GB2329293A - Distance measurement device - Google Patents
Distance measurement device Download PDFInfo
- Publication number
- GB2329293A GB2329293A GB9826819A GB9826819A GB2329293A GB 2329293 A GB2329293 A GB 2329293A GB 9826819 A GB9826819 A GB 9826819A GB 9826819 A GB9826819 A GB 9826819A GB 2329293 A GB2329293 A GB 2329293A
- Authority
- GB
- United Kingdom
- Prior art keywords
- distance
- distance measuring
- distance measurement
- result
- judging means
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P13/00—Indicating or recording presence, absence, or direction, of movement
- G01P13/02—Indicating direction only, e.g. by weather vane
- G01P13/04—Indicating positive or negative direction of a linear movement or clockwise or anti-clockwise direction of a rotational movement
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
- G01S15/06—Systems determining the position data of a target
- G01S15/08—Systems for measuring distance only
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/50—Systems of measurement based on relative movement of target
- G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Length Measuring Devices With Unspecified Measuring Means (AREA)
- Measurement Of Optical Distance (AREA)
Abstract
Device 1 measures the distance to a target T and assigns it to one of three range bands. The measured distance is stored and compared with a subsequent distance measurement to indicate the direction of movement (i.e. towards, away from or stationary) of the target with respect to the device. In one embodiment, the direction of movement of the target is deduced by analysing a predetermined number of past direction of movement results stored in storage means 8. The result is output along with the range band information to terminals TDa, TDb, TDc, TDd. In another embodiment, the target is deemed to have moved only if the current distance measurement differs from the preceding distance measurement by more than a predetermined distance. The distance measurements may be determined using infra-red or ultrasound. The device is used on a camera.
Description
DISTANCE MEASURING APPARATUS
The present invention generally relates to a distance measuring apparatus for measuring the distance of an object. More specifically, the present invention is directed to a distance measuring apparatus capable of judging a distance region to which the object under measurement belongs, and also a direction of movement based on the measured distance when a distance measuring range of this distance measuring apparatus is divided into a plurality of distance regions. The invention also relates to a camera having a distance measuring apparatus in accordance with the invention-.
Japanese Patent Application No. 6-213883 discloses a distance measuring apparatus in which the measurable distance range is divided into a plurality of distance regions, the distance region to which the object under measurement belongs is determined from the distance measurement result, and this judgement result is output.
The known distance measuring apparatus merely determines in which distance region the object is present, but no clear judgement is made as to whether the object is being moved toward the near side or the far side of the determined distance region. In order to make a judgement regarding the direction of movement of the object, it is necessary to wait until the object enters another distance region. Accordingly, this known distance measuring apparatus has only a limited application.
The present invention seeks to provide a distance measuring apparatus capable of judging both a distance region in which an object under measurement is present, and whether this object is moved toward a near side or a far side, or otherwise is stationary.
According to one aspect of the present invention, there is provided a distance measuring apparatus comprising:
distance measuring means, having a measurable distance range, for measuring a distance to an object;
region judging means for judging to which region among a plurality of distance regions within the measurable distance range of the distance measuring means a distance measurement of the distance measuring means belongs;
storage means for storing therein the result of the distance measurement;
direction judging means for determining movement of the object by comparing the present distance measurement result with a preceding distance measurement result stored in the storage means;
direction storage means for storing and updating a predetermined number of past moving direction results which have been judged by said direction judging means,
wherein the direction judging means determines the moving direction using a predetermined number of moving directions stored in said direction storage means; and
output means for outputting the results of the region judging means and the direction judging means.
For a better understanding of the present invention, and to show how it may be brought into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
Figure 1 is a circuit block diagram indicating an arrangement of a distance measuring apparatus.
Figure 2 is a diagram explaining distance regions introduced into the distance measuring apparatus of
Figure 1.
Figure 3 is a table representing a combination of output levels derived from the distance measuring apparatus of Figure 1.
Figure 4 is a circuit block diagram showing an arrangement of a distance measuring apparatus according to an embodiment of the present invention.
A distance measuring apparatus shown in the accompanying drawings will now be described in detail.
Figure 1 is a circuit block diagram representing an arrangement of a distance measuring apparatus. For the sake of simplicity, in the following description the measurable distance range of a distance measuring means is divided into three distance regions by two specific distance points (which will be referred to as "splitting points" hereinafter), although the invention is not limited to this number.
In Figure 1, reference numeral 1 indicates a distance measuring means for measuring a distance of an object T to be measured and for converting the measurement result into a digital signal. Means for emitting infrared light and for detecting the infrared light reflected from the object T to be measured by way of a position detecting element (PSD), or means for measuring a distance from the object T to be measured by utilizing ultrasonic waves may be used as the distance measuring means. Reference numeral 3 denotes a setting means for setting one splitting point Pa, and reference numeral 4 indicates another setting means for setting the other splitting point Pb. It should be noted that in Figure 1, these setting means 3 and 4 are shown as digital switches having 4-bit signal lines.
Thus in each case, 16 different splitting points Pa and
Pb are settable by 4-bit levels.
This relationship will now be explained with reference to Figure 2, which is a diagram for explaining the distance range. In Figure 2, the abscissa shows a distance measured from the distance measuring means, in which the furthest measurable point is defined as "LF" (for example, 3.7m) and the nearest measurable point is defined as "LN" (for instance, 0.5m). Assuming now that the distance measuring area (tNF) is equally divided by 16 distance points, and respective ones of the 16 possible splitting points settable by the setting means 4 are allocated to these 16 possible splitting points. As shown in Figure 2a, any one of distance points Pan ("n" being natural numbers from 0 to 15) may be set as the splitting point
Pa. In Figure 2a, the splitting point Pa is set to Pa8 (n=8), and a distance from the distance measuring means 1 becomes 2.lm (0.5m + 8 x 0.2m) Similarly, as illustrated in Figure 2b, the other splitting point Pb may be set at any one of distance points Pbm ("run" being natural numbers from 0 to 15) by setting means 3. In Figure 2b, the other splitting point Pb is set at Pb3 (m=3), and a distance from the distance measuring means 1 is 1.lem (0.5m + 3 x 0.2m).
In other words, it is understood that the splitting point Pa is set to the distance of 2.lm by the setting means 3, whereas the other splitting point Pb is set to the distance of 1.lem by the other setting means 4.
Referring back to Figure 1, the distance measuring means 1 is provided with an input terminal SS for inputting a trigger signal by which a distance measuring operation is stored. Reference numeral 2 indicates region judging means for judging whether the distance measuring result of the distance measuring means 1 falls in any one of three distance regions Z1,
Z2, Z3 (see Figure 2c) defined by dividing the measurable distance region by splitting point Pa and splitting point Pb, and for generating the judgement result to an output means 7. The output means 7 generates from two output terminals TDa and TDb, two outputs Da and Db with levels as indicated in a table of Figure 2d based upon the judgement result of the region judging means 2. That is to say, assuming that a high level is indicated as "H", and a low level is indicated as "L", the levels of the outputs are as follows: for the distance region Z1 at the near side, divided by the splitting point Pa, Da="H" and Db='lH''; for the central distance region Z2 divided by the splitting points Pa and Pb, Da="L" and Db="H"; and for distance region 23 at the far side, divided by the splitting point Pb, Da="H" and Db="L".
When the distance measured by the distance measuring means 1 is, for instance, 1.5m, the distance region is Z2, and the output levels are given by Da="L" and Db="H".
It should be noted that alternatively, the outputs of the three distance regions Z1, Z2, 23 may be allocated to three output terminals corresponding to the respective distance regions, and then only the output level at the output terminal corresponding to such a distance region to which the object T under measurement belongs may be different from the output levels at other output terminals.
Further, it will be obvious that various other means for indicating the result of the measurement means are possible.
Reference numeral 5 indicates a storage means for storing the distance measured by the distance measuring means 1, into which the previous distance measuring result is continually stored and updated. Reference numeral 6 denotes a moving direction judging means with an input terminal SS into which a trigger signal is entered. This moving direction judging means compares the updated distance measurement result (which will be referred to as "a present distance measurement result" hereinafter) obtained by measuring the distance by the distance measuring means with the previous distance measurement result stored in the storage means 5, and also judges whether the present distance measurement result is closer or further away with respect to the previous distance measuring result, or is not changed (stationary state).
The output means 7 outputs the judgement result of the moving direction judging means 6 with output levels of Dc and Dd to two output terminals TDc and TDd, respectively. As one example, if the present distance measurement result is equal to the previous distance measurement result, then the output levels at the output terminals of the output means 7 are expressed by Dc="L" and Dd="L". When the present distance measurement result is closer than the previous distance measuring result, the output levels of the output terminals are given by Dc="H" and'Dd=L". Then, when the present distance measuring result is further away than the previous distance measurement result, the output levels of the output signals are given by Dc="L" and Dd="H".
It should be noted that although in the above described arrangement the output terminals TDa and T.Db used to output the signals indicative of the distance region are provided separately from the terminals TDc and TDd employed to output the signals representative of the moving direction, these information signals may be mixed with each other to be output.
In a table of Figure 3, one example of combinations of these output levels is illustrated.
That is, Figure 3 shows a situation in which four outputs (Da, Db, Dc, Dd) are employed to represent that the number of distance regions is 3 (Z1, Z2, Z3), and the number of directions of movement is 3 (namely, "N" indicates a movement from near side to far side, "F" denotes a movement from far side to near side, and "S" represents a stationary condition). Since, as explained above, the number of distance regions is selected to be 3 and the number of directions is selected to be 3, the outputs must represent 9 conditions, and thus the number of output terminals becomes 4, which is the same as in the above described embodiment.
Assuming now that the direction S of the distance region Z3 is not required, the outputs may represent 8 conditions. As a result, 3 output terminals only (i.e., Da, Db, Dc of Figure 3) are sufficient, so that the total number of output terminals may be reduced.
Generally speaking, even when a distance between the distance measuring means 1 and the object T under measurement is constant, an error is produced in a distance measurement result. Also, even when an object such as a living body is stationary, the living body is actually slightly moving. In this situation, the moving direction judging means 6 would generate different judgement results every time the distance is measured, resulting in unstable measurement values. To avoid such a difficulty, both of the two preceding distance measurement results may be stored in the storage means 5, and the moving direction judging means 6 may compare the present distance measurement with both of the two preceding distance measurement. As a consequence, more correct distance judgement can be achieved by determining the following rule, as compared with that of the above described comparison. For instance, when the present distance measurement result is the same as the previous distance measuring result and also becomes farther than that of the second previous distance measuring result, the moving direction judging means 6 judges this moving direction as a "far side. When the present distance measuring result is the same as the second previous distance measuring result and also becomes nearer (or farther) than that of the previous distance measuring result, the moving direction judging means 6 judges the moving direction as "stationary".
Also, the moving direction judging means 6 may recognize that the present distance measuring result has been changed only when the difference between the present distance measuring result and the previous distance measuring result stored in the storage means 5 is larger than a predetermined distance, and thus may vary its output. At this time, assuming now that while the object T under measurement is slowly moved, any of changes in the distance values for each of these distance measuring operations is limited to the above described predetermined distance, the moving direction judging means 6 may continuously judge this condition as "stationary", depending upon the set value of this predetermined distance. A description will now be made of a method capable of solving this problem.
In Figure 4, a circuit block diagram of a distance measuring apparatus according to an embodiment of the present invention is illustrated. It should be understood that the same reference numerals shown in
Figure 1 will be employed for the same circuit blocks indicated in Figure 4. In Figure 4, reference numeral 8 comprises a moving direction storage means for storing and updating a predetermined number of current moving direction results which are judged by a moving direction judging means 46.
The moving direction judging means 46 compares the present distance measurement result obtained by performing the distance measuring operation with the previous distance measurement result stored in the storage means 5, thereby judging whether or not the present distance measurement result has changed with regard to the previous distance measurement result and, if so, in which direction. Moreover, the moving direction judging means 46 investigates a predetermined number of moving directions such as the previous moving direction and the second previous moving direction, which have been stored in the moving direction storage means 8. Then, this moving direction judging means 46 judges that the investigated moving direction is changed into such a direction if the changing direction of the moving direction is the same, or owns the same trend.
For example, if the 8 most recent direction of movement of distance measurement results are given as follows: 4 times toward the near side; 1 time toward the far side; and 3 times stationary, it is possible to judge by the majority decision that the object T under measurement is being moved toward the near side based on the distance measuring results obtained 5 times excluding the stationary results obtained 3 times.
As described above, even when such judgement results about the movements from the near side to the far side and the stationary result are given among a large number of moving direction judgement results such as the object T under measurement is moved from the far side to the near side every time the distance measuring operating is carried out, it is possible to judge that the object T under measurement is moved from the far.
side to the near side.
As previously described in detail, according to the distance measuring arrangement of the present invention, it is possible to not only determine to which distance region within a plurality of divided distance regions an object belongs, based on the measurement result, but also to determine the direction of movement of the object under measurement within this relevant distance region. As a consequence, this distance measuring apparatus is very useful to measure any moving objects, and thus has a broad field of application.
A distance measuring apparatus comprising:
distance measuring means, having a measurable distance range, for measuring a distance to an object;
region judging means for judging to which region among a plurality of distance regions within the measurable distance range of the distance measuring means a distance measurement of the distance measuring means belongs;
storage means for storing therein the result of the distance measurement;
direction judging means determining movement of the object by comparing the present distance measurement result with a preceding distance measurement result stored in the storage means wherein the direction judging means judges that the object has moved when the current distance measurement differs by more than a predetermined distance from the preceding distance measuring result; and
output means for outputting the results of the region judging means and the direction judging means, as described herein, is described and claimed in copending application No. 9520174.5 (publication No.
2293937).
Claims (4)
1. A distance measuring apparatus comprising:
distance measuring means, having a measurable distance range, for measuring a distance to an object;
region judging means for judging to which region among a plurality of distance regions within the measurable distance range of the distance measuring means a distance measurement of the distance measuring means belongs;
storage means for storing therein the result of the distance measurement;
direction judging means for determining movement of the object by comparing the present distance measurement result with a preceding distance measurement result stored in the storage means;
direction storage means for storing and updating a predetermined number of past moving direction results which have been judged by said direction judging means,
wherein the direction judging means determines the moving direction using a predetermined number of moving directions stored in said direction storage means; and
output means for outputting the results of the region judging means and the direction judging means.
2. A distance measuring apparatus as claimed in claim 1 wherein when said predetermined number of past moving directions are the same direction, or represent a trend in the direction of movement of the object, said direction judging means determines the moving direction of the object to be that direction.
3. A distance measuring apparatus substantially as herein described with reference to Figures 2-4 of the accompanying drawings.
4. A camera having a distance measuring apparatus as claimed in any preceding claim.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6238895A JPH08105742A (en) | 1994-10-03 | 1994-10-03 | Distance measuring apparatus |
| GB9520174A GB2293937B (en) | 1994-10-03 | 1995-10-03 | Distance measuring apparatus |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9826819D0 GB9826819D0 (en) | 1999-01-27 |
| GB2329293A true GB2329293A (en) | 1999-03-17 |
| GB2329293B GB2329293B (en) | 1999-04-28 |
Family
ID=26307867
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9826819A Expired - Fee Related GB2329293B (en) | 1994-10-03 | 1995-10-03 | Distance measuring apparatus |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2329293B (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1208615A (en) * | 1967-02-13 | 1970-10-14 | Westinghouse Electric Corp | Doppler radar system |
| GB1367600A (en) * | 1972-09-15 | 1974-09-18 | Siemens Ag | Radar systems |
| US4527894A (en) * | 1981-12-17 | 1985-07-09 | Zellweger Uster Ltd. | Method and apparatus for measuring the velocity of moved objects or the like |
| GB2226467A (en) * | 1988-11-30 | 1990-06-27 | Seikosha Kk | Camera with object speed measurement |
| US5049887A (en) * | 1990-10-16 | 1991-09-17 | Sperry Marine Inc. | Target range detector with moving target indication |
| EP0588687A1 (en) * | 1992-09-15 | 1994-03-23 | Thomson-Csf | System for determining at least one control parameter for vehicular traffic |
-
1995
- 1995-10-03 GB GB9826819A patent/GB2329293B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1208615A (en) * | 1967-02-13 | 1970-10-14 | Westinghouse Electric Corp | Doppler radar system |
| GB1367600A (en) * | 1972-09-15 | 1974-09-18 | Siemens Ag | Radar systems |
| US4527894A (en) * | 1981-12-17 | 1985-07-09 | Zellweger Uster Ltd. | Method and apparatus for measuring the velocity of moved objects or the like |
| GB2226467A (en) * | 1988-11-30 | 1990-06-27 | Seikosha Kk | Camera with object speed measurement |
| US5049887A (en) * | 1990-10-16 | 1991-09-17 | Sperry Marine Inc. | Target range detector with moving target indication |
| EP0588687A1 (en) * | 1992-09-15 | 1994-03-23 | Thomson-Csf | System for determining at least one control parameter for vehicular traffic |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2329293B (en) | 1999-04-28 |
| GB9826819D0 (en) | 1999-01-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 746 | Register noted 'licences of right' (sect. 46/1977) |
Effective date: 20040212 |
|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20051003 |