Mobile Robot Precision Docking System and Method

Abstract

The present invention relates to a precision docking system for a mobile robot for precisely stopping the mobile robot at a target position close to a docking target equipment. The mobile robot comprises a main body equipped with wheels capable of forward, backward, left, right, and / or rotational movement; a pair of distance measuring sensors mounted on the side of the main body at a predetermined distance apart and measuring the distance to the side wall of the docking target equipment; and a control unit provided on the main body that controls the side of the main body to maintain parallelism with the side wall of the docking target equipment by comparing distance data measured by the pair of distance measuring sensors.

Description

Technology Field

[0001] The present invention relates to a precision docking system for a mobile robot, and more specifically, to a system that enables a mobile robot to stop precisely at a target location and a method for implementing the same. Background Technology

[0002] Recently, mobile robots such as Autonomous Mobile Robots (AMRs) are being used in logistics warehouses, manufacturing sites, and smart factories to perform tasks such as automated material transfer and assembly line integration. These mobile robots are designed to autonomously recognize and navigate routes by pre-setting driving paths or utilizing technologies such as LiDAR, vision sensors, magnetic tapes, and QR codes.

[0003] Mobile robots play an important role in automation systems, capable of moving along designated paths or calculating routes in real time to reach a destination, transporting cargo or workpieces to specific locations, and performing unloading or coordinated operations with machinery at designated locations when necessary.

[0004] However, mobile robots applied to date have the disadvantage of lacking precise docking capabilities. In other words, AGVs generally lack precise horizontal alignment and position stopping capabilities even when they reach a target position, which can lead to positional errors during workpiece transfer, potentially resulting in workpiece damage or safety accidents caused by falling workpieces. The problem to be solved

[0005] The objective of the present invention is to provide a mobile robot precision docking system and method that enables accurate horizontal alignment and positional stopping between a mobile robot and a docking target device.

[0006] Another objective of the present invention is to provide a mobile robot precision docking system and method that enables the mobile robot to be aligned with the docking target equipment without error, thereby enabling stable transfer of workpieces and improved efficiency of the automation process. means of solving the problem

[0007] To solve the aforementioned problem, the present invention provides a precision docking system for a mobile robot, comprising: a main body equipped with wheels capable of forward, backward, left, right, and / or rotational movement; a pair of distance measuring sensors mounted on the side of the main body at a predetermined distance apart and measuring the distance to the side wall of the docking target equipment; and a control unit provided on the main body and controlling the side of the main body to maintain parallelism with the side wall of the docking target equipment by comparing distance data measured by each of the pair of distance measuring sensors.

[0008] According to one feature, a marker is attached to the side wall of the docking target equipment, and the mobile robot further includes a marker recognition sensor mounted on the side of the main body to recognize the marker, and when the marker recognition sensor detects the marker, the control unit stops the forward and backward movement of the main body.

[0009] In addition, to solve the aforementioned problem, the present invention provides a method for precisely stopping a mobile robot at a target position close to a docking target equipment, comprising the steps of: driving the mobile robot toward the docking target equipment and, when approaching the docking target equipment, advancing it in a direction parallel to the side wall of the docking target equipment; measuring the distance to the side wall of the docking target equipment through a pair of distance measuring sensors mounted on the side of the advancing mobile robot, and controlling the mobile robot so that the side of the mobile robot is parallel to the side wall of the docking target equipment, thereby driving the mobile robot while maintaining the side of the mobile robot parallel to the side wall of the docking target equipment; and stopping the forward and backward movement of the mobile robot when the mobile robot reaches a target position in front of the side wall of the docking target equipment.

[0010] According to one feature, the stopping step of the mobile robot includes the step of stopping the forward and backward movement of the mobile robot when a marker recognition sensor mounted on the side of the mobile robot detects a marker attached to the side wall of the docking target equipment.

[0011] According to another feature, if the distance between the side of the mobile robot and the side wall of the docking target equipment exceeds a preset reference value or is smaller than the reference value, the method further includes the step of moving the mobile robot laterally toward the side wall of the docking target equipment or moving it in the opposite direction. Effects of the invention

[0012] According to the mobile robot precision docking system and method of the present invention, by equipping the mobile robot with a pair of distance measuring sensors and marker recognition sensors, the mobile robot can travel while maintaining accurate parallelism with the side wall of the equipment to be docked and can stop accurately at a set target position. Accordingly, error-free precision docking between the mobile robot and the equipment to be docked becomes possible, thereby improving work efficiency and increasing safety. Brief explanation of the drawing

[0013] FIG. 1 is a conceptual diagram illustrating a precision docking system for a mobile robot according to an embodiment of the present invention. FIG. 2 is a perspective view of a mobile robot according to an embodiment of the present invention. FIG. 3 is a side view of a mobile robot according to an embodiment of the present invention. FIGS. 4a to 4d are drawings for explaining the process of a mobile robot docking to a side wall of a docking target equipment according to an embodiment of the present invention. FIG. 5 is a drawing illustrating another example of the process of a mobile robot docking to a side wall of a docking target equipment according to an embodiment of the present invention. Specific details for implementing the invention

[0014] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the embodiments described below are merely intended to provide a detailed description sufficient for a person skilled in the art to easily practice the invention, and the scope of protection of the present invention is not limited to the embodiments described below.

[0015] The mobile robot precision docking system and method according to the present invention relates to a system and method for precisely positioning and stopping a mobile robot at a target location close to a docking target device.

[0016] As illustrated in FIGS. 1 to 4d, the mobile robot (100) includes a main body (110), a pair of distance measuring sensors (120), a marker recognition sensor (130), and a control unit (not shown).

[0017] The main body (110) includes wheels (111, 112) capable of forward, backward, left, right, and / or rotational movement for driving, and a motor (not shown). FIGS. 2 and 3 illustrate that the main body (110) is equipped with a driving wheel (111) for forward and backward movement and a rotating wheel (112) mounted to the main body (110) so as to be axially rotatable. The mobile robot (100) can move in a straight line by means of the driving wheel (111) and can rotate in place by means of the rotating wheel (112). Accordingly, by operating the driving wheel (111) and the rotating wheel (112) simultaneously, the mobile robot (100) can change direction while driving in a straight line, and accordingly, the side of the mobile robot (100) can be adjusted to be accurately aligned parallel to the side wall of the docking target equipment (200).

[0018] An item loading plate (140) may be mounted on the upper part of the main body (110), and items to be transported are loaded on the item loading plate (140). When the mobile robot (100) is docked to the docking target equipment (200), the items loaded on the item loading plate (140) are moved and delivered to the docking target equipment (200). Although not shown in the drawing, the movement and delivery of items may be automatically transported by conveyor belts installed on the mobile robot (100) and the docking target equipment (200), respectively. In this case, the safety and reliability of item transport can be ensured by maintaining a state of precision docking, that is, a state in which the gap between the mobile robot (100) and the docking target equipment (200) is minimized. Meanwhile, the transfer of goods may be carried out by directly extracting or loading goods loaded on the goods loading plate (140) of the mobile robot (100) by means of a goods transfer means, such as a robot arm provided on the mobile robot (100) or the docking target equipment (200).

[0019] Meanwhile, in the embodiment of the present invention, the mobile robot (100) is not limited to an AMR (Autonomous Mobile Robot), and although not shown in the drawings, the mobile robot (100) may be in a form equipped with a work means such as a robot arm instead of an item loading plate (140). That is, in addition to the function of loading or unloading items after docking, the mobile robot (100) may also be implemented in a structure capable of performing work using a robot arm.

[0020] A pair of distance measuring sensors (120) are mounted on the side of the main body (110) at a predetermined distance apart and measure the distance to the side wall of the docking target equipment (200) in real time. The distance data measured by the distance measuring sensors (120) is used to horizontally align the main body (110) with respect to the side wall of the docking target equipment (200), and this is performed by the control unit described later. In an embodiment of the present invention, by providing a pair of distance measuring sensors (120) spaced apart at a predetermined distance, each distance measuring sensor (120) measures the distance to the side wall of the docking target equipment (200), and when the measured distances of the two sensors are the same, the side of the main body (110) and the side wall of the docking target equipment (200) are accurately parallel.

[0021] The distance measuring sensor (120) may optionally be one of a Time of Flight (TOF) sensor, an infrared sensor, and an ultrasonic sensor. Each sensor may be selected according to the system's requirements and usage environment.

[0022] For example, a TOF sensor is a sensor that calculates distance by emitting light, primarily infrared or laser, and measuring the time it takes for the light to reflect off an object and return. This sensor offers high precision and fast response speeds, and has the advantage of enabling precise distance measurement in real time. TOF sensors are capable of precise measurements down to the millimeter level and are particularly suitable for the system of the present invention, which requires precise docking. However, measurement accuracy may be slightly degraded under strong external light sources (e.g., sunlight), although technologies to compensate for this are being utilized. Although TOF sensors are expensive, they are the most suitable choice for systems that prioritize precision and response speed.

[0023] An infrared sensor is a sensor that emits infrared light at an object and detects distance using the intensity of the reflected light or triangulation. This sensor is suitable for short-range measurements and can be used at a relatively low cost. Although infrared sensors have a fast response speed due to their simple structure, measurement errors may occur depending on the object's color, surface reflectivity, and ambient lighting conditions. Therefore, while precision may be somewhat lower, they can be usefully employed in systems that prioritize cost efficiency or in fixed indoor environments. In this invention, the infrared sensor can be utilized as an auxiliary sensor that supports short-range docking, even if its precision is somewhat lower.

[0024] An ultrasonic sensor emits ultrasonic waves into the air and calculates distance by measuring the time it takes for the waves to reflect back from an object. Since ultrasonic sensors are not affected by light, they have the advantage of being able to detect objects of various materials regardless of illuminance or color. Additionally, ultrasonic sensors are suitable for medium to long-distance measurement and can generally detect distances ranging from 2 cm to a maximum of about 5 m. However, ultrasonic sensors can be affected by environmental factors such as air temperature, humidity, and pressure, and their measurement speed is slower than that of TOF sensors. In the present invention, an ultrasonic sensor can be selectively used when stable distance measurement is required in various environments.

[0025] A marker recognition sensor (130) is mounted on the side of the main body (110) and recognizes a marker (210) attached to the side wall of the docking target equipment (200). When the marker recognition sensor (130) detects the marker (210), the movement of the main body (110) is stopped by the control of the control unit described later. The marker recognition sensor (130) is used to ensure that the mobile robot (100) stops accurately at the set docking position. As described above, while the mobile robot (100) is advancing with its side maintaining parallelism with the side wall of the docking target equipment (200), the marker recognition sensor (130) recognizes the marker (210). This indicates that the mobile robot (100) has reached the target position, and thus the movement of the mobile robot (100) is stopped.

[0026] The control unit is provided in the main body (110) and controls the main body (110) so that its side is kept exactly parallel to the side wall of the docking target equipment (200) by comparing distance data measured by a pair of distance measuring sensors (120). Additionally, the control unit stops the forward and backward movement of the main body (110) when the marker recognition sensor (130) detects a marker (210) attached to the side wall of the docking target equipment (200). That is, the control unit controls the movement of the main body (110) by comparing distance data input from a pair of distance measuring sensors (120) in real time so that the side of the main body (110) maintains horizontal alignment with the side wall of the docking target equipment (200), and also controls the main body (110) to immediately stop its forward and backward movement when the marker recognition sensor (130) detects the marker (210) of the docking target equipment (200).

[0027] Hereinafter, the docking process of a mobile robot (100) according to an embodiment of the present invention will be described.

[0028] First, the mobile robot (100) travels along a driving path toward the docking target equipment (200). The mobile robot (100) can move forward and backward, left and right, and / or rotate, and travels toward the docking target equipment (200) along the driving path of the workplace.

[0029] Subsequently, when the mobile robot (100) approaches the docking target equipment (200), the mobile robot (100) moves forward in a direction parallel to the side wall of the docking target equipment (200). That is, the driving direction of the mobile robot (100) becomes aligned with the side wall of the docking target equipment (200). At this time, the mobile robot (100) can drive while maintaining perfect parallelism with the side wall of the docking target equipment (200), but due to errors during the movement process or the influence of the surrounding environment, the mobile robot (100) may not be able to maintain perfect parallelism and may enter the side of the docking target equipment (200) with a slight incline.

[0030] Subsequently, a pair of distance measuring sensors (120) mounted on the side of the mobile robot (100) each measure the distance to the side wall of the docking target equipment (200) in real time, and the control unit controls the position of the mobile robot (100) so that these distance values ​​become equal. That is, as described above, if the mobile robot (100) does not maintain a perfectly parallel position and enters the side of the docking target equipment (200) with a slight incline, a difference occurs in the distance values ​​measured by each distance measuring sensor (120). At this time, the control unit controls the operation of the driving wheel (111) and the rotating wheel (112) based on the distance values ​​of the distance measuring sensors (120) to correct the posture of the mobile robot (100), thereby controlling its side to be perfectly parallel to the side wall of the docking target equipment (200), and the mobile robot (100) continues to drive while maintaining a parallel position to the side wall of the docking target equipment (200).

[0031] Subsequently, when the mobile robot (100) reaches a set target position in front of the side wall of the docking target equipment (200), the control unit stops the mobile robot (100). At this time, the marker recognition sensor (130) of the mobile robot (100) detects the marker (210) of the docking target equipment (200), and the control unit recognizes this and stops the movement of the mobile robot (100), thereby completing the docking.

[0032] Therefore, the mobile robot (100) stops accurately at a set target position with its side precisely parallel to the side wall of the docking target equipment (200), and accordingly, the efficiency of subsequent work such as transporting goods is improved and safety is increased.

[0033] Meanwhile, when the marker recognition sensor (130) detects the marker (210) and the mobile robot (100) stops, an additional step may be performed to reconfirm whether the side of the mobile robot (100) and the side wall of the docking target equipment (200) are parallel using a distance measuring sensor (120) in order to ensure more precise docking. At this time, if it is determined that both sides are parallel as a result of the reconfirmation, the docking is determined to be complete and subsequent operations such as workpiece transfer are performed. Conversely, if it is determined that they are not parallel, the control unit can correct the posture of the mobile robot (100) based on the distance value input from the distance measuring sensor (120) so that the side becomes parallel to the side wall of the docking target equipment (200). After that, when the marker recognition sensor (130) detects the marker (210) again, the control unit stops the movement of the mobile robot (100) and completes the docking.

[0034] Meanwhile, as shown in FIG. 6, when the movement of the mobile robot (100) is stopped, if it is determined that the distance between the side of the mobile robot (100) and the side wall of the docking target equipment (200) exceeds a preset reference value, the control unit can control the mobile robot (100) to move laterally toward the side wall of the docking target equipment (200).

[0035] In contrast, if the distance between the side of the mobile robot (100) and the side wall of the docking target equipment (200) is smaller than a preset reference value, that is, if it is determined that the side of the mobile robot (100) is excessively close to the side wall of the docking target equipment (200), the control unit may control the mobile robot (100) to move in the opposite direction to the side wall of the docking target equipment (200). During this lateral movement process, the side of the mobile robot (100) may not be parallel to the side wall of the docking target equipment (200). In such cases, the side of the mobile robot (100) can be maintained to be exactly parallel to the side wall of the docking target equipment (200) by repeatedly performing the parallelity reconfirmation step using the distance measuring sensor (120) and the attitude correction control process as described above.

[0036] Although not shown in the drawing, the distance value to the side wall of the docking target equipment (200) measured by a pair of distance measuring sensors (120) must always be the same for the mobile robot (100) to be parallel to the side wall of the docking target equipment (200). This is because a certain offset may exist depending on the installation position or sensitivity difference of the distance measuring sensors (120) or the error between the sensors, and the side wall of the docking target equipment (200) may not necessarily be completely flat or formed in a straight structure.

[0037] For example, there may be a side wall cover or other structure protruding from the docking point of the docking target equipment (200), and if docking alignment is to be performed based on such protruding structures, the measurement values ​​of each distance measuring sensor (120) may be set so that they are not identical. Accordingly, through a pre-set reference value or offset correction, the side of the mobile robot (100) and the side wall of the docking target equipment (200) can be determined and aligned so that they are substantially parallel.

[0038] Although embodiments of the present invention have been described above, those skilled in the art will be able to make various modifications without departing from the scope of the claims of the present invention. Explanation of the symbols

[0039] 100 : Mobile robot 110 : Main body 111: Driving wheels 112: Swivel wheel 120: Distance measuring sensor 130: Marker recognition sensor 140: Goods loading plate 200 : Docking target equipment 210 : Marker

Claims

Claim 1 A precision docking system for a mobile robot, comprising: a main body equipped with wheels capable of forward, backward, left, right, and / or rotational movement; a pair of distance measuring sensors mounted on the side of the main body at a predetermined distance apart and measuring the distance to the side wall of the docking target equipment; and a control unit provided on the main body and controlling the side of the main body to maintain parallelism with the side wall of the docking target equipment by comparing distance data measured by each of the pair of distance measuring sensors. Claim 2 A precision docking system for a mobile robot according to claim 1, wherein a marker is attached to the side wall of the docking target equipment, and the mobile robot further includes a marker recognition sensor mounted on the side of the main body to recognize the marker, and when the marker recognition sensor detects the marker, the control unit stops the forward and backward movement of the main body. Claim 3 A method for precisely stopping a mobile robot at a target position close to a docking target equipment, comprising: a step of driving the mobile robot toward the docking target equipment and, when approaching the docking target equipment, advancing it in a direction parallel to the side wall of the docking target equipment; a step of measuring the distance to the side wall of the docking target equipment through a pair of distance measuring sensors mounted on the side of the advancing mobile robot, and controlling the mobile robot based on the measured distance values ​​so that the side of the mobile robot is parallel to the side wall of the docking target equipment, thereby driving the mobile robot while maintaining the side of the mobile robot parallel to the side wall of the docking target equipment; and a step of stopping the forward and backward movement of the mobile robot when the mobile robot reaches a target position in front of the side wall of the docking target equipment. Claim 4 A precision docking method for a mobile robot according to claim 1, wherein the stopping step of the mobile robot includes the step of stopping the forward and backward movement of the mobile robot when a marker recognition sensor mounted on the side of the mobile robot detects a marker attached to the side wall of the docking target equipment. Claim 5 A mobile robot precision docking method according to claim 4, further comprising the step of moving the mobile robot laterally toward the side wall of the docking target equipment or moving it in the opposite direction when the distance between the side of the mobile robot and the side wall of the docking target equipment exceeds or falls short of a preset reference value.

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