Method for controlling an automated guide vehicle and system for such a vehicle

Abstract

A method of controlling an automated guided vehicle (AGV), the AGV including: a base; at least one drive wheel connected to the base, each drive wheel rotatable relative to the base about a drive axis to generate a traction force in a forward direction transverse to the drive axis; and a control system configured to control the AGV; wherein the method comprises: selecting a compliance direction on which the base should exhibit a compliance behavior; providing an AGV control program in the control system and based on the selected compliance direction, the AGV control program including program code that, when executed by the control system, causes the control system to control the AGV to be positioned in a stopped state such that a forward direction of each drive wheel is aligned with the compliance direction; and executing the AGV control program through the control system.

Description

Technical Field

[0001] This disclosure generally relates to automated guided vehicles (AGVs). Specifically, a method for controlling an AGV, the AGV itself, and a system including the AGV are provided. Background Technology

[0002] Automated Guided Vehicles (AGVs) are typically self-powered, self-propelled vehicles used to transport materials and other items from one location to another without the need for a driver. AGVs are commonly used in manufacturing sites, warehouses, post offices, libraries, ports, airports, and some hazardous locations and specialized industries. In some applications where AGVs are stationary in the workplace, it can be beneficial if a human user can temporarily move the AGVs to free up space when necessary.

[0003] JP 2011232815 A discloses a mobile robot comprising an upper body, a moving part, and differential drive wheels. Force sensors are used to detect the external force vector applied to the upper body. Mechanical resistance can be set based on the external force vector. Thus, a person can push the mobile robot by hand to move it.

[0004] The principle described in JP 2011232815 A requires continuous knowledge of the external force vector to set the mechanical resistance, thus it is a reactive control principle. Furthermore, when a person attempts to push the mobile robot, the robot must first detect the applied external force vector, then align the drive wheels with the force vector, and finally set the mechanical resistance of the drive wheels. Therefore, unless the person pushes (or pulls) the mobile robot in the direction of travel of the drive wheels, it takes a very long time for the mobile robot to conform to the pushing (or pulling) direction. During this time, the person may conclude that the mobile robot cannot be moved manually and stop pushing it. Summary of the Invention

[0005] One object of the present invention is to provide an improved method for controlling automated guided vehicles (AGVs).

[0006] Another object of the present invention is to provide an improved AGV.

[0007] Another object of the present invention is to provide an improved system including an AGV and a programming device.

[0008] Another object of the present invention is to provide an improved system including an AGV and a display device.

[0009] These objectives are achieved by the method according to appended claim 1, by the AGV according to appended claim 10, by the system according to claim 12, and by the system according to claim 13.

[0010] This invention is based on the understanding that by selecting a conformance direction in which the AGV's base should conform, and by providing an AGV control program that takes into account the selected conformance direction, active rather than passive conformance is provided, which improves safety and user experience.

[0011] According to a first aspect, a method for controlling an Automated Guided Vehicle (AGV) is provided, the AGV comprising: a base; at least one drive wheel connected to the base, each drive wheel being rotatable relative to the base about a drive axis to generate traction in a forward direction transverse to the drive axis; and a control system configured to control the AGV; wherein the method comprises: selecting a compliance direction in which the base should exhibit compliant behavior; providing an AGV control program in the control system and based on the selected compliance direction, the AGV control program including program code, when executed by the control system, causing the control system to position the AGV in a stopped state, aligning the forward direction of each drive wheel with the compliance direction, and causing the base to exhibit compliant behavior in the compliance direction; and executing the AGV control program via the control system.

[0012] This method provides the AGV with a selected compliant behavior. This selection can be made by a human user or automatically by the control system. If the user pushes the base in the compliant direction, the AGV will immediately move in that direction due to the compliant behavior exhibited by the base. Therefore, this method makes it easier for the user to manually move the AGV. As a result, this method improves the safety of the AGV in the environment.

[0013] This method also offers the advantage that the base can exhibit compliant behavior only in the compliant direction. In these cases, the AGV will move in the compliant direction even if the human user does not push the base exactly in that direction. Therefore, the AGV can be better integrated into complex environments, for example, to avoid collisions with any fragile obstacles when pushed by the user.

[0014] Because an AGV includes at least one drive wheel that can rotate about a drive axis to generate traction in the forward direction, the AGV does not have compliant behavior in a direction transverse to the forward direction. Therefore, the at least one drive wheel is different from, for example, a Swedish wheel. The compliant direction can be parallel to the plane that includes the drive axis and the forward direction of the at least one drive wheel.

[0015] When the AGV is stationary, the base is in a static position, for example, a fixed position in the global coordinate system. However, while the base is stationary, other components of the AGV may move. The AGV control program may also include program code that, when executed by the control system, causes the control system to control the AGV to move from a starting position to a target position, and then to position the AGV at the target position, aligning the forward direction of each drive wheel with the compliant direction, and causing the base to exhibit compliant behavior in the compliant direction. When the AGV moves from the starting position to the target position, the base moves from the starting position to the target position. Therefore, if the AGV is traveling on a horizontal ground surface, the target position can be horizontally at least 1 meter away from the starting position.

[0016] An AGV may include multiple wheels. Each wheel may contact a ground surface (such as a horizontal ground surface, such as a floor). The directional bearing may be parallel to that ground surface. One, some, or all of these wheels may be drive wheels. One, some, or none of these wheels may be non-drive wheels, such as swivel casters.

[0017] An AGV can be configured to perform omnidirectional motion of a base or a body attached to a base relative to the ground surface. Omnidirectional motion allows the base or body to move in three degrees of freedom: along the ground surface in any direction, and rotating in any direction about an axis transverse to the ground surface (such as a vertical axis). The base can be, for example, a platform.

[0018] The AGV may optionally include a manipulator. The manipulator can be a programmable robotic arm on three or more axes (such as six or seven axes). The manipulator can be supported on a base and can move relative to the base. The AGV can be, for example, an autonomous mobile robot (AMR) or an autonomous mobile manipulator robot (AMMR) including a manipulator. When the AGV including the manipulator is in a stopped state, the base is stationary, but the manipulator can move relative to the base.

[0019] An AGV may, for example, include at least one steerable drive wheel, i.e., it may also rotate relative to the base about a steering axis (e.g., about a vertical steering axis) that is transverse to both the drive axis and the direction of travel. For any position of the base, each steerable drive wheel can be positioned arbitrarily about its steering axis. This can be referred to as redundancy in the AGV. The first aspect of the method utilizes this redundancy by positioning each steerable drive wheel about its steering axis such that the direction of travel of each steerable drive wheel is aligned with the compliant direction, and such that the base exhibits compliant behavior in the compliant direction.

[0020] As another example, the AGV may include a differential drive comprising two drive wheels that are not rotatable relative to the base about a steering axis. In this case, the AGV may include a body attached to the base and arranged to rotate relative to the base about a vertical axis. Such a body may, for example, be the first link of a manipulator. For any position of the body, the base and drive wheels can be oriented arbitrarily in one or more planes parallel to the ground surface. This is another example of redundancy in the AGV. The approach of the first aspect utilizes this redundancy by driving the drive wheels to position the base such that the forward direction of each drive wheel is aligned with the compliant direction, and the base exhibits compliant behavior in the compliant direction.

[0021] The aligning direction can be selected in a global coordinate system where the AGV is configured to move or in a local coordinate system where it is fixed to the base.

[0022] Selecting the camber direction can include receiving camber selection input from a user via a programming device. Therefore, the camber direction can be set during AGV programming, such as when programming an AGV to perform tasks in the workplace. The camber selection input can be transmitted electrically (e.g., wirelessly or via signal cable) from the programming device to the control system.

[0023] Alternatively, the control system can be configured (e.g., based on a map of the environment in which the AGV will perform its tasks) to select a conforming direction or suggest a selection to the user. For example, if there is available free space next to the AGV, the control system can be configured to select a conforming direction toward that free space, or suggest a corresponding selection to the user, for example, via a programming device.

[0024] The direction selection input can include a selection indicating a linear compliance direction and / or a rotational compliance direction. If the compliance direction is linear, each forward direction can be parallel to the compliance direction. If the compliance direction is rotational, the compliance direction can be defined by a circle. In the latter case, each forward direction can be oriented transversely to the line between the center of the circle and the corresponding drive wheel, so that each forward direction is aligned with the compliance direction. If the AGV includes multiple steerable drive wheels, each drive wheel can be oriented such that its instantaneous center of rotation (ICR) coincides with the center of the circle.

[0025] The direction selection input can include the selection of position and / or orientation in the AGV's local coordinate system or in the AGV's global coordinate system, indicating the direction of orientation.

[0026] The method may also include selecting a mechanical impedance at which the base should exhibit compliant behavior. In these cases, AGV control programs can be provided based on the selected mechanical impedance. For a relatively low mechanical impedance, the base behaves more compliantly than for a second, relatively higher mechanical impedance, which is higher than the relatively low mechanical impedance. Therefore, the mechanical impedance is a measure of how much force the base resists in the compliant direction.

[0027] Selecting mechanical impedance may include receiving impedance selection input from a user via a programming device. The impedance selection input can be electrically (e.g., wirelessly or via a signal cable) transmitted from the programming device to the control system.

[0028] The method may also include providing a visual indication of the selected compliant direction via a display device. With this visual indication, the user can determine in which direction the base exhibits compliant behavior. This improves the user experience. The interaction between the user and the AGV is also enhanced, and the user will be more inclined to attempt to physically move the base in the compliant direction more frequently. This contributes to improved safety in the AGV's environment.

[0029] Furthermore, in some implementations, for example, for safety or aesthetic reasons, the AGV may include a skirt covering the drive wheels. In these cases, the user may not be able to see how each drive wheel is oriented, and the use of visual cues is particularly advantageous. However, in some other implementations, one or more drive wheels may be visible to the user, allowing the user to understand the orientation of the homing direction. Moreover, sometimes the choice of homing direction is clearly visible from the surrounding environment.

[0030] The display device can be included in the AGV. The display device can be attached, for example, to a base or its manipulator. Alternatively, the display device can be fixed in the global coordinate system in which the AGV moves, for example, attached to a stationary structure.

[0031] The display device may be a projector. In these cases, providing visual cues may include projecting a beam of light from the projector to provide visual cues. The beam of light may be projected, for example, onto a ground surface or a base. Alternatively, the display device may include a display screen configured to provide visual cues.

[0032] The method may also include position control or speed control of each drive wheel around its corresponding drive axis. In both cases, the base exhibits compliant behavior in the compliant direction.

[0033] According to a second aspect, an Automated Guided Vehicle (AGV) is provided, the AGV comprising: a base; at least one drive wheel connected to the base, each drive wheel being rotatable relative to the base about a drive axis to generate traction in a forward direction transverse to the drive axis; and a control system configured to control the AGV, the control system including at least one data processing device and at least one memory storing at least one computer program, the at least one computer program including program code, which, when executed by the at least one data processing device, causes the at least one data processing device to select or receive a selection of a compliance direction on which the base should exhibit compliant behavior; and providing an AGV control program based on the selected compliance direction, the AGV control program including program code, which, when executed by the at least one data processing device, causes the at least one data processing device to control the AGV to be positioned in a stopped state, such that the forward direction of each drive wheel is aligned with the compliance direction, and such that the base exhibits compliant behavior in the compliance direction. The AGV according to the second aspect can be any type combined with those mentioned in the first aspect, or vice versa.

[0034] AGVs may also include manipulators that are programmable on three or more axes and supported on a base.

[0035] According to a third aspect, a system is provided comprising an AGV according to a second aspect and a programming device configured to communicate signals with a control system and to receive a direction selection input from a user indicating a directional orientation. The signal communication can be wireless or via a signal cable. The programming device can be, for example, a teach pendant unit (TPU). The programming device according to the third aspect can be any type mentioned in combination with or without the first and second aspects.

[0036] According to a fourth aspect, a system is provided comprising an AGV according to a second aspect and a display device configured to provide visual indication of a selected homing direction. According to a third aspect, the display device can be any type mentioned in combination with any of the first to third aspects, or vice versa.

[0037] The display device can be a projector configured to project a beam of light to provide visual indication.

[0038] The systems according to the third and fourth aspects can be the same system. Each system according to the third and fourth aspects can be called an Automated Guided Vehicle (AGV) system. Attached Figure Description

[0039] Further details, advantages, and aspects of this disclosure will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0040] Figure 1 : A schematic side view of a system including AGVs and programming equipment;

[0041] Figure 2 : A schematic side view of the cross-section of the drive unit of an AGV;

[0042] Figure 3 A schematic top view, orientation, and visual indication of an AGV in a stopped state;

[0043] Figure 4 Another top view schematically showing the AGV in a stopped state;

[0044] Figure 5 : A schematic top view of an AGV and another example of its orientation;

[0045] Figure 6 : A schematic top view of an AGV and another example of its orientation;

[0046] Figure 7 : A schematic top view of an AGV and another example of its orientation;

[0047] Figure 8a This is a schematic example illustrating the selection of a programming device and coordinate system for input.

[0048] Figure 8b : An example illustrating a programming device and orientation selection input;

[0049] Figure 8c Other examples illustrating programming devices and orientation selection inputs;

[0050] Figure 8d Other examples illustrating programming devices and orientation selection inputs;

[0051] Figure 8e : A schematic representation of an example of a programming device and impedance selection input;

[0052] Figure 8f : An example illustrating programming devices and control type inputs;

[0053] Figure 9 : A cross-sectional side view schematically illustrating yet another example of an AGV drive unit;

[0054] Figure 10 : Indicatively indicates according to including Figure 9A top view of an AGV, another example of a drive unit;

[0055] Figure 11 : Indicatively indicates according to including Figure 2 A top view of another example of an AGV's drive unit; and

[0056] Figure 12 This is a flowchart outlining the general steps of the method. Detailed Implementation

[0057] The following will describe methods for controlling AGVs, AGVs themselves, and systems including AGVs. The same or similar reference numerals will be used to denote the same or similar structural features.

[0058] Figure 1 A schematic side view of system 10 is shown. System 10 includes an automated guided vehicle (AGV) 12a. Therefore, system 10 can be referred to as an AGV system. Figure 1 In this context, AGV 12a is positioned on a horizontal ground surface 14, which is illustrated here as a floor. Figure 1 The human user 16 is also shown next to the AGV 12a.

[0059] AGV 12a includes a base 18, which is illustrated herein as a platform. This example AGV 12a also includes a traction arrangement 20a. This example traction arrangement 20a includes a plurality of drive wheels 22a, here four drive wheels 22a (…). Figure 1 Only two drive wheels are visible in the image. Each drive wheel 22a is connected to the base 18. The AGV 12a may also include a power source (not shown) (such as a battery) to power the drive wheels 22a.

[0060] Figure 1 Local coordinate system 24-1 and global coordinate system 24-2 are also shown. In this example, local coordinate system 24-1 is fixed relative to base 18, and global coordinate system 24-2 is fixed relative to ground surface 14.

[0061] The AGV 12a of this example also includes a manipulator 26, which is illustrated herein as a serial robotic arm programmable on at least three axes. The manipulator 26 can be supported on a base 18 and can move relative to the base 18. The manipulator 26 of this example includes a plurality of links, including a first link 28. The first link 28 is rotatable relative to the base 18 about a vertical axis, as indicated by the corresponding arrow. The first link 28 is an example of a body according to this disclosure. The manipulator 26 of this example is a compliant manipulator, for example, including a power-limited motor so as not to have the ability to harm humans.

[0062] AGV 12a also includes an electronic control system 30 configured to control AGV 12a. The control system 30 in this example includes a data processing device 32 and a memory 34. A computer program is stored in the memory 34. The computer program includes program code that, when executed by the data processing device 32, causes the data processing device 32 to perform or command the execution of various steps as described herein. An AGV control program is also stored in the memory 34. When the AGV control program is executed, the AGV 12a is controlled to perform various tasks.

[0063] The base 18 in this example includes a skirt 36. (As...) Figure 1 As shown, the skirt 36 partially covers the drive wheel 22a. Therefore, the user 16 may not be able to see the corresponding orientation of the drive wheel 22a.

[0064] The system 10 in this example also includes a programming device 38, which is illustrated herein as a teach pendant unit (TPU). User 16 can use the programming device 38 to create and / or modify AGV control programs. In this example, the programming device 38 is configured to communicate wirelessly with the control system 30.

[0065] The system 10 in this example also includes a projector 40. The projector 40 is an example of a display device according to this disclosure. In this example, the projector 40 is fixed to the base 18, but it can also alternatively be positioned elsewhere, such as at a stationary position in global coordinate system 24-2. The projector 40 communicates signalingly with the control system 30. Figure 1 As shown, the projector 40 is configured to project a beam 42 to provide a visual indication 44, i.e., a projection in this example. The visual indication 44 is projected here by the projector 40 onto the ground surface 14. However, the visual indication 44 may alternatively be located elsewhere in the environment of the AGV 12a, such as on the base 18.

[0066] Figure 2 A cross-sectional view schematically illustrating a specific example of the drive unit 46a of the AGV 12a; Figure 2 Only a partial illustration of the AGV 12a is shown. Each drive unit 46a includes a drive wheel 22a and is connected to a base 18. This specific, non-limiting example of the AGV 12a includes four drive units 46a of the same design.

[0067] The drive unit 46a in this specific, non-limiting example also includes a driven steering member 48. The drive wheel 22a is rotatable about a drive axis 50 to generate traction in a forward direction transverse to the drive axis 50. The driven steering member 48 and the drive wheel 22a are rotatable about a steering axis 52. The drive axis 50 is perpendicular to the steering axis 52. Furthermore, the drive axis 50 intersects the steering axis 52. Figure 2 In this configuration, the drive axis 50 is horizontal and the steering axis 52 is vertical. The drive axis 50 provides the drive unit 46a with a first degree of freedom. The steering axis 52 provides the drive unit 46a with a second degree of freedom.

[0068] The drive unit 46a also includes an electric synchronous wheel motor 54. The wheel motor 54 is arranged to rotatably drive the drive wheel 22a about the drive axis 50. In this example, the wheel motor 54 is arranged to directly drive the drive wheel 22a, that is, there is no intermediate gearing between the wheel motor 54 and the drive wheel 22a.

[0069] The drive unit 46a also includes an electric synchronous steering motor 56. The steering motor 56 is arranged to rotatably drive the driven steering member 48 about the steering axis 52. The steering motor 56 and the wheel motor 54 can each provide, for example, a torque of at least 5 Nm. Therefore, the drive wheels 22a are steerable drive wheels. Since the AGV 12a in this example includes four drive wheels 22a, the AGV 12a can perform omnidirectional movement of the base 18.

[0070] The steering motor 56 is arranged to directly drive the driven steering member 48, that is, there is no intermediate gear device between the steering motor 56 and the driven steering member 48. Figure 2 The example of the driven steering member 48 includes a base portion 58 and two arm portions 60 extending downward from the base portion 58.

[0071] The drive unit 46a also includes a steering shaft 62 and two steering bearings 64 for rotatably supporting the driven steering member 48 about the steering axis 52. The steering shaft 62 is rigidly connected to the base 18 of the AGV 12a. The steering motor 56 includes a steering stator 66, a steering rotor 68, and a steering coil 70. The steering rotor 68 is disposed inside the base portion 58. The steering coil 70 is disposed on the steering stator 66. In this example, the base portion 58 is an integrated portion of the steering rotor 68.

[0072] The drive unit 46a also includes a steering sensor device 72. The steering sensor device 72 determines the rotational position of the driven steering member 48, and therefore also the rotational position of the drive wheel 22a about the steering axis 52. The steering sensor device 72 communicates with the control system 30. This example of the steering sensor device 72 includes an active portion (here composed of a Hall effect steering sensor 74) and a passive portion (here composed of a multi-pole steering encoder ring 76).

[0073] The drive unit 46a also includes a steering circuit board 78. A Hall effect steering sensor 74 is mounted on the steering circuit board 78. A steering encoder ring 76 is connected to the driven steering member 48.

[0074] The wheel motor 54 includes a wheel stator 80, a wheel rotor 82, and a wheel coil 84. The wheel stator 80 is arranged inside the drive wheel 22a. The wheel coil 84 is arranged on the wheel stator 80. The drive unit 46a also includes a wheel axle 86 and two wheel bearings 88 for rotatably supporting the drive wheel 22a about the drive axis 50. The wheel axle 86 is rigidly connected to the arm portion 60 of the driven steering member 48.

[0075] The drive unit 46a also includes a wheel sensor device 90. The wheel sensor device 90 may be of the same type as the steering sensor device 72. The wheel sensor device 90 determines the rotational position of the drive wheel 22a about the drive axis 50. The wheel sensor device 90 communicates with the control system 30. This example wheel sensor device 90 includes an active portion (here composed of a Hall effect wheel sensor 92) and a passive portion (here composed of a multi-pole wheel encoder ring 94).

[0076] The drive unit 46a also includes a wheel circuit board 96. A Hall effect wheel sensor 92 is mounted on the wheel circuit board 96. A wheel encoder ring 94 is connected to the drive wheel 22a.

[0077] Figure 3 A schematic top view of AGV 12a with the manipulator 26 omitted. Figure 3 In the current configuration, AGV 12a is stationary, and the forward direction 98 of each drive wheel 22a is aligned with a selected compliance direction 100a, causing the base 18 to exhibit compliant behavior in the compliance direction 100a. User 16 can thus push the base 18 to move AGV 12a along the ground surface 14 and away from its stationary position. The compliance direction 100a is the direction in which AGV 12a exhibits compliance when pushed or pulled by user 16. When AGV 12a is stationary, the manipulator 26 can move relative to the base 18 to perform tasks.

[0078] The conformance direction 100a can be selected by the user 16 or the control system 30. In either case, the AGV control program is provided by the control system 30, for example, created or updated based on the selected conformance direction 100a. The conformance direction 100a can be selected in any way within the horizontal plane.

[0079] In this example, position control is performed on each drive wheel 22a via control system 30. This gives each drive wheel 22a compliance in the forward direction 98. When position control is performed on each drive wheel 22a, a position control loop can be used, in which the measured drive wheel position of each drive wheel 22a (e.g., determined based on signals from the corresponding wheel sensor device 90) is fed back and compared with the corresponding target drive wheel position. For example, the gain of the position control loop can be varied to adjust the compliance of the drive wheel 22a in the forward direction 98. When the gain is set to a relatively low value, the compliance is relatively high. Conversely, when the gain is set to a relatively high value (higher than a relatively low value), the compliance is relatively low, i.e., less than a relatively high compliance. For example, the gain can also be increased proportionally with the increase of the error between the measured drive wheel position and the target drive wheel position. Thus, the base 18 will exhibit gradually increasing resistance when the user 16 manually applies force in the compliance direction 100a away from the stationary position.

[0080] Through position control, the base 18 acts as a spring when pushed away from the target position and returns to the target position when the thrust is released. Once the AGV 12a detects a deviation of the base 18 from the target position, for example based on a signal from the corresponding wheel sensor device 90, any operation performed by the manipulator 26 can be stopped. Once the AGV 12a returns to the target position, the manipulator 26 can resume its operation.

[0081] As an alternative, speed control can be applied to each drive wheel 22a. In this case, a speed control loop can be used, in which the measured drive wheel speed of each drive wheel 22a (e.g., determined based on signals from the wheel sensor device 90) is fed back and compared with a corresponding target drive wheel speed, which can be set to zero when the vehicle is stationary. For example, the gain of the speed control loop can be varied to adjust the compliance of the drive wheels 22a in the forward direction 98.

[0082] The position control loop and speed control loop mentioned above are well known to those skilled in the art. Each drive wheel 22a can be controlled such that a force of at least 30 N acting on the base 18 in the homing direction 100a will cause the base 18 to move.

[0083] If AGV 12a is occupying the work area and user 16 needs to quickly pick up an item on the ground surface 14 below AGV 12a, user 16 can easily push AGV 12a away in the directional direction 100a, pick up the item, and then stop pushing AGV 12a. When position control is applied to the drive wheel 22a, AGV 12a will return to its original position when user 16 stops pushing AGV 12a.

[0084] If the manipulator 26 is instead attached to a stationary structure and positioned close to the singularity, its inherent compliant behavior may be reduced, considering that, for example, a fully extended manipulator 26 may lose its ability to be compliant in the extension direction. However, when the manipulator 26 attached to the base 18 is pushed along the compliant direction 100a, the compliant behavior exhibited by the AGV 12a by aligning the forward direction 98 of each drive wheel 22a with the compliant direction 100a can be used to provide compliance to the manipulator 26 even when approaching the singularity.

[0085] Figure 3 An example of a visual indicator 44 is also shown. The visual indicator 44 is illustrated here as an arrow projected onto the ground surface 14 in the aligning direction 100a, thus indicating the aligning direction 100a. The control system 30 is configured to control the projector 40 to provide the visual indicator 44 corresponding to the selected aligning direction 100a.

[0086] Figure 4 A schematic top view of AGV 12a. Figure 4 In the middle, AGV 12a is in conjunction with Figure 3 It is in a stopped state in different positions. Figure 3 In the process, under the control of the AGV control program, the AGV 12a moves along a path from the starting position 102 to the target position 104 in the global coordinate system 24-2 by driving the drive wheel 22a. The distance between the starting position 102 and the target position 104 can be at least one meter. When the AGV 12a has stopped at the target position 104, the drive wheel 22a is controlled to be oriented so that the forward direction 98 is aligned with the homing direction 100a.

[0087] In this example, the conformation direction 100a is defined in the local coordinate system 24-1. Therefore, regardless of the orientation of the base 18 in the global coordinate system 24-2, the conformation direction 100a is the same in the local coordinate system 24-1 when the AGV 12a is already stopped at the target position 104.

[0088] Figure 5 A schematic top view of AGV 12a and another example in homing direction 100a are shown. Figure 5In the global coordinate system 24-2, the conforming direction 100a is defined. Therefore, regardless of the orientation of the base 18 in the global coordinate system 24-2, when the AGV 12a is already stopped at the target position 104, the conforming direction 100a is the same in the global coordinate system 24-2.

[0089] Figure 6 A schematic top view of AGV 12a and another example of the aligning direction 100b are shown. In this example, the aligning direction 100b is a circle. As shown, each drive wheel 22a is oriented here such that the forward direction 98 is aligned with the circle of the aligning direction 100b. Therefore, each forward direction 98 is oriented transversely to a line between the center of the circle and the corresponding drive wheel 22a.

[0090] Visual indicator 44 is now projected as a corresponding circle to indicate to user 16 that aligning direction 100b is circular. One or both aligning directions 100a and 100b may also be referred to using the reference numeral "100".

[0091] Figure 7 A schematic top view of AGV 12a and another example of homing direction 100b are shown. Figure 7 In this configuration, the compliant direction 100b is circular and centered outside the base 18. As shown, each drive wheel 22a is oriented such that its instantaneous rotation center (ICR) 106 is centered on the circle of the compliant direction 100b. That is, the drive axes 50 of all drive wheels 22a coincide at ICR 106. Furthermore, the base 18 thus exhibits compliant behavior in the compliant direction 100b. The visual indication 44 of this example is now projected as a frame and a circle, where the frame represents the base 18 and the circle represents the compliant direction 100b and its relationship to the base 18.

[0092] Figure 8a Programming device 38 is schematically represented. This example programming device 38 includes a display 108. Programming device 38 is configured to provide various user interfaces on display 108 through which user 16 can set the conformity orientation 100 and its various characteristics.

[0093] exist Figure 8a In this configuration, programming device 38 displays a dialog box 110a on display 108, allowing user 16 to provide the display 108 with a choice regarding whether the conformal direction 100 should be defined in local coordinate system 24-1 or global coordinate system 24-2. User 16 can provide a first coordinate system selection input 112a to select local coordinate system 24-1 and a second coordinate system selection input 112b to select global coordinate system 24-2.

[0094] Figure 8b The programming device 38, schematically illustrating another example of a dialog box 110b displayed on a monitor 108, allows the user 16 to provide the monitor 108 with a choice regarding whether the conformation direction should be linear conformation direction 100a or circular conformation direction 100b. The user 16 can provide a first direction selection input 114a to select linear conformation direction 100a and a second direction selection input 114b to select circular conformation direction 100b.

[0095] Figure 8c The programming device 38 is illustrated when another example of dialog box 110c is displayed on monitor 108. Figure 8c In this example, assume user 16 has selected a linear conformance direction 100a, and this conformance direction 100a should be defined in global coordinate system 24-2. In response to dialog box 110c, user 16 can provide a third direction selection input 114c and a fourth direction selection input 114d to define the direction of conformance direction 100a in global coordinate system 24-2. In this example, the third direction selection input 114c is a value in the X2 direction of global coordinate system 24-2, and the fourth direction selection input 114d is a value in the Y2 direction of global coordinate system 24-2. As illustrated, by entering a value "0" as the third direction selection input 114c and a value "1" as the fourth direction selection input 114d, conformance direction 100a can be defined as parallel to the Y2 direction.

[0096] Figure 8d The illustration schematically shows the programming device 38 when another example of dialog box 110d is shown on display 108. Figure 8d In this example, assume user 16 has selected a circular alignment direction 100b, and this alignment direction 100b should be defined in local coordinate system 24-1. In response to dialog box 110d, user 16 can provide a fifth direction selection input 114e and a sixth direction selection input 114f to define the position of the circle in alignment direction 100b in local coordinate system 24-1, which is also ICR 106. In this example, the fifth direction selection input 114e is a value in the X1 direction of local coordinate system 24-1, and the sixth direction selection input 114f is a value in the Y1 direction of local coordinate system 24-1. As illustrated, by entering the value "-50" as the fifth direction selection input 114e and the value "50" as the sixth direction selection input 114f, the position of ICR 106 in local coordinate system 24-1 is defined by vector 116. If the circle is selected to align with direction 100b, user 16 can also provide a direction selection input (not shown) to select the radius of the circle aligning with direction 100b.

[0097] Figure 8eThe programming device 38 is illustrated when another example of dialog box 110e is shown on display 108. In response to dialog box 110e, user 16 can provide impedance selection input 118 as a selection of mechanical impedance at which base 18 should exhibit compliant behavior. Low mechanical impedance provides high compliance of base 18, and vice versa. Alternatively, the mechanical impedance can be automatically selected by control system 30.

[0098] Figure 8f The programming device 38 is schematically shown when another example of dialog box 110f is displayed on display 108. In response to dialog box 110f, user 16 can provide a first control type input 120a to select position control 122 of drive wheel 22a, and provide a second control type input 120b to select speed control 124 of drive wheel 22a.

[0099] One, several, or all of the coordinate system selection inputs 112a and 112b, direction selection inputs 114a-114f, impedance selection input 118, and control type inputs 120a and 120b can be transmitted from the programming device 38 to the control system 30. Before providing any of these inputs, the user 16 can, for example, consider environmental space constraints, human movement patterns, and / or a simulation of the environment of the AGV 12a (such as in RobotStudio®) to select characteristics of appropriate compliant behavior for the compliant direction 100 and / or the base 18. Alternatively, the control system 30 can automatically select characteristics of appropriate compliant behavior for the compliant direction 100 and the base 18. In any case, after selecting the compliant direction 100, an AGV control program is provided in the control system 30 based on the selected compliant direction 100 and its associated characteristics, for example, through a computer program therein. The AGV control program may include movement instructions to move AGV 12a from starting position 102 to target position 104, bring AGV 12a to a stop at target position 104, and then control drive wheel 22a such that while AGV 12a is stopped at target position 104, forward direction 98 becomes aligned with compliant direction 100. User 16 may later modify the compliant direction 100 and / or the compliant behavior characteristics of base 18 via programming device 38.

[0100] Figure 9 A schematic cross-sectional side view of another example of drive unit 46b is shown. The differences between drive unit 46b and drive unit 46a will be primarily described. Drive unit 46b includes drive wheel 22b, but not drive wheel 22a. Drive unit 46b does not include steering motor 56. Instead, arm portion 60 is fixed to base 18. Therefore, drive wheel 22b can only rotate about drive axis 50, and not about steering axis 52.

[0101] Figure 10 A schematic top view of AGV 12b according to yet another example is shown. The differences between AGV 12a and AGV 12b will be mainly described. AGV 12b includes a traction arrangement 20b. The traction arrangement 20b includes two drive units 46b. Therefore, the traction arrangement 20b of this example is a differential drive. The traction arrangement 20b of this example also includes two swivel casters 126.

[0102] exist Figure 10 In this configuration, each drive wheel 22b is positioned about its respective drive axis 50. Consequently, the base 18 exhibits compliant behavior in both the linear compliant direction 100a and the circular compliant direction 100b. The projector 40 provides corresponding visual indications 44 on the ground surface 14.

[0103] Figure 10 The manipulator 26 is omitted in the illustration. However, due to the ability of the first link 28 to rotate relative to the base 18, the AGV 12b can perform omnidirectional movement of the first link 28 relative to the ground surface 14.

[0104] Figure 11 A schematic top view of AGV 12c according to yet another example is shown. The differences between AGV 12c and AGV 12a will be mainly described. AGV 12c includes a traction arrangement 20c. The traction arrangement 20c in this example includes a single drive wheel 22a and two swivel casters 126. Therefore, the base 18 is compliant in the forward direction 98 of the drive wheel 22a. The projector 40 provides corresponding visual indications 44 on the ground surface 14.

[0105] Figure 12 This is a flowchart outlining the general steps of the method. The method includes: selecting S10 compliant directions 100a and 100b, such that the base 18 should exhibit compliant behavior in compliant directions 100a and 100b. The method also includes: providing S22 an AGV control program in the control system 30 and based on the selected compliant directions 100a and 100b, the AGV control program including program code that, when executed by the control system 30, causes the control system 30 to position AGVs 12a-12c in a stopped state, aligns the forward direction 98 of each drive wheel 22a and 22b with compliant directions 100a and 100b, and causes the base 18 to exhibit compliant behavior in compliant directions 100a and 100b. The method further includes: executing S24 an AGV control program via the control system 30.

[0106] Selecting S10 compliant directions 100a and 100b may include receiving S12 direction selection inputs 114a-114f from user 16 via programming device 38. Alternatively, selecting compliant directions 100a and 100b may include automatically selecting S14 compliant directions 100a and 100b via control system 30.

[0107] The method may further include: selecting a mechanical impedance under which the S16 base 18 should exhibit compliant behavior, wherein the S22 AGV control program is provided based on the selected mechanical impedance. Selecting the S16 mechanical impedance may include: receiving an S18 impedance selection input 118 from the user 16 via a programming device 38. Alternatively, selecting the S16 mechanical impedance may include: automatically selecting the S20 mechanical impedance via a control system 30.

[0108] The execution of the AGV control program S24 may also include: providing visual indications 44 via a display device to select the compliant directions 100a and 100b.

[0109] The execution of the AGV control program S24 may also include: position control S28 or speed control S30 for each drive wheel 22a and 22b around the corresponding drive axis 50.

[0110] Although this disclosure has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to what has been described above. For example, it should be understood that the dimensions of the various parts may vary as needed. Therefore, the invention is intended to be limited only by the scope of the appended claims.

Claims

1. A method for controlling automated guided vehicles (AGVs) (12a-12c), said AGVs (12a-12c) comprising: -Base (18); - At least one drive wheel (22a; 22b) is connected to the base (18), each drive wheel (22a; 22b) being rotatable relative to the base (18) about a drive axis (50) to generate a traction force in a forward direction (98) transverse to the drive axis (50); as well as - Control system (30), the control system (30) is configured to control the AGV (12a-12c); The method includes: - Select (S10) compliant direction (100a, 100b), the base (18) should exhibit compliant behavior in the compliant direction (100a, 100b); - In the control system (30) and based on the selected compliant direction (100a, 100b), an AGV control program (S22) is provided, the AGV control program including program code that, when executed by the control system (30), causes the control system (30) to control the AGV (12a-12c) to be placed in a stopped state, such that the forward direction (98) of each drive wheel (22a; 22b) is aligned with the compliant direction (100a, 100b), and causes the base (18) to exhibit the compliant behavior in the compliant direction (100a, 100b); as well as - The AGV control program is executed (S24) by the control system (30).

2. The method according to claim 1, wherein the selection (S10) of the conforming direction (100a, 100b) comprises: The programming device (38) receives (S12) directional selection inputs (114a-114f) from the user (16).

3. The method of claim 2, wherein the direction selection input (114a, 114b) includes selection of a linear compliance direction (100a) and / or a rotational compliance direction (100b).

4. The method according to claim 2 or 3, wherein the direction selection input (114c-114f) includes a selection indicating the position and / or orientation of the conforming directions (100a, 100b) in the local coordinate system (24-1) of the AGV (12a-12c) or in the global coordinate system (24-2) of the AGV (12a-12c).

5. The method according to any one of the preceding claims further comprises: The selection (S16) of the base (18) should exhibit the mechanical resistance of the compliant behavior, wherein the provision (S22) of the AGV control program is made based on the selected mechanical resistance.

6. The method of claim 5, wherein the selection (S16) of the provision (S22) of the mechanical impedance comprises: The impedance selection input (118) is received (S18) from the user (16) by the programming device (38).

7. The method according to any one of the preceding claims further comprises: The display device (40) provides (S26) a visual indication (44) indicating the selected conformation direction (100a, 100b).

8. The method of claim 7, wherein the display device (40) is a projector, and wherein the provision (S26) of the visual indication (44) comprises: The projector projects a beam of light (42) to provide the visual indication (44).

9. The method according to any one of the preceding claims further comprises: Position control (S28) or speed control (S30) is performed on each drive wheel (22a; 22b) around the corresponding drive axis (50).

10. An Automated Guided Vehicle (AGV) (12a-12c), said AGV (12a-12c) comprising: -Base (18); - At least one drive wheel (22a; 22b) is connected to the base (18), each drive wheel (22a; 22b) being rotatable relative to the base (18) about a drive axis (50) to generate a traction force in a forward direction (98) transverse to the drive axis (50); as well as - A control system (300) configured to control the AGVs (12a-12c), the control system (30) including at least one data processing device (32) and at least one memory (34), the at least one memory (34) storing at least one computer program, the at least one computer program including program code, the program code, when executed by the at least one data processing device (32), causing the at least one data processing device (32) to: - Select or receive a selection of the compliant direction (100a, 100b), wherein the base (18) shall exhibit compliant behavior in the compliant direction (100a, 100b); as well as - An AGV control program is provided based on the selected compliant direction (100a, 100b), the AGV control program including program code, which, when executed by the at least one data processing device (32), causes the at least one data processing device (32) to control the AGV (12a-12c) to be placed in a stopped state, such that the forward direction (98) of each drive wheel (22a; 22b) is aligned with the compliant direction (100a, 100b), and the base (18) exhibits the compliant behavior in the compliant direction (100a, 100b).

11. The AGV (12a-12c) according to claim 10 further includes a manipulator (26) that is programmable on three or more axes and is supported on the base (18).

12. A system (10) comprising an AGV (12a-12c) according to claim 10 or 11 and a programming device (38) configured to communicate with the control system (30) and configured to receive a direction selection input (114a-114f) from a user (16) indicating the compliant direction (100a, 100b).

13. A system (10) comprising an AGV (12a-12c) according to claim 10 or 11 and a display device (40) configured to provide a visual indication (44) indicating the selected compliant direction (100a, 100b).

14. The system (10) of claim 13, wherein the display device (40) is a projector configured to project a beam of light (42) to provide the visual indication (44).

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