JPS6046403A - Device and method of detecting position and/or attitude - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to position and/or attitude sensing apparatus and methods, and in particular, but not exclusively, to solid state position and/or attitude sensing apparatus.

SUMMARY OF THE INVENTION According to one aspect of the invention, a method for measuring the position and/or orientation of a member includes the step of attaching one or more optical sensors to the member. scanning an area with a scanning light beam whose position as a function of time is known; measuring the time of arrival of the scanning light beam at the sensor or each sensor; and determining the position of the member from the time of arrival. A method of sensing position and/or orientation is provided that includes the process of measuring orientation.

According to another aspect of the invention, there is provided a device for measuring the position and/or orientation of a member, comprising one or more optical sensors attached to the member in the state of use of the device, as a function of time. means for generating a scanning light beam whose position is known; means for measuring the time at which the scanning light beam reaches the sensor or each sensor; and determining the position and/or orientation of the member from the time of arrival. An apparatus for sensing position and/or orientation is provided, comprising means.

According to still another aspect of the present invention, there is provided a method for controlling the position and/or attitude of a member provided with an optical sensor, comprising:
the process of driving the member to a desired position and detecting a light beam at a position corresponding to the desired position with the optical sensor at the desired position; closed loop control of the member at the desired position when the light beam position is changed; controlling the position and/or attitude, including monitoring until a new desired position is selected by the light beam, and driving the member to re-detect the light beam, thereby taking the new desired position. A method is provided.

Embodiments Embodiments of the invention will now be described with reference to the accompanying drawings.

First, a basic one-dimensional position sensing device will be explained with reference to FIGS. 1-4. Device 1 in the Y direction of the area
Assume that it is required to know the location of A photodetector such as a photodiode 2 is attached to the member (or device) 1, for example. A scanning light beam 3 (FIGS. 2, 3) is generated by a scanning device 4 (FIG. 1) and is generally directed towards the member 1. An embodiment of the scanning device 1 is shown in FIG. At a particular time relative to the start of the scan, i.e. at time t in FIG. 3, a light beam 3 illuminates the photodiode 2, resulting in an electrical output signal from the photodiode as shown in FIG. .

The position sensing device shown in FIG. 1 includes, for example, a photodiode 2 coupled to an electronic circuit 5 for signal processing, a scanning device 4
, control and synchronization means 6 , timing device 7 and data converter 8 . The scanning device 4 shown in FIG.
control electronic circuit 10, acousto-optic deflector 11, deflector 1
1, and an RF drive means 14 for the deflector 11.

The acousto-optic deflector 11 is made of, for example, lithium niobate (Li
It consists of an object of an acousto-optic material, such as NbOs (NbOs), into which acoustic waves can be emitted from a suitable transducer to produce a frequency-controllable diffraction grating. Light incident on this grating at an appropriate angle is then coupled into a first granting order, which can be scanned in proportion to the grating period. The device can be implemented in either internal or surface corrugations. For random access operation, the response of the device is determined by the travel time of the acoustic wave across the optical beam. The transit time will typically be less than 20 microseconds.

Rask scanning is also possible at speeds approaching approximately 100 microseconds per scan without significant penalty in resolution.

The time reference of the timing device 7 and the acousto-optic deflector 11 of the scanning device 4 are synchronized by the control and synchronization device 6 so that the direction of the scanning light beam is a known function of time, so that the position of the photodiode 2 and thus of the member 1 is can be obtained from the time at which the electrical output signal of photodiode 2 appears.

The time information obtained by the timing device 7 can be converted into distance (position) information, for example. In this manner, position information of the member is obtained from the time at which the scanning light beam reaches the photodiode attached to the member.

A basic one-dimensional attitude sensing device will be described below with reference to FIGS. 5 and 6. FIG. 5 shows a plan view of the one-dimensional attitude detection device. The member whose posture is to be detected is equipped with two photodetectors, for example a photodiode 16.
and 17 are attached. Photodiodes 16 and 17 are separated by a known distance r. The scanning light beam 18 should have a bar-shaped cross-section rather than a spot-shaped cross-section as in the embodiment of FIGS. 1-4. The light propagates in the Z direction and the beam scans in the X direction. The output signal of the photodiode has a waveform shown in number 60. By knowing the time difference Δt between the two photodiode output signals and the beam position as a function of time, the
The difference in direction ΔX can be obtained. The attitude angle θ can be obtained from the following relational expression.

The determination of θ-cos-'< Δx/r) ΔX, and therefore θ, can be immediately performed by a pre-programmed ROM-based data converter circuit. Attitude information is thus obtained from the arrival time of the scanning light beam with a bar-shaped cross section on the photodiode.

By combining the above-described position sensing device and posture sensing device, it is possible to obtain complete three-dimensional posture and position information of the member. A single position photodiode, or multiple position photodiodes as described below, may be
It should preferably be placed in a suitable position on the member such that it is unaffected by angular changes in the member. Alternatively, appropriate post-processing of the position data may be required.

As mentioned above, the acousto-optic deflector is a random access deflector.
mode, i.e. in which the beam position is changed from one position to another without scanning the intervening positions, the deflector is thus can be used to control the position of the sensor and thus the position of the member carrying the sensor. Such a position controller can operate as follows. A photodetector (sensor) on the member senses the deflected beam when the member is in the desired position, and a closed loop control means then maintains the member in this position. When a new position is requested, as it has been programmed, the sensor is automatically moved towards the new position and once the sensor detects the corresponding deflected beam at the new position. Hold the member in place.

The basic position control device described above detects the arrival time of the scanning light beam. Since the beam is of finite width, the device resolution is such that electrical pulses of finite width are constructed from the photodiode, e.g. by using a threshold comparator after the photodiode so that the photodiode output reaches e.g. 80% of its maximum value. can be increased by having an output signal generated when The ROM for the time-to-distance data converter must in this case be carefully programmed so that the corresponding day-to-day measurements give the correct distance (position)). An arrangement using a color comparator 18 is shown in FIG. 7. The photodiode 2, the photodiode electronics 5, the scanning device 4, and the control and synchronization bag w6 correspond to those in FIG. 1. To,
It includes a device number counter and oscillator 19, and a data converter 20.

In this device, the output nockle of the comparator 18 is used to stop the counting of the counter and the counter of the oscillator 19, which counter starts counting when the light beam starts scanning and therefore of the time. Start measurement. Thus, an electronic method is provided to improve the resolution of the device by sensing the leading edge of the electrical pulse generated by the photodiode.

Improving the signal-to-noise ratio (SNR) can be achieved in various ways. For example, it is possible to place an optical film on the photodetector, and the filter has the characteristic of bandpassing the wavelengths used in the scanning device. Therefore, other light wavelengths undergo greater attenuation before reaching the photodetector. Alternatively, an electrical high-pass filter can be used after the photodetector. The lower frequency unit of the filter should be just below the reciprocal of the period of travel of the scanning beam across the photodiode. A third possibility is intensity, which modulates the scanning beam such that the photodetector pinkamps several cycles of the intensity modulation frequency during one scan. In this case,
An intensity modulating frequency bandpass filter is used after the photodetector.

A technique for enhancing position indication using several photodetectors (photodiodes) is described below with reference to FIGS. 8-10. A schematic plan view of the arrangement is shown in FIG. The scanning light beam scans along the array line of photodiodes 21, 22, 23 and 24. The greater the number of photodiodes, the better the discrimination against noise and the better the position resolution. An overall schematic block diagram of a multiple photodiode type position sensing device is shown in FIG. The position sensing device comprises a scanning device 4, synchronization and control means 6,
Photodiode electronic circuit 25, each photodiode 21~
24, monostable multi-bi break circuit triggered on each rising edge 26.27.28 or 29, bandpass amplifier 30, counter and oscillator 31, reference oscillator 32
, a phase detector 33, an analog-to-digital (A-D) converter 34, and a data converter 35.

The output pulses of photodiodes 21-24 are shown symbolically in FIG. 10A. Each of these output pulses is applied individually to a respective monostable circuit 26-29 which outputs a short pulse compared to the scanning time of the light beam across the photodiode. The obtained pulse is the 10th
As shown in Figure B, the pulses are then fed through a bandpass amplifier 30 whose center frequency corresponds to the period between the pulses. The output signal of the bandpass amplifier 30 has a sinusoidal waveform as shown in FIG. 10C. Since the time position of the pulse in FIG. 10B depends on the photodiode position, the phase of the sinusoidal signal in FIG. 10C depends on the photodiode position. Therefore, by measuring the phase of the sinusoidal signal, the fine position of the photodiode can be determined.

For this purpose, the phase of the output signal of the bandpass amplifier 30 is detected by a phase detector 33 by comparing the sinusoidal signal with the output signal of the reference oscillator 32 .

The analog output signal of the detector 33 is converted to digital form by a converter 34 and to the required output format by a data converter 35. The output signal thus corresponds to the fine position of the photodiode. The coarse position of the photodiode is determined by measuring the time of arrival of the scanning beam on the photodiode, as described above.

In the above two optical scanning devices, the scanning light spot and the scanning light bar have been described. The optical system for generating the scanning spot or scanning bar depends in detail on the requirements of the sensing device. Generally, to generate a scanned light spot, an optical system is required to shape and collimate the input beam, and an optical system following the scanner is required to generate the desired scanning geometry from the scanner output. It is said that The scanner output beam should have the desired cross-sectional area and should typically be collimated. The beam position as a function of time should be known. Two forms of scanning apparatus that fulfill these requirements are shown in FIG. In FIG. 11a, only the position of the beam changes, its angle does not change, and if, for example, the scan rate is constant, the position across the scan is known as a function of time. FIG. 11b shows a scanning device in which the output beam pivots about a point, the angular position of which can be known as a function of time. For this form of scanning, the distance of the beam along the axis being scanned from the center position is determined relative to the center position if the distance between the pivot axis and the center position axis is known. It can be calculated from the beam angle.

Two scanning devices in the form of a pivot as shown in FIG. 11, acting at right angles as shown in FIG. 12, determine the X and Y position of the sensor (photodetector) with respect to the origin. It can be used to make decisions. The pivot point of one of the scanning devices is located at a point 36 at a distance 11 measured in the Y-axis direction from the origin 37 of coordinates (0,0). The pivot point of the other scanning device is located at a point 38 at a distance ■ measured from the origin 37 in the X-axis direction. The beam of one scanner is pivoted between the extremes of -01 and +θ' with respect to its center position, while the beam of the other scanner is rotated between the extremes of -01 and +θ' with respect to its center position. Swirled between values. For the sensor at point 39, its coordinates (x,y) can be calculated from the following relationship:

The sensor (x,y) position can thus be calculated for all positions within the overlapping field, ie within the area 40 indicated by the dashed line.

The essential feature of acousto-optic beam deflectors is relatively small angle, scanning deflection. The output typically travels between about ±1.5° about its center position, and the optical aperture must be large to make the device "high resolution." The optics at the output of the scanning device should reduce the beam size, re-parallel it, and increase the angular scan as much as possible. These requirements are the 13th
This can be satisfied by using a telephoto lens system as shown in the figure. Lenses 41 and 42 have positive focal lengths fA and fB, respectively, and are arranged so that their focal planes coincide. The collimated input beam is focused by lens 41 and re-collimated by lens 42. The angular magnification of the system is approximately f
a/f is given by m, and the size of the cross-sectional area of the beam is varied approximately by fn/fA. In reality, the system may use several lenses to correct aberrations, and the effect of each element is not clear. Most acousto-optic deflectors have rectangular apertures and the scanned beam cannot be internally shaped, so the system may also include cylindrical lenses, prisms and other anamorphic elements. .

The scan produced with most acousto-optic deflectors is of the form shown in Figure 11b. A scan of the form shown in Figure 11a can be generated by adding additional optical elements to the output of the acousto-optic deflector. A positive single focal length lens 43 with a focal point located at the position of the scanning device is suitable (FIG. 14a) or a holographic element 44 can be used (first
Figure 4b).

A scanning light bar can be generated from a scanning beam (in the form of a light spot) by using a cylindrical optical system 45, as shown in FIG.

Devices and methods for detecting the position and/or orientation of solid-state objects as described above, such as automatic abrasive cutting machines, pre-programmed robot arms, laser disc readers and writers, etc. can be applied to devices with many parts that must be sensed. The inventive approach is particularly suited for such applications because position and orientation information can be obtained at high speed and with high resolution. The scanning light beam or light is generated by a solid-state acousto-optic deflector, which can be either of the surface acoustic wave or internal acoustic wave type. The use of a scanning light beam or bar also means that no mechanical contact with the location is required.

Another possible application is "electronic memo paper." 2
The dimensional position sensing device is coupled to a cathode ray tube or liquid crystal display and appropriate electrical circuitry to form a "memo pad."

The "pen" has two photodiodes mounted at right angles to it.

The X and Y position of the "pen" is sensed using a "memo pad" scanning device. A dot is electronically written on the screen or display at the "pen" location. Information can also be stored in RAM. "pen"
As the is moved across the screen or display, a trajectory can be drawn thereon. Such "electronic memo paper" can be used as a replacement for a cathode ray tube "light pen" or to electronically record handwritten information and replace pen and paper.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the basic configuration of a position detection device, FIG. 2 is a schematic diagram showing an example of a scanning device in the device shown in FIG. 1, FIG. 3 is a schematic diagram showing a scanning light beam and a photodiode, and FIG. Figure 4 is a diagram showing the electrical output signal of the photodiode in Figure 3, Figure 5 is a schematic diagram showing the attitude detection arrangement, and Figure 6
The figure shows the electrical output signal of the photodiode in Figure 5,
FIG. 7 is a schematic diagram showing a modification of the position detection device of FIG. 1 with enhanced resolution; FIG. 8 is a schematic diagram showing a plurality of diodes and a scanning light beam used to enhance the position resolution; FIG. 9 is a schematic diagram showing the basic configuration of a multi-photodiode type position sensing device, and FIGS. 10A, 10B, and 10C are electrical output signals of the photodiode, monostable circuit, and bandpass filter, respectively. FIGS. 11a and 11b are schematic diagrams showing two forms of the light beam scanning device, FIG. 12 is a diagram showing two practical forms of use as an X-Y position indicator, and , FIG. 15 is a schematic diagram showing the generation of a scanning light bar from a scanning beam. 1--device (member), 2--photodiode, 4--scanning device, 5--photodiode electronic circuit, 6-control and synchronization means, 7--timing device, 8--data converter, 9-・Laser, 10-・Control electronic circuit, 11-
・Acousto-optic deflector, 12-human power optical system, 13--output optical system, 1t-RF drive means, 16.17--photodiode, 18-rule threshold comparator, 19--counter and oscillator, 20--data converter, 21-24--photodiode, 26-29-monostable circuit, 3o-bandpass amplifier, 32--reference oscillator, 33--phase detector, 35--data converter . The following is the margin on page X (no changes to the content) ~・l ~・3 Procedural amendment (method) August 2g, 1980 Commissioner of the Patent Office Shiga Gakudon 1, Indication of the case 1988 Patent Application No. 89587 2, Name of the invention Apparatus and method for detecting position and/or orientation 3, Relationship with the person making the amendment Patent applicant name International Standard Electric Cobo Reishimin 4, Agent 5, Date of amendment order Showa July 31, 1959 (shipment date) 6. Subject of amendment fil "Representative of applicant" column (2) Delegation of application
Letter (3) Drawing 7, Contents of amendment (1021 As shown in attached sheet (31 Drawings changed (31!, none)) 8, List of attached documents (11 Request for correction vi 1 letter (2) Power of attorney and translation 1 copy each (1 copy of 31 engraving drawings)

Claims (1)

[Claims] 1. A method of measuring the position and/or orientation of a member, the method comprising: attaching one or more optical sensors to the member; position and/or orientation, including scanning with a known scanning light beam, measuring the time of arrival of the scanning light beam at the sensor, and measuring the position and/or orientation of the member from the time of arrival. , or a method to detect posture. 2. The method of claim 1, wherein the scanning light beam is generated by a solid-state acousto-optic deflector. 3. A method as claimed in claim 1 or 2, in which the optical sensor comprises a photodetector characterized by an electrical pulse upon arrival thereof by the scanning light beam. 4. The method according to claim 3, characterized by the step of detecting the leading edge of the electric pulse. 5. A method for measuring the attitude angle (θ) of the member with respect to a first direction, comprising: attaching two sensors to the member spaced apart by a first distance (r); a light beam in the form of a bar; scanning the area with a sensor, measuring a difference in position (ΔX) of the two sensors in a first direction, and
Relational expression, θ = CO5-' (△x/r) to θ
Claims 1 to 4 are characterized in that the
The method described in any of the sections. 6. Each sensor consists of a plurality of photodiodes, and the process of measuring the position of the large force on the member from the arrival time of the scanning light beam to the first one of the plurality of photodiodes; 4. The method according to claim 1 or 2, which includes the step of minutely measuring the position of the member from the arrival time of the beam. 7. A device for measuring the position and/or orientation of a member, the device being in use, one or more optical sensors attached to the member, generating a scanning light beam whose position as a function of time is known. An apparatus for sensing position and/or orientation, comprising: means for measuring the time of arrival of the scanning light beam at the sensor; and means for determining the position and/or orientation of the member from the time of arrival. 8. The apparatus according to claim 7, wherein the scanning light beam generating means is a solid-state acousto-optic deflector. 9. The device according to claim 7 or 8, wherein the optical sensor comprises a photodetector, and in the state of use of the device, the photodetector is characterized by an electric pulse when the scanning light beam reaches it. . 10. The apparatus of claim 9, wherein the means for measuring the time of arrival of the scanning light beam serves to detect the leading edge of the electrical pulse. 11. An apparatus for determining the attitude angle (θ) of the member with respect to a first direction, comprising two sensors attached to the member spaced apart by a first distance (r) in the state of use; The scanning light beam consists of a scanning light bar, and the measuring means measures the difference in position of the two sensors in the first direction (
ΔX) and θ from the relational expression %).
Apparatus according to any of clauses 10. 12. Each sensor consists of a plurality of photodiodes, the arrival time of the scanning light beam to the first of the plurality of photodiodes serves to determine the position of the force on the member, and the scanning light beam to all of the photodiodes 9. A device according to claim 7 or 8, wherein the arrival time of serves for finely determining the position of the member. 13. a plurality of rising edge triggered monostable circuits, with a photodiode output applied to each monostable; a bandpass amplifier to which the monostable output is applied; and a bandpass amplifier to which the monostable output is applied; 13. The device of claim 12, further comprising means for measuring the phase of the output signal of a pass-through amplifier, the phase being dependent on the photodiode position. 14. includes an optical filter disposed between the photodetector and the scanning light beam generator, the optical filter having bandpass properties for the wavelengths used in the scanning device, thereby improving the signal pairing of the device; 14. The device according to any one of claims 9 to 13, characterized by a noise ratio. 15. includes an electrical high-pass filter for filtering the photodetector output prior to application to the measurement means, the frequency unit of the filter being less than or equal to the reciprocal of the period of travel of the scanning beam across the photodetector; 14. A device according to any one of claims 9 to 13, characterized in that there is a signal-to-noise ratio of the device. 16.1 means for intensity modulating the scanning beam to detect several cycles of the intensity modulation frequency during the scan, and a bandpass filter for filtering the detector output at the intensity modulation frequency; A device according to any one of claims 9 to 13, characterized in that the signal-to-noise ratio of the device is characterized by: 17. A method for controlling the position and/or attitude of a member equipped with a light sensor, the method comprising: driving the member to a desired position; and at the desired position, the optical sensor emits a light beam at a position corresponding to the desired position; monitoring the member at the desired position when the light beam position is changed until a new desired position is selected by closed-loop control; and driving the member to re-detect the light beam. A method for controlling a position and/or posture, which includes the process of controlling the position and/or posture thereby obtaining a new desired position. 18. The light beam is generated by an acousto-optic deflector operating in a random access mode.
The method described in Section 7.