Abstract:
A modular robot mechanism utilizing fixed drives, power sources, power delivery cables and electrical components for 4 or more axes in a protective enclosure while making it possible to provide spatial positioning and tilting degrees of freedom to an end effector suitable for using in a consumer product. Furthermore a robotic head mechanism is disclosed that creates additional degrees of freedom or states by combination of existing axes with spring loaded lock mechanisms eliminating need for conventional electrically actuated solenoid or pneumatic grippers making it possible for use as a home appliance. A method to control the robot mechanism and additional axis utilizing a matrix to decouple the input position to the remote actuator and Cartesian motion produced at the end effector.

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to a robotic mechanism for use in an apparatus for preparing dishes using recipe steps and cooking conditions coded as a computer program recipe executed by a kitchen top robotic cooking machine supplied with the required ingredients with minimal user intervention while adjusting recipe to tastes of the user. 
     A need exists for a robotic mechanism for use in automated home cooking machines as disclosed in U.S. Pat. No. 9,131,807. Gantry robots with three or more axes disclosed in prior art such as U.S. Pat. No. 8,973,768 are serial mechanism and each axis carries the next one. The first gantry axis such as x-axis is driven by an actuator in combination with a linear motion device such as ball screw driven by a motor or integrated as in a linear motor, the actuator and motion elements for the second axis such as y-axis are mounted onto the first axis or x-axis and all elements of the y-axis move along x-axis, further more a third axis such as a z-axis is made possible by similar actuator and linear motion devices by attaching them to the y-axis firmly. So for any x-motion the actuators and mechanism for y and z axis move along x-axis and for any y-axis motion all elements of z-axis move along the y-direction. So only the motor for first axis is stationary and the rest of the actuators or motors are in constant motion. This requires all the power cables and encoder feedbacks cables are carried as well and flexible to allow changing shapes due to changing positions between connected cable ends. Constant motion can cause cables and motors to fail eventually and increasing the cost with reduced reliability. 
     Further the user can be exposed to the hazardous voltages being carried to the second and third motors by fatigue failure of cable insulations due to stress fatigue or attack from corrosive elements in workspace. Cable design and management is a very critical aspect of such robotic mechanisms. Having to carry secondary axes also creates additional force and strength requirement from the primary axes requiring overdesign for primary axes. 
     A need exists for a robot that is able to meet the needs of a cooking machine that is used in a harsh environment as in the case of household cooking where the robot mechanism is exposed to various unsuitable conditions such as heat, moisture, grease, fumes, acids and bases. Further the robot needs to be reliable for use for long periods of times without requiring any servicing in a home user environment as compared to an industrial environment where regular daily, weekly, monthly and annual preventive maintenance and inspections are common. The robot also needs to be safe for average users not familiar with industrial machinery. The robot needs to be able to carry weights ranging from light to relatively heavy for its size. Electrical cables and connections should not be exposed to cooking environment such as high temperatures, moisture, fumes, grease and other particulate material as this can cause their gradual degradation as well as electrical shock and fire hazards caused by compromised insulation. Furthermore an industrial robot with cables and motors moving around are not a welcome sight for a consumer device. 
     Further a need exists for a robot that has positioning precision suitable for a consumer application for home cooking by transporting ingredients and intermediates efficiently but cost effective at the same time. The positioning accuracy and overall functionally should not be impacted by the operating conditions such as temperatures and moisture. The robot mechanism must be compact to be able to fit in a conventional kitchen and of comparable size to a home appliance. The robot also needs to provide continuous operation without need for periodic servicing as in case of industrial robots. The robot should have safety features to coexist with members of a household including children. The robot mechanism should allow it to be design compatible with government food preparation and health standards and keep industrial machinery components such as lubricants, hazardous design materials away from the operation area. 
     A need therefore exists to provide a robot that can be used for a consumer food preparation device which can survive the harsh conditions over long periods of time. The electrical systems and drives can be located such that they are remote from the food preparation areas and are not accessible to the user. There are no moving cables or electrical power delivery components including electrical connections exposed to the cooking environment. The electrical systems and drives are safety isolated from the average customer but can be accessed and serviced by qualified technicians. The robot mechanism providing a large number or controlled degrees of freedom as needed for three dimensional positioning, tilting and gripping utilizing fewer motors and controlled axis to be cost effective for a consumer application. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a robot mechanism utilizing fixed drives, power sources, power delivery cables and electrical components for four or more axes in a protective enclosure while making it possible to provide spatial positioning and tilting degrees of freedom to an end effector such as an ingredient container being moved to a cooking pot. 
     An object of the invention is to provide a three or more axes robotic mechanism that has source of motion actuators such as electric motors remotely located with respect to the robot workspace and stationary. All such fixed motors are powered by cables and other motion elements that do not move with the end effector or impacted by the work environment. Another object of the invention is to have all the actuator motors and supporting elements located safely in a protective enclosure allowing placing such a device for home use by average consumers not trained to be around industrial robots. 
     According to an embodiment of the invention the actuator motors are connected to the corresponding axes by means of a pulley and belt arrangements such that the belt pulley mechanisms for each axes are stacked spatially. Furthermore a robotic head mechanism is disclosed that creates additional degrees of freedom or states by combination of existing axes with spring loaded lock mechanisms eliminating need for conventional electrically actuated solenoid or pneumatic grippers. Further it allows actuator resource sharing such as electronic or PLC robot controllers the cost of which is proportional to the number of degrees of freedom. 
     Yet another object of the invention is to use restoring forces such as spring in substantially orthogonal direction clasping on a universal lift component that or features of which are part of any target object to be picked and tilted. Once the target object is picked it is secured well enough to even allow contents to be disposed by tilting to an upside down position of the target object such as a raw ingredient basket. 
     A further object of the invention is to amplify the tilt of the end effector robot head by means of gears or other mechanical rotation multiplication devices as known in the art. 
     A further object is to be able to wash down parts of the robot mechanism exposed to the workspace area that can cause it to be contaminated requiring cleaning as per food preparation equipment codes as well as need reduced periodic maintenance. 
     Additional features and advantages of the present invention are described in, and will be apparent from, the detailed description of the preferred embodiments and from the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The following is a description, by way of example only, of different embodiments of the mechanism, its variations, derivations and reductions. 
         FIG. 1  shows a 4-axis robot moving an ingredient basket along X, Y and Z axes as shown in supporting  FIG. 1 b    while tilting along T-axis as shown in supporting  FIG. 1 b    with T-axis parallel to and offset from Y-axis driven by fixed motors and pulley stacks. 
         FIG. 2 a    shows a detailed 3D view of the pulley stacks for X, Y, Z and T axes. 
         FIG. 2 b    shows a detailed top view of the pulley stacks for X, Y, Z and T axes. 
         FIG. 3 a    shows a detailed view of robot head assembly along with Z and Tilt mechanism. 
         FIG. 3 b    shows a detailed view of robot head assembly along with Z and Tilt mechanism in a different position and tilt angle. 
         FIG. 4  shows an alternate Z and Tilt mechanism using a worm gear mechanism. 
         FIG. 5  shows a universal lift bar attached to an ingredient basket. 
         FIG. 6 a    shows robot head in a position ready to pick an ingredient basket 
         FIG. 6 b    shows robot head in a position ready to engage the horizontal lock pins to the corresponding universal lift bar lock holes to attached to the ingredient basket 
         FIG. 6 c    shows robot head in a position with horizontal lock pins already engaged and ready to lock with the vertical lock pins aligned to corresponding universal bar lock holes attached to the ingredient basket. 
         FIG. 6 d    shows robot head in a position with the ingredient basket picked up and universal lift bar securely locked to the robot head. 
         FIG. 7 a    shows a tilt rotation multiplication means utilizing a gears 
         FIG. 7 b    shows an alternate view of the components of tilt with enhanced rotation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Now referring to the drawings, wherein like numerals designate like components,  FIG. 1  shows a four axis gantry robot mechanism comprising a robot head assembly R moving a target object such as raw ingredients basket or container  5  along translating axes X, Y, Z as shown in supporting  FIG. 1 b    and tilting about tilt axis T as shown in supporting  FIG. 1 b   . A target object or container  5  has 4 degrees of freedom controlled by stationary remote motors  11 ,  12 ,  13  and  14 . Motors  11 ,  12 ,  13  and  14  are mounted to a fixed frame F. The motors mounting can be substantially rigid or based on the application environment has spring and dampers to isolate vibration as known in the art. The fixed frame F also acts as a protective enclosure, not fully shown for clarity, the motors and other components are contained within to limit access to only trained personnel with safety interlocks that can trip or turn off power as needed. The motors also have integrated encoder and controller interphase  26  that are connected to motor drivers and controllers. 
     The robot head assembly R is mounted using a linear guide rail mechanism to y-axis guide rail  10   a  by a x-axis linear motion guide block  7   a  secured to robot head assembly base  2  such that the robot head assembly R can move along x-axis guide rail  10   a . An additional linear motion x-axis guide block  7   b  along with an additional x-axis guide rail  10   b  parallel to x-axis guide rail  10   a  is used for added strength to allow use of smaller size linear motion components with larger payloads. A third x-axis rail guide rail  10   c  is fixed to x-axis guide rail  10   a  and x-axis guide rail  10   b  using a x-axis base member  1   c  such that the x-axis linear motion guide rails  10   a ,  10   b ,  10   c  are parallel and do not move relative to each other or the x-axis base member  1   c . The x-axis guide rail  10   a  is secured to y-axis linear motion block  6   a  which can move onto the y-axis linear motion guide rail  9   a  fixed to the frame F. The y-axis linear motion guide block  6   a  is secured to x-axis base member  1   a  such that all x-axis motion parts  1   a ,  1   b ,  1   c ,  10   a ,  10   b ,  10   c  move together along y-axis guide rail  9   a  while carrying the robot head assembly R along x-axis as well. 
     An additional y-axis guide rail  9   b , also fixed to frame F is used to provide additional support to the x-axis base members  1   a ,  1   b ,  1   c  and linear motion guide members by mounting them to the additional y-axis guide rail  9   b  using an additional y-axis linear motion block  6   b  through x-axis secondary base member  8  and x-axis secondary linear motion guide  7   c . The x-axis linear motion members could be directly mounted by securing x-axis linear motion guide rail  10   a ,  10   b  or  10   c  directly to x-axis secondary base member  8  eliminating linear motion guide  7   c  as well, but that would cause stress and failure due to thermal environments causing expansion of x-axis guide rails with y-axis guide rails fixed to frame F. Having a secondary x-axis linear motion guide block  7   c  in series allows this new mechanisms to eliminate any operational failure conditions due to thermal expansion or contractions. 
     The robot head assembly base  2  has two controllable degrees of freedom one each along horizontal axes X and Y. The robot head assembly comprises of a first translating link  3   a  which moves along the axes X, Y same as robot head assembly base  2  but possesses a third controlled degree of freedom to move along a vertical z-axis as will be explained further referring to  FIGS. 3 a  and 3 b   . The robot head assembly further comprises of a second translating link  3   b  also with three controlled degrees of freedom and an end effector link  4  having four controlled degrees of freedom to be explained further referring to  FIGS. 3 a  and 3 b   . The said two, three and four degrees of freedom of end effector link  4  are controlled by motors  11 ,  12 ,  13 ,  14  driving respective motor shafts  15 ,  16 ,  17 ,  18  through motion transmission pulley stacks PS 1 , PS 4  mounted to frame F by shafts  19 ,  21  fixed at ends  20 ,  22  respectively; pulley stacks PS 3 , PS 4 , PS 5  mounted to y-axis frame member  1   a  by fixed shafts  23 ,  24 ,  25  respectively, pulley belts  33 ,  34 ,  35 ,  36 , ball screw nut driver pulleys  69 ,  70 , ball screw shafts  75 ,  77  and idler tensioner pulleys mounted on supports  27 ,  28 ,  29 ,  30 . A gearbox  37  is used for motor  12  to increase torque. The end effector link  4  uses these four degrees of freedom to manipulate ingredient basket or container  5  by attaching to itself. 
       FIG. 2 a    is a three dimensional view and  FIG. 2 b   . a top view, both illustrating the motion transmission elements of the four axis gantry robot mechanism shown in  FIG. 1  in detail. Y-axis drive pulley  65  is mounted onto shaft  15  (referring back to  FIG. 1 ) which is driven by motor  11 . Y-axis drive pulley  65  drives a y-axis drive belt  33  that loops around over y-axis idler near pulley  44  of pulley stack PS 1 , y-axis idler far pulley of pulley stack PS 4  and pushed by y-axis idler tensioner pulley  57  mounted on support  27 . Since all the pulley and idler elements remain at rest with respect to frame F the drive belt  33  loop around length is constant regardless of the pulley motion or for any position. Referring back to  FIG. 1 , y-axis belt  33  is attached to x-axis base member  1   a  and so any rotation of y-axis motor  11  causes all the x-axis base members  1   a ,  1   b ,  1   c , guide rails  10   a ,  10   b ,  10   c  and any subsequent members attached to them including robot head assembly R to translate along y-axis. The members  33 ,  65 ,  44 ,  47  and  57  together make a y-axis motion transmission layer. 
     Further, looking at  FIGS. 2 a  and 2 b   , X-axis drive pulley  66  is mounted on shaft  16  (referring back to  FIG. 1 ) which is driven by driven by gearbox  37  using motor  12 . X-axis drive pulley  66  drives a x-axis belt  34  that loops over around x-axis idler near pulley  43  of pulley stack PS 1 , x-axis idler y-intermediate near pulley  53  of pulley stack PS 2 , x-axis idler end pulley  50  of pulley stack PS 5 , x-axis idler y-intermediate far pulley  56  of pulley stack PS 3 , x-axis idler far pulley  46  of pulley stack PS 4  and x-axis tensioner pulley  58  mounted on support  28 . With pulley stacks PS 1 , PS 4  are rotatable mounted to stationary frame F and pulley stacks PS 2 , PS 3 , PS 5  rotatable mounted to x-axis base members and so moving along y-axis the closed loop around length of x-axis pulley belt  34  is maintained same regardless of pulley motion due to the reduction or increase in distance between pulley stacks PS 1 , PS 2  being compensated by an opposite increase or reduction in pulley stacks PS 3 , PS 4 . Referring back to  FIG. 1 , x-axis pulley belt  34  is attached to robot head assembly base  2  such that a rotation caused by motor  12  will result in a translation of robot head assembly R along x-axis However due to this arrangement there are interactions between y-axis motor causing x-axis motion of robot head assembly even when x-axis motor is not rotating and vice versa. So if a motion in either x-axis or y-axis is desired then the other motor has to move in opposite direction to nullify this effect. This means there is a transfer matrix between motor x-axis and y-axis motion rotation and subsequent linear translation seen along x-axis and y-axis for robot head assembly R. The members  34 ,  43 ,  53 ,  50 ,  56  and  58  together make x-axis motion transmission layer. 
     Even further, looking at  FIGS. 2 a  and 2 b    two additional z-axis and tilt-axis transmission layers are formed similar to the x-axis transmission layer. The z-axis transmission layer is made of z-axis belt  35 , z-axis drive pulley  67 , z-axis idler pulley  59 , z-axis idler near pulley  42 , z-axis idler y-intermediate near pulley  52 , z-axis idler end pulley  49 , z-axis secondary far idler pulley  63 , z-axis ball screw nut driver pulley  70 , z-axis secondary near idler pulley  61 , z-axis idler intermediate far pulley  55  and z-axis idler far pulley  45 . As will be explained in detail further referring to additional figures pulleys  63 ,  69 ,  61  are all fixed in position on robot head assembly base member and do not suffer from any relative translation motion such that the z-axis belt length changes between pulleys  49 ,  63  are compensated by equal and opposite change between pulleys  61 ,  59 . 
     Similar to z-axis transmission layer, the tilt-axis transmission layer is made of tilt-axis belt  36 , tilt-axis drive pulley  68 , tilt-axis idler pulley  60 , tilt-axis idler near pulley  41 , tilt-axis idler y-intermediate near pulley  51 , tilt-axis idler end pulley  48 , tilt-axis secondary idler far pulley  62 , tilt-axis ball screw nut driver pulley  69 , tilt-axis secondary near idler pulley  64 , tilt-axis idler intermediate far pulley  54  and tilt-axis idler far pulley  44 . As will be explained in detail further referring to additional figures pulleys  62 ,  70 ,  64  are all fixed in position on robot head assembly base member and do not suffer from any relative translation motion such that the tilt-axis belt  36  length changes between pulleys  49 ,  63  are compensated by equal and opposite change between pulleys  61 ,  59 . Similar to the interactions between x-axis and y-axis motor rotations versus robot head translations, the z-axis and tilt-axis are also impacted. In fact due to this stationary motor arrangement controlling the end effector member  4  via the four transmission layer a four rows by four columns translation matrix exists between the rotations of motors and the motion produced along x, y, z and tilt axes. In another embodiment the pulley and belt transmission are substituted with a pair of ball screws connected via a worm gear mechanism. 
       FIGS. 3 a  and 3 b    illustrate the mechanism to convert the rotation of z-axis ball screw nut driver pulley  70  attached to a z-axis ball screw nut  76  connected with a z-axis hollow shaft  94  supported on robot head base assembly  2  by z-axis bearing  95  and into vertical motion of first translating link  3   a  fixed onto z-axis ball screw shaft  75  along z-axis. Further the rotation of tilt-axis ball screw nut driver pulley  69  attached to a tilt-axis ball screw nut  78  connected with a tilt-axis hollow shaft  92  supported on robot head base assembly  2  by tilt-axis bearing  93  and into vertical motion of second translating link  3   b  fixed onto tilt-axis ball screw shaft  77 . The end effector link  4  is connected to first translating link by a hinge joint using bearings  85   a  and  85   b  on each side and connected to the second translating link  3   b  by a sliding joint using bearings made by slots  80   a ,  80   b  on the end effector link  4  and bearings  84   a ,  84   b  mounted on second translating link  3   b . Each of the first translating link  3   a  and second translating link  3   b  have an independent degree of freedom relative to robot assembly base  2  controlled by motors  13 ,  14  allowing them to be independently positioned along z-axis. This independent positioning capability of the first translating link  3   a  and second translating link  3   b  is converted into a z-axis and a tilt position of end effector link  4 .  FIG. 3 b    when compared to  FIG. 3 a    shows two different z-axis and tilt positions for end effector link  4  with respect to robot assembly base  2 . 
     Further referring to  FIG. 3 a    and  FIG. 3 b   , a first linear guide shaft assembly comprised of linear guide shaft  79 , linear guide bearing  81  connects first translating link assembly  3   a  to robot assembly base  2  for added strength for moments in all directions properly constraining first translating link  3   a  to move along z-axis only with respect to robot assembly base  2 . A second linear guide shaft assembly comprised of linear guide shaft  82 , linear guide bearing  83  connects first translating link assembly  3   a  to robot assembly base  2  for even more added mechanical strength. 
     Continuing to refer to  FIG. 3 a    and  FIG. 3 b   , a locking assembly mechanism is shown comprised of first locking pins  91   a ,  91   b  mounted on end effector link  4 , second locking pins  92   a  and  92   b  mounted on locking plate  89  supported on end effector link  4  by locking plate guide shaft spring assembly  87   a ,  87   b  fixed to guide shaft mounts  86   a ,  86   b  attached onto end effector link  4 . Locking plate  89  is able to move along the locking plate guide shaft spring assembly  86   a ,  86   b  when pushed by locking plate guide rollers  90   a ,  90   b  away from the end effector link  4  along the guide shaft spring assembly  87   a ,  87   b . When no force is applied the locking plate  89  maintains continuous contact to the mating surface on the end effector link  4  constrained by the guide shaft spring assembly  87   a ,  87   b  restoration forces. The first locking pins and second locking pins are preferably perpendicular to each other. 
       FIG. 4 . Illustrates and alternate embodiment with end effector link  104  attached an end effector link gear  104   a  attached to a z-axis ball screw shaft  175  by hinge joint bearing  104   b , the end effector link gear being driven by a worm  103   b  mounted on a ball screw shaft  176 . The end effector link has two controllable degrees of freedom similar to end effector link  4 . 
       FIG. 5 . Shows a universal lift bar  95  attached to ingredient basket  5  using screws  98 . The universal lift bar has first lock pin holes  96   a ,  96   b  and second lock pin holes  97   a ,  97   b . The first lock pin holes and second lock pin holes are preferably perpendicular to each other. The universal lift bar can be attached to any target object which is intended to be picked up and operated by the robot head assembly R successfully regardless of the target objects shaft or size as illustrated by  FIG. 6 a   ,  FIG. 6 b   ,  FIG. 6 c    and  FIG. 6 d    depicting a picking sequence.  FIG. 6 a    shows the relative positions for robot head assembly R and universal lift bar  95  such that the first locking pins  91   a ,  91   b  are lined up with the first lock pin holes  96   a ,  96   b . However the first locking pins and lock pin holes cannot be engaged due to the second locking pins  92   a ,  92   b  coming in the way of universal lift bar  95 .  FIG. 6 b    shows the relative positions now with the locking plate guide rollers  90   a ,  90   b  running into a base frame surface and pushed up to cause the locking plate  89 , second locking pins  92   a ,  92   b  to move out of the way. The robot head assembly R can now move towards the universal lift bar  95  and successfully engage the first locking pins  91   a ,  91   b  into the first lock pin holes  96   a ,  96   b  respectively as seen in  FIG. 6 c   . In this first set of locks engaged the second locking pins  92   a ,  92   b  are also aligned up to the second pin holes  97   a ,  97   b . As can be seen in  FIG. 6 d    the robot assembly R moves up allowing the locking plate guide rollers  90   a ,  90   b  to go free causing the locking plate guide  89  restored to its normal position resting against the end effector link  4  with the second set of locking pins and lock pin holes engaged as can be seen in  FIG. 6   d.    
     The universal link bar  95  and ingredient basket  5  are now fully secured to the robot head assembly R as seen in  FIG. 1  or  FIG. 6 d    and will not drop for any position or tilt of the robot head assembly R. Utilizing this locking mechanism by reuse of the four degrees of freedom of the robot head assembly along with motion restoring components eliminates the need to use additional motorized, solenoid or pneumatic grippers and any resources such additional electrical or pneumatic power sources, controls for such gripping devices. It also eliminated cables or pneumatic lines to be routed, connected and carried by the robot head assembly. This also allows wash down capability for the robot head assembly R as needed for food preparation equipment. 
       FIGS. 7 a  and 7 b    illustrate a mechanism for enhancing the tilt angle range of end effector link  4  using a secondary end effector link tilt multiplication pinion  100  mounted onto secondary end effector link base  98  using a bearing. The secondary end effector link base  98  is rigidly attached to the first translating link  3   a  with a tilt multiplication gear  99  rigidly attached to end effector link  4 . Any tilt of the end effector link  4  relative to the first translating link  3   a  causes an enhanced rotation of the secondary end effector link pinion  100  decided by the ratio of teeth of the gear pinion combination. 
     The end effector link  4  has four degrees of freedom along with additional derived degrees of freedom by use of passive elements and has been sown to be able to pick and transport and ingredient basket  5 . The end effector link  4  can also transport other target objects permanently attached of via universal lift bars attached to target objects such as a preferably wireless camera, variation sensors including temperature measurement, air or water delivery jets for cleaning etc. 
     In another embodiment shaking sequences on end effector link  4  are used for dispensing ingredients out of an ingredient basket or container  5  by generating a shaking sequence by putting any or a combination of input commands to motors  11 ,  12 ,  13 ,  14  for reciprocating rotation at a desired frequency and amplitude. 
     All though the invention has been described herein in connection with various preferred embodiments, there is no intention to limit the invention to those embodiments. It should be understood that various changes and modifications to the preferred embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. Therefore, the appended claims are intended to cover such changes and modifications.