JP2007052527A - Robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the simple and safe automatic follow-up of a robot to a follow-up object. <P>SOLUTION: This robot is provided with a rope equipped with a connection mechanism to which moment is not applied in the direction of rotation at both ends, and whose one end is connected to an object, and whose other end is connected to a robot; an inclination detecting part for detecting the inclination of the rope at the other end; a tension detecting part for detecting a tension to be applied to the other end; a position calculating part for calculating the relative position of the object and the robot from the inclination detected by the inclination detecting part and the tension detected by the tension detecting part; a moving mechanism for moving the robot; and a control part for controlling the moving mechanism on the basis of the relative position calculated by the position calculating part. Thus, it is possible to easily and safely achieve the automatic follow-up of the robot to the follow-up object. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for following a target of a robot.

  In the conventional technology related to the tracking of the target of a robot represented by an automatic cart or the like, the relative position of the leading target is measured using a wireless medium, and the robot is moved based on the relative position. Some perform tracking by moving them (see, for example, Patent Documents 1 to 3).

  A prior art example 1 described in Patent Documents 1 to 3 will be described with reference to FIG. Here, FIG. 5 is a diagram showing the configuration of the robot of Example 1 of the prior art.

  As shown in FIG. 5, the robot is a robot 11 that follows the target 10, and the target has a wireless transmission unit 10 a that transmits ultrasonic waves, infrared rays, radio waves, and the like. Further, the robot 11 includes a moving mechanism 11a such as a wheel, a wireless reception unit 11b that receives wireless information transmitted from the wireless transmission unit 10a, and a relative relationship with the target 10 based on the reception information of the wireless reception unit 11b. A position calculation unit 11c that calculates a correct position, and a control unit 11d that controls the movement mechanism 11a based on the relative position calculated by the position calculation unit 11c.

  In another conventional technique, a relative position is calculated by measuring the length and direction of the rope via a rope that can be wound between the target and the robot, and the robot is based on the calculation result. There is one that performs tracking by moving (see, for example, Patent Documents 4 and 5).

  A prior art example 2 described in Patent Documents 4 and 5 will be described with reference to FIG. Here, FIG. 6 is a diagram showing the configuration of the robot of Example 2 of the prior art.

As shown in FIG. 6, the robot is a robot 12 that follows the target 10, and a rope 13 that can be wound is interposed between the target 10 and the robot 12. The robot 12 also has a moving mechanism 12a such as a wheel, a winding mechanism 12b that winds the rope 13, and a relative position to the target 10 from the winding amount and the direction in which the rope 13 is stretched. A position calculation unit 12c to calculate and a control unit 12d to control the moving mechanism 12a based on the relative position calculated by the position calculation unit 12c are provided. In the robot 12 described above, the rope 13 is tensioned by the winding mechanism 12b and the rope 13 is wound so that the rope 13 does not slack and the shortest distance is formed between the target 10 and the robot 12. The relative position with the target is calculated from the amount of winding and the direction in which the rope 13 is stretched.
Japanese Patent No. 3343386 JP-A-8-126822 JP 2003-177820 A JP-A-6-105938 JP-A-8-207850

  However, when applying the conventional techniques listed above, there are the following problems.

  In Conventional Example 1 described in Patent Documents 1 to 3, since a wireless medium is used to detect a relative position, for example, when an obstacle exists between the target and the robot, the wireless receiver May not be able to be received. Further, when the relative distance exceeds a certain distance due to the limit of the output of the wireless transmission unit, a state in which the wireless reception unit cannot receive similarly occurs. Moreover, since it is a wireless medium, the robot cannot physically prevent movement beyond the reception range. Therefore, if the case where the wireless reception unit cannot receive is continued, the robot loses sight of the target and cannot follow it. In addition, for example, when a reflection from a nearby wall is received, erroneous detection may occur due to characteristics of the wireless medium. At this time, the robot moves in a direction different from the target, and depending on the movement of the robot, the robot may collide with an obstacle or target existing in the traveling direction.

  An example of a problem that occurs in Example 1 of the related art will be described with reference to FIG. Here, FIG. 7 shows the positional relationship of the target (denoted as T) and the robot (denoted as R) as viewed from above. In particular, FIGS. (C) has shown the example which moves to a different direction.

  For example, as illustrated in FIG. 7A, when an obstacle 14 exists between the target 10 and the robot 11, the wireless medium 15 is absorbed by the obstacle 14 or blocked, and the robot 11 is wirelessly mediumd. 14 cannot be received, and the target 10 cannot be tracked.

  Also, for example, as shown in FIG. 7B, when the distance between the target 10 and the robot 11 is long, the robot 11 cannot receive the wireless medium 15 because it exceeds the reachable area 16 of the wireless medium 15, and the target It becomes impossible to follow the object 10.

  Further, for example, as shown in FIG. 7C, when the wall 17 exists in the vicinity of the target 10 and the robot 11, when the wireless medium 15 is reflected by the wall 17 and receives the signal, the reflected light is reflected. The robot 11 moves toward the signal.

  Moreover, in the prior art example 2 described in Patent Documents 4 and 5, the rope is wound and tensioned so as not to sag for the purpose of accurately detecting the relative position, but the mass of the rope is large. If it is long or long, the tension becomes very large. At this time, it is a burden on the target and the robot, and in some cases, the operation may be hindered. Furthermore, if the rope breaks or the target releases the rope with a high tension, the rope may fly to the robot due to the tension and cause damage to the robot. It may move too much and contact with surrounding objects to cause damage. Further, when the winding speed is slower than the moving speed or when the tension is insufficient, a trouble may occur in the winding mechanism such as a rope getting tangled. In addition, the winding mechanism, which is a movable part, is prone to trouble, and if the winding cannot be performed due to the trouble, the robot may collide without noticing that it is too close to the following object.

  An example of a problem that occurs in Example 2 of the related art will be described with reference to FIG. Here, FIGS. 8A to 8B show examples of problems when the tension increases, and FIG. 8C shows examples of problems when trouble occurs in the winding mechanism.

  For example, as shown in FIG. 8A, when a large tension 18 is generated between the target 10 and the robot 12, the target 10 is pulled, so that the operation is hindered. Even if the object 10 tries to move, it can be pulled by the tension 18 and cannot move. Further, when the rope 13 is broken in this state, the broken rope 13a may fly to the target 10 or the robot 12 as shown in FIG. Moreover, when the target 10 releases the rope 13, the same phenomenon may occur.

  Further, for example, when a trouble occurs in the winding mechanism and the winding cannot be performed, the rope 13 remains long even when the robot 12 approaches the target 10 as shown in FIG. Therefore, the approach cannot be detected, and if the target 10 is at the position 19 calculated by the robot, it may be misunderstood to move and collide.

  In order to solve the problems of the inventions described in Patent Documents 4 and 5, a method of eliminating the rope winding mechanism and applying no tension is conceivable. However, when the winding mechanism is not used, there is slack in the rope. Will occur, and the relative position between the target and the robot cannot be measured. In that case, a method of calculating the relative position of the target by calculating the slack state of the rope can be considered, but since the slack state of the rope is represented by a complex differential equation, the robot was equipped with It is not easy to calculate a relative position with respect to a target necessary for tracking using only a measuring device.

  For example, as shown in FIG. 9, when the rope inclination of the robot connection unit is used as a means for measuring the slack state of the rope, the distance to the target differs depending on the height and inclination of the rope on the target side. When the slopes of the shear ropes are the same (ξ), for example, there are the first sagging example 20 and the second sagging example 21, so the relative position to the target cannot be calculated uniquely.

  In addition, when there is slack in the rope, the rope may sway as it moves. When a swing occurs, for example, as shown in FIGS. 10 (a) and 10 (b), even if the relative position is the same as shown in FIG. May be different. Therefore, there are cases where the correct relative position cannot be calculated even if the sagging state is calculated as it is.

  An object of the present invention is to solve the above-mentioned problems and to provide a robot that can easily and safely follow a target.

  In order to solve the above problems, the robot of the present invention has a connection mechanism that does not apply a moment in the rotational direction particularly to both ends, a rope having one end connected to the target and the other end connected to the robot, An inclination detector that detects the inclination of the rope at the other end, a tension detector that detects the tension applied to the other end, and an inclination detected by the inclination detector and the tension detector A position calculating unit that calculates a relative position between the target and the robot from tension; a moving mechanism that moves the robot; and the moving mechanism based on the relative position calculated by the position calculating unit. A robot comprising a control unit for controlling. In addition, it further includes a storage unit that stores data of the inclination detected by the inclination detection unit and the tension detected by the tension detection unit in time series, and corrects the calculation of the sag state based on the data stored in the storage unit. A robot including a correction unit.

  According to the robot as described above, since the target and the robot are physically constrained by the rope, they are not lost. Further, since an external force other than gravity is not applied to the rope, it is possible to prevent the movement of the target from being hindered and damage caused by the rope when the rope is released or cut. Further, since there is no winding mechanism, troubles due to the failure can be avoided. Further, since the slack state of the robot is uniquely determined, the relative position with respect to the target can be uniquely calculated. Furthermore, it is possible to perform an appropriate correction for the shake and to follow an appropriate target.

  Therefore, it is possible to easily and safely automatically follow the target.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a configuration of a robot according to the present invention.

  FIG. 2 shows an example of the structure of the end of the rope and the method of detecting the inclination and tension of the rope.

  FIG. 3 shows the coordinate system of the rope and modeling of the minute part.

  FIG. 4 shows a state of swinging of the rope having slack.

  For example, as shown in FIG. 1, the robot of the present invention is a robot 2 that follows a target 1. In particular, the robot 2 includes a connection mechanism 2 i that does not apply a moment in the rotational direction at one end, and one end is at the target 1. And a rope 2a having the other end connected to the robot 2, an inclination detection unit 2b for detecting the inclination of the rope 2a at the other end, and a tension detection for detecting the tension applied to the other end. A position calculating unit 2d that calculates a relative position between the target 1 and the robot 2 from the inclination detected by the inclination detecting unit 2b and the tension detected by the tension detecting unit 2c, and the robot 2 and a control unit 2f for controlling the moving mechanism 2e based on the relative position calculated by the position calculating unit 2d.

  Here, in the position calculation unit 2d, first, the slack state of the rope 2a is calculated from the inclination detected by the inclination detection unit 2b and the tension detected by the tension detection unit 2c, and the target 1 is calculated from the calculated slack state. The relative position of is calculated.

  Furthermore, the storage unit 2g that stores the data detected by the inclination detection unit 2b and the tension detected by the tension detection unit 2c in time series, and the calculation of the sag state is corrected based on the data stored in the storage unit 2g. A correction unit 2h is provided, and the correction unit 2h corrects data sent from the inclination detection unit 2b and the tension detection unit 2c to the position detection unit 2d.

  Here, both ends of the rope 2a mounted on the robot 2 of the invention have a structure in which no moment is applied in the rotation direction. For example, as shown in FIG. 2 (a), the end of the rope is composed of three rotating shafts. It is also possible to use the mechanism 2j and attach an encoder 2k to each rotary shaft at the end on the robot side to detect the inclination, and place a strain gauge 2m at the base of the mechanism to detect the tension. Further, for example, as shown in FIG. 2B, the end of the rope is a ball joint 2n, and a mark 2p by color or magnetism is attached near the end of the rope, and this is detected by a mark detection sensor 2q such as a camera or a magnetic sensor. The inclination may be detected by detecting the mark position, and the tension may be detected by using the spring-like sensor 2r at the base of the joint 2n. In FIG. 2, the same structure is used at both ends on the robot side and the target side, but different structures may be used.

  For example, in the present embodiment, the slack state calculation method and the relative position calculation method performed by the position calculation unit are as follows.

  Here, a method of calculating the slack state of the rope from the inclination and tension of the rope end, which is the basis for realizing the solution means of the present invention, and calculating the distance between both ends will be described with reference to FIG. FIG. 3B shows the setting of the coordinate system of the rope causing the slack. FIG. 3C shows a model in which a small portion of the rope is modeled.

  First, as shown in FIGS. 3 (a) and 3 (b) as a coordinate system, the origin is a point where the rope 2a is connected by the robot 2, and the X dimension is the X axis in the horizontal direction in which the rope 2a extends, and the Y axis is the vertically downward Y axis. The coordinate system is used. Here, it is assumed that a force H of a horizontal component of tension and a force V of a vertical component are applied to the rope 2a. Further, the connection portion of the target 1 is (Xh, Yh), and the total length of the rope is L. Note that the above XY coordinates are set to be inclined by φ with respect to the direction of the robot.

  At this time, the geometric relationship in an arbitrary minute portion of the rope shown in FIG. 3C is that the length of the minute portion of the rope is ds, the X direction component of ds is dx, the Y direction component is dy, and the unit length If the mass per unit is w, it can be expressed by the following formula.

  Further, considering the balance of the minute portions, it can be expressed by the following equation.

  The above 2) and 3) can be summarized as the following differential equation.

  The length of the rope is

  Therefore, from the equation 1), it can be expressed as follows.

  By solving the equation 4) in the above equation representing the sag, the sag state represented by the X and Y equations is calculated. Further, by using the calculated sag formula and setting the length of the rope as a constraint, solving the formula 5) makes it possible to calculate the relative distance to the object as the distance in the X-axis direction between both ends of the rope.

  Here, the differential equation 4) cannot be uniquely solved by this formula alone. However, if the structure is such that no moment is applied to both ends of the rope as in the present invention, it is not necessary to calculate the moment from the start end to the end of the rope. Since the calculation can be performed under the conditions, the slack state is uniquely determined by calculating, for example, the following steps using the initial value of the rope slope and tension at the robot end, which is the starting end. Can be calculated.

  In Step 1, the initial value of the slope of the rope is the detected slope of the rope at the end on the robot side. By repeating Steps 1 and 2, the slack state of the rope is calculated by the expressions X and Y. In Step 3, the X coordinate when the distance from the rope start end coincides with the length of the rope is the relative distance from the robot to the target, and the Y coordinate is the height of the end on the target side.

  Further, the target direction φ can be calculated by projecting the slope of the rope onto a plane (XZ plane) that includes the origin and is perpendicular to the Y axis, and is combined with the relative distance obtained as described above. The relative position with is fixed.

  Furthermore, the robot of the present invention corrects the shake as follows.

  For example, in a normal follow-up state, the swing of the rope having slack is as shown in FIGS. At this time, when the robot direction, the rope direction, the angle deviation (η), and the height (h) of an arbitrary point P1 on the rope are graphed, the angle deviation 44, as shown in FIG. The P1 height 45 is a sinusoidal vibration, and the frequency deviation vibration is half of the P1 height vibration. Further, it can be seen that the lowest point of the height of P1 is obtained at a point 43 between the both ends 41 and 42 of the amplitude of the angle deviation.

  In addition, the state without shaking is a state in which the shaking is minimized, and the sagging state 43 where the height of P1, which is the convergence point when the shaking is reduced, at the lowest point is the sagging when there is no shaking. Indicates the state. Therefore, by detecting both ends of the amplitude from the time-series angle deviation data and calculating the position using the data at the intermediate point, the influence of the fluctuation in the calculation of the sag state can be eliminated.

  Therefore, the correction unit provided in the robot of the present invention can correct the shake by the following steps, for example.

  Step 1: Take out the slope data of the rope end stored in time series, and project the angle data in the XZ plane of FIG. 4 to calculate the angle deviation seen from above, and create time series angle deviation data.

  Step 2: Data at both ends of the amplitude is extracted from the time-series angle deviation data calculated in Step 1.

  Step 3: The inclination data and tension data of the rope end at the time of the intermediate position of the data extracted in Step 2 are extracted from the storage unit and sent to the position calculation unit.

  According to the robot as described above, since the target and the robot are physically constrained by the rope, they are not lost. Further, since an external force other than gravity is not applied to the rope, it is possible to prevent the movement of the target from being hindered and damage caused by the rope when the rope is released or cut. Further, since there is no winding mechanism, troubles due to the failure can be avoided. Further, since the slack state of the robot is uniquely determined, the relative position of the target can be calculated uniquely. Furthermore, it is possible to perform an appropriate correction for the shake and to follow an appropriate target.

  Therefore, it is possible to easily and safely automatically follow the target.

  Since the robot of the present invention can easily and safely automatically follow a target, it can be applied to an automatic cart or a transport robot at home, a hotel, a golf course, a factory, an airport, or the like.

Explanatory drawing which shows the structure of the robot of this invention (A) Explanatory diagram showing the structure of the rope end and the method of detecting the inclination and tension of the rope (b) Explanatory diagram showing the structure of the rope end and the method of detecting the inclination and tension of the rope (A) Explanatory view showing the coordinate system of the rope (b) Explanatory view from the side showing the coordinate system of the rope (c) Explanatory view showing the geometrical relationship per unit length of the rope (A) Explanatory view showing the state of the swaying of the rope with slack (b) Explanatory view showing the state of the swaying of the rope with slack (c) Direction and angle deviation of the rope and any on the rope Showing the height of point P1 Explanatory drawing which shows the structure of the mobile robot of the prior art example 1. Explanatory drawing which shows the structure of the mobile robot of the prior art example 2. (A) Explanatory drawing which shows the subject which arises in example 1 of prior art (b) Explanatory drawing which shows the subject which arises in example 1 of a prior art (c) Explanatory drawing which shows the subject which arises in example 1 of a prior art (A) Explanatory drawing which shows the subject which arises in example 2 of prior art (b) Explanatory drawing which shows the subject which arises in example 2 of a prior art (c) Explanatory drawing which shows the subject which arises in example 2 of a prior art Explanatory diagram showing problems due to sagging (A) Explanatory drawing which shows the subject of the fluctuation | variation produced by a sagging (b) Explanatory drawing which shows the subject of the shaking produced by a sagging

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Target 2 Robot 2a Rope 2b Tilt detection part 2c Tension detection part 2d Position calculation part 2e Movement mechanism 2f Control part 2i Connection mechanism

Claims (3)

A rope having a connection mechanism that does not apply a moment in the rotational direction to both ends, one end connected to the target, and the other end connected to the robot;
An inclination detector for detecting the inclination of the rope at the other end;
A tension detector that detects the tension applied to the other end;
A position calculation unit that calculates a relative position between the target and the robot from the inclination detected by the inclination detection unit and the tension detected by the tension detection unit;
A moving mechanism for moving the robot;
A robot comprising a control unit that controls the moving mechanism based on a relative position calculated by the position calculation unit. In the position calculation unit, a slack state of the rope is calculated from the inclination detected by the inclination detection unit and the tension detected by the tension detection unit, and the relative position between the target and the robot is calculated from the calculated slack state. The robot according to claim 1, wherein the robot is calculated. A storage unit for storing data of the tilt detected by the tilt detection unit and the tension detected by the tension detection unit in time series;
The robot according to claim 2, further comprising a correction unit that corrects the calculation of the sag state based on the data stored in the storage unit.

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