Patent Publication Number: US-2021174310-A1

Title: Efficient service rack system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 16/570,398, filed on Sep. 13, 2019. The aforementioned application is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Typical vehicle maintenance visits at a vehicle service facility require a service technician to perform discrete and repeatable maintenance tasks on a vehicle, or set of vehicles. For example, typical vehicle maintenance may require a service technician to perform an oil change, check fluid levels, inspect or replace filters, inspect and repair tires, etc. In some instances, the performance of such maintenance tasks may be subject to inefficiencies that cause service time delays. Because the maintenance tasks are performed frequently and potentially on multiple vehicles, the service time delays can cause significant throughput delays within a service facility. 
     BRIEF SUMMARY OF THE INVENTION 
     The present disclosure presents new and innovative systems for ensuring service carts are stocked. In one aspect, a service rack system is provided including a service rack and one or more totes. Each of the one or more totes have a full indicator and a refill indicator. The service rack includes a front side, a back side, a right side, and a left side. The front side is directly opposite the back side. The service rack also includes a panel on each of the right and left sides, at least one supply rack angled towards the front side, and at least one return rack angled towards the back side. The at least one supply rack is constructed to support one or more columns of totes such that each column includes at least two totes. Each column of totes has a full state and a refill state. The full state includes at least two totes positioned such that the full indicator of one tote faces the front side. The refill state includes a tote positioned such that its refill indicator is directly adjacent to the front side. 
     In a second aspect according to any of the previous aspects, the full indicator is a first color and the refill indicator is a second color different than the first color. 
     In a third aspect according to the second aspect, the panel is a third color different than the first color and the second color. 
     In a fourth aspect according to any of the previous aspects, the full state includes two totes and the totes are positioned such that the full indicator of a first tote faces the front side and the full indicator of a second tote faces the back side. 
     In a fifth aspect according to any of the previous aspects, the refill state of a column of totes includes one tote remaining in the column of totes. 
     In a sixth aspect according to any of the previous aspects, the at least one return rack is constructed to support one or more columns of totes. 
     In a seventh aspect according to any of the previous aspects, the at least one supply rack and the at least on return rack include one or more adjustable rollers. 
     In an eighth aspect according to any of the previous aspects, the at least one supply rack or the at least one return rack include dividers separating each of the one or more columns. 
     In a ninth aspect according to any of the previous aspects, the at least one supply rack is angled to cause totes located on the at least one supply rack to move towards the front side and the at least one return rack is angled to cause totes located on the at least one return rack to move towards the back side. 
     In a tenth aspect, a service rack system is provided including a service rack and one or more totes. The service rack includes a front side, a back side, a right side, and a left side. The front side is directly opposite the back side. The service rack also includes at least one supply rack angled towards the front side that includes one or more adjustable rollers, and at least one return rack angled towards the back side that includes one or more adjustable rollers. The one or more totes each include at least a full indicator and a refill indicator. The one or more totes are positioned on the at least one supply rack in one or more columns that each include at least two totes. The totes in each column are positioned in one of a full state and a refill state. The full state includes at least two totes positioned such that the full indicator of one tote faces the front side. The refill state includes one tote positioned such that its refill indicator is directly adjacent to the front side. 
     In an eleventh aspect according to the tenth aspect, the service rack includes a panel on each of the right side and the left side of the service rack. 
     In a twelfth aspect according to any of the tenth to eleventh aspects, the full indicator is a first color and the refill indicator is a second color different than the first color. 
     In a thirteenth aspect according to any of the tenth to twelfth aspects, the full state includes two totes, and the totes are positioned such that the full indicator of a first tote faces the front side and the full indicator of a second tote faces the back side. 
     In a fourteenth aspect according to any of the tenth to thirteenth aspects, the refill state of a column of totes includes one tote remaining in the column of totes. 
     In a fifteenth aspect according to any of the tenth to fourteenth aspects, the at least one supply rack or the at least one return rack includes dividers separating each of the one or more columns. 
     In a sixteenth aspect according to any of the tenth to fifteenth aspects, the at least one supply rack is angled to cause totes located on the at least one supply rack to move towards the front side and the at least one return rack is angled to cause totes located on the at least one return rack to move towards the back side. 
     In a seventeenth aspect, a method is provided which includes receiving vehicle fleet data specifying the types of vehicles operating in a vehicle fleet. The method also includes determining, based on the vehicle fleet data, a distribution of vehicle models in the vehicle fleet, and identifying, based on the distribution of vehicle models, vehicle models that are most common in the vehicle fleet. The method also includes identifying service items compatible with the vehicle models that are most common in the vehicle fleet, and identifying, from among the service items compatible with the vehicle models that are most common in the vehicle fleet, service items for storage on a service rack. 
     In an eighteenth aspect according to the seventeenth aspect, the service items for storage on the service rack are also selected to correspond to maintenance tasks that are most frequently performed on vehicles in the vehicle fleet. 
     The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the figures and description. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the disclosed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  illustrates a service facility according to an example of the present disclosure. 
         FIGS. 2A and 2B  illustrate a perspective and front view, respectively, of an empty service rack according to an example of the present disclosure. 
         FIGS. 3A and 3B  illustrate a front view of a service rack with totes and a side view along plane A-A′, respectively, according to an example of the present disclosure. 
         FIGS. 4A and 4B  illustrate individual supply racks constructed to fit more than two totes, according to an example of the present disclosure. 
         FIGS. 5A and 5B  illustrate a perspective view and side view, respectively, of an empty tote according to an example of the present disclosure. 
         FIGS. 6A and 6B  illustrate two aspects of a service station according to an example of the present disclosure. 
         FIG. 7  illustrates a service facility according to an example of the present disclosure. 
         FIG. 8  illustrates a perspective view of a service rack with dividers according to an example of the present disclosure. 
         FIG. 9  illustrates a perspective view of a service rack with spaced apart rollers according to an example of the present disclosure. 
         FIG. 10  illustrates a perspective view of a service rack with panels according to an example of the present disclosure. 
         FIG. 11  depicts a method according to an exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Service facility efficiency may be essential to keep pace with changes in vehicle technology. For example, as vehicle technology advances and becomes more sophisticated, transportation providers may be unaware of how their vehicles actually function and, as a result, transportation providers may be unable to provide specific information to a service technician with respect to any particular problems their vehicle is currently experiencing. Thus, service technicians may perform multiple maintenance tasks on a vehicle in an attempt to rule out certain causes of the problems and/or to detect problems that the transportation provider may not have identified or otherwise noticed. Performing multiple maintenance tasks on a vehicle in an attempt to resolve current maintenance problems and prevent potential maintenance problems is a strategy often used by organizations that rely on fleets of cars for operation. For example, transportation network companies (TNCs) rely on fleets of cars that are used to service transportation requests (e.g., rideshare requests). A vehicle associated with the TNC may be brought in for servicing without any preliminary technical understanding of the maintenance issues the vehicle may be experiencing. Thus, a TNC may systematically perform multiple maintenance tasks on the vehicle in an attempt to identify maintenance issues. While the vehicle is being serviced by the TNC, the vehicle is not available to service transportation requests in the transportation network. 
     Accordingly, any reduction in time spent servicing TNC vehicles may result in additional fleet capacity for the TNC (i.e., the vehicle can spend more time on the road servicing transportation requests). Furthermore, reductions in service times at a service facility may increase the frequency with which vehicle operators (e.g., transportation providers) bring a vehicle to a service facility for servicing (e.g., a driver may be incentivized to service the vehicle because it will not take an extreme amount of time to do so), allowing for continuous maintenance to be performed on the vehicle. Performing continuous and rapid maintenance tasks on the vehicle may increase long-term vehicle reliability of the vehicle because future vehicle problems may be avoided. 
     Maintenance efficiency problems may be even more evident for fleets of autonomous vehicles (AVs). For example, as more rideshare requests are serviced by AVs, TNCs may cultivate AV fleets. Because AVs do not have transportation providers, there is no individual who can provide feedback on the current operation of the vehicle outside of the information available from vehicle&#39;s pre-installed sensors. Therefore, when servicing AVs, maintenance personnel may have to perform an even more rigorous set of maintenance tasks w to identify problems and to determine the causes of identified problems. 
     For example, in a typical vehicle service scenario, service personnel may discuss problems associated with the vehicle being serviced to identify any known problems that the service personnel should address, in addition to performing standard maintenance servicing. For example, a driver may request oil change but may explain to a service technician that one of the tire assemblies vibrates at high speeds. In response, service personnel may inspect the tire assembly in addition to servicing the vehicle (e.g., performing the oil change). If a problem is identified, the service personnel may formulate a repair to resolve the issue, which may require waiting for replacement parts for the tire assembly. Once the tire assembly is repaired, the service technician may test drive the vehicle to verify the repair and, upon completion of the servicing, the driver may pick up their vehicle. 
     For AVs, since there is no driver to identify additional issues with the vehicle, the service personnel may have to perform additional maintenance tasks on a regular basis to identify potential maintenance problems. For example, rather than relying on a driver to identify that a tire assembly is vibrating at high speeds before inspecting a tire assembly, AV service personnel may routinely perform the tire assembly inspection. In the context of TNC fleets of AVs, AV service personnel may inspect the vehicle&#39;s tire assemblies during regular maintenance visits, in addition to performing other maintenance tasks. 
     Vehicle fleet operators such as TNCs may also incorporate additional maintenance tasks for preventative purposes, even for vehicles that are not autonomous. For example, if the tire assemblies are inspected at each maintenance visit, potential problems with the tire assemblies may be detected and repaired before the tire assembly becomes a more serious maintenance issue. Such preventative maintenance may increase vehicle uptime for the TNCs and may allow transportation providers to continue operating their vehicles more often and/or for longer periods of time. Furthermore, as the size of vehicle fleets grows, there may be greater pressure on service facilities to process a greater number of vehicles in the same amount of time, which increases the need to perform maintenance tasks (e.g., preventative and/or standard maintenance tasks) in a time-efficient manner. Accordingly, there exists a need to expedite the performance of maintenance tasks on vehicles that are serviced within a service facility. 
     Another factor contributing to inefficiencies with regard to maintenance tasks is ensuring service technicians have the necessary service items (e.g., tools, parts, consumables, equipment, etc.) for completing any given maintenance task, so that the service technicians do not have to spend significant amounts of time locating the necessary service items. As used throughout this disclosure, service items may refer to any tool, part, consumable, equipment, etc. that a service technician may need to perform a maintenance task on a vehicle. Such tools may be wrenches, sockets, tire irons, and other tooling used for vehicle maintenance. Such parts may be drain plugs, lug nuts, hex bolts, oil caps, O-rings, air filters, oil filters, fuel filters, and other vehicular parts. Consumables may be automobile oil, transmission fluid, battery cleaner, brake cleaner, and other chemicals, fluids, etc., used for and/or during the performance of maintenance tasks. Equipment may be gloves, ear plugs, face masks, and/or other personal safety items a service technician may need to complete a service task. 
     For instance, when a vehicle arrives for at a service facility for maintenance, a service technician either already knows the maintenance task that is required (e.g., from a repair order) or must perform a diagnostic to identify a needed maintenance task. Once the maintenance task is determined, the service technician must obtain the necessary service items for the task that are compatible with the specific vehicle (e.g., model or type) being serviced. For example, the service technician may need to change the transmission fluid in the vehicle and thus must obtain transmission fluid, or the service technician may need to obtain a wrench and bolt to replace a bolt on a wheel. If the necessary service items are not nearby, the service technician may have to walk across a service facility to obtain the service items from another location, such as a parts storage location or room, which ultimately lengthens the time required to perform and complete the maintenance task. In some instances, the service technician may not know where to find a particular service item, thus further increasing the time required to perform the maintenance task. Because most, if not all, maintenance tasks require at least one service item, any decrease in the amount of time required for a service technician to obtain the necessary service items may drastically improve a service facility&#39;s ability to service more vehicles and thereby improve the overall performance of the service facility. 
     One solution to the problem described above is to establish a service facility that effectively divides maintenance tasks into subgroups that can be performed at different stations located within the service facility. For example,  FIG. 1  depicts a service facility  100  including service stations  20 ,  30  servicing separate vehicles  10 ,  12 . Each service station  20 ,  30  may correspond to the performance of different maintenance tasks. For example, service station  20  may correspond to performing maintenance tasks related to fluids (e.g., changing the oil, checking transmission fluid). Service station  30  may correspond to performing inspections and repairs of tire assemblies. As servicing is complete at one station  20 ,  30 , the vehicles  10 ,  12  may move to the next station. For example, after vehicle  10  has its oil changed at station  20 , the vehicle  10  may proceed to service station  30  for tire assembly inspection. 
     Each service station  20 ,  30  may require separate service items for performing the maintenance tasks corresponding to the respective station. For example, the service station  20  includes a rack  26  storing fluids which may be replaced during maintenance, along with fluid lines  24 , which may route to larger tanks of fluids (e.g., different types of oil) that are commonly replaced during maintenance of a vehicle. Similarly, service station  30  includes a compressed air line  34 , which may be used to refill tires (e.g., to a desired tire pressure). Both service stations  20 ,  30  also include a tool cart  22 ,  36  respectively. These tool carts  22 ,  36  may contain certain service items necessary for performing the maintenance tasks at service station  20 ,  30 . For example, the tool cart  22  may include tools such as wrenches or sockets in common sizes necessary to loosen drain plugs on oil pans, and may also include replacement drain plugs for a variety of vehicles. As another example, the tool cart  36  may include filters (e.g., fuel filters or oil filters) for replacing old filters on vehicles. Each service station  20 ,  30  also includes a lift  28 ,  32  for use in performing maintenance tasks on vehicles, although other service stations that are not depicted may not include a lift in certain instances. 
     Even though efficiency may increase by separating the maintenance tasks into different service stations  20 ,  30 , the performance of certain maintenance tasks may still be improved. For example, in some instances, a tool cart  22 ,  36  may run out of a certain service item, causing the service technician t to spend time retrieving the service item that could have otherwise been spent performing maintenance tasks. Thus, the time that it takes to obtain the necessary service item increases the amount of time it takes to complete the maintenance task, and accordingly limits efficiency. One solution to this problem is for service technicians to notify a service facility worker when a particular service item in the tool cart  22 ,  36  is low so that the service facility worker can restock the particular service item prior to it running out. However, a service technician may easily forget to notify a service facility worker, and they may easily forget to restock the service item. Additionally, notifying the service facility worker to restock service items consumes time that a service technician could instead spend performing maintenance tasks. 
     Another solution is for the service facility worker to periodically check the levels of all the service items in the tool carts  22 ,  36  and restock the service items that are low. However, different service items are used at different rates, sometimes unpredictably, and thus service items may run out between instances in which the service facility worker checks the service item levels. Additionally, the service facility worker may check the tool carts  22 ,  36  and see that none of the service items are running low, causing the service facility technician to waste time. Furthermore, such a process is inefficient because the tool carts  22 ,  36  are only accessible from a single side, and each drawer must be inspected individually. Such configurations require the service facility technician to intervene in the performance of maintenance tasks by the service technician, further reducing the efficiency of performed maintenance tasks. 
     To solve these technical problems, among others, the present disclosure provides a service rack system that can be utilized to efficiently ensure that service technicians have the necessary service items at their disposal to perform maintenance tasks in a time-efficient manner. The service rack system may include a service rack with multiple racks and multiple totes positioned on the multiple racks. The multiple totes may contain various service items. Some of the multiple racks may be angled towards the front side of the service rack and some of the racks may be angled towards the back side of the service rack. Each of the totes may include two indicators, the first indicator indicating that the supply of the respective service items is full, or sufficiently full, and the second indicator indicating that a refill is needed for the respective service item. Accordingly, the totes may be positioned on the racks angled to the front side such that when the racks are full and a service technician views a service rack from its front side, the service technician sees only the first indicator of each tote at the service rack&#39;s front side. 
     When a tote is empty, a service technician may remove it from its rack, which causes a full tote behind the empty tote to move into the empty tote&#39;s place due to the rack&#39;s angle toward the front side of the service rack. In some examples, the full tote may be positioned on the rack such that the service technician sees its second indicator at the rack&#39;s front side, thus indicating to the service technician that the service items corresponding to or otherwise associated with the tote need a refill. The service technician may place the empty tote on a rack angled to the back side with the tote&#39;s second indicator facing the back side. Thus, when a service facility worker views the service rack from its back side, the worker knows one or more service items need refilling in the event the worker can see the second indicator of any totes. Accordingly, the technician may refill the empty totes and place them back on a rack angled to the front side before the service technician runs out of any service item. 
       FIGS. 2A and 2B  illustrate a service rack  200  according to an example of the present disclosure. The service rack  200  may include at least one supply rack  210  and at least one return rack  220 . For instance, the service rack  200  is shown as having four supply racks  210  and one return rack  220 . In other instances, however, the service rack  200  may include more or less supply racks  210  and/or more return racks  220 . In some examples, the service rack  200  is configured top of the service rack  200  is located at a height from the ground that does not interfere with the vision across the service facility for a majority of people (e.g., the service rack  200  does not block a line of sight). For instance, the service rack  200  may be no more than four and a half feet tall in some examples given that a majority of people may see over such a service rack  200 . In such implementations, the service rack  200  may allow those working in the service facility to visually survey the service facility (e.g., see a tote&#39;s second indicator on a service rack from across the facility) and thus enhance efficiency. 
     As depicted in  FIGS. 2A and 2B , each of the supply racks  210  is angled towards the front side of the service rack  200  and the return rack  220  is angled in the opposite direction towards the back side of the service rack  200  (will be additionally depicted and explained in further figures). In some examples, each of the supply racks  210  and return racks  220  include multiple rollers  230 , which will be described in more detail below. In some examples, the service rack  200  may also include wheels  240 A-D (wheel  240 D not depicted). The wheels  240 A-D may enable easier movement of the service rack  200 . For example, the service rack  200  may be moved from service station  20  to service station  30 , for example if/when the service item requirements of the stations change. 
       FIGS. 3A and 3B  illustrate a service rack system  300  that includes a service rack  200  and multiple totes  310 , according to an example of the present disclosure. In particular,  FIG. 3B  illustrates a side view of the service rack system  300  at the plane A-A′ designated in  FIG. 3A . Each of the totes  310  is constructed to hold one or more of various service items. For clarity, only a single tote  310  is labeled, but references to totes  310  should be understood to refer to any such depicted tote. The totes  310  are positioned on the supply racks  210  in multiple columns and at least two rows. For instance, the totes  310  are positioned in columns r-z and rows g, h in the example service rack system  300 . Accordingly,  FIG. 3B  depicts a side view of column v of the service rack system  300  along plane A-A′. In some examples, each column r-z is dedicated to a particular service item, and thus each tote  310  in a specific column (e.g., two totes  310  if there are two rows) holds one or more of the particular service item. In some examples, each tote  310  may be labeled with the name of the particular service item the tote is supposed to hold. A column of totes  310  may either be in a full state or a refill state, which will be described in more detail below. 
     In various examples of the present disclosure, each of the totes  310  includes a full indicator  320  (e.g., first indicator) and a refill indicator  330  (e.g., second indicator). The full indicator  320  may indicate that there is a sufficient amount of the particular service item associated with a column of totes  310  on the supply rack  210 . The refill indicator  330  may indicate that there is not a sufficient amount, and further, that the particular service item associated with the column of totes  310  needs to be refilled. In some examples, the full indicator  320  may be a first color (e.g., blue) such that a portion of a tote  310  is the first color, and the refill indicator  330  may be a second, different color (e.g., orange) such that the remaining portion of the tote  310  is the second color. In some examples, the two colors are distinctly different such that they may be quickly differentiated (e.g., orange and blue, red and green). The two different colors are depicted in the accompanying figures by two different shading patterns on the totes  310 . In other examples, color associated with the full indicator  320  and the color associated with the refill indicator  330  color may collectively cover a portion of the tote  310  less than the entirety of the tote  310  (e.g., only the front and back, respectively). In other examples, the full and refill indicators  320 ,  330  may be distinctive visual indications other than colors, for instance, text, lights, images, tote design, visual patterns, etc. 
     In at least one example of the present disclosure, the service rack system  300  may additionally include optical sensors on the service rack  200 . The optical sensors may be configured to detect the color of a surface. In the at least one example, the optical sensors may be positioned on the service rack  200  such that they sense the surface color of the portion of each of the totes  310  that is adjacent to the front side of a supply rack  210  and/or adjacent to the back side of a return rack  220 . Accordingly, when the optical sensors detect that the color of the refill indicator  330  is present, the optical sensors may cause an action to be triggered. For instance, the optical sensors may light up, may cause the service rack  200  to light up, or may cause an empty tote  310  to light up when detecting the refill indicator  330  color. In other instances, as will be described in more detail below, the optical sensors may send a signal to an automated robot when detecting the refill indicator  330  color, thus causing the automated robot to activate and refill an empty tote  310 . 
     In at least one example of the present disclosure, the service rack system  300  may additionally include radio frequency identification (“RFID”) sensors, such as a virtual wall, and the service items in the totes  310  may include RFID tags. Accordingly, the RFID sensors (e.g., virtual wall) may detect service items being used and may cause additional service items to be ordered when the remaining service items reach a certain threshold. In some instances, the virtual wall may span the entire front side of the service rack  200 , the entire rear side of the service rack  200 , and/or may span across each side of the service rack  200 . 
     In various aspects, the totes  310  may be positioned on the supply racks  210  and return racks  220  based on their indicators  320 ,  330 . As will be further described below, the tote  310  positioning provides visual indications to those working in a service facility as to the state of the supply of various service items on the service rack  200 . A service rack  200  may be considered full when there is a tote  310  in every column and every row on each of the supply racks  210 , or when there is a tote in every column and every row of the supply racks in which a part is intended to be stored. In some examples, when a service rack  200  is full, there are no totes  310  on any return rack  230  of the full service rack  200 . The totes  310  on a full service rack  200  may be positioned such that each of the totes  310  adjacent to the front side of the service rack  200  (e.g., row h in  FIG. 3B ) has its full indicator  320  facing towards the front side of the service rack  200  (e.g., the front side of the supply rack  210  the tote  310  is on). Accordingly, when a service technician or other person views a full service rack  200  from the front, they will primarily see only the full indicator  320  of each tote  310 , and will primarily not see the refill indicator  330  of any tote  310 . In addition, the totes  310  on a full service rack  200  may be positioned such that each of the totes  310  closest to the back side of the service rack  200  (e.g., row g in  FIG. 3B ) has its full indicator  320  facing towards the back side of the service rack  200 . Accordingly, when a service facility worker or other person views a full service rack  200  from the back, they will primarily see only the full indicator  320  of each tote  310 , and will primarily not see the refill indicator  330  of any tote  310 . Therefore, a column of totes  310  on a respective supply rack  210  is in a full state when there are at least two totes  310  in the column, the tote  310  adjacent to the front side of the service rack  200  has its full indicator  320  facing towards the front side, and the tote  310  closest to the back side of the service rack  200  has its full indicator  320  facing towards the back side. 
     In some examples of the present disclosure, such as the illustrated examples, the service rack  200  is constructed such that its respective supply racks  210  fit two rows of totes  310 . The respective return racks  220  may also fit two rows or may fit other numbers of rows (e.g., 1 or 3). In such examples, in accordance with the description in the preceding paragraph, the two totes  310  in the same column on the same supply rack  210  of a full service rack  200  are positioned such that their respective refill indicators  330  face one another. Thus, when the front side tote  310  is removed from the supply rack  210 , the back side tote  310  moves forward to take its place and the back side tote  310  then accordingly has its refill indicator  330  facing towards the front side of the supply rack  210  (e.g., the front side of the service rack  200 ). Such a column of totes  310  is therefore in a refill state because a tote  310  in the column has its refill indicator  330  adjacent to the front side of the supply rack  210 . When the front side tote  310  is removed, due its initial orientation on the supply rack  210 , the front side tote  310  may be placed on the return rack  220  with its refill indicator  330  facing towards the back side of the return rack  220  (e.g., the back side of the service rack  200 ). For instance, the tote  314  is illustrated in  FIGS. 3A and 3B  as having been removed from column v on the second supply rack  210  from the top and subsequently placed on the return rack  220  with its refill indicator  330  adjacent to the back side of the return rack  220 . Accordingly, the tote  312  is illustrated as having moved forward to take the place of the tote  314 , and the tote  312  has its refill indicator  330  adjacent to the front side of the supply rack  210 . 
     Therefore, in this way, when the example service rack system  300  is viewed from the front as illustrated, the refill indicator  330  of the tote  312  is visible, thus indicating that the service items associated with the totes  312 ,  314  are low on the service rack  200 . In addition, the refill indicator  330  of the tote  314  is visible when the example service rack system  300  is viewed from the back. Therefore, no matter if the service rack system  300  is viewed from the front or the back, those working in the service facility may be able to see the refill indicator  330  and can accordingly restock the service items of the respective tote  310  before the service rack system  300  runs out of that service item. 
     In other aspects of the present disclosure, the service rack  200  is constructed such that its respective supply racks  210  fit more than two rows of totes  310 . In such examples, the one or more return racks  220  may fit the same number of rows as the corresponding supply racks  210  or may fit a different number of rows. In some examples in which the supply racks  210  fit more than two rows, the totes  310  in the middle of the front side tote  310  and the back side tote  310  may be positioned in the same manner as the front side tote  310 . For instance, as illustrated in  FIG. 4A  on the example supply rack  410 , the totes  404  and  406  are in the middle of the front side tote  402  and the back side tote  408 , and are positioned with their respective full indicators  320  and refill indicators  330  in the same manner as the front side tote  402 . For clarity, the full and refill indicators  320  and  330  are only labeled on the tote  402 ; however, they are consistent with the shading patterns among the totes  404 - 408  indicating that the totes  404 - 408  include similar indicators. Accordingly, when the tote  402  is removed from the supply rack  410  and the tote  404  moves forward to replace it, the tote  404  has its full indicator  320  adjacent to the front side of the supply rack  410 . Similarly, when the tote  404  is removed and the tote  406  moves to replace it, the tote  406  has its full indicator  320  adjacent to the front side of the supply rack  410 . However, when the tote  406  is removed and the back side tote  408  reaches the front side of the supply rack  210 , the tote  408  has its refill indicator  330  adjacent to the front side indicating to those in the service facility that the service items in the respective column need to be refilled. The removed totes  402 - 406  may be placed on the return rack  220  consistent with the preceding description to indicate to those viewing the service rack system  300  from behind, of which the example supply rack  410  is a part, that the service items need to be refilled. 
     In other examples in which the supply racks  210  fit more than two rows, it may be desired to indicate to those in the service facility that a particular service item needs to be refilled prior to the back side tote  310  reaching the front side of the supply rack  210 . In such instances, one or more of the middle totes  310  may be positioned in the same manner as the back side tote  310 . For instance, as illustrated in  FIG. 4B  on the example supply rack  410 , the tote  406  is positioned with its full indicator  320  and refill indicator  330  in the same manner as the back side tote  408 . Accordingly, when the tote  402  is removed from the supply rack  410  and the tote  404  moves to replace it, the tote  404  has its full indicator  320  adjacent to the front side of the supply rack  410 . However, in contrast to the example illustrated in  FIG. 4A , when the tote  404  is removed and the tote  406  moves to replace it, the tote  406  has its refill indicator  330  adjacent to the front side of the supply rack  410 . Therefore, it is indicated to those in the service facility that the service items in the respective column need to be refilled when there are still the two totes  406  and  408  on the supply rack  410 . Again, the removed totes  402 ,  404  may be placed on the return rack  220  to indicate to those viewing the service rack system  300  from behind (of which the example supply rack  410  is a part) that the respective service items need to be refilled. Accordingly, the indication being made with two full totes  406 ,  408  remaining on the supply rack  410  may provide additional time for those in the service facility to refill the respective service items prior to the service rack system  300  running out of the respective service item, as compared to the example described in  FIG. 4A . Thus, efficiency and/or supply level resiliency may be increased in such configurations. 
     As described above in connection with multiple examples, a tote  310  may move on its respective supply rack  210  or return rack  220 . For instance, a tote  310  may move when a tote  310  in front of it is removed, or when the tote  310  is placed on the supply rack  210  or the return rack  220  without a tote  310  in front of it. The totes  310  may move due to the angle of the supply racks  210  and return racks  220  that cause the totes  310  to have a tendency to move towards the lowest part of its respective supply rack  210  or return rack  220  due to gravitational forces. For example, the totes  310  on supply racks  210  have a tendency to move towards the front side of the service rack  300  and the totes  310  on return racks  220  have a tendency to move towards the back side of the service rack  300 . In some examples of the present disclosure, the surface of each of the supply racks  210  and return racks  220  may help facilitate the totes  310  moving. For instance, the surface of each may have a low coefficient of friction (e.g., a slick surface) such that the totes  310  may slide along the surface due to only gravitational forces. In other examples, each of the supply racks  210  and return racks  220  may have multiple rollers  230  that rotate as the totes  310  move over them in accordance with gravitational forces. The rollers  230  may reduce sliding forces on the bottom of the totes  310  even further, and thus may prolong the life of the totes  310  before needing to be replaced. 
       FIGS. 5A and 5B  illustrate perspective and side views of a tote  310 , according to an example of the present disclosure. As described above, the tote  310  includes a full indicator  320  and a refill indicator  330 , which each may be a color over a portion of the tote  310 . In various examples, each tote  310  may also include a label at location  500 , the label designating which service items are in the respective tote  310 . In other examples, each tote  310  may include a label at a different location. The label may be text, an image, a color, or another designation for specifying the service items stored or intended for storage in the tote. Each tote  310  is constructed to hold one or more service items, and thus may have any suitable design that enables the tote  310  to both hold one or more service items, and be positioned on the supply racks  210  and return racks  220  as described above. Accordingly, the illustrated design of the tote  310  is merely one example. In some examples of the present disclosure, there may be totes  310  of different sizes and designs utilized on the same service rack  200 . 
       FIG. 6A  depicts one example of a service station  600  in which a service technician  602  is performing a maintenance task on a vehicle  12  and a service facility worker  604  is placing a refilled tote  610  on a service rack system  300 . The service technician  602  is at the front side of the service rack system  300  and the service facility worker  604  is at the back side of the service rack system  300 . For instance, the service technician  602  may have previously used all of the service items in the tote  610  and placed an empty tote  610  on the return rack  220  with its refill indicator  330  facing the back side. The tote  612  therefore moved forward with its refill indicator  330  adjacent to the front side. The service facility worker  604  may have then seen the refill indicator  330  of either the tote  610  or the tote  612  and accordingly took the empty tote  610  to refill it.  FIG. 6A  illustrates the service facility worker  604  placing the refilled tote  610  back on the service rack  200  on its respective supply rack  210  at its respective column. 
     In some aspects of the present disclosure, the service facility worker  604  may place the refilled tote  610  on the supply rack  210  such that its full indicator  320  faces towards the front side of the supply rack  210 . Accordingly, in such instances, when the tote  612  is removed and refilled, the tote  610  will move forward and its full indicator  320  will be adjacent to the front side. This aspect is illustrated in  FIG. 6A . In other aspects of the present disclosure, the service facility worker  604  may place the refilled tote  610  on the supply rack  210  such that its refill indicator  230  faces towards the front side of the service cart  300  and also may position the tote  612  such that its full indicator  220  is adjacent to the front side of the service cart  300 . Accordingly, in this way, the service facility worker  604 , after refilling the tote  610 , positions the totes  610  and  612  to reflect that their respective column is in a full state. 
       FIG. 6B  illustrates another example of the service station  600  in which a service technician  602  is performing a maintenance task on a vehicle  12  and an automated service robot  620  refills and replaces the tote  610  on the supply rack  210 . The automated service robot  620  may be in addition to or may replace the service facility worker  604  in various instances. In some examples, the automated service robot  620  may include an arm with multiple links and joints and a gripper for gripping items, such as the totes  610  and  612 . In other examples, the automated service robot  620  may have other suitable configurations for retrieving empty totes  310  from a return rack  220 , refilling the empty tote  310 , and placing the refilled tote  310  on a supply rack  210 . 
     In some examples, a service facility worker  604 , service technician  602 , or other person may trigger the automated service robot  620  to cause it to retrieve and refill totes  310 , for example, by pressing a button. In other examples, the automated service robot  620  may be automatically activated. For instance, in examples in which the service rack  200  includes optical sensors as described above, the optical sensors may send a signal to the automated service robot  620  upon detecting a refill indicator  330 , the signal activating the automated service robot  620 . 
     In some instances, such as that illustrated in  FIG. 6B , the automated service robot  620  may retrieve an empty tote  610  from a return rack  220 , with its refill indicator  330  adjacent the back side of the return rack  220 , and may then raise the empty tote  610  and place it on its respective supply rack  210  with its refill indicator  330  facing the front side of the supply rack  210 . The automated service robot  620  may then refill the tote  610  with service items when the tote  610  is on the supply rack  210 , in such instances. For example, the automated service robot  620  may obtain service items directly from a truck and place them in the tote  610  on the supply rack  210 . In other instances, the automated service robot  620  may retrieve an empty tote  610  from a return rack  220  and transport it to another area in the service facility to refill the tote  610  with service items. For example, the automated service robot  620  may transport the tote  610  to an area by a truck containing service items and may refill the tote  610  with service items directly from the truck. The automated service robot  620  may then transport and place the refilled tote  610  on its respective supply rack  210 . 
     The service station  600  may be located in a service facility similar to the service facility  100 . For example,  FIG. 7  illustrates a service facility  700  including two service stations  600 , each with a service rack system  300 . The service facility  700  also includes the other components described in connection with the service facility  100 . Accordingly, the service rack systems  300  can be used to enhance the station-based maintenance facilities discussed above, further improving service times and overall facility throughput as increasingly necessary to servicing vehicles and vehicle fleets. 
     In addition to the above discussed and illustrated examples of the service rack  200 , further examples may also be utilized. For example,  FIG. 8  illustrates an example service rack  800  that includes dividers  802  on each of the supply racks  810 . The dividers  802  may delineate each of the columns of totes  310 , and accordingly may enhance the organization of the totes  310  on the supply racks  810 . In some examples, the one or more return racks  820  may also have dividers  802 . In addition, the supply racks  810  are illustrated as having a slick surface  804  (e.g., a surface having a low coefficient of friction) as described above. The return rack  820  is illustrated as having rollers  230 . In other examples, the return rack  820  may also have a slick surface  804 . In other examples, the supply racks  810  may have rollers  230  and the return rack may have a slick surface  804 . 
       FIG. 9  illustrates an example service rack  900  with adjustable rollers  230 . For instance, the supply rack  910  is shown as having rollers  230  spaced apart with a gap P in between each individual strip of rollers  230 . In comparison, the supply rack  912  is shown as having rollers  230  spaced apart with a gap Q in between each individual strip of rollers  230 . In addition, the supply rack  910  has eight strips of rollers  230  whereas the supply rack  912  has four strips of rollers  230 , thus indicating that in some instances the strips of rollers  230  may be removable. The adjustability of the rollers  230  may help reduce material costs for a service facility. For instance, larger totes  310  or other items may be larger than the gap Q and thus may move on two adjacent rollers  230  while remaining on the supply rack  912 . A tote  310  or other item narrower than the gap Q would fall through the gap or would have to balance on one strip of rollers  230 , thus such totes  310  or other smaller items require rollers  230  with narrower gaps in between, such as the gap P in the supply rack  910 . Accordingly, for the larger items, fewer strips of rollers  230  are required and can be used elsewhere, such as other supply racks or other service racks, thus helping reduce material costs for the service facility. 
       FIG. 10  illustrates an example service rack  1000  with a panel  1002  on each of the left side and the right side of the service rack  1000 . In some examples, each panel  1002  may be opaque and may be any color. In some examples, each panel  1002  may be a color that is different than a full indicator  320  color and a refill indicator  330  color in order to create contrast between the three colors. For instance, each panel  1002  may be white, while the full indicator  320  is blue and the refill indicator  330  is orange. The panels  1002  may prevent a line of sight to the totes  310  when viewing a service rack system  300  from the side. For instance, viewing a service rack system  300  without panels  1002  from the side (e.g.,  FIG. 6 ) results in seeing both the full indicators  320  and the refill indicators  330  of each of the totes  310  on the service rack  200 . Conversely, viewing the service rack  1000  with panels  1002  from the side results in seeing only a panel  1002 . Accordingly, the full indicators  320  and refill indicators  330  of the totes  310  on the service rack  1000  may only be viewed from the front or back of the service rack  1000 . The effect of the panels  1002 , therefore, is that those in the service facility will primarily only see a refill indicator  330  of a tote  310  if a tote  310  needs to be refilled, rather than sometimes seeing a refill indicator  330  from the side even though the service rack system  300  is full. As such, when a refill indicator  330  is visible, it will always indicate a problem with the respective service rack system  300  and service items that must be refilled. Efficiency may accordingly be improved. 
       FIG. 11  depicts a method  1100  according to an exemplary embodiment of the present disclosure. The method  1100  may be performed to identify and select service items for storage within service racks  200 ,  800 ,  900 ,  1000 . In particular, the method  1100  may be performed to select the service items stored in the totes  310 ,  402 ,  404 ,  406 ,  408 ,  500 ,  610 ,  612 . The method  1100  may be implemented by a computer system, such as a computer system containing a processor and a memory. The method  1100  may also be implemented by a set of instructions stored on a computer-readable medium that, when executed by a processor, cause the computer system to perform the method. Although the examples below are described with reference to the flowchart illustrated in  FIG. 11 , many other methods of performing the acts associated with  FIG. 11  may be combined with other blocks, one or more of the blocks may be repeated, and some of the blocks described may be optional. 
     The method  1100  begins with receiving vehicle fleet data (block  1102 ). The vehicle fleet data may specify the types of vehicles that operate in a given fleet (e.g., vehicles providing services in connection with a TNC). In particular, the vehicle fleet data may specify the make and model of vehicles operating in the vehicle fleet. Based on this data, a distribution of vehicle models may be determined (block  1104 ). For example, the vehicle fleet data may be analyzed to determine how many of each vehicle model operate in the vehicle fleet. In particular, the distribution of vehicle models may indicate a percentage of vehicles each vehicle model represents within the vehicle fleet. The most common vehicle models may then be identified (block  1106 ). For example, the most common vehicle models may be identified within the distribution of vehicle models. In certain implementations, the most common vehicle models may be selected as a predetermined number of most common vehicles (e.g., the  10 ,  20 , or  50  most common vehicle models). In other implementations, the most common vehicle models may be selected to represent a certain percentage of vehicles in the vehicle fleet (e.g., the most common vehicle models that represent 50%, 75%, 90%, 95% of the vehicles in the vehicle fleet). In certain implementations, the vehicle fleet data may specify a year of manufacture for the vehicles in the vehicle fleet. In such instances, the distribution of vehicle models and the most common vehicle models may also specify the year of manufacture for their respective vehicle models. 
     Service items may then be identified that are compatible with the most common vehicle models (block  1108 ). For example, service item data may be analyzed that specifies which types of vehicle models the service items are compatible with. In certain instances, service items may be compatible with more than one type of vehicle or vehicle model. Similarly, in certain instances, certain vehicle models may be compatible with more than one of the same type of service item. The service items for storage may then be selected from among the service items that are compatible with the most common vehicle models (block  1110 ). For example, the service items may be selected to reduce the total number of individual types of service items, and therefore totes  310 ,  402 ,  404 ,  406 ,  408 ,  500 ,  610 ,  612 , on the service racks  200 ,  800 ,  900 ,  1000 . In particular, service items may be preferentially selected where possible that are compatible with more than one of the most common vehicle models. As another example, the service items may be selected to represent the most common maintenance tasks. In particular, service items associated with common maintenance tasks (e.g., fluid changes, filter replacement) may be selected, while service items associated with less common maintenance tasks (e.g., vehicle body repairs) may not be selected. 
     Once selected, the service items may be stored on service racks  200 ,  800 ,  900 ,  1000  for use during vehicle maintenance operations as described above. By selecting the parts according to the method  1100 , the total number of parts necessary for storage on the service racks  200 ,  800 ,  900 ,  1000  may be reduced, which may allow the service racks  200 ,  800 ,  900 ,  1000  to store additional parts (e.g., parts for more vehicle models and/or parts to service more types of vehicle maintenance tasks). 
     Without further elaboration, it is believed that one skilled in the art can use the preceding description to utilize the claimed inventions to their fullest extent. The examples and embodiments disclosed herein are to be construed as merely illustrative and not a limitation of the scope of the present disclosure in any way. It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles discussed. In other words, various modifications and improvements of the embodiments specifically disclosed in the description above are within the scope of the appended claims. For example, any suitable combination of features of the various embodiments described is contemplated. The scope of the invention is therefore defined by the following claims.