Patent Publication Number: US-2023148454-A9

Title: Mobile robot

Description:
CROSS REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY 
     The present application is a continuation of U.S. application Ser. No. 16/317,353, filed Nov. 12, 2019, as a national entry of international PCT Application No. PCT/CA2017/000170, filed on Jul. 13, 2017, which claims priority to U.S. Provisional Application No. 63/361,621, filed on Jul. 13, 2016, the contents of which are all incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present application relates to mobile robots or mobile platforms that can be customized for specific robotic applications. 
     BACKGROUND OF THE INVENTION 
     Our previous U.S. Pat. No. 8,994,776 disclosed a mobile robot that utilized a three omni-wheel design to achieve holonomic motion that included a number of distinct sub-assemblies or modules. The modular assembly provides advantages with respect to packaging and shipping with the end user completing the final assembly. This modular design also provides a mobile platform that can be customized by the end user for particular specific often specialized applications. 
     The ability to allow customization of the mobile robot or allowing a user to finalize or add different modules to the mobile platform is particularly advantageous in that the mobile platform can be used in multiple applications and is not limited to a solitary application. 
     SUMMARY OF THE INVENTION 
     A mobile robot according to the present invention has a base module with 3 omni-wheels, each having a separate electric drive motor connected to an electric battery supported in the base module and wherein the omni-wheels are commonly supported by a tri-axle supported in said base module. 
     In an aspect of the invention, the tri-axle is a single fixed component having 3 axle sections connected to each other at a central point with said axle sections extending outwardly from said central point and being located in a common plane and each omni-wheel is supported on one of said axle sections. 
     A mobile robot of the present invention uses a tri-axle arrangement which is cost-effective to produce, yet effectively distributes the weight of the robot, including the base module and batteries to the wheels in an efficient manner, reducing twisting or other deformations. The base module, in a preferred embodiment, includes a base shell which is preferably made by injection molding where the relatively inexpensive production part can be made of a plastic composite material with the exoskeleton design of this module significantly contributing to the final strength. This particular structure preferably cooperates with a tri-axle and allows for substantial load carrying capability of the mobile platform and also allows for modification of the mobile base module to carry higher loads by providing additional wheels on each of the ends of the tri-axle. In this design the axles do not rotate and the wheels provided on the axles rotate on stub shaft projections at each of the three ends of the tri-axle. 
     The present application also discloses a unique hub design where a wheel cover (or hub-cap) can be non-rotatably mounted on the axle. With this embodiment, a sensor, such as an ultrasonic or time of flight depth sensor or a computer vision camera, can be mounted in the wheel cover and the sensor can be connected with a wiring harness to a computer processor provided in the base module by a through passage in the axle if a direct connection is required. It is also possible that the sensor can be a multi-part arrangement with a portion rotating with the wheel and a nearby part or parts of such sensor arrangement held stationary and fixed to the wheel cover. Such sensor arrangement might, for example, provide a timing measurement delivering accurate wheel speed information. 
     In a different aspect of the invention, an arrangement is disclosed that uses two or more vertical connecting rods or long bolts that pass through the individual modules and can be tensioned to pull the modules together and thereby contribute to the structural integrity of the assembled robot. Further enhancing the structure, the lower end of these rods is preferably secured near the tri-axle in the base module shell and could also be welded perpendicularly onto the tri-axle for heavy weight applications, typically also deploying multiple wheels per end of the tri-axle. Because the end of the tri-axle does not rotate, it is also anticipated that for high load robots, additional shell or support structures could be inexpensively, and solidly, attached to each end of the tri-axle. 
     A further aspect of the inventive robot is a head-tilt arrangement that allows a screen, and any associated equipment that is part of the screen or touch screen, to be easily adjusted for particular applications. 
     In a further aspect of the invention, a motor mount arrangement is disclosed which allows different capacity motors to be used in the device depending upon the particular application. In this way the performance capabilities of the base module are easily varied, without impacting base module exoskeleton tooling. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       Preferred embodiments of the invention are shown in the drawings wherein: 
         FIG.  1    is a perspective view of the virtual telepresence robot according to an embodiment of the present invention; 
         FIG.  2    is an exploded view of the virtual telepresence robot according to an embodiment of the present invention; 
         FIG.  3    is an exploded view of the base module; 
         FIG.  4    is an internal perspective view of the assembled base module, minus the base plate; 
         FIG.  5    is an external perspective view of the base shell according to an embodiment of the present invention; 
         FIG.  6    is a top-down view of the base shell according to an embodiment of the present invention; 
         FIG.  7    is a bottom view of the base shell according to an embodiment of the present invention; 
         FIG.  8    is an internal perspective view of the base shell according to an embodiment of the present invention; 
         FIG.  9    is a perspective view of the base plate according to an embodiment of the present invention; 
         FIG.  10    is a top-down view of the base plate according to an embodiment of the present invention; 
         FIG.  11    is a bottom view of the base plate according to an embodiment of the present invention; 
         FIGS.  12  and  13    are a side view and exploded view of the motor module according to an embodiment of the present invention; 
         FIG.  13 B  is another possible embodiment of the motor module; 
         FIG.  14    is a perspective view of the assembled wheel tri-axle module; 
         FIG.  15    is a perspective view of the tri-axle; 
         FIG.  16    is an exploded view of the wheel sub-module, with the tri-axle; 
         FIG.  16 B  is a perspective view of the opposite side of the wheel hub cap in  FIG.  16   ; 
         FIG.  17    is an exploded view of the wheel hub subassembly; 
         FIG.  18    is a perspective view of double wheels on the tri-axle; 
         FIG.  19    is a perspective view of the wheel hub cap with the sensor; 
         FIG.  20    is an external perspective view of the transition module; 
         FIG.  21    is a bottom view of the transition module; 
         FIG.  22    is an internal perspective view of the transition module; 
         FIGS.  23  and  24    are exploded views of possible sensors and sensors mounts for the transition module; 
         FIG.  25    is a perspective view of the extra battery compartment; 
         FIG.  26    is a perspective view of the rain cover module for a double-wheeled base; 
         FIG.  27    is the rain module cover in  FIG.  26    on a doubled-wheeled base; 
         FIG.  28    is a perspective view of the mid-section module; 
         FIG.  29    is an exploded view of the mid-section module; 
         FIG.  30    is a perspective view of the head module; 
         FIG.  31    is an exploded perspective view of the head module; 
         FIG.  32    is an exploded side view of the head module; 
         FIG.  33    is side view of the head module with the tablet in a horizontal orientation; 
         FIG.  34    is a section view of where the axle is within the base shell and base plate; 
         FIG.  35    is an exploded view of the tri-axle&#39;s placement within the base shell and base plate; 
         FIG.  36    is a perspective view of the shopping basket module on the base module; 
         FIG.  37    is a perspective view of the vacuuming module on the base module; and 
         FIG.  38    is a perspective view of the ultra-violet light cleaning module on the base module. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The mobile robot  600  as shown in  FIGS.  1  to  2    has four distinct subassemblies or modules: the base sub-assembly  1 , the transition sub-assembly  2 , the mid-section sub-assembly  3 , and the head sub-assembly  4 . The base sub-assembly has a tri-axle wheel support arrangement that cooperates with the injection molded housing to improve structural integrity and load carrying capability. This relatively lightweight arrangement efficiently distributes loads to the wheels without significant deformation. 
     Turning specifically to  FIGS.  3  to  4   , the base sub-assembly is now composed of several different modules: the base shell ( FIGS.  5  to  8   ), 3 identical motor plate modules  31 , the tri-axle wheel module  32 , and the base plate module  5 . These modules allow for improved assembly and maintainability. 
     The base shell is an injection molded part designed to effectively receive various components in the base sub-assembly. It is designed to be inexpensively made of injection-molded composite plastics and is both an esthetic component and, as an exoskeleton design, it also serves as a structural member. The base shell easily supports the weight of the modules above, and often the mobile robot is designed to carry significant loads as part of its customized application which often rest along the top edge  56 . 
     Referring to  FIGS.  5  to  6   , the battery compartment  50  is able to hold a standard  12 V lead-acid battery. These batteries are inexpensive, widely available, and can be replaced easily. The centralized battery provides the robot with a central center of mass and a low center of gravity. The battery compartment may be lined with foam to reduce transmission of vibrations to the battery. The holes  51  may be used to affix straps in order to further secure the battery. Higher cost alternative rechargeable batteries can also be used and the compartment size can be varied to accommodate the alternate battery and maintain or improve strength and low center of gravity. 
     The large slots  52  are access ports for connectors from the main circuit board  33  in  FIG.  3   , to connect to any circuit cards and sensors in the other upper modules. The large slots  52  provide easy access to various ports like USB and diagnostic connectors used during assembly of the robot, and debugging and programming for advanced third party users. Indentations  53  around the top edge  56  of the base shell provide support positions for various sensors including ultrasonic and infrared sensors if required. Holes  54  and the top edge  56  can be used by third parties to build customized platforms or attach other components to the base. In such a situation, the transition module or upper modules may not be needed. One such possibility is shown in  FIG.  36   , where a shopping basket module  360  is mounted to the base module and with appropriate software, acts as an autonomous shopping cart for a shopper or in conjunction with other autonomous picking robots. Such a shopping cart can be used in diverse applications such as order picking in warehouses to retail grocery selection are two examples. Two (2), three (3) or more wheels  361  may be mounted to each axle spoke or section to increase the robot&#39;s load carrying capacity and broaden the robot&#39;s footprint to increase stability as desired. Other customized platforms may include a vacuuming module  380  in  FIG.  38    or an ultra-violet light cleaning module  370  in  FIG.  37   . 
     Referring to  FIGS.  7  to  8   , large hole  70  is for the fan  35 , which draws air from above the base shell and pulls it into the interior of the base shell. The fan circulates the air throughout the base shell to cool the main circuit board  33  and motors  120  before exiting via the small gaps around the wheel hubs. The base shell incorporates guides  71  for the main circuit board. This is structurally inter-connected to the battery box to increase its strength. The main circuit board is intended to be one of the first parts inserted into the base module, and contains all necessary electronics components required to operate the base module separately. 
     The base shell also incorporates guides  72  for the motor plate sub-assemblies. These motor plate guide rails are relatively thick and cooperate with the base shell walls to improve the strength. One side of these guides is shorter than the other in order to allow the motor plate sub-assembly to be cleanly inserted into the holder after the timing belt  142  has been looped around the toothed pulley  122  on the motor shaft. They include holes  73  that go through the entirety of the base shell and can also be used by third parties to secure components as was previously discussed. Holes  81  fit screws used to secure the base plate onto the base shell, which in turn securely prevents the motor plates from moving out of their guides. There is an indentation  74  which allows passing wires from the motor on the far side of the main circuit card, without requiring longer wires on that individual motor. 
     The tri-axle and wheel sub-assembly  32  is held in place by ‘U’-shaped channels  75 . These channels meet at one end. The co-planar channels are equally spaced  120  with respect to one another to form a 360° circle. The channels have notches  82 , which fit into a corresponding spot  97  on the base plate. These notches further strengthen the holder and provide protection against possible horizontal movement from any torque on the tri-axle  140 . There are two axle holders  76  out apart from the main battery box holder that are also used to support the tri-axle. These are in place to provide the same amount of vertical support to these two sides as the longest axle channel, which is under the battery box. There is a large indentation  77  which can accommodate less accurate axle welds or axle weld reinforcement or coupler where the three arms or spokes of the tri-axle are joined. There are indentations  80  around the ends of the tri-axle that can be used to hold ultra-high-molecular-weight (UHMW) plastic bearings  40 . There are also various walls  78  within the base plate that provide structural support as well as help channel airflow from the fan throughout the base shell. 
     Referring to  FIGS.  9  to  11   , the base plate is another large injection molded component of the base sub-assembly. It has the other half of the unique tri-axle holder  91  that is part of the base shell. The base plate also increases the overall strength of the base sub-assembly. The depressions  92  in the side that provide clearance for the drive pulleys  162  of the tri-wheel axle assembly, also protrude into the base shell wall axle holes and prevent possible rotation of the base plate with the base shell, without requiring the tri-axle  140  being in place. The outer perimeter of the base plate is tightly fitted to that of the inner walls of the base shell providing further structural support and resistance to any inward bending of the base shell caused by impacts. There are multiple points of connection  93  and  94  where the base plate may be screwed onto the base shell to ensure the tri-axle is held in place securely. The design allows for the installation of sensors (like ultrasonic, time-of-flight, or infrared)  95  at each corner as well. 
     A further aspect of the base shell depth and base plate design concerns cases where the robot is bumped up near the head from any direction. Bumps typically push the robot up onto two wheels, with the third wheel which is closest to the source of the impact, elevating from the ground. As the robot moves up on two wheels, it then tilts until the bottom edge of the base plate between such two wheels hits the ground. This impact increases the resistance to the incoming force. Should the force overcome this further resistance, one or both of the wheels which were still on the floor now lift off the floor and the robot then begins to pivot on the edge of the base plate towards one or the other wheel which has just left the floor. 
     The robot is designed such that the distance from the centre point of the base plate between any two wheels and the ground at this point will be closed to zero in the event of a bump before the robot&#39;s centre of gravity is beyond the touch points on the ground. Thus, the robot will self-right if the force is removed before the two wheels have left the floor. 
     Furthermore, the robot is designed such that if the force continues, and these two wheels leave the floor and the robot pivots on the base plate between such two elevated wheels toward one wheel, in many cases, the robot will still right itself since the centre of gravity is still behind the point or points of contact with the ground. 
     Holders  96  are for the vertical connecting rods or long bolts  7 , which are screwed into the press fit hex nuts  111  on the underside of the base plate. Walls  98  are to direct airflow from the fan to not exit the base plate from specific sides but to instead flow around to the opposite side of the base an out around the axle for the far wheel. Those walls may also provide additional protection from water and debris entering along the axle sections. Small holes  100  allow any water or other liquid that may have entered past the wheel module  141  and onto the base plate, to drain back to the external environment. The base plate may also include a central charging apparatus (such as an induction charging pad)  110  that allows for recharging the battery no matter what direction the robot may be facing. 
     Referring to  FIGS.  12  to  13   , the motor plate subassembly is designed to be easily slid into grooves or tracks in the base shell and thus these components can be easily maintained or replaced. The preferred embodiment utilizes a DC brushless motor  120  mounted to a motor mounting plate  121  such that the toothed pulley  122  on the motor shaft extends through the mounting plate. The toothed pulley on the motor shaft is then situated in a coplanar manner with the large toothed drive pulley  162  on the tri-axle wheel assembly  32 . Although these pulleys feature flanges on one or both sides of the teeth, if flex between the motor and drive pulley was such that these two pulleys would no longer be coplanar, the belt  142  would have an increased likelihood of derailing. The tri-axle integrity in cooperation with the base shell provides a number of advantages. 
     The position of the motor on the motor plate as well as the diameter of toothed drive pulley can be adjusted to achieve different gear-reduction ratios as required. Ribbing  123  provides some structural support to the motor plate to protect against resonance, and also acts as a grip for the user. Motor seat  124  allows for accommodating different motors with varying shaft lengths, and may be a separate component from the motor plate. Screws  125  secure the motor  120  to the motor plate  121 . The positions of those screws can be moved and is not in the path of the timing belt  142 .  FIG.  13 B  shows a different embodiment of the motor plate module. In this embodiment, the motor  130  has a longer shaft  131 , and as such the motor plate  134  has a similarly longer motor seat  132  to accommodate the longer shaft. The ribbing  133  is different to account for the different resonant characteristics of this motor. This embodiment also illustrates that out runner-type motors (like  130 ) can be used with freely rotating components with respect to the motor plate, rather than just fixed case motors (like  120 ). There is sufficient room in the vicinity of where the motor modules are placed within the base shell to accommodate various wiring arrangements, motor sizes, and motor shaft lengths without the need for retooling of the base shell. 
     Referring to  FIGS.  14  to  15   , the tri-axle wheel assembly consists of a tri-axle  140  and three identical wheel sub-assemblies  141 . The tri-axle in the preferred embodiment has three cylindrical rods or spokes  150  positioned on a plane surface at  120  with respect to one another, making a 360° circle, and welded at the point where the these three rods intersect  151 . The weld must be sufficiently strong to ensure the axles are essentially one piece, and do not move with respect to one another. There are slots  152  and holes  153  at the end of each axle that fit into a corresponding area ( 168  in  FIG.  16 B ), to keep the wheel hub cap from rotating with respect to the tri-axle when affixed with screw  165 . 
     Now referring to  FIG.  16   , the wheel sub-assembly consists of the omni-wheel sub-assembly  160 , wheel hub cap  161 , three plastic bearings  163 , and the toothed drive pulley  162 . The UHMW plastic bearings are pressed into the hole on the drive pulley, the omni-wheel hub, and the wheel hub cap (visible in  FIG.  16 B ). These plastic bearings have a low coefficient of friction and allow the wheel sub-assemblies to rotate freely with respect to the tri-axle, while being constrained between the wheel hub cap  161  and the axle holder on the base shell  76 . In the present embodiment, these bearings will not require any lubrication, which can be hazardous in the cases of leaks in some service environments, like medical facilities. These bearings can also include slotted polymer bushing designs enabling the robot to operate in sandy conditions where the slots effectively clear sand and dirt from the axle segments. Screw  165  goes through the wheel module and screws into the hole  153  at the end of the tri-axle. Cap cover  164  can be used to hide the screw to improve aesthetics of the hub cap. 
     The omni-wheel sub-assembly is seen in  FIG.  17   . The omni-wheel is split into two halves  170  and  171 . These allow for easy assembly and replacement of the rollers  172  or roller axles  173 . One half  170  of the omni-wheel remains stationary, while the roller assemblies  174  are placed into it. The other half  171  is then pressed onto the stationary half  170 , securing the roller assemblies in place. A timing belt  142  is looped around the drive pulley before the wheel sub-assembly is secured onto the tri-axle. Protrusions  175  fit into holes  167  of the drive pulley  162  to ensure that when the pulley is turned by the motor, the omni-wheel turns. 
     It is also possible to add a second omni-wheel  180  onto the axle shown in  FIG.  18   , allowing for two omni-wheels per axle, and a greater carrying capacity for the base. Even more wheels could be placed onto the axle in a similar manner to further increase stability, carrying capacity and broaden the footprint of the robot, like  361  in  FIG.  36   , although a longer axle may be required in some cases. The second omni-wheel hub&#39;s protrusions  175  would fit into holes  166  of the first wheel hub. Those holes and protrusions are slightly offset from one another, so that any additional omni-wheel hub&#39;s rollers will have a different orientation from the previous one. This also allows for greater roller to ground contact at the angles where there was previously minimal contact with a single omni-wheel (such as the area between two roller assemblies). The omni-wheel hub cap  161  is screwed onto the end of the tri-axle. Having stationary wheel hub caps allows company or client branding to remain upright at all times during the robot&#39;s motion. 
     Hub motors to power the omni-wheels instead of the belt drive arrangement, and infrared, time-of-flight, or ultrasonic sensors  190  may be affixed to the tri-axle segments. Sensors are typically placed on the hub cap, as seen in  FIG.  19   . In such a case, a longer hollowed out tri-axle  191  could be used to accommodate the wiring  195  from such sensors (or hub motors). Wiring may be thin ribbon cable to allow the wire to exit holes  194  and plug into a connector on the main circuit card  33 . Holes  194  may have some insulator to hold the wire in place and at a fixed length. To wire the sensor through the axle to the main circuit board  33 , the screw  165  cannot be used like  FIG.  16   . To secure this wheel hub cap  196 , the end of the tri-axle segment  191  would instead be threaded  193  and held by a nut  195 . This embodiment shows a different small wheel hub cap  196 , and does not show the larger wheel hub cap that would typically encase the end of the nut  195  and protect the components in front of  196 , while leaving room for sensor  190  to see the ground. 
     The transition section module is shown in  FIGS.  20  to  22   . The transition section is a relatively large injection molded part, but has a similar height as the base shell to ensure easier packaging and shipping to the consumer. The transition section has the same triangular base profile as the base shell, but then tapers off higher up to create a rectangular/trapezoidal shape  200  that provides the guiding shape for the midsection ( FIG.  28   ). The transition fits tightly around the lip of the base shell, to provide strength and minimize any vibrational noise during the robot&#39;s movement. There are small guides  210  that help keep the battery locked into place. The transition incorporates slots  211 , with a spacing of X, around its six edges that allow for placement for sensor modules seen in  FIGS.  22  to  23   . These sensor modules can be in a variety of shapes and sizes (as long as their rear dimension does not exceed X), and can be created by third parties as well. These modules can hold various sensors, including ultrasonic and infrared. These sensors may be used to detect an object&#39;s proximity to the base and prevent collision with the object. Another example is being able to detect the edge of downward stairs, and prevent the robot from falling down them. There are also wire clips  212  around the periphery that can keep the wires from the sensor modules organized. At the top of the transition section there are various holes  203  and  204 . These holes  203  allow air to be pulled down through the transition section from the mid-section sub-assembly, in order to reach the fan  35  on the base sub-assembly. These holes  203  also allow wires from connectors on the main circuit board  33  of the base sub-assembly to pass through the transition section, so that they can connect with the circuit boards in the mid-section module. Holes  204  allow for pass-through of long bolts  7 . There are several indentations  201  that allow for connection of various first or third party peripherals. One such use is for a guide for the holder for a second battery  FIG.  25   , which doubles the runtime of the robot. Holes  213  are also used for attachment of a rain cover accessory as seen in  FIGS.  26  and  27   . This rain cover accessory is intended for waterproofing an outdoor version of the robot. This module would preferably be secured to each section of the tri-axle at their outer ends using screws threaded into holes  153 , and may not require the wheel hub cap  161 . 
     The mid-section module is shown in  FIGS.  28  to  29   . The mid-section module includes the front half  290 , the back half  291 , fan grill  292 , two reflective domes  293  and  294 , and the mid-section circuit board  295 . The mid-section has two main injection molded parts; the front half and the back half The front half has a hole  296  that allows air to flow from the mid-section downwards into the transition section, so that the fan  35  in the base shell sub-assembly can pull the air into the base shell to cool the main circuit board  33  and the mid-section circuit board. The hole  296  is covered by a fan grill  292 , which can prevent dust and debris from entering the robot with a removable mesh lining.  298  indicates an area that may be used as a microphone or as another speaker.  292 ,  293  and  294  may be mountable to  290  and  291  through the use of magnets to allow for easy maintenance or replacement. The indentation  280  is an area that can hold wire from one of the USB type-c connectors, since there is little room between the top of the mid-section circuit board and the circuit board in the head module. The mid-section circuit board is screwed securely onto the back half, and it acts as the host for the robot. A shutdown button  297  may be included on the back half, to provide an easily accessible area for the user to manually power down the robot. The two reflective domes are used for the vision system. As was mentioned in the US Patent  8 , 994 , 776 , there are obstructions in the view at  90   0  and  270  due to the design of the midsection, however these blind spots in the vision have been reduced due to the reduced curved profile around those areas  281 . 
     The head module is shown in  FIGS.  30  to  33   . In the present embodiment, the head module includes the tablet  302 , tablet mount  303 , front half  300 , back half  310 , top holders  313  and  313 b, speaker  311 , speaker grill  301 , head circuit board  318 , motor  317 , worm  316 , worm gear  312 , worm protector  319 , worm gear covers  314  and  314 b, O-rings  315 , top holder spacers  321 , and several plastic bearings  320 . The tablet is mounted at such a height so that the user can maintain comfortable eye contact with others. The tablet mounts are interchangeable to allow the user to use whatever tablet they prefer or currently own. A third party may also choose to use a modified tablet mount  303  to mount other small sensors to augment the robot capabilities, such as an Intel RealSense® sensor. 
     Although the head is mounted at a fixed height in this embodiment (which could easily be changed with a longer or shorter head module, or a spacer between such modules), it can still tilt within a large range of approximately  340 . With this design supporting a large range of motion, when desired, the tablet can almost completely flip to a rear-facing position, as shown in  FIG.  33   . In such a position, for example, a user can view and use the tablet screen while the robot can move forwards with the optimal orientation of the omni-wheels with regards to speed and stability. An example of such a case could be an elderly person using the robot as a walker (with another customized module). The tablet is able to quickly and quietly tilt through the use of the brushless dc motor  317 , which might also be the same ones used in the base to achieve further volume cost reductions. The speed of this motor enables the tablet to “nod” quickly up and down, under software control, should the robot be operating in an autonomous mode and wish to acknowledge a command or other visual or auditable signal. A further advantage of the reverse tablet position is in cases where the tablet has internal “depth” and structure mapping capabilities (typical of Google “Tango®” and other augmented reality systems) and needs to verify a path in a forward or reverse direction or to enable avatar-like capabilities where a remote telepresence user is able to see and experience the world through the robot. In all such cases, the bracket adapter holding such third-party tablets or cell phones or other devices must ensure that embedded cameras are not obscured by such bracket. 
     A further advantage of the speed of tilt can be understood by looking at the example of a restaurant or theme park operator. When deploying these robots in autonomous operations to take food orders or assist in crowd and queue management, the robot may be bumped in such a manner that it would topple over. During the fall, gyros in the system will anticipate the point of impact and quickly tilt the tablet or integrated display to a position where it will not hit the ground. Typically, taller telepresence and other larger robots are not able to re-configure themselves during a fall and suffer serious damage. The modular robot design anticipates a fall and through reinforcement of the speaker housing and on the reverse side, the motor housing, a fall will not result in structural damage, and assuming the display is autonomously tilted out of the way, the display will not be damaged either. 
     Compared to U.S. Pat. No. 8,994,776, the improved design has the motor on the back of the head module, thus making it more hidden and aesthetically pleasing. There are also array microphones and a large speaker  311  incorporated into the design, which allows the user to more effectively communicate with others (especially in noisy environments or with hearing impaired people), versus just the tablet&#39;s speakers and microphones. 
     Although the figures illustrate a separate tablet mounted to the head tilt assembly, some robots using this system can include integrated displays which mount directly in the bracket and cannot be removed by an end-user. 
     The speaker grill  301  is designed in such a way to not protrude too far from the front half  300 , and it flows into the sides of  300  rather than wrapping around onto the back half  310 , to increase aesthetic appeal and provide easier maintenance. The speaker grill and following worm protector may also be attachable with magnets, similar to  292 ,  293 , and  294  in the midsection module. The worm protector  319  protects the user from the worm and worm gear teeth from the front. It provides a suitable surface stop for the tablet mount  303  as well. Also, on the top of  313  and  313 b a flexible rubber or bristle-like material that protects the user from the teeth of  312  from the rear. Worm gear covers  314  and  314   b  straddle both sides of the worm gear  312 , and their shape allows them to move freely through the aforementioned material.  314  and  314   b  have holes that allow for secure mounting to  303  at area  324 . O-rings  315  are placed between  312  and  314 / 314   b.  The purpose of the O-rings  315  is to allow the tablet to be manually moved to any position (such as a doctor or nurse moving it into a writing position) without causing any damage to gears  312  or  316 . The channels in  312 ,  314  and  314   b  have ridges which provide a sufficient amount of friction for  315  such that the tablet will not droop due to gravity, but the tablet can be moved with sufficient manual force. Spacers  321  may be used to adjust the amount of force on  315 . Areas  322  and  325  are to allow for pass-through of wires from within the head module to the tablet  302 . Area  323  provides a space to tighten the long bolts  7  that will be further discussed later. Areas  323  and  325  are hidden from view once the speaker grill is placed on the front half. Nuts in  323  must be loosened in order to disassemble the head module  4 . There are no exterior facing screws (to increase aesthetic appeal) to completely disassemble  4 . Rather screws at  326  and tabs at  327  keep 4 together, and are held down by  313  and  313   b.  There is an axle embedded into  313  which provides the central axis for head tilt. 
     The design allows for force sensors to be installed within the head tilt assembly where the bracket joins to the assembly so that a powered response to external, manually applied tilting forces (like those applied by a user simply trying to re-adjust the tilt) may be used to ease such tilting by driving the motor in a direction corresponding to the manually applied force. In the case of a senior or physically challenged user for example, a light touch could then be applied to re-position the head rather than pulling it manually against the friction of the O-rings. These force sensors could also be used to detect possible pinched fingers or other end limits of motion by software algorithms which would correspondingly limit or modify motor speed and direction in response to such external forces. 
     The lips  56  and  200  that the base shell and transition sections have are also a part of the midsection and head modules. The areas where the lips enter the module directly above them are hollowed out to match the size of the lip and provide a tight fit between modules. With the lip connectors being a direct part of each main module of the robot, extra connectors like screws are not required between adjacent main modules. This allows for allow for quick and easy assembly without fastening by an unskilled consumer. Similarly, this allows for quick and easy disassembly or replacement of modules, without requiring extra tools. The protruding lip connectors are placed on the top of the modules rather than the bottom, which provides protection to the electronics in the event of rain or water around those areas. If the top of the modules was a hollowed out section rather than a protruding lip, water could potentially drip in due to gravity and damage various electronic components. 
     Although the lips provide a tight connection between main modules, there may still be a possibility of an upper module becoming detached from the base module and transition section due to application of a strong vertical or horizontal force. Therefore, long bolts  7  ( FIG.  2   ) are placed vertically inside of the robot. They extend through the head module and go through every main module ending at the base plate where they are tightened into the press fit nuts. The long bolts may be split into two parts to allow for easier shipping and overall assembly by user. These bolts provide a strong compressive backbone for the robot increasing its overall structural strength, and prevent the main modules from becoming unintentionally detached from one another. 
       FIGS.  34  and  35    illustrate the tri-axle supported within the base module.  FIG.  34    shows a cross-section of the tri-axle support within the base module. Tri-axle  140  is held in place by  340  and  341  from the base shell, and  342  and  343  from the base plate.  340  and  342  are separate axle supports spaced away from the central weld of the tri-axle  151  in  FIG.  15   , the same distance as the support on the battery box labelled as  80  in  FIG.  7   . This equal spacing provides an equal distribution of forces on the tri-axle.  341  and  343  just indicate areas around the axle channels on the battery box that support the axle as well.  FIG.  35    shows a view of the tri-axle with some bearings and where their respective place is within the axle supports. For example, the individual bearing labelled as 40 fits within  350  of the base shell and  351  of the base plate. 
     As shown in the drawings, the tri-axle arrangement is a one piece solid axle or a three piece axle having a very strong central connection that is supported outwardly at the wheels and is not prone to deflection. This axle can be of different lengths if additional wheels are required or the wheels can actually be coupled to themselves with only a single wheel connected to the axle. The axle can be made to carry high loads and effectively the weight on the base module is transferred from the wheels to the axle via the various wheel bearings or bushings in the base module and the number of transfer locations can be adjusted to more effectively distribute the forces through the base module and support different upper module configurations. 
     This disclosed tri-axle design is effective in distributing forces while also significantly reducing distortions of the overall base module of the robot, not only due to loading from upper module payloads, but also due to unexpected impact or collision. It also enables one or more omni-wheels at each of the ends of the sections or spokes of the tri-axle to rotate and be powered by the motors as shown in the drawings. The drawings clearly show the use of multiple wheels for each axle which can be of great assistance in effectively reducing the load per omni-wheel allowing a lower cost wheel to be used and to enable a wheel that is designed for lighter applications to be deployed in a double or triple or larger combination for carrying higher loads or operating on softer surfaces. The omni-wheel design continues to function in the normal manner whether used individually or used in combination with other omni-wheels. The base module has also been divided essentially horizontally to allow the tri-axle to be placed in the base unit with the bearing support portions being part of the base molding. Additional components can then be added and a bottom plate  5  is also used to provide a further structural component and mount for circuitry  33  etc. As shown in  FIG.  3    (where the base module is inverted for illustration purposes), the motor drives  34  for the individual or sets of wheels  32  at the ends of the tri-axle are mounted on separate slider-card mounts  31  for stiffening of the injection molding base module as well as allowing the motor drive arrangement to be inserted as a finished unit as it simplifies the assembly of the base unit and also allows the base unit to be easily customized for different applications and power requirements. Each of the individual motors preferably include their own fan unit  35  for cooling or selective cooling as required. It is possible to re-use a single fan within the lower chamber of the base unit for drawing of air into the base unit and out thereof for cooling the components. In this way the mount board of the motors cooperates with the base module to increase strength. 
     Preferably the individual modules of the mobile robot are interconnected by two or more vertical rods  7  as illustrated in  FIG.  2    that pass through bearing type portions of each of the modules. These rods provide a common vertical support reinforcing the connection of the modules and the rods preferably include an arrangement for applying a compressive force to the individual modules to draw them together with respect to the vertical direction. With this arrangement, the rods significantly increase the structural integrity of the connected modules and integrate the modular components in a cost effective manner. In the present design, two rods as shown are particularly desirable as the center portion of one of the modules includes a large port to allow effective viewing both forwardly and rearwardly and as much as possible to each of the sides. Viewing in the vertical planes is also advantageously provided by the two opposed domes. The use of two rods either side of this large center opening has proven effective. The rods are preferably of a metal or a high strength reinforced plastic material. Although in the figures, these rods enter and are secured in the base module at either side of the battery compartment within the plastic composite exoskeleton, where maximal strength is required, rods can be perpendicularly welded to the tri-axle itself. Alternatively, one of more nut or other connectors can be welded or affixed onto the upper surface of the tri-axle, or the tri-axle could have a bored threaded hole, such that the vertical rods can thread or otherwise be attached to the tri-axle at any point. Support structures or rods need not be attached to the tri-axle inside of the wheels. For example, each axle arm or spoke of the tri-axle can extend beyond the wheel or set of wheels and at its extremely, a bored and threaded hole can then be made available for perpendicular rod attachment. Alternatively, threads at the end of each axle arm or spoke of the tri-axle can accept mating structural components. 
       FIGS.  15  and  16    clearly illustrate how an individual omni-wheel is rotatably supported on the stationary axle arm  140  of the tri-axle by means of bearings  163 . The drive pully  162  is mechanically secured to the omni-wheel and includes a toothed surface for cooperating with the notched drive belt. The wheel hub  163  can be mechanically fastened by the bolt  165  to the axle arm  140 . This wheel cover  161  can engage the slot  152  provided at the end of the axle arm such that the wheel cover does not rotate. This fixed, non-rotating cover offers a number of aesthetic visual design choices, but more importantly, with this arrangement, the wheel cover can provide a support position for the sensor or part of the sensor used to sense a wheel movement. Any electric connection can also passed through the axle if desired. In addition to sensing wheel movement, other sensors can be provided in the wheel cover  161  and the position of the sensors can be known as the wheel cover need not rotate. Such an arrangement is shown in  FIG.  19   . 
     A further advantage of the fixed, non-rotating wheel cover is an optional employment of hub motors instead of the toothed belt drive or possible gear drive. Because the wheel cover doesn&#39;t rotate, the tri-axle design could use the channel inside the axle to carry power and control signal wires feeding one or more hub motors. The powered coils for these motors would be stationary on each arm or spoke of the tri-axle while permeant magnets or, in the case of axial-flux type motors, coils, would be mounted within the spinning part of one or more wheels on each of such axle arms. 
     Returning to the base module and structure as shown in  FIG.  3   , the motor mount arrangement  31  allows for different size of motors to be available and for the mobile robot to be easily customized for a particular user&#39;s requirement without modifying costly tooling for the base module exoskeleton shell. It has been found that while robots with mobile platforms have many diverse applications, these applications commonly require a base unit having the necessary wheels and axle support etc. as well as power drives for moving of the base unit about its environment. There is a large market for such a mobile base where disparate users can effectively use the mobile base as a component of their customized process or application. In the present application, the base unit, drive for the base unit, as well as power that is available at the base unit for driving other user determined requirements is advantageously used by individuals in companies seeking to offer their own customized mobile platform. This particular base unit with its ability to easily change a power drive arrangement for the wheels, the ability to provide additional wheels for higher load carrying capabilities and a larger, more stable footprint, the ability to use different sensors generating a variety of sources of information, in combination with providing a base where a user can easily provide instructions to the power base in an appropriate manner and in any direction, is very advantageous. 
     The Applicant has found the welded tri-axle arrangement particularly for higher load applications can be made of high strength steel and the base unit can be designed for distributing the force on the axles throughout the base module. It can be appreciated that the base unit is adapted to accommodate modifications of the tri-axle if necessary or desired. Furthermore, the base unit has been described with respect to a particular battery and storage location of the battery near the base of the base module, however variations can be made to that structure as appropriate including for extended runtime where multiple batteries can be boarded. Different applications may require a different battery source and the present design easily accommodates variation in the individual components while still providing an effective platform which can be manufactured in a cost effective manner. 
     Although preferred embodiments of the present invention have been disclosed herein in detail, it will be understood by those skilled in the art, that variations may be made thereto without departing from the claims and the principals of the numerous inventions disclosed herein.