WO2023004490A1

WO2023004490A1 - Mobility system for railed facilities

Info

Publication number: WO2023004490A1
Application number: PCT/CA2022/000042
Authority: WO
Inventors: Farhang BIDRAM; Patrick MEGAN
Original assignee: Advanced Intelligent Systems Inc.
Priority date: 2021-07-29
Filing date: 2022-07-22
Publication date: 2023-02-02

Abstract

A holonomic pipe rail transfer system is disclosed, which allows for a robot to transition from traveling on ground with holonomic motion to traveling on parallel rails with linear motion and vice-versa. In an aspect, a ground vehicle apparatus including at least four independently actuated omnidirectional wheels, a plurality of rail rollers and a plurality of actuators is provided. Each actuator is configured to independently drive one of the omnidirectional wheels and a corresponding rail roller co-axially coupled to the omnidirectional wheel. In another aspect, a method for transferring a ground vehicle apparatus to a rail system is provided, in which a controller detects a rail system and generates commands to holonomically drive the ground vehicle apparatus towards the detected rail system using a primary drive and engage an auxiliary drive, coupled to the primary drive, with the detected rail system.

Description

MOBILITY SYSTEM FOR RAILED FACILITIES

RELATED APPLICATIONS

This application claims the benefit of United States Provisional Patent Application No. 63/227,283 entitled "Holonomic Pipe Rail Transfer System", filed on July 29, 2021 and incorporated herein by reference in its entirety. This application also claims the benefit of United States Provisional Patent Application No. 63/330,198 entitled "Mobility System for Railed Facilities", filed on April 12, 2022 and incorporated herein by reference in its entirety.

BACKGROUND

1. Field

This disclosure relates generally to mobility systems for autonomous ground vehicles, and more specifically autonomous vehicles configured to move both along flat surfaces and on rails.

2. Description of Related Art

Many facilities such as greenhouse nurseries are equipped with parallel pipe rail systems for facilitating access by vehicular tools, such as autonomous robots or manually operated lifts, to different articles such as plants within a growing or harvesting area. In case of autonomous mobile robots, typically, the rails only allow for autonomous travel along said rails, requiring operator input to transition from one set of rails to the next due to limitations of the mobility systems, which may slow down processes within a greenhouse and require manpower.

SUMMARY

A holonomic pipe rail transfer system is provided, which allows for a robot to transition from traveling on ground with holonomic motion to traveling on parallel rails with linear motion and vice-versa. This allows the robot to rapidly transition from a set of parallel rails to the next with shortest transition paths and minimum transition time. In applications where there are rows of parallel rails side by side, a robot is able to move laterally or diagonally to transition from one set of rails to the next.

In accordance with one disclosed aspect, there is provided a ground vehicle apparatus. The ground vehicle apparatus includes: a primary drive for holonomic travel along a surface, comprising at least four independently actuated omnidirectional wheels; an auxiliary drive coupled to the primary drive for constrained travel along a rail system, the auxiliary drive comprising a plurality of rail rollers, each rail roller co-axially coupled to one of the omnidirectional wheels; a plurality of actuators coupled to the primary drive, each actuator coupled to one of the omnidirectional wheels and configured to independently drive the omnidirectional wheel and the corresponding rail roller coupled to the omnidirectional wheel; and a controller configured to selectively control the plurality of actuators to holonomically drive the primary drive along the surface and to drive the auxiliary drive along the rail system.

The omnidirectional wheels may each comprise a mecanum wheel.

The ground vehicle apparatus may further comprise a protector configured to prevent entanglement of objects with an omnidirectional wheel from the at least four independently actuated omnidirectional wheels.

The protector may comprise a wheel cover configured to cover cavities in the independently actuated omnidirectional wheel. The wheel cover may be integrated in a wheel frame, in which the wheel frame pivotally holds the omnidirectional wheel.

The protector may comprise one or more of a brush and a blower. The protector may be configured to push the objects away from the omnidirectional wheel.

The ground vehicle apparatus may further comprise a serrated insert configured to cut objects entangled on the ground vehicle apparatus.

The ground vehicle apparatus may also have a guide device for aligning the auxiliary drive with the rail system.

The ground vehicle apparatus may further comprise a sensor configured to generate data regarding the rail system, and wherein the controller processes the data to detect the rail system. The sensor may be a vision- based sensor configured to capture images from the rail system. The controller may be configured to, in response to the detection of the rail system, generate commands signals to transfer the ground vehicle apparatus to the detected rail system.

In accordance with another disclosed aspect, there is provided a method for transferring a ground vehicle apparatus to a rail system, the method comprising: detecting the rail system using a controller of the ground vehicle apparatus, wherein the controller is operatively coupled to a sensor and is configured to obtain data regarding the rail system from the sensor; in response to detecting the rail system, generating first command signals, by the controller, to holonomically drive the ground vehicle apparatus toward the detected rail system along a surface using a primary drive of the ground vehicle apparatus; and causing the controller to generate second command signals to drive the primary drive to the detected rail system and to engage an auxiliary drive, coupled to the primary drive, to transfer the ground vehicle apparatus to the detected rail system.

In the disclosed method, detecting the rail system may comprise calculating a position and an alignment of the rail system with respect to the ground vehicle apparatus.

The sensor may comprise a vision-based sensor configured to take vision-based images of the rail system.

The method may also involve receiving, by the controller, signals from a rail presence sensor indicating the ground vehicle has transferred to the rail system, and generating third command signals, by the controller, to move the ground vehicle apparatus on the rail system by driving the auxiliary drive.

The method may also involve transmitting the first command signals to the primary drive and transmitting the second command signals to the auxiliary drive.

In another aspect, a memory is provided. The memory stores program codes which, when executed by a microprocessor, cause the microprocessor to perform any of the methods described herein.

Other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific disclosed embodiments in conjunction with the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the present disclosure will be described with reference to the appended drawings. However, various embodiments of the present disclosure are not limited to the arrangements shown in the drawings.

Fig. 1A is a front view of a mobile robot having a holonomic pipe rail transfer system;

Fig. IB is a bottom view of the mobile robot having shown in Fig. 1A;

Fig. 2 is a perspective view of the mobile robot of Fig. 1A transferring from a flat surface to a pipe rail system;

Fig. 3 is a schematic block diagram showing an embodiment of a controller of the holonomic pipe rail transfer system of Fig. 1A;

Fig 4A - Fig 4E are a series of top views from the mobile robot of Fig. 1A;

Fig. 5A - Fig. 5E are a series of views of omnidirectional wheels used in the from the mobile robot of Fig. 1A; and

Fig. 6 is a plan view of a portion of a greenhouse showing the mobile robot of Fig. 1A navigating between pipe rails.

DETAILED DESCRIPTION

Referring to Fig. 1A, a mobile robot having a holonomic pipe rail transfer system is shown generally at 10 from a front view. The mobile robot 10 may also be referred to as a ground vehicle or a ground vehicle apparatus, for example. The mobile robot 10 comprises a chassis 110 having a holonomic pipe rail transfer system 100. The holonomic pipe rail transfer system 100 comprises a holonomic wheel apparatus 102, shown in Fig. 1A as a mecanum wheel, but may be any other method of achieving holonomic motion control over a flat surface, such as another type of omnidirectional wheel, for example. A holonomic wheel system provides controlled movement in all possible degrees of freedom of the 2-dimentional planar space of a ground mobile robot, such as mobile robot 10. Holonomic wheel apparatus 102 facilitates navigating the mobile robot 10 to a target position with a target orientation with a simple motion planning and with the shortest path possible.

The holonomic pipe rail transfer system 100 also comprises a rail travel system 104, shown in Fig. 1 as a face- mounted flanged wheel, for riding on a rail system 120, shown in Fig. 1 as a pipe rail system commonly found in greenhouse nurseries. The face-mounted flanged wheel shown in Fig. 1 is an example of a rail roller, and in general, the rail travel system 104 may comprise any suitable rail roller. It is contemplated that the holonomic pipe rail transfer system 100 may be suitable for transferring onto other types of rail systems.

The holonomic wheel apparatuses 102 may form a primary drive, also referred to as a primary wheel system, for holonomic travel of the mobile robot10 along a surface. The rail travel systems104 may form an auxiliary drive, coupled to the primary drive, for constrained travel along the rail system 120. The auxiliary drive may also be referred to as an auxiliary wheel system. The holonomic wheel apparatuses 102 and the rail travel systems 104 may collectively be referred to as the wheel systems 102,104.

As shown in Fig. IB, each holonomic wheel apparatus 102 is driven using an independent wheel actuator 160 through a shaft162, thus requiring the mobile robot10 to have at least four wheel actuators 160 to drive the mobile robot 10 in various directions. Each holonomic wheel apparatus 102 may thus comprise an independently actuated, or actuatable, omnidirectional wheel. In some embodiments the actuator 160 may be directly coupled to the wheel apparatus 102 and have the same axis of rotation, however in other embodiments the actuator 160 axis may be different from the wheel apparatus 102 axis of rotation and coupled to the shaft 162 through a chain, belt, gear system, or any other means of torque transmission.

In particular embodiments, each holonomic wheel apparatus 102 and each rail travel system 104 are co axially coupled together and share a common actuator 160 in order to be driven. This arrangement reduces the total number of wheel actuators 160 in the mobile robot 10 and also saves space in the chassis 110.

Another important advantage is that each rail travel system 104 is driven independently which provides enhanced controllability for the mobile robot 10 movement on the rail system 120. For example, referring to Fig. 2, if there are uneven conditions on one side of a rail 120A compared to other side 120B, the independently driven rail travel system 104 may be configured to compensate for the unevenness. For example, the drive of the rail travel system 104 on rail 120B may be adjusted, such as by reducing the speed, to compensate or slippage of the rail travel system 104 on rail 120A happens due to wetness. This may avoid deviation of the robot 10 on the rail system 120 and reduce the risk of the robot 10 falling off the rail system 120. Moreover, in cases where the rail system 120 is not geometrically even, such as when rails 120A and 120B have bumps or deviations, the separately driven rail travel system 104 can be used to adjust the movement of the robot 10 on the rail system 120 by independently adjusting the speed of each rail travel system 104.

Other benefits of this arrangement include using common peripheral components and subassemblies, such as a wheel suspension system and/or a brake system, for both the wheel apparatus 102 and the rail travel system 104. Using common components may reduce the overall complexity and cost of the mobile robot 10 and increase its reliability. However, in some embodiments, the drive of the holonomic wheel apparatus 102 may be different from the drive of the rail travel system 104 to facilitate independent actuation of each wheel apparatus 102 and rail travel system 104. In some embodiments, the suspension of each pipe rail transfer system 100 may be independent, such that each pipe rail transfer system 100 can be adjusted. This allows for accommodating bumps in the ground and/or the rail.

Each holonomic wheel apparatus 102 may be directly co-axially coupled to its respective rail travel system 104. Alternatively, each holonomic wheel apparatus102 may be indirectly co-axially coupled to its respective rail travel system 104. For example, each holonomic wheel apparatus 102 may be co-axially coupled to its respective rail travel system 104 via their respective common actuator 160. Thus, for example, the common actuator 160 may be between the holonomic wheel apparatus 102 and the rail travel system 104.

As shown in Fig. 2, the mobile robot 10 is capable of holonomic movement along a surface 130 in a longitudinal direction 200, a lateral direction 201, and any direction in between, and can seamlessly transition to traveling longitudinally 200 along the rail system 120 through use of the holonomic pipe rail transfer system 100. The holonomic wheel apparatus 102 drives the mobile robot 10 on the surface 130 until the rail travel system 104 engages with the rail system 120. Then, the traction between rail travel system 104 and the rail system 120 can drive the mobile robot 10 on the rail.

The holonomic pipe rail transfer system 100 may additionally comprise a bumper guide 106. The bumper guide 106 may alternatively be referred to as a guide device. The bumper guide 106 is shaped to receive a loading end 122 of the rail system 120. The bumper guide106 may allow a greater lateral positional deviation and/or a greater angle between the chassis 110 and the rail system 120, for example, facilitating a more efficient transfer. The inner sides of the bumper guide 106, where the bumper guide may come in contact with the rail system 120, may comprise one or more rollers (not shown) to reduce the friction between the bumper guide 106 and the rail system 120 and facilitate a smoother transition and travel of the mobile robot 10 on the rail system 120. In some embodiments, the mobile robot 10 may have a second bumper guide 106 on the opposite end of the robot 10 of the first bumper guide 106 to allow bi-directional loading onto the rail system 120.

The mobile robot 10 may further include a controller or a controller box 140 configured to control the drive of the wheel systems 102 and 104. The controller may include a single or a plurality of microprocessors and drivers onboard the robot 10. The controller may be configured to facilitate autonomous movement and navigation of the mobile robot 10 in an environment by sending command signals to the drivers of the wheel systems 102 and 104. The command signals may be generated by using and processing the data received at the controller 140 from sensory signals. Other input signals such as operator instructions may be used to generate the drive commands for the wheel systems.

The mobile robot 10 may further include a rail detection sensor 150 configured to acquire data about the rails. The rail detection sensor 150 may be an optical camera, a sonar sensor, an IR sensor, a thermal camera, or any other sensor that can provide data about the rails. In particular embodiments, the rail detection system 150 comprises vision-based sensors, such as an RGB camera and/or an RGBD camera, configured to take live images of the rail 120 to allow visual detection of the rails reliably and without any need to use external artificial landmarks. For example, radio frequency identification(RFID) -based or barcode-based rail detection systems require artificial landmarks and additional layers of infrastructure which are not preferred. Additionally, unlike artificial landmarks, direct visual detection can provide data about the position and angle of attach of the rail 120 dynamically while being able to update the rail 120 position data relative to the robot 10 as the mobile robot 10 is moving. The rail detection system 150 may, in general, comprise one or more vision-based sensors.

Also, proximity-based sensors such as magnetic, IR, or sonar sensors rely on qualitative rail detection and are more likely to encounter false-positive rail detections or inaccurate rail adjustment or alignment which may result in improper mounting on the rail, for example, and thus are not ideal. The data acquired by the rail detection sensor 150 may be used by the controller 140 to detect the location of the rail and generate commands for the wheels of the holonomic pipe rail transfer system 100 to navigate and transfer to the rail system 120.

Referring to Fig. 3, a block diagram for the controller 140 is shown according to one embodiment. The controller 140 may be implemented using an embedded processor circuit such as a Microsoft Windows^® industrial PC which may also be an on-board central processing unit of the mobile robot 10. In other embodiments, some or all of the functionality of the controller 140 may be performed by an external controller, such as a local server or a cloud server in communication with the mobile robot 10. The mobile device 10 may be provided with a local controller for communicating with the external controller. For example, the local controller may control the drive of the holonomic wheel apparatuses 102 and the rail travel systems 104 based on command signals received from the external controller. The local controller may send sensory signals to the external controller for use in generating the command signals.

Referring to Fig. 3, the controller 140 includes a microprocessor 342, a memory 380, and an input output (I/O) 343, all of which are in communication with the microprocessor 342. The I/O 343 includes a wireless interface 356 (such as an IEEE 802.11 interface) for wirelessly receiving and transmitting data communication signals between the controller 140 and a remote network 360 such as a cloud server. The I/O 343 also includes a wired network interface 152 (such as an Ethernet interface) for connecting to a sensor suite 350.

The sensor suite 350 may include the rail detention sensor 150. The sensor suite 350 may also include other sensors. For example, the sensor suite 350 may also comprise a localizer, such as a global navigation satellite system (e.g., GPS) or LiDAR sensor configured to detect the position of the mobile robot within the greenhouse.

The I/O 343 also includes an interface 354, such as a USB interface, for connecting to a digital to analog converter (DAC) 348. The DAC 348 includes a plurality of ports for receiving analog signals and converting the analog signals into digital data representing the signals and/or producing analog control signals. In the embodiment shown the DAC 348 includes a port 370 for producing control signals for controlling the actuators 160 and driving the wheel apparatus 102 and the rail travel system 104 of the holonomic pipe rail transfer system 100 for moving and steering the mobile robot 10. Program codes for directing the microprocessor 342 to carry out various functions are stored in a location 382 of the memory 380, which may be implemented as a flash memory, for example. The program codes 382 direct the microprocessor 342 to implement an operating system (such as Microsoft Windows for example) and to perform various other system functions associated with operation of the mobile robot 10. The memory 380 also includes variable storage locations 384 for storing variable and parameter data associated with operation of the mobile robot 10, such as a control criterion for steering the holonomic pipe rail transfer system 100. The controller 140 may send signals to the wheel drives according to manual commands provided by an operator of the mobile robot 10, automatically generated commands for example using artificial intelligence algorithms provided on the program codes 382, or a combination thereof.

In one embodiment, the controller 140 obtains data, such as visual camera data, regarding the rail system 120, from the rail detection sensor 150, and processes the data using the microprocessor 342 to detect the presence and location of the rail system 120 with respect to the mobile robot 10. The orientation between the detected rail and the mobile robot 10 may be calculated as well. The controller 140 may obtain the orientation by using Principal Component Analysis (PCA) algorithms or machine learning algorithms, for example, stored in the program codes 382 in the memory 380. Accordingly, the microprocessor 342 may generate command signals according to an action plan stored in the memory 380. For example, the generated command signals may be commands for the wheel drivers of the holonomic pipe rail transfer system 100 to navigate to the nearest detected rail and align the mobile robot 10 with the rail for proper transfer and mounting to the rail with certain speed. Due to the holonomic wheel apparatus 102, the mobile robot 10 can be driven to a target location and orientation with variety of convenient motion planning options and through the shortest paths possible.

To enable holonomic movement for the mobile robot 10, different types of omni-directional wheels, such as different types of mecanum wheels, with different configurations such as X and 3-wheel configurations may be use. However, in particular embodiments of this disclosure, 4 omnidirectional wheels are used and driven as shown by the top views in Figured4A to4E. In Fig. 4A to Fig.4E, the omnidirectional wheels are mecanum wheels, but in general they may be any type of omnidirectional wheels. In Fig. 4A to Fig. 4E, a series of exemplary top views from the mobile robot 10, show examples of wheel drive direction 170 of each holonomic wheel apparatus 102 to arrive at a robot movement direction 172 for the mobile robot 10. For example, referring to Fig. 4A, driving each wheel apparatus 102 in the same wheel drive direction 170 with the same speed, results in the robot 10 to move in direction X. Referring to Fig. 4B, driving the wheel apparatuses 102BL (wheel at back left) and 102FR (wheel at front right) in drive direction 170B (backward) while driving wheel apparatuses 102FL and 102BR in drive direction 170F (forward) will result in sideways robot movement direction along Y axis.

Referring to Fig. 4C, driving two diagonal wheels, such as wheels 102BL and 102FR, in the same direction, such as direction 170F, while not driving the other diagonal wheels, will result in a diagonal movement of the robot.

Referring to Fig. 4D, driving two wheels on one side of the robot 10, such as wheels 102BL and 102FL, in one direction and driving the other two wheels on the other side of the robot 10 in the opposite direction, will cause the robot to rotate around its center axis 174C. Referring to Fig. 4E, driving two wheels on one front of the robot, for example wheels 102BL and 102BR on the back of the robot 10, with opposite wheel directions 170B and 170F, will result the robot 10 to rotate around the front center axis 174F. A person skilled in the art would know that by combining various wheel drive directions 170 and various wheel rotational speeds, various robot movement directions 172 may be resulted. The wheel actuator 160 drive control commands corresponding to such combinations may be programed into the program codes 382 of the memory 380 such that the microprocessor 342 could generate suitable drive commands for the wheel apparatus 102 to navigate the robot 10 to a target location with a target orientation, such as a target location determined by the microprocessor 342 using the rail detection sensor 150, to align and mount the robot on the rail system 120.

Several embodiments of omnidirectional wheels are shown in Fig. 5A to Fig. 5E. In particular embodiments, the holonomic wheel apparatus 102 is a mecanum wheel comprising a plurality of wheel rollers 210 pivotally sandwiched between two wheel plates 220. As shown in Fig. 5A, in some embodiments of the wheel apparatus 102, there exist wheel cavities 230 around the wheel rollers 210 and the wheel plates 220. These cavities 230 may be problematic during the operation of the mobile robot 10 in a greenhouse facility by allowing vines, or greenhouse ropes or cables around pipe rails of the greenhouse to entangle the wheel apparatus 102 as the wheel apparatus 102 is rotating. Thus, in particular embodiments of the wheel apparatus 102, the wheel cavities 230 are covered to reduce the risk of undesired entanglements. Fig. 5B shows an improved embodiment of a typical mecanum wheel, in which the cavities are partially covered using wheel caps 240. The wheel caps 240 may also be referred to as wheel covers. The wheel caps 240 may effectively reduce or eliminate the wheel cavities 230. The wheel caps 240 may be screwed or welded, for example, between the rail travel system 104 and the inner wheel plate 2201 of the wheel apparatus 102, and on the outer wheel plate 220 of the wheel apparatus 102. In some embodiments, the wheel caps may be integrated into a wheel frame which pivotally holds the wheel rollers 210 with minimum gap or clearance between the rollers and the frame. The wheel frame may be injection-molded, for example.

Referring to Fig. 5C, another embodiment of the pipe rail transfer system 100 is presented according to another aspect of the present disclosure. The pipe rail transfer system 100 may include brushes or gaskets 250 around the holonomic wheel apparatus 102 configured to avoid potential entanglement of objects into the wheel apparatus 102 by preventing the objects to meet the wheel apparatus 102 and pushing the objects away from the vicinity of the wheel 102. The brushes 250 may be actuated, vibrated, or stationary. In other embodiments, other methods may be used to prevent entanglement of objects with the pipe rail transfer system 100. For example, referring to Fig. 5D, pressurized air may be blown out of the wheel apparatus 102 in direction 260 through the wheel cavities to prevent foreign objects to meet the cavities and get entangled with the wheel 102. The system 100 may, for example, comprise one or more blowers for blowing the pressurized air. In general, any suitable protector, such as a cover, brush or blower, may be used to prevent objects from engaging with the pipe rail transfer system 100.

According to some embodiments, the pipe rail transfer system 100 may include means and mechanisms to cut entangled objects such as vines and cables in case they are entangled to the rail transfer system 100. Fig. 5E shows an example of such means. Referring to Fig. 5E, a serrated insert270 may be coupled to the chassis 110 and is configured to include sharp edges to cut objects that are entangled to the edge between the rail travel system 104 and the inner side of the wheel apparatus 102.

Referring to Fig. 6, a method for navigating the mobile robot 10 from one rail to another rail within a greenhouse facility 400 is disclosed according to one embodiment. In the embodiment shown, the mobile robot10 is already engaged with a rail 420 and the rail travel system 104 is steering on the rail 420 in direction 440. The method starts by driving the mobile robot to the beginning of the rail 420 and disengaging the mobile robot 10 from the rail 420. The mobile robot 10 may comprise a rail presence sensor (not shown), such as a metal proximity detector as part of the sensor suite 350, configured to confirm the disengagement of the mobile robot 10 from the rail 420. The rail presence sensor may further confirm that the holonomic wheel apparatus 102 is in contact with the ground. The rail presence sensor may transmit signals which, when processed by the controller 140, indicate to the controller 140 that the mobile robot 10 has disengaged from the rail system 420.

Then, the controller 140 may generate control commands to drive the wheel apparatus 102 to cause the mobile robot 10 to move sideways, in direction 442, using the holonomic wheel apparatus 102. In this step, the mobile robot 10 may use the rail detection sensor 150 (as shown in Fig. 1), particularly a vision-based rail detection sensor, and the generated signals from the controller 140 regarding the location and orientation of the next detected rail 422, to adjust its orientation and navigate to the next rail 422. Using holonomic wheel apparatus 102 in this step allows for efficient and quick alignment of the mobile robot 10 from the rail 420 to the next rail 422. The mobile robot 10 may move in any other direction, such as diagonally, to navigate toward the next rail 422. As mentioned before under Fig. 3, a vision-based rail detection sensor wherein images of the rail 422 is captured and processed, enables acquiring accurate and live (or dynamic) location information about the rail 422, its head (as shown by 122 in Fig. 2), and its heading (the direction, orientation, or otherwise the alignment of the rail 422) in the controller 140 which then could be used to conveniently navigate and align the mobile robot 10 for proper mounting to the rail 422.

In the next step of the method, the mobile robot 10 moves in direction 444 to mount and transfer to the next rail 422 (the next rail could be programmed to be the neighboring rail or any other subsequent rail). In this step, the holonomic wheel apparatus 102 may be used to make final orientation adjustment to facilitate proper transfer of the mobile robot 10 to the next rail 422. Once the mobile robot 10 is transferred to the next rail 422, the rail travel system 104 may be used to move the mobile robot 10 on the next rail 422 in direction 444. The rail presence sensor may further be configured to confirm that the mobile robot 10 is engaged with the rail system 422. The rail presence sensor signals may be transmitted to the controller 140 to indicate the full transfer of the mobile robot 10 to the rail system 422. By processing the rail presence sensor signals, the controller 140 may confirm that the mobile robot has transferred to the rail system 422.

Then, the controller 140 may generate control commands, also referred to as command signals, to drive the rail travel system 104 to cause the mobile robot 10 move on the rail 422. The controller 140 may transmit the command signals to the driver of the rail travel system 104.

This method may be used continuously to sweep the mobile robot 10 on any and all of the rails within the facility in an efficient way. While specific embodiments have been described and illustrated, such embodiments should be considered illustrative only and not as limiting the disclosed embodiments as construed in accordance with the accompanying claims.

Claims

What is claimed is:

1. A ground vehicle apparatus comprising: a primary drive for holonomic travel along a surface, comprising at least four independently actuated omnidirectional wheels; an auxiliary drive coupled to the primary wheel system for constrained travel along a rail system, the auxiliary drive comprising a plurality of rail rollers, each rail roller co-axially coupled to one of the omnidirectional wheels; a plurality of actuators coupled to the primary drive, each actuator coupled to one of the omnidirectional wheels and configured to independently drive the omnidirectional wheel and the corresponding rail roller coupled to the omnidirectional wheel; and a controller configured to selectively control the plurality of actuators to holonomically drive the primary drive along the surface and to drive the auxiliary drive along the rail system.

2. The ground vehicle apparatus of claim 1 wherein the omnidirectional wheels each comprise a mecanum wheel.

3. The ground vehicle apparatus of claim 1 or claim 2, further comprising a protector configured to prevent entanglement of objects with an omnidirectional wheel from the omnidirectional wheels.

4. The ground vehicle apparatus of claim 3, wherein the protector comprises a wheel cover configured to cover cavities in the omnidirectional wheel.

5. The ground vehicle apparatus of claim 4, wherein the wheel cover is integrated in a wheel frame, the wheel frame pivotally holding the omnidirectional wheel.

6. The ground vehicle apparatus of claim 3, wherein the protector comprises one or more of a brush and a blower, the protector being configured to push the objects away from the omnidirectional wheel.

7. The ground vehicle apparatus of any one of claims 1 to 6, further comprising a serrated insert configured to cut objects entangled on the ground vehicle apparatus.

8. The ground vehicle apparatus of any one of claims 1 to 7, further comprising a guide device for aligning the auxiliary drive with the rail system.

9. The ground vehicle apparatus of any one of claims 1 to 8, further comprising a sensor configured to generate data regarding the rail system and wherein the controller is configured to process the data to detect the rail system.

10. The ground vehicle apparatus of claim 9, wherein the sensor comprises a vision-based sensor.

11. The ground vehicle apparatus of claim 9 or claim 10, wherein in response to the detection of the rail system, the controller is configured to generate command signals to transfer the ground vehicle apparatus to the detected rail system.

12. A method for transferring a ground vehicle apparatus to a rail system, the method comprising: detecting the rail system using a controller of the ground vehicle apparatus, wherein the controller is operatively coupled to a sensor and is configured to obtain data regarding the rail system from the sensor; in response to detecting the rail system, generating first command signals, by the controller, to holonomically drive the ground vehicle apparatus towards the detected rail system along a surface using a primary drive of the ground vehicle apparatus; and causing the controller to generate second command signals to drive the primary drive to the detected rail system and to engage an auxiliary drive coupled to the primary drive to transfer the ground vehicle apparatus to the detected rail system.

13. The method of claim 12, wherein detecting the rail system comprises dynamically calculating a position and an alignment of the rail system with respect to the ground vehicle apparatus.

14. The method of claim 12 or claim 13, wherein the sensor comprises a vision-based sensor configured to take vision-based images of the rail system.

15. The method of any one of claims 12 to 14, further comprising: receiving, by the controller, signals from a rail presence sensor indicating the ground vehicle has transferred to the rail system; and generating third command signals, by the controller, to move the ground vehicle apparatus on the rail system by driving the auxiliary drive.

16. The method of any one of claims 12 to 16, further comprising: transmitting the first command signals to the primary drive; and transmitting the second command signals to the auxiliary drive.

17. A memory storing program codes which, when executed by a microprocessor, cause the microprocessor to perform the method according to any one of claims 12 to 16.