JP2010175533A - Contact sensor and mobile robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact sensor that allows the force and direction of contact to be estimated by a relatively small number of contact sensors, and that reduces the risk that a contact part damages that surround objects to be reduced. <P>SOLUTION: In this contact sensor, shafts and rotation sensors are arranged at both ends of a slender elastic material, and the elastic material is bent into a circular form. When an object is brought into contact with the circular elastic material, the elastic material deforms according to the force and contact direction, and the shafts at both ends rotate in interlock with it. The force and direction applied to the circular elastic material are estimated, based on the variation in the rotational angle of the shafts at both ends. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a contact sensor for determining whether or not there is an obstacle when a mobile robot performs autonomous traveling or semi-autonomous traveling and for determining a traveling direction.

  The present invention also relates to a contact sensor that detects a force and its direction by providing rotation sensors at both ends that rotate by deformation of a soft elastic material that is bent in a circular shape.

  As a mobile robot that runs autonomously, a method is known in which a plurality of contact sensors such as insect antennae are mounted, the presence or absence of an object is detected, and the traveling direction is determined. Alternatively, there is a method of autonomously running by arranging a plurality of non-contact sensors such as an infrared distance sensor. A sensor using a non-contact sensor has an advantage that there is no danger of damaging an object, and is therefore used for many autonomous robots. The method using the contact sensor has an advantage that the presence or absence of an object can be reliably detected by directly touching the object, and a contact force can be obtained. Therefore, it is used when detecting an object having a complicated surface shape.

  Further, in such a robot, it is necessary to provide at least two sensors on the left and right sides in order to determine the traveling direction. Furthermore, detecting the direction of the object around the entire circumference is realized by providing a large number of sensors around the robot.

  When a non-contact sensor is used, there is a high possibility that accurate detection cannot be performed when the surface of the object has a complicated shape, is too close to the sensor, or the shape of the object is thin and complicated.

  When a contact sensor such as an insect antenna is used, if the object to be contacted is easily damaged such as a plant stem or leaf, there is a risk that the contact sensor may damage the object.

  In order to detect an object in all directions, a large number of sensors are required. As a result, the structure becomes larger, which is disadvantageous in reducing the size of the robot.

  An object of the present invention is to provide a contact sensor that can estimate the force and direction of contact with a relatively small number of contact sensors, and further reduce the risk of the contact portion damaging surrounding objects. And

  The contact sensor of the present invention for solving the above-mentioned problems is formed by arranging a shaft and a rotation sensor at both ends of an elongated elastic material and bending it in a circular shape. When an object is brought into contact with the circular elastic material, the elastic material is deformed according to the force and the contact direction, and the shafts at both ends are rotated in conjunction with the deformation. The force and direction applied to the circular elastic material are estimated from the change in the rotation angle of the shafts at both ends.

  Since the contact sensor of the present invention obtains a force and its direction from changes in the rotation angle of the two rotation sensors, it does not require a large number of sensors as in the prior art. In addition, since the contact portion is a surface, it is easy to reduce damage to surrounding objects or to perform processing for reducing damage.

  FIG. 1 shows the pedestal of the sensor. The shaft, rotation sensor, and elastic material fixing part rotate in conjunction with each other. Here, a variable resistor was used as the rotation sensor. The elastic material is removed with a tightening screw.

  FIG. 2 shows the configuration of the contact sensor of the present invention. The elastic material bent in a circle is fixed to the elastic material fixing portions of the two shafts. Here, a nylon band having a length of 500 mm and a width of 9 mm is used as the elastic material, and the diameter when bent in a circular shape is about 165 mm.

  When a force is applied to the sensor and released, the elastic material needs to return to its original shape. Therefore, it is necessary to attach an elastic material such as a spring to the shaft so that the elastic material maintains a certain shape. Here, a rubber band is used, and a model diagram thereof is shown in FIG. In FIG. 1, FIG. 2, FIG. 4, FIG. 6, FIG. 8, and FIG. 9, this is omitted for simplification.

  According to the first aspect of the present invention, the contact sensor of the present invention estimates the applied force and direction by discriminating deformation of the elastic material with the rotation sensors provided at both ends. Here, as shown in FIG. 4, forces of 1N, 2N, and 3N were applied to the center of the elastic material. FIG. 5 is a graph showing changes in the rotation angle of the left and right axes when force is applied as shown in FIG. Next, as shown in FIG. 6, the contact position was changed in the range of −40 to +40 mm from the center of the elastic body, and a force of 3N was applied vertically. FIG. 7 is a graph showing changes in the rotation angle of the left and right axes when a force is applied as shown in FIG. The rotation angle is + for right rotation.

  According to claim 2, the contact sensor of the present invention is used as means for determining the traveling direction of the object of the mobile robot. FIG. 8 shows an external view of a crawler type mobile robot equipped with the sensor of the present invention. The robot is a mobile robot that can move forward and backward and turn left and right. The contact sensor according to the present invention is disposed in front of the mobile robot so as to face left and right. Autonomous traveling is performed by traveling while the left and right sensors detect contact with an object. At this time, since it is not necessary to obtain the direction of the applied force, one rotation sensor is used on each of the left and right sides.

  The sensor shown in FIG. 2 was attached to a crawler-type mobile robot as shown in FIG. 8, and was run on a test field simulating a farm field. This test site stands on the ground of 1.3m x 0.9m, with a glass rod placed on the ground at an interval of approximately 650mm in width and 200mm. The glass rod is a crop, and the space between the glass rods (650mm) is a gap. It is likened to. FIG. 9 shows the traveling direction of the crawler-type mobile robot at the starting point and the ending point when traveling on the test site. FIG. 10 shows the trajectory of the mobile robot. Here, the starting point of travel is A, the end point is B, the front part of the crawler-type mobile robot is 1, the rear part is 2, and points A1, A2, B1, and B2 are represented. The point (end point) B1- is the state where the straight direction is 0 ° and the travel starts from the point (start point) A1-A2 in the direction of travel 30 °, the glass rod is detected, and the mobile robot changes direction. The traveling direction of B2 was −6.8 °. The angle indicating the traveling direction is + for clockwise rotation. Even when the traveling direction of the mobile robot deviates greatly from the straight traveling direction, the traveling direction can be corrected by the left and right sensors, and autonomous traveling is possible.

This is the pedestal part of the sensor. It is a block diagram of a sensor. It is a supplement to the sensor configuration schematic. It is a figure for demonstrating the force applied to the sensor. This is a graph of the force applied to the sensor and the change in the rotation angle of the shaft. It is a figure for demonstrating the position of the force added to the sensor. It is a graph of changes in the position of the force applied to the sensor and the rotation angle of the shaft. It is a general view of a crawler type mobile robot equipped with a sensor. It is the figure of the test field which imitated the farm field, and the figure which showed the advancing direction of the starting point when the crawler type mobile robot is made to travel. It is a figure showing a locus when a crawler type mobile robot is made to run.

DESCRIPTION OF SYMBOLS 1 axis | shaft 2 rotation sensor 3 elastic material fixing | fixed part 4 fastening screw 5 elastic material 6 rubber band 7 left axis 8 right axis 9 crawler type mobile robot 10 glass rod 11 A1
12 A2
13 B1
14 B2

Claims (2)

Using a curved elastic material or a circular or semi-circular elastic material for the contact part, and detecting the deformation of the elastic material with rotation sensors provided at both ends, applied force and direction, or either A contact sensor that can reduce the risk of damage and entanglement of the contacted object. A mobile robot comprising the contact sensor according to claim 1 as means for detecting an object and determining a traveling direction.

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