Robotic livery printing system
The present disclosure provides a robotic printing system for printing images on the surface of an object. One exemplary system includes a printing module carried by a motion platform to directly eject printing materials on a surface. One aspect of this disclosure provides methods for accurately controlling the motion of the motion platform, generating accurate triggering signals for printing heads, and properly aligning adjacent swaths of an image.
1. A method for printing a livery image on a surface of an object and for use in association with a motion platform, the method comprising the steps of:
acquiring data from a local sensing suite;
acquiring data from one or more global motion tracking devices;
creating a first measurement product by fusing said acquired data from said local sensing suite and said one or more global motion tracking devices to control the motion platform to move a printing module across said surface by
commanding the motion platform to move the printing module along a pre-planned path relative to the surface;
computing an error between said first measurement product and a desired position, orientation, and velocity of said printing module relative to said surface; and
applying a plurality of motion correcting commands to the motion platform to correct said errors in the position, orientation, and velocity of the printing module relative to said surface; and
creating a second measurement product by fusing said acquired data from said local sensing suite and said one or more global motion tracking devices to control the timing of ejection of the print material from said printing module.
2. The method of claim 1 , wherein said pre-planned path relative to the surface is determined by the steps of:
dividing said livery image into a plurality of swaths; and
generating a plurality of paths corresponding to the plurality of swaths for the printing module to follow.
3. The method according to claim 2 , wherein dividing a livery image into a plurality of swaths comprises:
loading a 3D representation of the surface from a computer file containing computer readable information of the surface;
overlaying a representation of the livery image to be printed onto the 3D representation of the surface; and
dividing the 3D representation of the livery image into a plurality of swaths.
4. The method according to claim 2 , wherein dividing a livery image into a plurality of swaths further comprises
acquiring data from a local sensing suite and one or more global motion tracking devices;
generating a 3D representation of the surface from said acquired data;
overlaying a representation of the livery image to be printed onto the 3D representation of the surface; and
dividing the 3D representation of the livery image into a plurality of swaths.
5. The method of claim 1 , wherein the local sensing suite comprises any one or combination of:
one or more range sensors for acquiring range data of the surface; and
one or more relative motion sensors for measuring relative motion of the printing module with respect to the surface.
6. The method according to claim 5 , wherein creating a second measurement product by fusing data from said local sensing suite and said one or more global motion tracking devices to control the timing of applying printing material from said printing module comprises the steps of:
receiving one or more travel distance measurements from the one or more relative motion sensors in the local sensing suite;
fusing said travel distance measurements with pose measurements of the printing module obtained from the one or more of global motion tracking devices;
generating a triggering pulse when said fused travel distance measurement is equal to or greater than a predetermined travel distance; and
sending the triggering pulse to the printing module wherein the triggering pulse controls the printing heads to apply the printing material.
7. The method according to claim 5 , wherein the one or more relative motion sensors for measuring relative motion of the printing module with respect to the surface comprise any of one or more wheel encoders travelling on the surface, one or more non-contact optical sensors estimating relative position or velocity, one or more non-contact capacitive sensors estimating relative motion, or a combination of thereof.
8. The method according to claim 1 , wherein the local sensing suite comprises:
one or more optical sensors for acquiring one of more images of the surface.
9. A method for printing a livery image on a surface of an object and for use in association with a motion platform, the method comprising the steps of:
acquiring data from a local sensing suite, said local sensing suite comprises any one or combination of one or more range sensors for acquiring range data of the surface and one or more relative motion sensors for measuring relative motion of the printing module with respect to the surface;
acquiring data from one or more global motion tracking devices;
creating a first measurement product by fusing said acquired data from said local sensing suite and said one or more global motion tracking devices to control the motion platform to move a printing module across said surface, and wherein said fusing includes
acquiring range data from one or more range sensors in the local sensing suite for measuring the distance of the printing module relative to a surface;
acquiring position and orientation measurements of the printing module and the surface from the one or more global motion tracking devices;
constructing a 3D representation of the surface by said data from the range sensors;
computing a position and orientation of the printing module in the 3D representation of the surface;
deriving a probabilistic quantification of said computed position and orientation of the printing module from one or more measuring characteristics of the one or more range sensors;
deriving a probabilistic quantification of said measured position and orientation measurements of the printing module and the surface from one or more measuring characteristics of the global motion tracking devices, and calculating the position and orientation of the printing module relative to the surface from the position and orientation measurements of the printing module and the surface from the global motion tracking devices; and
merging the probabilistic quantification of the position and orientation of the printing module relative to the surface from the one or more range sensors and the probabilistic quantification of the position of the printing module relative to the surface from the global motion tracking devices; and
creating a second measurement product by fusing said acquired data from said local sensing suite and said one or more global motion tracking devices to control the timing of ejection of the print material from said printing module.
10. The method according to claim 9 , wherein creating a second measurement product by fusing data from said local sensing suite and said one or more global motion tracking devices to control the timing of applying printing material from said printing module comprises the steps of:
receiving one or more travel distance measurements from the one or more relative motion sensors in the local sensing suite;
fusing said travel distance measurements with pose measurements of the printing module obtained from the one or more of global motion tracking devices;
generating a triggering pulse when said fused travel distance measurement is equal to or greater than a predetermined travel distance; and
sending the triggering pulse to the printing module wherein the triggering pulse controls the printing heads to apply the printing material.
11. The method according to claim 9 , wherein the local sensing suite further comprises:
one or more optical sensors for acquiring one of more images of the surface.
12. The method according to claim 9 , wherein the one or more relative motion sensors for measuring relative motion of the printing module with respect to the surface comprise any of one or more wheel encoders travelling on the surface, one or more non-contact optical sensors estimating relative position or velocity, one or more non-contact capacitive sensors estimating relative motion, or a combination of thereof.
13. A method for printing a livery image on a surface of an object and for use in association with a motion platform, the method comprising the steps of:
acquiring data from a local sensing suite;
acquiring data from one or more global motion tracking devices;
creating a first measurement product by fusing said acquired data from said local sensing suite and said one or more global motion tracking devices to control the motion platform to move a printing module across said surface;
creating a second measurement product by fusing said acquired data from said local sensing suite and said one or more global motion tracking devices to control the timing of ejection of the print material from said printing module;
i) controlling the mobile platform to move the printing module to follow a first path corresponding to a first swath of the plurality of swaths wherein a print material from the printing module is applied to form a first printed swath corresponding to the plurality of swaths;
ii) determining a location for a next swath to be printed and aligning the next swath to be printed with the first printed swath;
iii) controlling the printing module to follow a path corresponding to the next swath to be printed wherein the print material from the printing module is applied to form a next printed swath; and
iv) repeating steps ii) to iii) until the plurality of swaths have been printed to form a plurality of printed swaths; and
wherein applying the printing material from the printing module to form the next printed swath in step iii) comprises applying the printing material to a plurality of regions in close proximity to the one or more boundaries of the first swath at a reduced intensity whereby the path of the next swath to be printed is shifted to allow for overlap between the first printed swath and the next printed swath.
14. The method according to claim 13 , wherein determining the location for the next swath to be printed and aligning the next swath to be printed to a first printed swath comprises the steps of:
determining a plurality of boundaries of said first printed swath;
computing a path shift for printing the next swath to be printed from said boundaries of said first swath; and
determining a new path to be followed by the printing module corresponding to the next swath to be printed by adding the path shift to the path corresponding to the first printed swath.
15. The method according to claim 14 , wherein determining a plurality of boundaries of a first printed swath comprises:
acquiring one or more images of said first swath from the one or more optical sensors in the local sensing suite;
detecting a plurality of boundary measurements of the first printed swath from the one or more images of said first swath;
deriving a probabilistic quantification of the boundary measurements from a plurality of measurement characteristics of the one or more optical sensors; and
computing the boundary of said first swaths by fusing the probabilistic quantification of the boundary measurements with the one or more global measurements from the one or more global motion tracking devices.
16. The method of claim 13 , wherein the local sensing suite comprises any one or combination of:
one or more range sensors for acquiring range data of the surface; and
one or more relative motion sensors for measuring relative motion of the printing module with respect to the surface.
17. The method according to claim 16 , wherein the one or more relative motion sensors for measuring relative motion of the printing module with respect to the surface comprise any of one or more wheel encoders travelling on the surface, one or more non-contact optical sensors estimating relative position or velocity, one or more non-contact capacitive sensors estimating relative motion, or a combination of thereof.
18. The method according to claim 13 , wherein the local sensing suite comprises:
one or more optical sensors for acquiring one of more images of the surface.