Abstract:
A method of operating a material transport vehicle (“MTV”), for transporting glass substrates used in the manufacture of image arrays in a clean room factory environment includes accepting a user input for initiating forward motion of the MTV, configuring a plurality of safety zones proximate to the MTV, detecting an intrusion into one of the plurality of safety zones, and limiting a maximum allowable forward motion of the MTV by an amount determined by the proximity of the safety zone to the MTV. The method includes further steps for additional safety, cleanliness, productivity, and maintainability improvements.

Description:
RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of priority to U.S. Patent Application No. 62/169,401, filed Jun. 1, 2015 which is hereby incorporated by reference in its entirety for all purposes as if fully set forth herein. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates, in general, to a material transport vehicle (“MTV”), and, more particularly, to software, systems and methods for improving the safety and the clean room compatibility of the MTV. 
       2. Relevant Background 
       [0003]    Material transport vehicles for transporting materials throughout a factory environment are well-known in the art. While such vehicles may be readily purchased, their suitability for transporting expensive materials in a clean room environment may be limited. For example, collisions with numerous obstacles in the factory environment may cause damage to the material payload. Further, commercially available vehicles may not possess the level of cleanliness demanded in a clean room environment due to the undesirable emission of particles. What is desired is a semi-automated MTV having further safety and cleanliness improvements, as well as other productivity and maintainability improvements, more suitable for transporting expensive materials in a clean room factory environment when compared to an existing commercially available MTV. 
       SUMMARY OF THE INVENTION 
       [0004]    Briefly stated, the present invention includes improvements to a semi-automated MTV used to transport cassettes containing glass substrates in the manufacturing of large area amorphous silicon imaging arrays or flat panel displays. These improvements enhance: safety of personnel, product, and equipment; improve production line efficiencies, increase product yields, and improve equipment uptime and maintainability. The MTV according to the present invention is an improved semi-automated platform that is driven by a human operator using a hardwired joystick to transport glass substrates held within containers called cassettes to various locations on the manufacturing floor. The improved MTV of the present invention includes a number of improvements to the current MTVs for providing enhanced point to point material transport of glass substrates inside a cleanroom environment. 
         [0005]    These improvements to the MTV are listed below in summary fashion and are further described below: 
         [0006]    The addition of a collision avoidance system to govern the speed and motion of the MTV, given a human operator&#39;s drive command input. 
         [0007]    The addition of a wireless material tracking system, providing identification of cassettes within the MTV and the location of the MTV while it is docked. 
         [0008]    Lower frame enhanced vibration control of the MTV by replacing the standard casters with shock absorbing spring loaded casters. 
         [0009]    Improved vibration control at the cassette level, by replacing the existing sorbothan pads with pneumatic spring mounts at the cassette support interface. 
         [0010]    Replacement of the motors on the cassette transfer mechanism, simplifying power requirements and increasing cassette transfer control. 
         [0011]    The elimination of extensive AC circuitry to power the cassette transfer motors and the removal of the complicated AC operation to DC operation switching circuitry. 
         [0012]    The reduction of particles by replacing particle generating materials and components such as the sorbothan pads, spring mounts, brushed motors and the soft durometer caster wheels. 
         [0013]    Increased reliability by replacing the physical matting electrical docking connections with a non-contact inductive charging system. 
         [0014]    Increased usability by implementing an automated docking to maneuver the MTV into the material transfer point/charging docking station. 
         [0015]    Increased safety, reliability, and maintainability by the incorporation of battery temperature, current, and voltage monitoring to prevent hazardous thermal run-a-way conditions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  shows a side view of an improved MTV according to the present invention; 
           [0017]      FIG. 2  shows a front view of an improved MTV according to the present invention; 
           [0018]      FIG. 3  shows a cassette transfer view of an improved MTV according to the present invention; 
           [0019]      FIG. 4  shows a collision avoidance block diagram for the MTV according to the present invention; 
           [0020]      FIG. 5  shows a plurality of safety zones associated with the operation of the MTV according to the present invention; 
           [0021]      FIG. 6  shows a safety zone flow chart associated with the operation of the MTV according to the present invention; 
           [0022]      FIG. 7  is a diagram of a wireless communication network associated with the operation of the MTV according to the present invention; 
           [0023]      FIG. 8  is a diagram of spring loaded casters used by the MTV according to the present invention; 
           [0024]      FIG. 9  shows a front view diagram of pneumatic vibration control mounts used by the MTV according to an embodiment of the present invention; 
           [0025]      FIG. 10  is a diagram of magnetic vibration control mounts used by the MTV according to an embodiment of the present invention; 
           [0026]      FIG. 11  is a diagram of the power source used by the MTV according to the present invention; and 
           [0027]      FIG. 12  is an electronics block diagram used by the MTV according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    A material transport vehicle overview is now described with particular reference to drawing  FIGS. 1-3 .  FIG. 1  shows a side view  100  of the MTV,  FIG. 2  shows a front view  200  of the MTV, and  FIG. 3  shows a cassette transfer side view  300  of the MTV.  FIGS. 1-3  show the same MTV and thus use the same component designation numerals. 
         [0029]      FIG. 1  depicts the side view of the Material Transport Vehicle (MTV). The MTV consists of several integrated components to provide advanced functionality as is described in further detail below. 
         [0030]    The MTV includes the following material tracking system components: 
         [0031]    Items in the material tracking system include: a wireless network client  1 , which can include, for example, a Moxa, AirWorks AWK-1121, a networked MTV docking barcode camera  2 , which can be, for example, a Keyence, SR-751, a networked cassette barcode camera  3 , which can be, for example a Keyence, SR-751, along with a network switch (not explicitly shown, but housed in electronics panels  13 ) make up the onboard wireless material tracking system. The wireless material tracking system communicates with a factory hest server via remote access points reporting the MTV docked locations and the specific cassette contained within the MTV. The wireless communication system of the MTV is described in further detail below with reference to  FIG. 7 . 
         [0032]    The MTV includes the following collision avoidance system components: 
         [0033]    Items in the collision avoidance system include: a safety laser scanner  6 , which can include, for example, a Keyence, SZ04M, a drive motor controller  12 , which can include, for example a RoboteQ, HBL2350, a joystick  14 , which can be of conventional design, and a programmable controller (not explicitly shown, but housed in electronics panels  13 ), which can be, for example a Mitsubishi, Q series PLC are the primary components of the collision avoidance system. These items are closely integrated to act as a speed and motion governor, limiting the available forward and turning speed the MTV given the proximity to objects in the area of motion. Additionally, modulated audible and visual indicators inform the MTV driver and persons within the immediate area of the approaching vehicle and the approximate speed that the vehicle is traveling. 
         [0034]    The MTV includes an automated docking system. 
         [0035]    Items in the automated docking system include: a track sensor  16 , which can be, for example a RoboteQ, MGS1600GY, the joystick  14 , the drive motor controller  12 , and the programmable controller allow for the automated docking function. Inputs from the track sensor and the joystick allow the MTV to self-maneuver into the docking station under the supervision of the MTV driver. 
         [0036]    The MTV includes wheel and vibration components. 
         [0037]    Components for the wheel and vibration components include: a standard caster  8 , drive wheels  9 , and spring loaded casters  10  are the wheels for the MTV. The four spring loaded casters  10 , replace the standard casters at those locations to reduce vibrations at the lower back end of the MTV, especially while driving over perforated floors commonly found in cleanrooms. The drive wheels  9  remain unchanged and also contain a spring loaded component to lessen vibration. The standard casters  10  are left as standard and not spring loaded to maintain a stable docking height at the cassette transfer/charging docking stations. The wheels on all of the casters are changed to a harder durometer as the softer durometer wheels exhibited excessive wear and shed large amounts of particles in the cleanroom. Additional vibration control is installed using pneumatic mounts  4 . The pneumatic mounts  4  provide good performance in damping low frequency vibrations. 
         [0038]    The MTV includes contactless inductive charging components: 
         [0039]    Items include: a secondary coil  7  of the inductive contact, a battery unit  11 , and the battery charge comprise the onboard components of the inductive charging system. The non-contact inductive charging is accomplished when the primary and secondary inductive coils come into close proximity of each other and transfer power via an oscillating electric field. This power is feed to the battery charger converting AC voltage to DC voltage, charging the onboard batteries. The secondary inductive coupler and the battery charger are the only remaining components requiring AC voltage, greatly simplifying the present onboard electrical panels. All other onboard components are powered from the batteries. 
         [0040]    The MTV includes a cassette transfer mechanism: 
         [0041]    The cassette transfer mechanism comprises: a vertical lift assembly  5 , a cassette transfer arm  15 , and the three X, Y, and Z axis motors  22 ,  26 , and  24 . These components are used to lift and extend the cassette, delivering and retrieving the cassette to and from given process points within the cleanroom factory. The vertical lift assembly  5  has a system of linear slides, rack/pinion gears and a ball screw allowing the cassette transfer mechanism to move in the three X, Y, and Z axis coordinates. The three axis of motion allows the cassette to be properly positioned and transferred to a cassette transfer point. The Y-axis motor  26  provides side-to-side movement to properly align the cassette to the docking port by determining the Y-axis offset from the magnetic tape sensor used in the automated docking system. The Z-axis motor  24  drives the cassette arm  15  up and down to lift the cassette to the correct transfer pass height. The X-axis motor  22  drives the cassette arm  15  to extend or retract a cassette to or from the cassette docking port. A typical transfer sequence includes: 1) drive Z-axis up to lift the cassette, clearing the cassette retaining bocks in the MTV and the clamping blocks on the cassette port. 2) Drive the Y-axis to center the cassette to the cassette port. 3) Drive the X-axis extending the cassette over the cassette port clearing the clamping block on the port. 4) Drive the Z-axis down placing the cassette onto the cassette port and lowering the cassette arm enough to clear the cassette. 5) Drive the X-axis retracting the cassette arm back into the MTV.  FIG. 3  shows cassette  20  in the extended position as it places a cassette  20  on a transfer/charging station located at the different processing points. The three X, Y, and Z axis motors  22 ,  26 , and  24  are replaced with DC motors and have built-in controllers, encoders and brakes for easier system implantation and improved cassette transfer control. 
         [0042]    The MTV according to the present invention includes electronics panel  13 . 
         [0043]    DC power distribution and the programmable controller system are located within the electronic panels  13 . These panels contain the necessary DC power/voltage converters and wiring distribution to the individual components. 
         [0044]    The collision avoidance system is described in further detail below. 
         [0045]      FIG. 4  shows the collision avoidance block diagram  400 . The collision avoidance system comprises three primary sections: input, control, and output. The individual components within these three sections are tightly integrated and designed to be a collaborative robotic system, providing an adaptive and cohesive human—machine interface. 
         [0046]    The input section includes the joystick  402  and safety laser scanner  410 , where the joystick  402  accepts the user&#39;s input to drive the MTV, while the driver walks just behind and to the left of the MTV. The joystick&#39;s analog signal passes through an analog to digital converter  404 , where the digital signal is then processed and evaluated by the programmable controller  406  given the environmental conditions detected by the safety laser scanner  410 . The safety laser scanner  410  itself is an intelligent programmable device, allowing it to be programmed and configured to meet a large variety of applications. Within the safety laser scanner&#39;s program, different zones can be uniquely configured:  FIG. 5  shows an example of the different configured safety zones, and is described in further detail below. Intrusion or lack thereof, within the different safety zones produce digital signals processed by the programmable controller  406 . The programmable controller processes these inputs using software algorithms to produce semi-automated outputs to the motor controller  418 —drive motors  420  and  422  are used to produce the desired and collaborative drive motion of the MTV. Additionally, the programmable controller  406  varies the audible/visual indicators shown in Table 1 to produce informative audible signal  414  and visual indicators  416 . These audible and visual signals are intended to make the MTV&#39;s driver and personnel in the vicinity aware of the MTV&#39;s speed. Digital I/O electronics couple the programmable controller  406  to the safety laser scanner  410 , the track sensor  412 , the audible signal generator  414  such as a speaker, and the visual signal generator  416  such as a strobe light.  FIG. 6  contains a flow chart of how the programmable controller software performs this control and is explained in further detail below. 
         [0047]      FIG. 5  shows a diagram of the safety zones  500  provided by the laser scanner in the MTV  502 . A safety zone  510  designated “Zone 3” is a semi-circle with a radius of about, for example, two feet. A safety zone  508  designated “Zone 2” is contiguous with safety zone  510  and has an outer radius of about, for example, four feet. A safety zone  506  designated “Zone 1” is contiguous with safety zone  508  and has an outer radius of about, for example, six feet. A safety zone  504  designated “Zone 0” lies beyond the outer radius of safety zone  506 . It will be apparent to those skilled in the art that other shapes or radii can be used for the safety zones according to the type of laser scanner selected and the specific type of programming used. 
         [0048]    The forward and turning motion of the MTV is accomplished by varying the speed to the two drive motors which are configured as a dual drive system providing a differential drive control. This differential drive control gives the MTV a “Tank-Like” drive and steering functionality. There are two drive signals used to control the MTV drive motion the 1 st  is to control the forward and reverse motion which drives the two drive wheels at the same speed and direction to accomplish linear motion. The  2   nd  drive signal varies the speed and direction of the two drive wheels allowing the MTV to turn or pivot about the MTV center.  FIG. 6  shows an example of a safety zone flow chart  600  used with the MTV of the present invention. The flow chart represents the method of operation for the collision avoidance system of the MTV according to the present invention. The method starts at step  602 . At step  604 , the joystick signal for initiating forward motion is detected. If at step  606  an object is detected in Zone 3 maximum turning is limited to 100% of allowed speed at step  608 . Forward speed is limited to 20% of allowed maximum speed at step  610 . An audible tone is set to a slow pulse at step  612 . A visible strobe is set to a slow pulse at step  614 . The method is then returned to step  604 . If at step  616  an object is detected in Zone 2, maximum turning is limited to 50% of allowed speed at step  618 . Forward speed is limited to 50% of allowed maximum speed at step  620 . An audible tone is set to a moderate pulse at step  622 . A visible strobe is set to a moderate pulse at step  624 . The method is then returned to step  604 . If at step  626  an object is detected in Zone 1, maximum turning is limited to 20% of allowed speed at step  628 . Forward speed is limited to 80% of allowed maximum speed at step  630 . An audible tone is set to a rapid pulse at step  632 . A visible strobe is set to a rapid pulse at step  634 . The method is then returned to step  604 . If at step  636  no object is detected, maximum turning is limited to 10% of allowed speed at step  638 . Forward speed is allowed to assume 100% of allowed maximum speed at step  640 . An audible tone is set to a fast rapid pulse at step  642 . A visible strobe is set to a fast rapid pulse at step  644 . The method is then returned to step  604 . 
         [0049]    Furthermore, the inputs sensors for determining the surrounding environment are not limited to simple laser scanners. This system and method of the present invention could easily accommodate more advanced visions systems such as 3D time-of-flight cameras allowing for a more sophisticated control system. 
         [0050]    The theory of operation for the collision avoidance system according to the present invention in conjunction with the safety zones is shown in table form below with respect to Table 1: 
         [0000]    
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Safety Zones 
               
               
                 Theory of Operation Table 
               
             
          
           
               
                 Safety Zone 
                 Allowable Forward Motion 
                 Allowable Turning Motion 
                 Audible Output 
                 Visual Output 
               
               
                   
               
               
                 Zone 0 
                 Maximum Vehicle Speed 
                 Very Regulated 
                 Fast Rapid Pulsed Tone 
                 Fast Rapid Strobe 
               
               
                 Zone 1 
                 Limited Max Vehicle Speed 
                 Highly Regulated 
                 Rapid Pulsed Tone 
                 Rapid Strobe 
               
               
                 Zone 2  
                 Moderate Vehicle Speed 
                 Moderately Regulated 
                 Moderate Pulsed Tone 
                 Moderate Strobe 
               
               
                 Zone 3 
                 Slow Vehicle Speed 
                 Slightly Regulated 
                 Slow Pulsed Tone 
                 Slow Strobe 
               
               
                   
               
             
          
         
       
     
         [0051]    The MTV of the present invention includes an automated docking function, which is described in further detail below. 
         [0052]    The automated docking function is intended to allow the MTV driver to position the MTV near a docking station and then command the MTV to automatically drive the remaining distance into the docking station. The track sensor  412  shown in  FIG. 4  is used to detect a magnetic or optical strip on the floor leading toward the docking station. Once the magnetic strip on the floor is detected an indicator lights up informing the MTV driver that it is in a position to be docked. The MTV driver presses a button on the joystick to disable the collision avoidance and commanding the MTV to drive into the docking station. The programmable controller uses the signals from the track sensor  412  to control the motors following the strip on the floor guiding the MTV into the docking station. 
         [0053]    The MTV of the present invention includes a wireless material tracking system, which is described in further detail below. 
         [0054]    The wireless material tracking system  700  is detailed in  FIG. 7 .  FIG. 7  shows the connectivity between the factory host network and the MTV&#39;s onboard network. The wireless client  708  on the MTV has consistent connectivity and communications with the factory host using advanced roaming techniques, switching between different wireless access points  702  while the MTV moves throughout the factory. The wireless client connects to a switch  706  and using standard internet protocols, enabling the MTV to communicate with multitude of internet devices. Given the emerging technology “Internet of Things” this configuration allows for many possible configurations and uses. In this example there are two internet barcode reading cameras  710 ,  712  with internal decoding, supporting a wide verity of barcode standards. One of the cameras  710  is positioned to read the barcode on the cassette containing the glass substrates and the other camera  712  is positioned to read the barcode located on the docking stations. Using a polling method, the cameras are triggered remotely by software services running on the factory host server  704  to read which cassette if any resides inside the MTV. The same polling method is used to read the barcode while the MTV is docked at a cassette transfer point, identifying where it is docked. Alternatively, cameras  710 ,  712  could be triggered by the onboard controller to make for a more effective solution. In this example, the MTV&#39;s onboard controller would initiate triggering the barcode reads given the detection of a cassette present or after the MTV detects that it is at docked at a cassette transfer point docking station. 
         [0055]    The MTV of the present invention uses a vibration control system, which is described in further detail below. 
         [0056]      FIG. 8  details the spring loaded casters in diagram  800 . The spring loaded casters  804  have cantilevered wheels with a spring on the opposite side of the pivot point allowing the wheel to have a vertical motion while supporting the load of the MTV. The cantilever arms  808  are pinned at the caster leg  810  providing a vertical motion on the wheel  806 . This vertical motion is controlled by the spring tension exerted by spring  820 . The spring  820  is held in place by the spring holder  818  which is secured to the caster leg  810 . The spring force is transferred to the cantilever arms  808  by the spring pin  822  and the spring retainer  816 . The spring loaded casters are swivel casters containing bearing within the horn base  812  allowing it to swivel about the mounting base  814 . Previous caster configurations utilized very low 65 durometer polyurethane wheels which did not effectively control vibrations and exhibited extensive wearing, causing particles within the cleanroom. The spring loaded casters, along with the harder 95 durometer wheels, provide the required vibration control while eliminating the particle generation. Different spring tensions could be used to allow for a variety of MTV&#39;s having different loads and payload requirements. 
         [0057]      FIG. 9  is a diagram  900  that shows the vibration control pneumatic mounts  906 . The pneumatic mounts are rubber supports with an internal air chamber which are molded to a metal base for mounting. A threaded fastener hole is molded into the top mount  904  of the unit to secure the load supports  902 . The pneumatic mounts provide very good vibration control especially at the lower frequency ranges. The internal air chamber can be pressurized to a range of air pressure, allowing a wide range of vibration control and loads. Low forcing frequencies are exhibited on the MTV while driving the MTV at normal walking speeds and even lower forcing frequencies are measured while maneuvering at slower speeds. The pneumatic vibration mounts react well to these low forcing frequencies and effectively dampen the vibrations without exuding uncontrolled oscillations (Bobble Head Effect). The pneumatic mounts are compatible with the cleanroom environment and replace both softer rubber and spring mounts which shed particles. 
         [0058]    Alternatively, in lieu of the pneumatic spring mounts, a magnetic spring could provide effective vibration control. Given the recent awareness of commercially available and inexpensive printed magnets, a custom engineered magnetic spring is a viable solution. Printable magnets are capable of having both N and S fields together enabling them to attract at a distance but repel when close, providing a levitated, in position force. Additionally, these magnets have a staying force keeping them aligned.  FIG. 10  is a diagram  1000  of an example of the magnetic spring mount vibration control. Using two opposing magnets, the magnetic Yield creates an air gap allowing vertical movement and damping vibration forcing frequencies.  FIG. 10  thus shows a top opposing magnet  1002 , a bottom opposing magnet  1004 , a base  1006 , and alignment shaft  1008 . 
         [0059]    The electronics for the MTV is described in further detail below. 
         [0060]    The power source  1100  is shown in  FIG. 11 .  FIG. 11  shows the recharging circuit for the two onboard sealed lead-acid batteries  1110  and  1112 . The 24V battery power  1114  is routed to all the onboard electronics and has the usual circuit isolation and protections using rated circuit breakers and fuses. DC to DC power converters are used as needed for devices that require different DC voltages. The only onboard AC is used to power the battery charger coming from the contactless inductive coupling. The primary side of the inductive coupling is part of a fixed docking station and facilitated with standard 115 VAC outlet power. These docking stations are located the various cassette transfer points throughout the factory.  FIG. 11  thus shows an AC power outlet  1102  coupled to a primary coil  1104 . These two components are stationary and do not form part of the mobile MTV. A secondary coil  1106  is coupled to a 24V charger  1108 , which is in turn coupled to the two batteries  1110  and  1112 , which generate the 24V power  1114  for the MTV. 
         [0061]    A block diagram  1200  of the MTV&#39;s onboard electronics is shown in  FIG. 12 . A common power bus  1202  of 24V is shown supplying power to all the onboard components; however, a variety of devices requiring different DC voltages are possible using DC to DC converters. The control signals represent different types of signals depending on the device it supports. The input  1208 , output  1210 , and auxiliary devices  1212  include discrete digital, analog, or protocols like RS232 or USB, for example. The drive motor controller  1206  provides the specific power signals to drive the motors  1214  and  1216 . These drive motors  1214  and  1216  may have specific requirements and could be part of a matching set. The control signals on the drive motors  1214  and  1216  comprise positioning information from encoders or Hall Effect feedback and a motor brake on/off. X, Y, and Z axis motors  1220 ,  1222 , and  1218  are also coupled to bus  1202 . 
         [0062]    Battery monitoring for the MTV is described in detail below. 
         [0063]    Battery temperature monitoring is used to prevent battery thermal run-a-way conditions during charging. Most battery chargers have built-in voltage and current monitoring and are self-regulating. These self-regulating charging circuits start with a full current quick charge and limit the current to low current trickle charge near the end of the charging cycle. These charging circuits, when working correctly, do not overcharge the battery; however, they can produce catastrophic battery damage when they fail. When these self-adjusting charging circuits or batteries fail, the sealed lead-acid batteries can go into a thermal run-a-way condition causing the batteries to become extremely hot, swell, and leak acid if the outer battery case is compromised. The programmable controller monitors the normal operating temperature using a thermocouple or other type of temperature sensing device. If the batteries exceed the normal operating temperature, the MTV is placed into an emergency off state and the charging voltage is removed. 
       PARTS LIST 
       [0064]      1  wireless network 
         [0065]      2  docking camera 
         [0066]      3  cassette camera 
         [0067]      4  pneumatic mounts 
         [0068]      5  vertical lift 
         [0069]      6  laser scanner 
         [0070]      7  secondary coil 
         [0071]      8  standard caster 
         [0072]      9  drive wheels 
         [0073]      10  spring loaded caster 
         [0074]      11  battery unit 
         [0075]      12  drive motor controller 
         [0076]      13  electronics panels 
         [0077]      14  joystick 
         [0078]      15  cassette transfer arm 
         [0079]      16  track sensor 
         [0080]      18  fan filter unit 
         [0081]      20  cassette 
         [0082]      22  X-axis motor 
         [0083]      24  Z-axis motor 
         [0084]      26  Y-axis motor 
         [0085]      100  MTV side view 
         [0086]      200  MTV front view 
         [0087]      300  MTV cassette transfer view 
         [0088]      400  collision avoidance block diagram 
         [0089]      402  joystick 
         [0090]      404  A/D converter 
         [0091]      406  programmable controller 
         [0092]      408  digital I/O 
         [0093]      410  safety laser scanner 
         [0094]      412  track sensor 
         [0095]      414  audible signal 
         [0096]      416  visual signal 
         [0097]      418  motor controller 
         [0098]      420  right motor 
         [0099]      422  left motor 
         [0100]      500  safety zones 
         [0101]      502  MTV 
         [0102]      504  zone 0 
         [0103]      506  zone 1 
         [0104]      508  zone 2 
         [0105]      510  zone 3 
         [0106]      600  safety zone flow chart 
         [0107]      602  start 
         [0108]      604  joystick forward motion 
         [0109]      606 - 614  object in zone 3 
         [0110]      616 - 624  object in zone 2 
         [0111]      626 - 634  object in zone 1 
         [0112]      636 - 644  no object detected 
         [0113]      700  wireless communications 
         [0114]      702  wireless access point 
         [0115]      704  factory host server 
         [0116]      706  network switch 
         [0117]      708  wireless network client 
         [0118]      710  cassette ID barcode camera 
         [0119]      712  docking station ID barcode camera 
         [0120]      800  spring loaded casters diagram 
         [0121]      802  lower frame 
         [0122]      804  spring loaded caster 
         [0123]      806  caster wheel 
         [0124]      808  cantilever arms 
         [0125]      810  caster leg 
         [0126]      812  horn base 
         [0127]      814  mounting base 
         [0128]      816  spring retainer 
         [0129]      818  spring holder 
         [0130]      820  spring 
         [0131]      822  spring pin 
         [0132]      900  pneumatic mounts diagram 
         [0133]      902  cassette supports 
         [0134]      904  top mount 
         [0135]      906  pneumatic mounts 
         [0136]      908  MTV plateform 
         [0137]      1000  magnetic vibration control mount diagram 
         [0138]      1002  top opposing magnet 
         [0139]      1004  bottom opposing magnet 
         [0140]      1006  base 
         [0141]      1008  alignment shaft 
         [0142]      1100  power source diagram 
         [0143]      1102  AC power outlet 
         [0144]      1104  primary coil 
         [0145]      1106  secondary coil 
         [0146]      1108  24 volt charger 
         [0147]      1110  12 volt battery 
         [0148]      1112  12 volt battery 
         [0149]      1114  24 Volt supply 
         [0150]      1200  electronics block diagram 
         [0151]      1202  24 Volt supply 
         [0152]      1204  programmable controller 
         [0153]      1206  drive motor controller 
         [0154]      1208  input devices 
         [0155]      1210  output devices 
         [0156]      1212  auxiliary devices 
         [0157]      1214  right drive motor 
         [0158]      1216  left drive motor 
         [0159]      1218  z-axis motor 
         [0160]      1220  x-axis motor 
         [0161]      1222  y-axis motor 
         [0162]    Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the combination and arrangement of parts can be resorted to by those skilled in the art without departing from the spirit and scope of the invention, as hereinafter claimed.