Object detection system and robot system

Abstract

To provide an object detection system that can expand an object detection range of an electrostatic type sensor.SOLUTION: An object detection system 6 for detecting an object comprises: an electrostatic type sensor 11 which outputs a sensor value according to an electrostatic capacity generating between an electrode for detection and an object; an optical sensor 12 which detects the object by a system different from that of the electrostatic type sensor 11 and outputs a sensor value, and in which drift generated in a sensor value due to ambient environment is smaller than that in the electrostatic type sensor 11; and a processor 13 which estimates an offset component generated in a sensor value of the electrostatic type sensor 11 by using the sensor value of the optical sensor 12, and corrects the sensor value by the offset component.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an object detection system that detects an object and a robot system. [Background technology]

[0002] There are cases where humans and robots work together to perform tasks on a workpiece. Robots used in such cases are called collaborative robots. Collaborative robots may be equipped with electrostatic sensors that can detect nearby objects, such as people.

[0003] For example, Patent Document 1 describes the use of both an electrostatic sensor and an optical sensor, and the electrostatic sensor detects an object located in an area not covered by the optical sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2020-532441 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, electrostatic sensors may experience drift in their output offset value due to environmental factors such as ambient temperature and humidity. Therefore, although electrostatic sensors can detect objects over a relatively wide angle, the detection signal for objects located at a long distance is small and may be obscured by the drift in the offset value, making it difficult to extend the range. For this reason, as in Patent Document 1, it is conceivable to detect objects while covering a range by using an electrostatic sensor and an optical sensor capable of long-distance detection. However, because optical sensors have a narrow detection angle, it is necessary to install multiple optical sensors.

[0006] In view of the above-mentioned problems, an object of the present invention is to provide an object detection system and a robot system that can expand the object detection range of an electrostatic sensor. [Means for solving the problem]

[0007] In order to solve the above problem, the object detection system of the present invention is an object detection system that detects an object, and includes: a first sensor that outputs a first sensor value corresponding to the capacitance generated between a detection electrode and the object; a second sensor that detects the object using a method different from that of the first sensor and outputs a second sensor value, and in which drift generated in the second sensor value due to the surrounding environment is smaller than that of the first sensor; and a processing device that uses the second sensor value to estimate an offset component generated in the first sensor value and corrects the first sensor value using the offset component.

[0008] Furthermore, in the object detection system, when the object is detected at the same timing by the first sensor and the second sensor, the processing device uses the second sensor value at that timing to estimate the offset component occurring in the first sensor at that timing.

[0009] Also, in the object detection system, the processing device estimates the distance between the second sensor and the object from the second sensor value, and estimates the offset component of the first sensor using the estimated value of the first sensor value corresponding to the distance and the first sensor value when the object is detected at the timing.

[0010] Furthermore, in the object detection system, after estimating the offset component, the processing device corrects the first sensor value using the estimated offset component until the first sensor and the second sensor again detect the object at the same timing and re-estimate the offset component.

[0011] The robot system also includes a plurality of arms, a control device that controls the operation of the arms, and the object detection system described above, and the control device stops or slows down the operation of the arms using the first sensor value corrected in the object detection system. [Effects of the Invention]

[0012] According to the object detection system and robot system of the present invention, the object detection range of the electrostatic sensor can be expanded. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of a robot system including an object detection system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of the object detection system of FIG. [Figure 3] 3 is a diagram showing an example of the detection angle ranges of the electrostatic sensor and the optical sensor of FIG. 2. FIG. [Figure 4] 3 is a diagram showing an example of relational data in the electrostatic sensor of FIG. 2. FIG. [Figure 5] 3 is a diagram showing an example of relational data in the optical sensor of FIG. 2. FIG. [Figure 6] 2 is a flowchart showing an example of a processing flow in the processing device of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicate descriptions will be omitted where appropriate.

[0015] === Implementation form === <Overall structure> FIG. 1 is a diagram schematically illustrating an example of the overall configuration of a robot system 2 equipped with an object detection system 6 according to an embodiment of the present invention.

[0016] The robot system 2 is an industrial robot that performs processes such as machining and transporting a workpiece, and is also a collaborative robot that works in the same space as a person, for example.

[0017] As shown in FIG. 1, the robot system 2 mainly includes a robot 4, a control device 5, and an object detection system 6.

[0018] The robot 4 is an articulated robot and has multiple arms and multiple joints. Specifically, the robot 4 includes a base 7, a first arm A1, a second arm A2, a third arm A3, and a fourth arm A4. The number of arms provided is not limited. The base 7 is the foundation of the robot 4. The base 7 is fixed to, for example, the floor or a wall, and supports the entire robot 4. The first arm A1 is connected to the base 7 via a rotation shaft. The first arm A1 is rotated around the rotation shaft relative to the base 7 by a motor (not shown). Similarly, the second arm A2, the third arm A3, and the fourth arm A4 are rotated around their respective rotation shafts by their respective motors (not shown). A tool 9 is provided at the tip of the fourth arm A4. The robot 4 performs a predetermined operation by moving each joint, and performs a predetermined process on a workpiece using the tool 9.

[0019] The control device 5 is an information processing device that controls the operation of the robot 4. The control device 5 is configured with, for example, a CPU, memory, a communication device, and a storage device, and performs various functions by executing predetermined programs. The control device 5 controls the operation of each arm of the robot 4 and the tool 9, causing the robot 4 to perform predetermined operations. For example, the control device 5 causes the robot 4 to perform predetermined operations such as gripping a workpiece with the tool 9 and transporting the workpiece from one position to another.

[0020] Furthermore, the control device 5 uses the output of the object detection system 6 (a corrected sensor value V1, which will be described later) to stop the movement of the robot 4. Specifically, the control device 5 compares the output of the object detection system 6 with a threshold value (a set range) to determine whether an object, such as a person, is approaching the robot 4. If the control device 5 determines that an object, such as a person, is approaching the robot 4, it stops the movement of the robot 4. For example, if the output of the object detection system 6 increases in response to the approach of an object, the control device 5 determines that an object is approaching when the output of the object detection system 6 (a corrected sensor value V1, which will be described later) becomes equal to or greater than a threshold value (exceeds the set range). For example, the control device 5 stops the movement of the robot 4 even if the robot 4 is in the middle of a predetermined movement. Note that the control device 5 is not limited to stopping the movement of the robot 4, and may also slow down the movement of the robot 4.

[0021] The object detection system 6 is a sensor system that detects objects such as people. In this embodiment, the term "object" is a broad concept that includes objects such as a person and a workpiece. Specifically, the object detection system 6 detects the proximity of an object. Note that the object detection system 6 may also detect the displacement of an object. In this embodiment, a case where the object detection system 6 detects the proximity of an object is taken as an example.

[0022] Fig. 2 is a diagram showing an example configuration of an object detection system 6. As shown in Fig. 2, the object detection system 6 mainly includes an electrostatic sensor 11 as a first sensor, an optical sensor 12 as a second sensor, and a processing device 13.

[0023] The electrostatic sensor 11 is a capacitance sensor (first sensor) that detects an object. The electrostatic sensor 11 is provided on the robot 4. For example, the electrostatic sensor 11 is provided on an arm of the robot 4. In this embodiment, a case where the electrostatic sensor 11 is provided on the fourth arm A4 will be described as an example. The electrostatic sensor 11 may be provided on another part of the robot 4 or on multiple arms, and the installation position is not limited. Furthermore, the electrostatic sensor 11 is not limited to being provided on the robot 4, but may also be installed in the surrounding environment of the robot 4, etc.

[0024] The electrostatic sensor 11 is configured using a detection electrode 25. The detection electrode 25 is, for example, a flat electrode that generates an electric field. The detection electrode 25 forms a capacitance with a nearby object and generates a voltage corresponding to the capacitance. Note that the capacitance changes depending on the distance between the detection electrode 25 and the object. The electrostatic sensor 11 outputs an output corresponding to the capacitance formed between the detection electrode 25 and the object as a sensor value V1. The sensor value V1 is a first sensor value. The electrostatic sensor 11 amplifies the voltage corresponding to the capacitance generated in the detection electrode 25 using an amplifier or the like and outputs the amplified voltage as the sensor value V1. Note that the specific circuit configuration is not limited as long as the sensor value V1 corresponding to the capacitance formed between the detection electrode 25 and the object is output.

[0025] The electrostatic sensor 11 may be affected by the surrounding environment because it uses the capacitance between the detection electrode 25 and the object. Examples of the surrounding environment include temperature and humidity. The surrounding environment may also include heat generated by a circuit or the like. Specifically, the electrostatic capacitance formed between the detection electrode 25 and the object of the electrostatic sensor 11 is affected by the surrounding environment, which causes the sensor value V1 (especially the offset value) to drift. The amount of drift in the sensor value V1 due to the surrounding environment is the "offset component." In other words, the offset component included in the sensor value V1 of the electrostatic sensor 11 varies depending on the surrounding environment. In this way, the sensor value V1 of the electrostatic sensor 11 may include an offset component, but the offset component is corrected by the processing device 13, which will be described later.

[0026] It should be noted that a shield electrode, an active shield electrode, or the like may be provided on the side of the detection electrode 25 opposite to the surface that generates the electric field. Also, although the above example illustrates a case in which the electrostatic sensor 11 is provided on the arm, it is also possible to provide the detection electrode 25 on the arm and not provide other components of the electrostatic sensor 11, such as an amplifier, on the arm. Also, the electrostatic sensor 11 may be disposed in a location other than the arm.

[0027] In this way, the electrostatic sensor 11 outputs a sensor value V1 according to the capacitance (i.e., distance) formed between the detection electrode 25 and the object. The sensor value V1 of the electrostatic sensor 11 is then output to the processing device 13.

[0028] The optical sensor 12 is an optical sensor (second sensor) that detects an object. That is, the optical sensor 12 is a sensor (photoelectric sensor) that detects an object using a method different from that of the electrostatic sensor 11. The optical sensor 12 is provided on the robot 4 together with the electrostatic sensor 11. For example, the optical sensor 12 is provided on the fourth arm A4 together with the electrostatic sensor 11. For example, the optical sensor 12 is provided at the center position of the detection electrode 25 of the electrostatic sensor 11. In this manner, the optical sensor 12 is installed as a set with the electrostatic sensor 11. FIG. 3 is a diagram showing an example of the detection angle ranges of the electrostatic sensor 11 and the optical sensor 12. The detection angle range is a range indicating an angle at which an object can be detected. As shown in FIG. 3, the electrostatic sensor 11 and the optical sensor 12 are provided so that the object detection angle range R1 of the electrostatic sensor 11 and the object detection angle range R2 of the optical sensor 12 overlap.

[0029] For example, optical sensor 12 emits visible light or infrared light and detects an object based on the reflected light it receives. Therefore, optical sensor 12 outputs an output corresponding to the distance to the object as sensor value V2. Sensor value V2 is a second sensor value. Note that the method of detecting an object by optical sensor 12 is not limited to the above.

[0030] Furthermore, the optical sensor 12 experiences less drift (fluctuation) in the sensor value V2 due to the surrounding environment than the electrostatic sensor 11. That is, the optical sensor 12 experiences less fluctuation in the offset component of the sensor value V2 due to the surrounding environment than the electrostatic sensor 11. For example, the optical sensor 12 experiences negligible drift due to the surrounding environment compared to the electrostatic sensor 11. Therefore, the optical sensor 12 is hardly affected by the surrounding environment and outputs the sensor value V2 stably.

[0031] The second sensor is not limited to the optical sensor 12, as long as it is a non-capacitive object detection sensor with smaller fluctuations in offset components due to the surrounding environment than the electrostatic sensor 11 (i.e., a sensor capable of long-distance object detection). For example, the second sensor may be an ultrasonic sensor. The ultrasonic sensor also does not depend on the electrostatic capacitance generated between it and the object, and fluctuations in offset components due to the surrounding environment are smaller than those of the electrostatic sensor 11.

[0032] In this way, the optical sensor 12 outputs the sensor value V2 according to the distance to the object. The sensor value V2 of the optical sensor 12 is then output to the processing device 13.

[0033] 2, the processing device 13 is an information processing device that corrects the sensor value V1 of the electrostatic sensor 11. Specifically, the processing device 13 estimates an offset component that occurs in the sensor value V1 of the electrostatic sensor 11 using the detection result from the optical sensor 12, and corrects the sensor value V1 of the electrostatic sensor 11 using this offset component. The processing device 13 is configured to include, for example, a CPU, memory, a communication device, and a storage device, and performs various functions by executing predetermined programs.

[0034] The processing device 13 includes a determination unit 31 , an estimation unit 32 , and a correction unit 33 .

[0035] The determination unit 31 determines the timing for estimating the offset component of the sensor value V1. Specifically, the determination unit 31 determines whether or not an object is detected at the same timing by the electrostatic sensor 11 and the optical sensor 12. In other words, the determination unit 31 determines that the same object is detected simultaneously by the electrostatic sensor 11 and the optical sensor 12.

[0036] The detection angle range R1 of the electrostatic sensor 11 and the detection angle range R2 of the optical sensor 12 overlap with each other. The detection angle range R2 of the optical sensor 12 is included in the detection angle range R1 of the electrostatic sensor 11. Therefore, the determination unit 31 determines whether or not an object has been detected by the optical sensor 12. Specifically, the optical sensor 12 has a characteristic in which the sensor value V2 diverges (or becomes 0) when an object is outside the detection range. Therefore, the determination unit 31 determines whether or not the sensor value V2 of the optical sensor 12 is within a valid range (a set range), and determines that an object has been detected when the sensor value V2 is within the valid range. The valid range is set in advance as a range of the sensor value V2 that indicates a state in which an object is within the detection range of the optical sensor 12. Note that the determination method is not limited to the above, as long as it is possible to determine whether or not an object has been detected by the optical sensor 12. Since detection angle range R2 is included in detection angle range R1, when an object is detected by optical sensor 12, the object is also detected by electrostatic sensor 11. In this way, when an object is detected by optical sensor 12, determination unit 31 determines that the same object has been detected simultaneously by electrostatic sensor 11 and optical sensor 12.

[0037] In this way, the determination unit 31 determines that an object has been detected simultaneously by the electrostatic sensor 11 and the optical sensor 12, and identifies the timing of the detection. The determination unit 31 defines the timing of the detection as the "simultaneous detection timing."

[0038] In the above example, the judgment unit 31 determines the simultaneous detection timing using the sensor value V2 of the optical sensor 12, but the simultaneous detection timing may also be determined using both the sensor value V1 of the electrostatic sensor 11 and the sensor value V2 of the optical sensor 12.

[0039] The estimation unit 32 estimates the offset component occurring in the electrostatic sensor 11 using the detection result of the optical sensor 12 at the simultaneous detection timing. Specifically, the estimation unit 32 estimates the offset component included in the sensor value V1 at the simultaneous detection timing using the sensor value V2 at the simultaneous detection timing.

[0040] The estimation unit 32 estimates the offset component using relationship data D1 indicating the relationship between the sensor value V1 of the electrostatic sensor 11 and the distance to the object, and relationship data D2 indicating the relationship between the sensor value V2 of the optical sensor 12 and the distance to the object. FIG. 4 is a diagram showing an example of the relationship data D1 for the electrostatic sensor 11. In FIG. 4, the vertical axis represents the sensor value V1 (voltage) and the horizontal axis represents the distance between the electrostatic sensor 11 and the object. The relationship data D1 in FIG. 4 is set in advance as a reference for the relationship between the sensor value V1 and the distance. For example, the relationship data D1 indicates the relationship between the sensor value V1 and the distance corresponding to the reference ambient environment. For example, the relationship data D1 preferably indicates the relationship between the sensor value V1 and the distance in a state where there is little (or no) offset component due to the ambient environment. As shown in FIG. 4, the sensor value V1 decreases as the distance between the electrostatic sensor 11 and the object increases. FIG. 5 is a diagram showing an example of the relationship data D2 for the optical sensor 12. In FIG. 5, the vertical axis represents the sensor value V2 (voltage), and the horizontal axis represents the distance between the optical sensor 12 and the object. The relationship data D2 in FIG. 5 is set in advance as a reference for the relationship between the sensor value V2 and the distance. For example, the relationship data D2 indicates the relationship between the sensor value V2 and the distance corresponding to the reference ambient environment. As shown in FIG. 5, the longer the distance between the optical sensor 12 and the object, the lower the sensor value V2. The relationship between the relationship data D1 and the relationship data D2 is specified in advance and set in the estimation unit 32. The relationship data D1 and the relationship data D2 may be represented as a relational expression or as table data.

[0041] The estimation unit 32 estimates the distance between the optical sensor 12 and the object using the sensor value V2 of the optical sensor 12 at the time of simultaneous detection. Specifically, the estimation unit 32 estimates the distance corresponding to the sensor value V2 using the relationship data D2. For example, if the sensor value V2 at the time of simultaneous detection is value S1, the estimation unit 32 estimates that the distance between the optical sensor 12 and the object is distance M2 using the relationship data D2.

[0042] Then, the estimation unit 32 estimates a sensor value V1 of the electrostatic sensor 11 corresponding to the estimated distance (for example, distance M2). It is assumed that the electrostatic sensor 11 (detection electrode 25) and the optical sensor 12 are provided at the same position, and that the distance between the optical sensor 12 and the object is equal to the distance between the electrostatic sensor 11 and the object. It is not limited to the above, and the distance between the optical sensor 12 and the object may be converted to the distance between the electrostatic sensor 11 and the object, and processing may be performed.

[0043] Specifically, the estimation unit 32 uses the relationship data D1 to identify the sensor value V1 corresponding to the estimated distance. For example, if the estimated distance between the optical sensor 12 and the object at the simultaneous detection timing is distance M2, the estimation unit 32 uses the relationship data D1 to estimate that the sensor value V1 of the electrostatic sensor 11 is S3. The estimation unit 32 sets the estimated sensor value V1 of the electrostatic sensor 11 as the "estimated sensor value S3." In other words, the estimated sensor value S3 is the estimated value of the sensor value V1 estimated using the relationship data D1.

[0044] The estimation unit 32 then estimates the offset component of the electrostatic sensor 11 using the estimated sensor value S3 and the sensor value V1 of the electrostatic sensor 11 at the simultaneous detection time. The sensor value V1 of the electrostatic sensor 11 at the simultaneous detection time is a value that includes an offset component that reflects the influence of the surrounding environment at the simultaneous detection time. Therefore, the estimation unit 32 calculates the difference between the sensor value V1 of the electrostatic sensor 11 at the simultaneous detection time and the estimated sensor value S3, and sets this difference as the offset component of the electrostatic sensor 11. For example, the estimation unit 32 calculates the offset component by subtracting the estimated sensor value S3 from the sensor value V1.

[0045] In this way, the offset component of the electrostatic sensor 11 corresponding to the simultaneous detection timing is estimated.

[0046] The correction unit 33 uses the estimated offset component to correct the sensor value V1 of the electrostatic sensor 11. Specifically, the correction unit 33 performs estimation so as to remove the estimated offset component from the sensor value V1 of the electrostatic sensor 11. For example, the correction unit 33 performs correction by subtracting the offset component from the sensor value V1 of the electrostatic sensor 11.

[0047] As a result, the offset component is suppressed from the sensor value V1 whether the electrostatic sensor 11 is detecting an object or not, so that the corrected sensor value V1 more accurately indicates the object detection result.

[0048] After estimating the offset component at the simultaneous detection timing, the correction unit 33 corrects the sensor value V1 of the electrostatic sensor 11 using the last estimated offset component until the next simultaneous detection timing and the next offset component are re-estimated. For example, offset components due to the surrounding environment tend to change slowly over time. For example, offset components tend to change on the order of several minutes or more. Therefore, once the offset component is estimated, it can be assumed that the offset component will not change immediately. Even if a certain amount of time passes between the simultaneous detection timing and the correction timing, accurate correction is possible. In this way, the sensor value V1 of the electrostatic sensor 11 is continuously corrected using the offset component estimated intermittently. Note that while the sensor value V2 is not available, the offset component may be estimated using another method (for example, a method using a state estimator such as a Kalman filter).

[0049] As described above, the processing device 13 estimates the offset component in accordance with the simultaneous detection timing, and after the estimation, corrects the sensor value V1 of the electrostatic sensor 11 to suppress the offset component, and outputs the corrected sensor value V1 to the control device 5.

[0050] <Processing flow> 6 is a flowchart showing an example of the flow of the processing device 13 according to this embodiment. Each of the following steps is executed, for example, when the operation of the robot 4 is started. Each of the steps is repeatedly executed at a predetermined control period. Note that the order and content of each of the following steps can be changed as appropriate.

[0051] (Step SP10) The determination unit 31 determines whether an object is detected at the same time by the electrostatic sensor 11 and the optical sensor 12. If an object is detected at the same time, the process proceeds to step SP11. If an object is not detected at the same time, the process proceeds to step SP15.

[0052] (Step SP11) The determination unit 31 determines the timing at which the same object is detected by the electrostatic sensor 11 and the optical sensor 12 as the simultaneous detection timing. Then, the process proceeds to step SP12.

[0053] (Step SP12) The estimation unit 32 estimates the distance between the optical sensor 12 and the object using the sensor value V2 of the optical sensor 12 at the time of simultaneous detection. Then, the process proceeds to step SP13.

[0054] (Step SP13) The estimation unit 32 estimates the sensor value V1 of the electrostatic sensor 11 corresponding to the estimated distance. The estimated sensor value V1 of the electrostatic sensor 11 becomes the estimated sensor value S3. Then, the process proceeds to step SP14.

[0055] (Step SP14) The estimation unit 32 estimates the offset component of the electrostatic sensor 11 using the estimated sensor value S3 and the sensor value V1 of the electrostatic sensor 11 at the simultaneous detection timing. Then, the process proceeds to step SP15.

[0056] (Step SP15) The correction unit 33 uses the estimated offset component to correct the sensor value V1 of the electrostatic sensor 11. The corrected sensor value V1 is output to the control device 5. Then, the process ends, and step SP10 is executed again at a predetermined control cycle.

[0057] The control device 5 sequentially acquires the corrected sensor value V1 and determines whether or not an object is approaching the robot 4. If the control device 5 determines that an object is approaching the robot 4, it stops the operation of the robot 4.

[0058] When performing the above process, a preset offset component may be used before estimating the offset component for the first time. Alternatively, the electrostatic sensor 11 and the optical sensor 12 may be intentionally made to detect an object to perform the offset component estimation process.

[0059] <Action and effect> As described above, in this embodiment, the processing device 13 estimates and corrects the offset component of the electrostatic sensor 11 serving as the first sensor based on the sensor value V2 (second sensor value) of the optical sensor 12 serving as the second sensor. The sensor value V1 of the electrostatic sensor 11 may drift (the offset component may fluctuate) due to environmental factors. Therefore, when the change in the sensor value V1 is small, it is difficult to distinguish whether the change is due to an object or environmental drift. This makes it difficult for the electrostatic sensor 11 to expand its detection range. However, by estimating and correcting the offset component, the offset component can be suppressed from the sensor value V1, making it possible to more accurately represent changes in the sensor value V1 due to objects. In other words, it becomes possible to detect distant objects that only cause small changes in the sensor value V1 while distinguishing these changes from environmental drift, enabling the electrostatic sensor 11 to stably detect objects over long distances. This allows the detection range of the electrostatic sensor 11 to be expanded. The electrostatic sensor 11 is characterized by a wide detection angle, and by expanding the detection range, it becomes possible to detect objects over a wider range (wider angle and longer distance).

[0060] Furthermore, the processing device 13 estimates the offset component when an object is detected at the same timing (simultaneous detection timing) by the electrostatic sensor 11 and the optical sensor 12. Therefore, the sensor value V2 of the optical sensor 12 can be used to accurately estimate the offset component occurring in the sensor value V1 of the electrostatic sensor 11 at the same timing.

[0061] Furthermore, the processing device 13 estimates the distance between the optical sensor 12 and the object from the sensor value V2, thereby estimating the sensor value V1 of the electrostatic sensor 11 corresponding to that distance. Then, by comparing the estimated sensor value V1 (estimated sensor value S3) with the sensor value V1 at the simultaneous detection timing, it becomes possible to estimate the offset component. In this way, it becomes possible to estimate the offset component of the electrostatic sensor 11 using another sensor (optical sensor 12).

[0062] Furthermore, after estimating the offset component, the processing device 13 corrects the sensor value V1 using the estimated offset component until the next estimation. Because fluctuations in the offset component due to the surrounding environment tend to change gradually over time, the sensor value V1 can be corrected with high accuracy even when the offset component is estimated intermittently. Furthermore, the processing load related to the estimation of the offset component can be reduced.

[0063] === Variations === The present invention is not limited to the above-described embodiments. In other words, designs that are produced by those skilled in the art with appropriate design modifications to the above-described specific examples are also included within the scope of the present invention as long as they include the features of the present invention. Furthermore, the elements of the above-described embodiments and the following modifications can be combined to the extent technically possible, and such combinations are also included within the scope of the present invention as long as they include the features of the present invention.

[0064] For example, in the above embodiment, the case where the object detection system 6 is provided in the robot 4 has been described as an example, but the object detection system 6 may be applied to a device other than the robot 4.

[0065] In addition, in the above embodiment, the case where the functions are divided between the control device 5 and the processing device 13 has been described, but some or all of the functions of the processing device 13 may be provided in the control device 5, or some of the functions of the control device 5 may be provided in the processing device 13. For example, in the above embodiment, the case where the control device 5 has the function of determining whether or not an object is near the robot 4 based on the corrected sensor value V1 has been described, but this function may be provided in the processing device 13.

[0066] Furthermore, since noise or errors may be included in the outputs of the electrostatic sensor 11 and the optical sensor 12, filtering may be performed. For example, the processing device 13 may perform filtering using a Kalman filter to estimate the offset component of the electrostatic sensor 11.

[0067] Furthermore, the sensor value V1 of the electrostatic sensor 11 corresponds to the capacitance formed between the detection electrode 25 and the object. Therefore, even if the distance is the same, the capacitance formed varies depending on the size of the object, and this is reflected in the sensor value V1. Therefore, the size of the detected object may be estimated by using the distance estimated from the sensor value V2 of the optical sensor 12 and the sensor value V1 (i.e., capacitance) of the electrostatic sensor 11. For example, it is possible to specify the size by previously setting a correspondence relationship between the distance corresponding to each size and the sensor value V1 (capacitance).

[0068] Furthermore, optical sensor 12 detects the distance in the front direction (not necessarily the center of the object), whereas electrostatic sensor 11 detects the distance to the approximate center of the object. Therefore, by comparing sensor value V1 of electrostatic sensor 11 with sensor value V2 of optical sensor 12, the direction (angle) of the object can be estimated.

[0069] Furthermore, in the above embodiment, the determination unit 31 determines the coincidence detection timing and estimates the offset component as an example. However, the coincidence detection timing may be intentionally set. For example, an object to be detected is prepared in advance in the work environment, and the robot 4 is controlled to detect the object using both the electrostatic sensor 11 and the optical sensor 12. That is, the coincidence detection timing is generated using the prepared object. For example, when the robot 4 starts operating or when a predetermined time has passed since the coincidence detection timing, the coincidence detection timing is intentionally generated using the object, and offset estimation is performed. Note that the coincidence detection timing may also be generated periodically using the object. By generating the coincidence detection timing using a predetermined object in this way, offset estimation can be performed more reliably. [Explanation of symbols]

[0070] 2: Robot system 5: Control device 6: Object detection system 11: Electrostatic sensor (first sensor) 12: Optical sensor (second sensor) 13: Processing equipment 25: Detection electrode A1: First arm (arm) A2: Second arm (arm) A3: Third arm (arm) A4: 4th arm (arm) M2: distance S3: Estimated sensor value V1: Sensor value (first sensor value) V2: Sensor value (second sensor value)

Claims

1. An object detection system for detecting an object, a first sensor that outputs a first sensor value corresponding to a capacitance generated between a detection electrode and the object; a second sensor that detects the object in a manner different from that of the first sensor and outputs a second sensor value, the second sensor value having a smaller drift due to the surrounding environment than that of the first sensor; a processing device that estimates an offset component occurring in the first sensor value using the second sensor value and corrects the first sensor value using the offset component; An object detection system comprising:

2. 2. The object detection system according to claim 1, wherein when the object is detected at the same timing by the first sensor and the second sensor, the processing device estimates the offset component occurring in the first sensor at the same timing using the second sensor value at the same timing.

3. 3. The object detection system according to claim 2, wherein the processing device estimates the distance between the second sensor and the object from the second sensor value, and estimates the offset component of the first sensor using the estimated value of the first sensor value corresponding to the distance and the first sensor value when the object is detected at the timing.

4. The object detection system according to claim 2 or 3, characterized in that, after estimating the offset component, the processing device corrects the first sensor value using the estimated offset component until the first sensor and the second sensor again detect the object at the same timing and re-estimate the offset component.

5. A plurality of arms; a control device that controls the operation of the arm; The object detection system according to any one of claims 1 to 3; Equipped with The robot system is characterized in that the control device stops or slows down the movement of the arm using the first sensor value corrected in the object detection system.

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