body having a function of injecting vibrations into an object through a contact ball 29. For example, a vibrator provided with a piezoelectric piezoelectric element made of PZT (lead zirconate titanate) and having two terminals is used. it can. The vibration detecting element 28 is a sensor having a function of detecting reflected vibration from the object via the contact ball 29, and a piezoelectric-piezoelectric element made of PZT similar to the vibrator 26 is used as a vibration-voltage converting element. Can be used. FIG. 2 shows an example in which the vibrator 26 and the vibration detecting element 28 are made of the same material and are stacked with a common ground electrode. The lead wire for the ground electrode is not shown. One terminal of the vibrator 26 is connected to the terminal 32 of the contact determination unit 30, and one terminal of the vibration detection element 28 is connected to the terminal 31 of the contact determination unit 30.

  The contact ball 29 is a plastic ball having a shape such as a hemisphere, and is a member having a function of smoothly contacting the living tissue 8, transmitting vibration to the living tissue 8 efficiently, and receiving vibration from the living tissue 8 efficiently. is there.

  The contact determination unit 30 is a circuit part related to the above-described phase compensation method, detects that the contact probe 24 has contacted the biological tissue 8, and outputs the contact information as a frequency deviation corresponding to the phase difference. It has a function. Specifically, a feedback loop of (contact ball 29) -vibration detecting element 28-terminal 31-DC cut capacitor-amplifier 34-phase compensation circuit 36-terminal 32-vibrator 26- (contact ball 29) is formed. Connected to. When the contact ball 29 comes into contact with the living tissue 8, the feedback loop includes the living tissue 8.

Accordingly, self-oscillation oscillation occurs even when the contact ball 29 is not in contact with the living tissue 8. The frequency at this time is assumed to be f ₀ . When the contact ball 29 comes into contact with the living tissue 8, the configuration of the feedback loop changes and the vibration changes. Here, since the phase compensation circuit 36 is connected in series to the feedback loop, it functions to maintain the self-oscillation oscillation by setting the phase difference to zero by its function. Since the phase compensation circuit 36 is a circuit that changes the frequency of vibration to make the phase difference zero, as a result of maintaining the self-excited oscillation, a frequency shift determined by the setting parameter of the phase compensation circuit 36 occurs. The self-oscillation oscillation continues at the shifted frequency f ₁ .

The frequency deviation detector 38 is a circuit that measures the frequency of the self-oscillation oscillation of the feedback loop and outputs a frequency deviation that is a change in the frequency. For example, the frequency deviation detector 38 can be configured by a counter circuit, a subtraction circuit, and a memory. Specifically, the frequency f ₀ when the contact ball 29 is not in contact with the living tissue 8 is first measured and stored, and thereafter the frequency f of the self-oscillation oscillation is measured every moment to obtain the frequency deviation. Δf = f−f ₀ is calculated, converted into a voltage value, and output to the terminal 39. The conversion to the voltage value is to facilitate subsequent processing, and may be output as an analog value or a digital value. The terminal 39 is connected to the output conversion unit 40.

  As shown in FIG. 2, the output conversion unit 40 generates a notification sound generator 42 for generating an output signal corresponding to the contact information and outputting it to the sounding body 52 in order to notify the operator of the contact information with sound, and a manipulator operation. A notification signal generator 44 for outputting contact information to the control unit 70 is provided. The sounding body 52 corresponds to the speaker portion of the headphone 50 in FIG. The notification sound generator 42 and the notification signal generator 44 have a function of outputting an output signal corresponding to the magnitude of the input signal when the input signal is below a certain threshold value and the output is zero. The two circuits are different in that the form of the output signal is suitable for the sound generator 52 or the manipulator operation controller 70.

  The reason for providing the threshold value is to reduce the influence of noise when detecting contact. If the threshold value is increased too much, the contact pressure applied to the living tissue 8 increases, so it is preferable to set the threshold value to an appropriate low value based on, for example, experimental results.

  The reason why the output signal corresponding to the magnitude of the input signal is output after exceeding the threshold value is to inform the degree of hardness of the living tissue 8. For example, when the parameter setting of the phase compensation circuit 36 is such that the frequency deviation increases as the hardness of the biological tissue increases, the frequency deviation decreases as the output signal decreases, and the hardness of the biological tissue decreases. I can inform you. Now, if the nature of the sound emitted from the sounding body 52 is changed according to the output signal of the notification sound generator 42, the operator only needs to listen to the change of the sound, and the living tissue 8 is soft and can be handled with care. Since it is preferable or because the living tissue 8 has a firm hardness, it is possible to easily know whether or not it is necessary to grip the living tissue 8 firmly.

As the notification sound generator 42, for example, when the sounding body 52 is an element driven by a pulse signal, a Vf converter with a threshold value can be used. FIG. 3 shows an example of a characteristic diagram of a Vf converter with a threshold. The horizontal axis represents voltage as the magnitude of the input signal, and the vertical axis represents the pulse frequency of the pulse signal output. is there. The frequencies f ₁ to f _{2 on the} vertical axis correspond to the audible frequency region in the sound output characteristics of the sound generator 52. That is, even if a pulse signal having a frequency f ₁ or lower is input to the sounding body 52, it is not output as a sound that can be perceived by hearing. Therefore, in FIG. 3, when the input voltage is equal to or lower than the predetermined threshold V _th , the pulse frequency is equal to or lower than f ₁ , and no audible sound is output from the sounding body 52, and the input voltage exceeds the threshold V _th. Depending on the magnitude of the sound, the sound generator 52 gradually outputs high frequency sounds.

  As the configuration of the notification sound generator 42, in addition to the Vf converter with a threshold value, a unit adapted to the characteristics of the sound generator 52 can be used. For example, when the sound generator 52 has a characteristic that the volume of the sound can be varied according to the voltage, the voltage value obtained by performing level shift for the threshold value as (output voltage = input voltage−threshold voltage). Can be configured to be supplied to the sounding body 52.

  Further, after the threshold value calculation is performed on the self-excited oscillation frequency so that the self-excited oscillation frequency of the feedback loop of the contact determination unit 30 is matched with the characteristics of the sound generator 52, a signal having the frequency is directly output to the sound generator. It is good also as what inputs to 52.

  The notification signal generator 44, like the notification sound generator 42, outputs zero when the input signal is below a certain threshold value, and outputs an output signal corresponding to the magnitude of the input signal when the threshold value is exceeded. This circuit has a function of outputting to the operation control unit 70. Specifically, the voltage value of the terminal 39 is used as an input signal, and (output voltage = input voltage−threshold voltage) and the level shifted by the threshold value are notified to the manipulator operation control unit 70 as a notification signal. Output.

  For example, when the manipulator 22 is driven by a servo motor, this notification signal can be supplied as contact information to a command value generation unit of the servo motor. As described above, the supplied contact information includes information on whether or not the contact is made and information on the hardness and softness of the living tissue at the time of contact. Can drive the manipulator with a small output torque, and can drive the manipulator with an output torque corresponding to the hardness of the living tissue 8 after contact.

  The notification signal generator 44 may be used according to an operator's selection. For example, when the operator operates the manipulator 22 with an operation ball or the like, the output of the notification signal generator 44 is prohibited, and the manipulator 22 can be driven exclusively by the operation ball of the operator. Further, the output of the notification signal generator 44 may be used to limit the upper limit of the output torque of the manipulator 22. In this case, erroneous operation of the operator can be prevented by using the output of the notification signal generator 44 even when the operator operates the manipulator 22 with an operation ball or the like.

1 is a block diagram of a surgery support system to which a contact notification device according to an embodiment of the present invention is applied. It is a detailed block diagram of the contact notification device in the embodiment according to the present invention. In embodiment concerning this invention, it is a figure which shows the example of the characteristic view of the Vf converter with a threshold value.

Explanation of symbols

  6 operating table, 8 biological tissue, 10 operation support system, 20 contact notification device, 22 manipulator, 23a, 23b manipulator movable piece, 24 contact probe, 26 vibrator, 28 vibration detection element, 29 contact ball, 30 contact judgment Unit, 34 amplifier, 36 phase compensation circuit, 38 frequency deviation detector, 40 output conversion unit, 42 notification sound generator, 44 notification signal generator, 50 headphones, 52 sound generator, 60 camera, 62 display, 70 manipulator operation control Department.

Claims (3)

When operating the manipulator, it is a contact notification device that detects that the manipulator contacts the object and outputs the result,
A contact probe that is attached to a manipulator and has a vibrator that injects vibration into an object, and a vibration detection sensor that detects a reflected wave from the object;
An amplifier having an input terminal connected to the signal output terminal of the vibration detection sensor;
Provided between the output end of the amplifier and the signal input end of the vibrator, the frequency of vibration is changed to make the phase difference generated between the input waveform to the vibrator and the output waveform from the vibration detection sensor zero. A phase compensation circuit;
When the frequency of self-oscillation oscillation that occurs by compensating the phase difference to zero by the feedback loop formed by the contact probe, amplifier, and phase compensation circuit is measured, and the contact probe is not in contact with the object A frequency deviation detector for detecting a deviation between the frequency of the contact and the frequency when contacting,
An output means for outputting a notification sound or a notification light when the detected frequency deviation exceeds a predetermined threshold;
A contact notification device characterized by comprising: The contact notification device according to claim 1,
The output means further changes the display content of the notification sound or the notification light according to the frequency deviation above a predetermined threshold value. The contact notification device according to claim 1,
The output means further outputs a notification signal corresponding to the magnitude of the frequency deviation above a predetermined threshold value to the operation unit of the manipulator.

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