Robot system, robot control device, robot control method and program

Abstract

To provide a robot system that enables a robot to grasp a self position.SOLUTION: A robot system includes: a light emitting unit that emits light to detect a guide line; a light receiving unit that receives reflected light emitted from the light emitting unit; a running control unit which detects the guide line from the light receiving result by the light receiving unit, and which controls the robot so as to run along the guide line; and a position detecting unit that detects the position of the robot based on a certain position when a certain pattern associated with the certain position in advance is detected from the light receiving result by the light receiving unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a robot system, a robot control device, a robot control method, and a program. [Background technology]

[0002] Conventionally, there are robots that can move autonomously while estimating their own position. Known methods for estimating their own position include SLAM (Simultaneous Localization and Mapping), which uses LiDAR (Light Detection and Ranging) to create a map of the surroundings (environmental map) and estimate their own position simultaneously, odometry, which estimates the amount of movement from the number of rotations of the wheels used for driving and then calculates the amount of movement to estimate their own position, and combinations of these methods.

[0003] There is also a robot that uses a line tracing technique to detect a guide line drawn on the floor and move along the guide line (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-143029 Summary of the Invention [Problem to be solved by the invention]

[0005] However, a robot that detects a guide line and moves along the guide line has the problem that it is not possible to determine the robot's own position.

[0006] The present invention has been made in view of the above circumstances, and provides a robot system, a robot control device, a robot control method, and a program that enable a robot to determine its own position. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and one aspect of the present invention is a robot system comprising: a light-emitting unit that emits light to detect a guide line; a light-receiving unit that receives reflected light of the light emitted by the light-emitting unit; a travel control unit that detects the guide line from the light-receiving unit's light-receiving results and controls the robot's travel so that it travels along the guide line; and a position detection unit that, when a specific pattern that is pre-associated with a specific position is detected from the light-receiving unit's light-receiving results, detects the position of the robot based on the specific position.

[0008] Another aspect of the present invention is the robot system described above, wherein the specific pattern is a pattern of brightness change.

[0009] Another aspect of the present invention is the robot system described above, wherein the specific pattern is a pattern of distance change.

[0010] Another aspect of the present invention is the robot system described above, wherein the uneven structure for generating the distance change pattern is covered with a material that transmits the light emitted by the light-emitting unit.

[0011] Another aspect of the present invention is the robot system described above, wherein the specific pattern is a pattern in a direction perpendicular to the guide line.

[0012] Another aspect of the present invention is the robot system described above, wherein the traveling control unit switches between estimating the position of the robot using odometry and LiDAR (Light Detection And Ranging) SLAM (Simultaneous Localization and Mapping) and detecting the position using the position detection unit.

[0013] Another aspect of the present invention is a robot control device that controls a robot having an emitting unit that emits light to detect a guide line and a light receiving unit that receives reflected light from the light emitting unit, and that includes a travel control unit that detects the guide line from the light receiving result of the light receiving unit and controls the travel of the robot so that it travels along the guide line, and a position detection unit that, when a specific pattern that is pre-associated with a specific position is detected from the light receiving result of the light receiving unit, detects the position of the robot based on the specific position.

[0014] Another aspect of the present invention is a robot control method including a first step of emitting light for detecting a guide line, a second step of receiving reflected light of the light emitted in the first step, a third step of detecting the guide line from the light reception result in the second step and controlling the movement of the robot so that it moves along the guide line, and a fourth step of detecting a position of the robot based on the specific position when a specific pattern previously associated with a specific position is detected from the light reception result in the second step.

[0015] Another aspect of the present invention is a program for causing a computer of a robot control device that controls a robot having a light-emitting unit that emits light to detect a guide line and a light-receiving unit that receives reflected light of the light emitted by the light-emitting unit to function as a travel control unit that detects the guide line from the light-receiving result of the light-receiving unit and controls the travel of the robot so that it travels along the guide line, and a position detection unit that, when a specific pattern that is previously associated with a specific position is detected from the light-receiving result of the light-receiving unit, detects the position of the robot based on the specific position. [Effects of the Invention]

[0016] According to the present invention, the robot system, robot control device, information presentation object, robot control method, and program enable the robot to determine its own position. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a robot system 100 according to an embodiment of the present invention. [Figure 2] FIG. 10 is a schematic diagram illustrating a second technique in the same embodiment. [Figure 3] 10 is a graph showing an example of a specific pattern in the embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a first example of a marker in the same embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a second example of the marker in the same embodiment. [Figure 6] FIG. 2 is a schematic block diagram showing the functional configuration of a robot system 100 according to the embodiment. [Figure 7] 10 is a flowchart illustrating the operation of the robot system 100 in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of a robot system 100 according to an embodiment of the present invention. The robot system 100 includes a robot 10, a robot control device 20, a position display terminal 30, a guide line GL, and markers M1 and M2 (information presentation objects). The robot 10 also includes a two-dimensional lidar 11. The robot system 100 grasps the self-position of the robot 10 by switching between two methods, a first and a second method.

[0019] The first method is a combination of odometry, which acquires current position and orientation information from the number of rotations of the wheels (which may be caterpillars) used for traveling, and SLAM, which performs self-position estimation and mapping using a two-dimensional lidar 11. However, with odometry, when traveling on a low-friction floor, the wheels may slip, reducing the accuracy of self-position estimation, or when moving to a different floor on a slope, the change in floor may not be recognized. Furthermore, with SLAM using a lidar such as the two-dimensional lidar 11, if the wall surface is black or transparent (such as glass), the reflected light emitted by the lidar is weak, making it difficult to detect the wall surface, and this may result in a decrease in the accuracy of self-position estimation.

[0020] The second method uses the two-dimensional lidar 11 to detect the guide line GL, and the robot 10 travels along the guide line GL to detect markers M1 and M2 whose patterns are pre-associated with specific positions, thereby detecting the self-position of the robot 10. The markers M1 and M2 are installed on or near the guide line GL.

[0021] The robot 10 has a traveling function using wheels. The robot 10 may have a traveling function other than traveling using wheels, such as traveling on caterpillar tracks or walking on multiple legs. The robot 10 communicates with the robot control device 20 wirelessly (such as via a wireless LAN (Local Area Network)) or via a wired connection (such as via a USB (Universal Serial Bus) cable). For example, the robot 10 transmits information such as the detection result of reflected light of light emitted by the two-dimensional lidar 11 and the number of rotations of the wheels to the robot control device 20. The robot 10 also receives operational instructions, such as instructions to travel, from the robot control device 20 and operates in accordance with the operational instructions.

[0022] The robot control device 20 communicates with the robot 10 and estimates the position of the robot 10 by switching between the first and second methods described above using information received from the robot 10. The robot control device 20 may normally use the first method, which combines odometry and SLAM, to estimate the position of the robot 10, and may switch to the second method, which uses the guide line GL and markers M1 and M2, when a specific condition is met. The specific condition may be that slippage of wheels or the like is detected, that surrounding walls cannot be detected, or that the position of the robot 10 is within a predetermined area. The robot control device 20 also transmits operation instructions to the robot 10. The robot control device 20 may be realized by one or more computers reading and executing a program, or some or all of its functions may be implemented on a cloud server.

[0023] The position display terminal 30 displays the position of the robot 10 estimated by the robot control device 20. The position of the robot 10 may be displayed using coordinate values, or a symbol indicating the position of the robot 10 may be displayed on a map.

[0024] The guide line GL is a line drawn on the floor surface, and may be tape (white tape, aluminum tape, retroreflective tape, etc.) stuck to the floor surface, or paint applied to the floor surface. The brightness of the light emitted from the two-dimensional lidar 11 reflected by the guide line GL is different from the brightness of the light reflected by the floor surface. The robot system 100 detects the guide line GL using this difference in brightness.

[0025] The markers M1 and M2 (information presentation objects) are installed on or near the guide line GL, and the reflected light of the light emitted by the two-dimensional lidar 11 forms a specific pattern. This specific pattern may be a pattern of brightness change or a pattern of distance change. This specific pattern may also be a pattern in a direction perpendicular to the guide line GL. The patterns of the reflected light from each of the markers M1 and M2 are associated with specific positions and stored by the robot system 100. The specific positions may be coordinate values ​​or specific floors.

[0026] For example, the guide line GL may be drawn on the floor of a slope connecting the first and second floors, with the pattern of reflected light from the marker M1 being associated with the first floor and the pattern of reflected light from the marker M2 being associated with the second floor. Alternatively, the guide line GL may be drawn on the floor of a corridor with black or glass walls, with the pattern of reflected light from the marker M1 being associated with the coordinates of the location where the marker M1 is installed, and the pattern of reflected light from the marker M2 being associated with the coordinates of the location where the marker M2 is installed.

[0027] FIG. 2 is a schematic diagram illustrating a second technique in this embodiment. The example shown in FIG. 2 is an example in which a marker M3 (information object) is placed on a guide line GL, and the specific pattern is a pattern of changing brightness. The marker M3 is, for example, a member such as a sticker on which a black shading pattern is formed in the width direction of the guide line GL. The robot 10 travels in the direction of the arrow RD, and one horizontal scan of the light emitted by the two-dimensional lidar 11 is reflected (scattered) at points P1, P2, . . . Pn on the floor and the marker M1. The robot 10 receives the reflected light at these points P1, P2, . . . Pn.

[0028] FIG. 3 is a graph showing an example of a specific pattern in this embodiment. The example shown in FIG. 3 is an example where the specific pattern is a pattern of changes in brightness (reflection intensity). FIG. 3 is a graph in which the brightness (reflection intensity) of reflected light for one scan (points P1, P2, . . . Pn) as shown in FIG. 2 is plotted in the scanning direction. In FIG. 3, graph Pt1 is a graph of the reflection intensity when, for example, marker M1 is scanned, and graph Pt2 is a graph of the reflection intensity when, for example, marker M2 is scanned. In this way, markers M1 and M2 are colored so that each graph is different. The robot control device 20 compares the reflection intensity distribution received from the robot 10 with multiple patterns stored in advance and finds one of the stored patterns that matches the received reflection intensity distribution.

[0029] FIG. 4 is a cross-sectional view of a first example of a marker in this embodiment. FIG. 4 is an example of a cross-sectional view taken along a plane perpendicular to the direction of the guide line when the specific pattern is a distance change pattern. The upper surface of the marker M4 (information presentation object), i.e., the reflective surface RS that reflects the light emitted by the two-dimensional lidar 11, has an uneven structure. The unevenness of the uneven structure of the marker M4 does not change in the direction of the guide line. When the specific pattern is a distance change pattern, the two-dimensional lidar 11 reads the distribution of unevenness in the scan direction (LiDAR scanning direction) W. Note that the step of the uneven structure may be within 3 mm, which is considered to be a level that is unlikely to cause a person to trip. The two-dimensional lidar 11 may also be an indirect time-of-flight (iToF) system, which is generally considered to have high distance resolution.

[0030] FIG. 5 is a cross-sectional view of a second example of a marker in this embodiment. FIG. 5 is an example of a cross-sectional view taken along a plane perpendicular to the direction of the guide line when the specific pattern is a distance change pattern. The upper surface of the marker M5 (information presentation object), i.e., the reflective surface RS that reflects the light emitted by the two-dimensional lidar 11, has an uneven structure similar to the marker M4 in FIG. 4, but is covered with a light-transmitting material PL. This makes it possible to make the surface smooth, which is aesthetically pleasing and prevents people from tripping over the unevenness. Furthermore, the movement of the robot 10 is not affected by the unevenness.

[0031] The optically transparent substance PL may be a curable resin such as a photocurable or thermosetting resin. By using such a curable resin, unevenness can be easily filled in while the viscosity is low before curing, and durability can be improved by curing after the surface has become smooth. The refractive index of the optically transparent substance PL may be greater than that of the atmosphere, such as 1.4 or more. This results in a larger optical path difference due to unevenness than when the optically transparent substance PL is not used, as shown in FIG. 4, making it easier for the two-dimensional lidar 11 to read the unevenness.

[0032] 6 is a schematic block diagram showing the functional configuration of a robot system 100 in this embodiment. The robot 10 includes a two-dimensional lidar 11 (light-emitting unit), a light-receiving unit 12, a communication unit 13, and a traveling function unit 14. The robot control device 20 includes a communication unit 21, a traveling control unit 22, a position detection unit 23, a pattern storage unit 24, a position estimation unit 25, and a map storage unit 26. The position display terminal 30 includes a display unit 31. Note that some or all of the functions of the robot control device 20 may be provided in the robot 10.

[0033] The two-dimensional lidar 11 emits light for detecting the guide line GL. The two-dimensional lidar 11 may be an iToF or dToF (direct Time of Flight). The light receiving unit 12 receives light emitted by the two-dimensional lidar 11 that is reflected by the marker M, the guide line GL, etc. The light receiving unit 12 may be a sensor included in the two-dimensional lidar 11. This allows the number of parts to be reduced. The light receiving unit 12 may also include a photodiode, a photomultiplier tube, or a CMOS (Complementary Metal Oxide Semiconductor) sensor that is separate from the two-dimensional lidar 11. In this case, a general two-dimensional lidar that outputs only distance can be used as the two-dimensional lidar 11.

[0034] The light (laser) used in the two-dimensional lidar 11 is often non-visible light, such as near-infrared light that is outside the visible light range, such as 850 nm or 940 nm. Therefore, if a material that modulates the reflection intensity using only near-infrared light is used for the marker M, people will not be able to see that the information is embedded, which is aesthetically pleasing and also safer from a security standpoint.

[0035] The communication unit 13 transmits the light reception results (brightness distribution, distance measurement results) by the light receiving unit 12 and the wheel rotation count measurement results by the traveling function unit 14 to the robot control device 20. The communication unit 13 also receives operation commands from the robot control device 20 and notifies the operation commands to the traveling function unit 14, etc. The traveling function unit 14 causes the robot 10 to travel using the wheels in accordance with the operation commands. The traveling function unit 14 also measures the wheel rotation count in order to transmit it from the communication unit 13.

[0036] The communication unit 21 receives the light reception results and the rotation count measurement results transmitted by the communication unit 13, and transmits the operation command generated by the travel control unit 22 to the communication unit 13. The travel control unit 22 estimates the position of the robot 10 and generates an operation command for the robot 10 using the light reception results and the rotation count measurement results received by the communication unit 13. The travel control unit 22 also detects a guide line GL from the light reception results of the light receiving unit 12 and controls the travel of the robot so that it travels along the guide line GL. At this time, the travel control unit 22 uses the detection result of the position of the robot 10 by the position detection unit 23. The travel control unit 22 may switch between estimating the position of the robot 10 using odometry and LiDAR SLAM (first method) and detecting the position by the position detection unit 23 (second method). The travel control unit 22 controls the travel of the robot using the estimation result of the position of the robot 10 by the position estimation unit 25.

[0037] When the position detection unit 23 detects a specific pattern that is previously associated with a specific position from the light reception result of the light receiving unit 12, it detects the position of the robot 10 based on the specific position. The pattern storage unit 24 stores information indicating the specific position and information indicating the specific pattern in association with each other.

[0038] The position estimation unit 25 estimates the position of the robot 10 by odometry and LiDAR SLAM using the light reception result of the light receiving unit 12 and the measurement result of the number of rotations. The map storage unit 26 stores the environmental map generated by the position estimation unit 25 using LiDAR SLAM.

[0039] The display unit 31 includes a display means such as a liquid crystal display or an organic EL (Electro Luminescence) display, and displays the position of the robot 10 based on the position of the robot 10 and an operation command to the robot 10 .

[0040] 7 is a flowchart illustrating the operation of the robot system 100 in this embodiment. First, the robot system 100 causes the robot 10 to autonomously navigate using SLAM (first method) assisted by odometry (step S1). When any of the following conditions is met: A) traveling on a low-friction floor (step S2a), B) traveling in an environment where SLAM is not suitable, such as a glass wall (step S2b), or C) traveling on a slope (step S2c), the process proceeds to step S3.

[0041] In step S3, the robot system 100 detects the guide line GL using the two-dimensional lidar 11. Next, the robot system 100 causes the robot 10 to travel on the guide line GL (step S4). Next, the robot system 100 detects a specific pattern on the guide line GL (step S5). Next, the robot system 100 recognizes a position previously associated with the specific pattern detected in step S5 as the current position of the robot 10 (step S6).

[0042] Next, the robot 10 escapes from the driving environments A, B, and C in steps S2a to S2c (step S7). Next, when the robot system 100 detects the end of the guide line GL (step S8), it returns to SLAM autonomous driving assisted by odometry (step S9) and returns to step S1.

[0043] As described above, the robot system 100 of this embodiment can read information on a line using the 2D LiDAR used in the SLAM technology, and therefore can process SLAM technology and line tracing technology in the same simple system. As a result, it is possible to achieve system stability and cost reduction. In addition, even when moving using SLAM technology at a position away from the guide line, the 2D LiDAR acquires information over a wide range to estimate its own position, so it is also possible to read information on a distant line. Furthermore, if necessary, it can be moved toward the guide line to switch from SLAM to line tracing.

[0044] The robot system 100 has a function of immediately transmitting an atypical signal to the robot control device 20 when the distribution of reflected light from a marker installed on the guide line differs from the distribution of reflected light on the guide line. When the robot control device 20 receives an atypical signal from the robot 10, it analyzes the pattern of the atypical signal, identifies the current position of the robot 10, and notifies the robot 10 of the current position.

[0045] The robot system 100 is a system that allows the robot 10 to precisely determine its current location, something that cannot be achieved by odometry technology, SLAM technology, or line tracing technology. For example, if a robot using these technologies moves across multiple floors, such as a slope, the robot cannot determine which floor it is currently on. However, by placing markers (information items) at the beginning and end of the slope, the robot 10 can be made to recognize its current location when it passes the markers. Furthermore, the markers are affixed to a portion of or near the guide line, and are small enough to be detected by 2D LiDAR, making it possible to precisely identify the location where they are affixed.

[0046] The present invention may be embodied as follows. (1) One embodiment of the present invention is a robot system including: a light-emitting unit that emits light to detect a guide line; a light-receiving unit that receives reflected light of the light emitted by the light-emitting unit; a travel control unit that detects the guide line from the light-receiving unit's light-receiving results and controls the robot's travel so that it travels along the guide line; and a position detection unit that, when a specific pattern that is pre-associated with a specific position is detected from the light-receiving unit's light-receiving results, detects the position of the robot based on the specific position.

[0047] (2) Another embodiment of the present invention is the robot system according to (1), wherein the specific pattern is a pattern of brightness change.

[0048] (3) Another embodiment of the present invention is the robot system described in (1), wherein the specific pattern is a pattern of distance change.

[0049] (4) Another embodiment of the present invention is the robot system described in (3), wherein the uneven structure for generating the distance change pattern is covered with a material that transmits the light emitted by the light-emitting unit.

[0050] (5) Another embodiment of the present invention is the robot system described in any one of (1) to (4), wherein the specific pattern is a pattern in a direction perpendicular to the guide line.

[0051] (6) Another embodiment of the present invention is a robot system described in any one of (1) to (5), wherein the traveling control unit switches between estimating the position of the robot using odometry and LiDAR (Light Detection And Ranging) SLAM (Simultaneous Localization and Mapping) and detecting the position using the position detection unit.

[0052] (7) Another embodiment of the present invention is a robot control device that controls a robot having a light-emitting unit that emits light to detect a guide line and a light-receiving unit that receives reflected light from the light-emitting unit, and that includes a travel control unit that detects the guide line from the light-receiving unit's light-receiving results and controls the robot's travel so that it travels along the guide line, and a position detection unit that, when a specific pattern that is previously associated with a specific position is detected from the light-receiving unit's light-receiving results, detects the position of the robot based on the specific position.

[0053] (8) Another embodiment of the present invention is a robot control method including a first step of emitting light for detecting a guide line, a second step of receiving reflected light of the light emitted in the first step, a third step of detecting the guide line from the light reception result of the second step and controlling the movement of the robot so that it moves along the guide line, and a fourth step of detecting a position of the robot based on a specific position when a specific pattern previously associated with the specific position is detected from the light reception result of the second step.

[0054] (9) Another embodiment of the present invention is a program for causing a computer of a robot control device that controls a robot having a light-emitting unit that emits light to detect a guide line and a light-receiving unit that receives reflected light of the light emitted by the light-emitting unit to function as a travel control unit that detects the guide line from the light-receiving unit's light-receiving results and controls the robot's travel so that it travels along the guide line, and a position detection unit that, when a specific pattern that is previously associated with a specific position is detected from the light-receiving unit's light-receiving results, detects the position of the robot based on the specific position.

[0055] 1 and 6 may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to realize the robot control device 20 and the position display terminal 30. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0056] "Computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording media" also includes devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, and devices that store programs for a fixed period of time, such as volatile memory within computer systems that serve as servers or clients. Furthermore, the programs may be programs that implement some of the aforementioned functions, or may be programs that can realize the aforementioned functions in combination with programs already stored in the computer system.

[0057] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0058] 10. Robot 11 2D Lidar 12 Light receiving part 13 Communications Department 14. Traveling function unit 20 Robot control device 21 Communications Department 22 Travel control unit 23 Position detection unit 24 Pattern memory section 25 Position estimation part 26 Map memory section 30 Location Display Terminal 31 Display section

Claims

1. a light emitting unit that emits light for detecting the guide line; a light receiving unit that receives reflected light of the light emitted by the light emitting unit; a travel control unit that detects the guide line from the light receiving result of the light receiving unit and controls the travel of the robot so that it travels along the guide line; a position detection unit that, when a specific pattern associated with a specific position in advance is detected from the light receiving result of the light receiving unit, detects the position of the robot based on the specific position; A robot system comprising:

2. The robot system according to claim 1 , wherein the specific pattern is a pattern of brightness change.

3. The robot system according to claim 1 , wherein the particular pattern is a pattern of distance change.

4. The robot system according to claim 3 , wherein the uneven structure for generating the pattern of distance changes is covered with a material that transmits the light emitted by the light emitting unit.

5. The specific pattern is a pattern in a direction perpendicular to the guide line. The robot system according to any one of claims 1 to 4.

6. The traveling control unit switches between estimating the position of the robot by odometry and LiDAR (Light Detection And Ranging) SLAM (Simultaneous Localization and Mapping) and detecting the position by the position detection unit. The robot system of claim 1 .

7. A robot control device for controlling a robot including a light emitting unit that emits light for detecting a guide line and a light receiving unit that receives reflected light of the light emitted by the light emitting unit, a travel control unit that detects the guide line from the light receiving result of the light receiving unit and controls the travel of the robot so that it travels along the guide line; a position detection unit that, when a specific pattern associated with a specific position in advance is detected from the light receiving result of the light receiving unit, detects the position of the robot based on the specific position; A robot control device comprising:

8. A first step of emitting light for detecting a guide line; a second step of receiving reflected light of the light emitted in the first step; a third step of detecting the guide line from the light receiving result of the second step and controlling the robot to travel along the guide line; a fourth step of detecting the position of the robot based on a specific position when a specific pattern previously associated with the specific position is detected from the light receiving result of the second step; A robot control method comprising:

9. A computer of a robot control device that controls a robot having a light emitting unit that emits light for detecting a guide line and a light receiving unit that receives reflected light of the light emitted by the light emitting unit, a travel control unit that detects the guide line from the light receiving result of the light receiving unit and controls the travel of the robot so that it travels along the guide line; a position detection unit that, when a specific pattern associated with a specific position in advance is detected from the light receiving result of the light receiving unit, detects the position of the robot based on the specific position; A program to function as a

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