JP2517240B2 - Unmanned vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention is equipped with at least a pair of independently driven forward and backward drive wheels to travel in a free direction and travel on a floor surrounded by a plurality of wall surfaces. Related to unmanned vehicles.

(B) Conventional technology For example, an unmanned vehicle that performs work while moving in a work area surrounded by a wall, such as a cleaning robot, independently identifies the work area and forms map data corresponding to it. , A travel route for working in the work area is created based on map data.

As described above, in order to form map data of the work area or to travel without departing from the travel route, a sensor that accurately detects the direction is required. Therefore, conventionally, a gyro means such as a gas rate gyro is used. Was used.

(C) Problems to be Solved by the Invention However, such a gyro means is expensive, which causes a problem that the cost of the unmanned vehicle increases.

Therefore, an object of the present invention is to provide an unmanned vehicle that can be realized at low cost without using an expensive sensor.

(D) Means for Solving the Problems The present invention provides an unmanned vehicle that includes at least a pair of independently driven forward and backward drive wheels, travels in a free direction, and travels on a floor surrounded by a plurality of wall surfaces. In the above, each of the plurality of wall surfaces is formed in advance as a reference surface, a memory that stores travel route data that represents a travel route that travels on the floor surface, and a rotation amount detector that detects the rotation amount of each drive wheel, A plurality of collision detectors arranged on the front surface of the vehicle body to detect collisions of the vehicle body with an object, and collision detectors arranged on both side surfaces of the vehicle body, respectively, to measure a distance between the vehicle body and a wall surface in the left-right direction. Holding the current position of the vehicle body on the travel route corresponding to the travel route data based on the output of the distance measuring means and the rotation amount detector as position data,
Control means for controlling the drive wheels so as to travel along the travel route based on the position data, wherein the control means operates from one or more of the collision detectors during travel on the floor. When there is a detection output of, it is determined that the vehicle collides with the wall surface in the forward direction of the vehicle body, and the drive wheels are stopped,
Only one of the driving wheels is driven forward until detection outputs are obtained from all of the collision detectors, and then the distance measuring means is operated to measure the distance from the wall surface in the left-right direction to the vehicle body, and the measurement is performed. It is characterized in that the position data is corrected based on the result.

(E) Action According to the present invention, the direction of the vehicle body is corrected so that the detection output can be obtained from all of the collision detectors each time the vehicle collides with the wall surface serving as the reference surface of the travel route, and at that time, the distance measuring means is obtained. Is operated to measure the distance from the wall surface in the left-right direction to the vehicle body, and the current position of the vehicle body is corrected based on the measurement result, so the vehicle body can be properly adjusted without using an expensive sensor such as a gas rate gyro. Can run.

(F) Embodiment FIG. 1 shows a traveling portion of an unmanned traveling vehicle according to an embodiment of the present invention.

In the figure, five collision sensors 2, 3, 4, for detecting that the vehicle body 1 has collided with a wall surface or the like are provided on the front surface of the vehicle body 1 in which a rectangular front portion is connected to a semicircular rear portion. 5, 6 are arranged at substantially equal intervals, and two contact sensors 7, 8 for detecting that the vehicle body 1 has come into contact with the wall surface are provided in front of the left side surface of the vehicle body 1 and substantially in the center. Has been done. As the collision sensors 2, 3, 4, 5 and 6 and the contact sensors 7 and 8, for example, micro switches or the like can be used.

Further, in order to measure the distance from the front wall surface facing the traveling direction of the vehicle body 1, and to measure the distance from the vehicle body 1 and the left and right wall surfaces by facing the left and right side surfaces of the vehicle body 1. The ultrasonic sensors 10 and 11 are provided respectively.

Drive wheels 12 and 13, drive wheels 12 and 13, motors 14 and 15 for independently driving the drive wheels 12 and 13, and drive wheels 12 and 13 are located at left and right target positions with respect to the floor center projection position G of the vehicle body center of gravity. Pulse encoders 16 and 17 for detecting the rotation amount of 13 are provided respectively. Further, driven wheels 18 and 19 composed of ball casters or free casters are disposed at symmetrical positions in front of and behind the position G.

Therefore, the vehicle body 1 moves forward or backward when the drive wheels 12 and 13 are both driven forward or backward, and when the drive wheel 12 is driven forward and the drive wheel 13 is driven backward at the same speed as the drive wheel 12. It rotates clockwise on the spot, the drive wheel 12 is driven forward, and the drive wheel 13 is driven.
When the vehicle is driven in reverse at a speed different from 12, it rotates clockwise corresponding to the speed difference, and when only the drive wheels 12 are driven forward, the fulcrum of the motion of the vehicle body 1 at that time (for example, the drive wheels 13 and the floor). Rotate clockwise around the contact point of the surface or a point on the front of the vehicle).

Similarly, in the vehicle body 1, the drive wheels 13 are driven forward to drive the drive wheels 12.
When the vehicle is driven in reverse, it rotates counterclockwise on the spot, and when the drive wheel 13 is driven forward and the drive wheel 12 is driven backward at a speed different from that of the drive wheel 13, the counterclockwise rotation corresponds to the speed difference. When the vehicle rotates in the rotation direction and only the drive wheels 13 are driven forward, in the counterclockwise direction around the fulcrum of the motion of the vehicle body 1 at that time (for example, the contact point between the drive wheels 12 and the floor surface or one point on the front surface of the vehicle body). Rotate.

When the vehicle body 1 moves (runs), the driven wheels 1
8 and 19 follow the direction of movement along the direction of movement, and rotate following.

In this way, when the vehicle body 1 moves, by integrating the output pulses of the pulse encoders 16 and 17, the difference between the moving distance of the vehicle body 1 and the moving direction before and after the movement, that is, the relative direction of the traveling direction. Can be detected.

For this purpose, two pulse encoders 16 and 17 are used.
The one that outputs the phase pulse signal is used so that the rotation directions of the drive wheels 12 and 13 can be identified. Also, an absolute encoder can be used instead of the pulse encoders 16 and 17.

An example of the travel control unit of this unmanned vehicle is shown in FIG.

In the figure, a control unit 20 for controlling the traveling of an unmanned vehicle is composed of a microprocessor and its peripheral circuits, etc., and is map data representing a work area (travel area), travel route data representing a travel route. A memory 21 for storing the current position of the vehicle body 1 and the like is provided, and the detection signals S2 to S8 of the collision sensors 2 to 6 and the contact sensors 7 and 8 are added to the control unit 20.

Further, when the transmission pulse signal TP1 is output from the control unit 20 to the transmission unit 22, a signal having a predetermined frequency and a predetermined pulse width is applied from the transmission unit 22 to the wave transmitter 9a of the ultrasonic sensor 9. A sound wave signal is emitted to the front wall. The echo from the wall surface is detected by the wave receiver 9b of the ultrasonic sensor 9, and the detection signal of the wave receiver 9b is detected by the reception unit 23 and waveform-shaped, and is received by the control unit 20 as the reception pulse signal EP1. Is output to.

The control unit 20 calculates the distance between the vehicle body 1 and the front wall surface based on the time from the output timing of the transmission pulse signal TP1 to the reception timing of the reception pulse signal EP1. This calculation result is obtained just before the vehicle body 1 collides with the front wall surface.
It is used when the speed of the vehicle body 1 is reduced according to the distance between the vehicle body 1 and the front wall surface.

Similarly, when the transmission pulse signals TP2, TP3 are output from the control unit 20 to the transmission units 24, 26, a signal having a predetermined pulse width at a predetermined frequency is transmitted from the transmission units 24, 26 to the ultrasonic wave transmitters of the ultrasonic sensors 10, 11. 10a,
11a, which causes an ultrasonic signal to be emitted to the left and right wall surfaces. The echoes from those walls are detected by the receivers 10b and 11b of the ultrasonic sensors 10 and 11, and the receivers
The detection signals of 10b and 11b are detected by the reception units 25 and 27, waveform-shaped, and output to the control unit 20 as reception pulse signals EP2 and EP3.

The control unit 20 calculates the distance between the vehicle body 1 and the left and right wall surfaces based on the time from the output timing of the transmission pulse signals TP2, TP3 to the reception timing of the reception pulse signals EP2, EP3. These calculation results are used when the position of the vehicle body 1 is corrected when the vehicle body 1 collides with a wall surface or an obstacle.

The control unit 20 also controls the motors 14 and 15 by outputting to the motor driving units 28 and 29 that drive the motors 14 and 15 a drive command signal including the rotation direction and rotation speed of the motors 14 and 15.

In addition, the pulse encoder 1
The two-phase pulse signals PP1 and PP2 output from 6 and 17 are output to the control unit 20, and the control unit 20 determines the rotation amounts of the drive wheels 12 and 13 based on these pulse signals PP1 and PP2. In addition to the calculation, the rotation directions thereof are identified, and the movement amount, the rotation direction, and the rotation amount (direction change amount) of the vehicle body 1 are calculated.

Thus, in this embodiment, the pulse encoder 1
Since the direction change amount and the like of the vehicle body 1 are calculated based on the two-phase pulse signals PP1 and PP2 output from 6 and 17, a direction sensor such as a gyro is not required.

It is considered that the vehicle body 1 travels on the travel route set in the work area with the above configuration.

Here, the vehicle body 1 is assumed to be a vehicle body of an unmanned traveling vehicle such as a cleaning robot for cleaning a floor surface surrounded by wall surfaces, and a cleaning unit (not shown) is attached to the lower portion thereof. Therefore, the work area in this case is the floor surface surrounded by the wall surface, and the traveling path is a path that fills the work area with no gap by the cleaning unit, for example,
It is a zigzag reciprocating route that allows you to write with a single stroke at intervals that correspond to the width of the cleaning unit.

First, map data representing a work area is formed on the unmanned vehicle. For that purpose, the vehicle body 1 may be placed at the cleaning start position of the floor surface and the unmanned traveling vehicle may be activated so that the contact sensor 8 can detect the wall surface surrounding the work area.

As a result, the control unit 20 drives and controls the drive wheels 12 and 13 so that the contact sensor 8 can always detect the wall surface, identifies the path that has passed at that time as the outermost frame of the work area, and represents it. Form map data. When forming this map data, the length of one side of the polygon forming the work area is calculated based on the calculated values of the pulse signals PP1 and PP2 output from the pulse encoders 16 and 17, and the polygon forming the work area is calculated. The angle of each vertex is calculated based on the difference between the count values of the pulse signals PP1 and PP2 when the vehicle body 1 is rotated at that vertex.

For example, when the contact sensor 8 cannot detect the wall surface for a predetermined time, the vehicle body 1 is rotated counterclockwise from that position until the contact sensor 7 detects the wall surface, and the apex thereof is determined based on the amount of rotation at that time. Calculate the angle at. This makes it possible to obtain the angle of the vertex of the polygon forming the work area, which protrudes into the polygon, that is, the angle at which the vehicle body 1 turns left.

When it is detected that the collision sensors 2 to 6 collide with the wall surface, the vehicle body 1 is retracted by a distance such that all the collision sensors 2 to 6 do not detect the collision, and the vehicle body 1 is advanced at that position. The vehicle body 1 is rotated in the clockwise direction until the direction is along the colliding wall surface, and the angle at the apex is calculated based on the amount of rotation at that time. This makes it possible to obtain the angle of the apexes of the polygon forming the work area, which protrude outside the polygon, that is, the angle at which the vehicle body 1 makes a right turn.

In this way, the map data is formed while the vehicle body 1 is running along the wall surface, and when the vehicle body 1 returns to the starting point, the formation of the map data is ended, and the map data is thereby completed. Then, the control unit 20 stores the formed map data in the memory 21.

In addition, when the map data is formed in this way, the cleaning unit can be appropriately operated to clean the outermost frame of the floor surface.

Next, based on the completed map data, the control unit 20 moves the entire work area in a zigzag reciprocating route with the center position G of the vehicle body 1 at intervals smaller than the width of the cleaning unit by a predetermined overlap amount. Such a one-stroke travel route is generated.

In this case, since the reference of the vehicle body direction during traveling is set to the wall surface that surrounds the work area, the vehicle body 1 collides with the wall surface that regulates both sides of the work area, and reciprocates between these wall surfaces. Generate a route as a travel route.

Then, the control unit 20 forms traveling route data including coordinate data corresponding to the traveling route thus generated, and stores the traveling route data in the memory 21.

The controller 20 refers to the travel route data stored in the memory 21 and operates the cleaning unit to operate the cleaning unit while traveling the vehicle body 1 along the travel route generated for working in the work area at that time. To clean.

In this way, when traveling on the traveling route, first,
The vehicle body 1 up to the start point of the one-way route forming the traveling route
When the vehicle is moved, the vehicle body 1 is rotated in either direction so as to ride on the one-way route, and thereby the vehicle body 1 is run until it collides with the facing wall surface. Then, when the vehicle collides with the peculiar surface in this manner, the vehicle body 1 is retracted by a slight distance, and the vehicle body 1 is rotated in either direction by a predetermined angle to move to the next one-way path, The vehicle body 1 is moved to the starting point. Such control is sequentially repeated to drive the vehicle body 1 along the generated travel route.

Further, when the vehicle body 1 travels in this way, the control unit 20 constantly monitors the current position of the vehicle body 1 on the travel route based on the outputs of the pulse encoders 16 and 17, and holds the position data. Then, the distance from the next collision wall surface is determined from this position data, and when the distance becomes smaller than a predetermined value, the operation of the ultrasonic sensor 9 is started to monitor the distance to the wall surface, As the vehicle 1 approaches the wall surface, the vehicle body 1 is decelerated, thereby causing the vehicle body 1 to collide with the wall surface at a minute speed.

Now, while the vehicle body 1 is traveling along the traveling route in this way, if the drive wheels 12, 13 are slipped or kicked due to the material of the floor surface, unevenness, etc., the vehicle body 1 will actually travel. The existing route is different from the initially generated reference traveling route, and a traveling error occurs.

For example, as shown in FIG. 3, when traveling on a traveling route RT1 parallel to the wall surface W1, at the start point of the traveling route (one-way route) RT1, the traveling direction of the vehicle body 1 is the traveling route R as in the state SS1.
When the vehicle is deviated by an angle θ from T1, the vehicle body 1 collides with the wall surface W2 with an inclination of the angle θ at the end point of the traveling route RT1 as in the state SS2.

When the distance of the travel route RT1 is L, the position error ER1 from the wall surface W1 of the vehicle body 1 at the end of the travel route RT1, i.e., the distance 1 ₀ between the travel path from the wall W1 of the vehicle body 1 at the start point of the travel route RT1 Wall surface W of car body 1 at the end of RT1
The difference from the distance 11 from ₁ is represented by the following equation (I).

_{ER1 = 1 1 -1 0 = Ltanθ} ··· (I) for example, when the distance L was 3m, and the angle theta 1 degree, the position error ER1 becomes 5.2 cm.

Now, in the state SS2, the wall surface W2, which is one of the wall surfaces serving as the reference of the traveling route, and the front surface of the vehicle body 1 collide at an angle. This is shown in FIG. 4 (a).
Here, of the collision sensors 2 to 6, only the collision sensor 2 detects the wall surface W2, and the wall surface W2 and the front surface of the vehicle body 1 form an angle ψ.

That is, when the vehicle body 1 collides with any wall surface, the control unit 20 determines that the vehicle body 1 does not face the reference direction unless all the collision sensors 2 to 6 detect the wall surface, and , Collision control 2 which detects the wall surface at that time
6 to 6 are discriminated to determine in which direction the direction is deviated.

In this case, since only the collision sensor 2 is turned on, the control unit 20 controls the drive wheels 13 until all the collision sensors 2 to 6 are turned on, as shown in FIG. 4 (b). Only drive forward. Also, at that time, the pulse encoder
Based on the pulse signal PP2 output from 17, it is possible to calculate the deviation angle ψ at that time.

At this time, the collision sensor 2 serves as the fulcrum of the motion until the vehicle body 1 changes from the state shown in FIG. 4 (a) to the state shown in FIG. 4 (b). the distance 1 ₂ in a direction parallel to the wall surface W2 to the center position G of Fig (b)
Error from the distance from the fulcrum to the center position G of the vehicle body 1 in the state of _{3 in the} direction parallel to the wall surface W2, that is, the vehicle body 1
Position error ER2 of car body 1 due to the correction of the direction
Is given by the following equation (II).

_{ER2 = 1 3 -1 2 = r} -Lcos (θ + ψ) = r-R / sinθ · (cosθcosψ-sinθsinψ) = r-R (cosψ / tanθ-sinψ) = r-rcosψ + Rsinψ = r (1-cosψ) + Rsinψ · .. (II) where R is the vertical length of the rectangle at the front of the vehicle body 1,
r is the radius of the semi-circle at the rear of the vehicle body 1. For example, if the length R is 25 cm, the radius r is 20 cm, and the angle ψ is 5 degrees, the position error ER2 is 2.3 cm.

In this case, when the orientation in the state SS2 is corrected, the control unit 20 operates the ultrasonic sensors 10 and 11 to measure the distance of the vehicle body 1 from the left and right wall surfaces, and based on the measurement result, the collision. The position is judged, and the position data internally formed is corrected according to the judgment result. Of course, when only the collision sensor 6 detects the wall surface, the vehicle body 1 is rotated in the opposite direction to correct the orientation of the vehicle body 1.

Then, based on the corrected position data, the direction and distance to the starting point of the next traveling route (one-way route) are calculated, and the vehicle body 1 is moved to the starting point of the next traveling route based on the calculation result. Let

In this way, each time the vehicle body 1 collides with the wall surface, its position error is corrected so that the vehicle body can be properly placed on the next traveling route. Therefore, even if the absolute azimuth of the vehicle body 1 is not detected, it is first generated. The vehicle body 1 can be run along the traveled route.

By the way, as shown in FIG.
When there is 30, the vehicle 30 collides with the obstacle 30 while the vehicle body 1 is traveling along the traveling route that was initially generated. The states are shown as state SS3 and state SS4.

In state SS3, as shown in FIG. 5A, only the collision sensor 2 detects the obstacle 30. Therefore, the control unit 20 drives the drive wheels 13 forward so that all the collision sensors 2 to 6 detect the obstacle 30. As a result, the vehicle body 1 rotates counterclockwise with the position of the collision sensor 2 as a fulcrum.

However, at this time, as shown in FIG.
Since all the collision sensors 2 to 6 are not in the state of detecting the obstacle 30, the control unit 20 further drives the drive wheels 13 forward, and as a result, as shown in FIG. The vehicle body 1 rotates counterclockwise around the position of the collision sensor 4.

At this time, the collision sensor 2 that was initially turned on is turned off, whereby the control unit 20 drives the drive wheel 12 on the opposite side forward, and as shown in FIG. The drive wheels 12 are stopped in a state where the collision sensor 2 which has been operated is turned on again.

In this way, the vehicle body 1 faces the obstacle 30,
The direction of the vehicle body 1 is corrected.

Further, in the state SS4, that state corresponds to FIG. 4 (c), and in this case, the vehicle body 1 is moved by a predetermined amount in either direction.
When the collision sensors 2 to 6 are turned on in that state and the collision sensors 2 to 6 do not turn on in that state, only the first two times the vehicle body 1 is moved in the opposite direction.
When the collision sensors 2 to 6 are still not turned on, the rotation of the vehicle body 1 is repeated while gradually increasing the rotation amount until one of the collision sensors 2 to 6 is turned on.
Finally, the vehicle body 1 is moved to a state similar to that shown in FIG. 4 (d), and the direction of the vehicle body 1 is corrected in this way.

Further, when the direction of the vehicle body 1 is corrected in this way, the position data of the vehicle body 1 is corrected in the same manner as in the case of the state SS2.

If the control unit 20 determines that the vehicle body 1 collides with an obstacle while the vehicle is traveling on the initially generated travel route, the control unit 20 follows the surroundings of the obstacle to determine its outer shape. It is also possible to correct the map data stored in the memory 21 based on that, and to correct the travel route that was initially generated based on the corrected map data.

By the way, in the above-described embodiment, when the direction of the vehicle body 1 is corrected, the ultrasonic sensors 10 and 11 are operated to measure the distance between the vehicle body 1 and the left and right wall surfaces, and the vehicle body 1 is measured based on the measurement result. Although the position data is corrected, the correction of the position data is not limited to this.

For example, every time the vehicle body 1 is run and collides against a wall surface,
At this time, the state of ON operation of the collision sensors 2 to 6 is determined to determine the deviation in the traveling direction of the vehicle body 1 and its direction, and any of the drive wheels 1 until all the collision sensors 2 to 6 are turned on.
Calculate the amount of deviation in that direction based on the amount of rotation of 2,13,
Based on the distances of the travel routes traveled when and between them, the above equations (I) and (II) are calculated to calculate the position error ER1,
ER2 is calculated, and the position data of the vehicle body 1 internally held at the time of collision with the wall surface is corrected based on the sum of those position errors ER1 and ER2.

However, since the drive wheels 12 and 13 may slip when the displacement in the traveling direction of the vehicle body 1 is corrected by colliding with the wall surface, when the calculated correction amount exceeds a predetermined value, the ultrasonic sensor 10, 11 is operated to measure the distance between the vehicle body 1 and the left and right wall surfaces, and the position data of the vehicle body 1 is corrected again based on the measurement result.

In the above-described embodiment, the contact sensor is attached to the left side surface of the vehicle body and the map data corresponding to the work area is formed by tracing the wall surface in the clockwise direction. Alternatively, the map data corresponding to the work area can be formed by tracing the wall surface in the counterclockwise direction. Further, the travel route is not limited to the round trip route.

Further, in the above-described embodiment, the present invention is applied to the cleaning robot that mounts the cleaning unit on the vehicle body and cleans the floor surface. However, the present invention is also applied to the unmanned vehicle that realizes other functions. The same applies.

(G) Effect of the Invention As described above, according to the present invention, the direction of the vehicle body is corrected each time the vehicle collides with the wall surface serving as the reference surface of the traveling route, and the distance measuring means is operated at that time to move the wall surface in the left-right direction The distance from the vehicle to the vehicle body is measured, and the current position of the vehicle body is corrected based on the measurement result. Therefore, it is possible to follow the travel route data that has been formed in advance without using an expensive sensor such as a gas rate gyro. The effect of being able to travel along the travel route is obtained.

[Brief description of drawings]

FIG. 1 is a schematic plan view illustrating a traveling system of an unmanned traveling vehicle according to an embodiment of the present invention, FIG. 2 is a block diagram illustrating an example of a traveling control system, and FIG. 3 is a schematic illustrating a traveling mode. FIGS. 4 (a) and 4 (b) are explanatory views showing an example of correction of the traveling direction of the vehicle body when the vehicle body collides with the wall surface, and FIG.
(A)-(d) is explanatory drawing which showed the correction example of the direction of a vehicle body when a vehicle body collides with an obstacle. 1 ... Body, 2-6 ... Collision sensor, 7,8 ... Contact sensor, 9,1
0,11 ... Ultrasonic sensor, 9a, 10a, 11a ... Transmitter, 9b, 10b, 11b
... Wave receiver, 12,13 ... Drive wheel, 14,15 ... Motor, 16,17 ... Pulse encoder, 18,19 ... Driven wheel, 20 Control unit, 21 ... Memory, 22, 24, 26 ... Transmitting unit, 23 , 25,27 ... Reception unit, 28,29 ... Motor drive unit.

Continuation of the front page (56) Reference JP-A-51-46971 (JP, A) JP-A-59-16016 (JP, A) JP-A-62-293320 (JP, A) JP-A-61-170811 (JP , A) JP-A-60-93522 (JP, A) JP-A-59-121408 (JP, A) Sekikai 59-122606 (JP, U)

Claims (1)

(57) [Claims] 1. An unmanned vehicle that includes at least a pair of independently driven forward and backward traveling wheels and travels in a free direction and travels on a floor surrounded by a plurality of wall surfaces. The memory that stores the travel route data that represents the travel route that travels the floor surface, the rotation amount detector that detects the rotation amount of each drive wheel, and the vehicle body A collision detector that detects a collision with an object, a distance measuring unit that is provided on each side of the vehicle body, and that measures a distance between the vehicle body and a wall surface in the left-right direction, and the rotation amount detection unit. The present position of the vehicle body on the traveling route corresponding to the traveling route data is held as position data based on the output of the device, and the driving is performed so as to travel along the traveling route based on the position data. Control means for controlling the wheels, wherein the control means, when there is a detection output from any one or more of the collision detectors while traveling on the floor surface, determines that the vehicle has collided with a wall surface in the forward direction of the vehicle body. After making a judgment, the drive wheels are stopped, and only one of the drive wheels is driven forward until detection outputs are obtained from all of the collision detectors, and then the distance measuring means is operated to move from the wall surface in the left-right direction. An unmanned traveling vehicle characterized by measuring a distance to a vehicle body and correcting the position data based on the measurement result.