Abstract:
Methods to systematize the development of machines using inexpensive, fast, and convenient fabrication processes are disclosed. In an embodiment, a folding pattern and corresponding circuit design can provide the blueprints for fabrication. The folding pattern may be provided (e.g. laser machined) on a flat sheet of substrate material, such as a polymer. The circuit pattern may be generated by etching or applying (e.g. sputtering) a copper foil layer onto the substrate. Circuit components and actuators may then be added at specified locations. The flat substrate may then be folded along the predefined locations to form the final machine. The machine may operate autonomously to perform a task.

Description:
RELATED APPLICATIONS 
     This application claims priority to and benefit of U.S. Provisional Patent Application No. 61/702,040, titled FOLDABLE MACHINES, filed Sep. 17, 2012, which is incorporated herein by reference in its entirety. 
    
    
     FEDERALLY SPONSORED RESEARCH 
     This invention was made with government support under Grant Nos. CCF-1138967 and EFRI-0735953 awarded by the National Science Foundation. The government may have certain rights in the invention. 
    
    
     BACKGROUND 
     The creation of new machines requires significant development time, financial resources, and technical expertise. While a wealth of tools exist for many robot development steps, there is not a single end-to-end process which begins with a novice user specifying a desired task and resulting in a fully functional robot able to perform that task. 
     An alternative to traditional machine design and fabrication may be referred to as “printable” and/or “foldable” machines. Such designs may utilize tools which are readily available, inexpensive to operate, and require minimal technical knowledge by a user. 
     As an illustrative example, assume a home owner needs a machine to explore areas of his basement in order to detect carbon monoxide and radon. The machine may be required to traverse a cluttered environment, carry a sensor, and report back to the user. Using traditional design and fabrication techniques to create such a machine may be time consuming and inconvenient for the user. However, if the user uses a foldable machine described below, the user may feed specifications to a foldable machine compiler, which chooses notional designs from a prepopulated database, refines geometries based upon the task to be performed, and produces detailed design and program files. The machine may then be fabricated from the design and program files, and the user may collect the machine and place it into operation. 
     In another example, a custom gripper may be desired for an electronics assembly line. The gripper could, for example, be utilized by a pick and place machine. The assembly line manager can specify traits of the part such as the mass and approximate geometry. These specifications may be provided to the foldable machine compiler and fabrication process to produce a custom gripper to meet the task needs. 
     SUMMARY 
     Methods to systematize the development of machines using inexpensive, fast, and convenient fabrication processes are disclosed. In an embodiment, a library of physical modules and their corresponding theoretical models are used. One advantage of such methods is that the deigns can be re-used based on a set of task criteria and custom parameters to tune the machine for use in a particular task. The resulting customized design, which may include a folding pattern and corresponding circuit design, can provide the blueprints for fabrication. The folding pattern may be provided (e.g. laser machined) on a flat sheet of substrate material, such as a polymer. The circuit pattern may be generated by etching or applying (e.g. sputtering) a copper foil layer onto the substrate. Circuit components and actuators may then be added at specified locations. The flat substrate may then be folded along the predefined locations to form the final machine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a foldable substrate. 
         FIGS. 2A-2F  are a series of line drawings of a process for printing and populating circuits. 
         FIG. 3  is a perspective view showing a folded machine. 
         FIG. 4  is a series of diagrams illustrating articulation of a folded machine. 
         FIG. 5  is a plan view of a foldable substrate. 
         FIGS. 6A, 6B, and 6C  are perspective views of a folded machine. 
         FIG. 7  is a block diagram of a computer architecture including a database for storing models of foldable machines. 
         FIG. 8  is an image representing data that can be stored in a foldable machine database. 
     
    
    
     Like numbers in the drawings denote like elements. Connectors within circuit or block diagrams may represent single wires, buses, or other types of connections between blocks. A single connector line should not be construed to limit the type of connection to a single wire. 
     The figures, including the flowcharts and block diagrams, are provided for exemplary purposes and are not intended to limit the scope of this disclosure. Although the figures depict diagrams and flowcharts with particular numbers of blocks connected in particular arrangements or sequences, these are examples only. Other arrangements and sequences are within the scope of this disclosure. 
     DETAILED DESCRIPTION 
       FIGS. 1-5  illustrate one example of a foldable machine: a hexapod crawler machine.  FIGS. 6-7  illustrate another example of a foldable machine: a two digit gripper. One skilled in the art will recognize that these are two examples of foldable machines and do not limit the scope of the disclosure; any type of two- or three-dimensional machine may be created using the methods described below. 
     In an embodiment, to create a foldable machine, a user may feed specifications to a foldable machine compiler, which may choose appropriate designs for completion of the specified task from a pre-populated database, refine geometries based upon the task to be performed, and produce detailed design and program files. The detailed design and program files may include a cutting pattern for cutting a template out of a sheet of substrate material, a circuit pattern for creating and populating a circuit on the template, and/or a folding pattern that can be applied to the template in order to form the template into the final machine. 
     Laser cutters, lamination, and PCB like component assembly followed by a final assembly that folds the substrate into its final form may be utilized. This so-called printable approach may allow for rapid development of low-cost machines using a general process that links specifications to prototypes, without requiring in-depth technical knowledge from the end user. The manufacturing process may include at least the following: (1) modeling of the machine; (2) parameter instantiation according to user specifications, i.e. modification of the model in order to tailor the machine to a particular task; (3) printed body fabrication; (4) printed electronics on the 2D body; (5) population of electronic components on the body; and (6) assembly of the 3D machine using folding. The resulting machines may be relatively light-weight (e.g. about 3 g) and may function as autonomous, programmable machines or robots. In an embodiment, a foldable machine may be fabricated in less than one day, less than 8 hours, less than four hours, less than two hours, less than one hour, or in any appropriate amount of time. 
     In an embodiment, the foldable machine compiler may operate similarly to programming language compilers that break down high-level specifications into functional component details. The foldable machine compiler may be able to choose from a large database of foldable machines and components, which may be pre-populated in the database by expert users. 
     Body Template 
     Referring to  FIG. 1 , a template  100  for forming a machine is shown. In an embodiment, the template  100  may be formed from, e.g. cut out of, a stock sheet of substrate. The substrate can be made of any appropriate material including plastics, cellulose, amalgam, or any other type of material that can be cut to form a template  100 . For example, the substrate may be polyetheretherketone (PEEK) having a width of about 0.125 mm, 5 mils, or any other appropriate width. 
     In an embodiment, the substrate material may be sufficiently foldable or flexible so that the template  100  can be folded into the shape or body of a machine, and so that parts or features of the body can move, bend, flex, and actuate as desired. The material may also be sufficiently stiff so that the machine can hold its shape and perform tasks (e.g. carrying a load) once folded into a final form. 
       FIG. 1  illustrates a template  100  that has been cut from a stock sheet. In an embodiment, the stock sheet can be etched, cut, and/or perforated so that a border  102  of the template  100  is formed. During the process, the stock sheet can be cut so that unnecessary material (i.e. substrate material that is not part of the template) can be removed, leaving only the template  100  behind. 
     The template may also include various cutouts, such as cutout  104  and hole  106 . These cutouts and holes may be used for various purposes. For example, cutout  104  may be designed to accept a tab, such as tab  108 , during folding. When the tab  108  is inserted into the cutout  104 , it may provide stability and structure to the body of the machine once the substrate is folded. As another example, the hole  106  may provide a portion of the body with additional flexibility. For example, the hole  106  may be placed at a movable joint. Having hole  106  at the joint location may allow the joint to move more freely once the body is folded into its final form. 
     The template may include additional holes (not shown) that can be used to accept through-hole electronic components, such as through hole chips, resistors, capacitors, etc. These additional holes may also be used to accept or mount electromechanical actuators that can allow the machine, once assembled in a final form, to move. 
     The template  100  may also include various fold lines  110 . These fold lines may define a folding pattern for the template  100 . In other words, once the template is folded according to the fold lines  110 , the template may be formed into the body of a machine. 
     The fold lines  110  may, in an embodiment, be perforated lines (i.e. a series of small holes) in the template  100 . The size of the holes and the distance between the holes may vary based upon the application. If the fold lines  110  are perforated, the lines may be folded in either direction. For example, if the fold line  112  is a perforated line, the square structure  114  may be folded up and over the remainder of the template  100 , or may be folded down and under the remainder of the template  100  with equal ease. 
     In another embodiment, the fold lines  110  may be etched into the template  100 . In other words, the fold lines  110  may be cut partway into the template  100  without cutting all the way through the template  100 . If the fold lines  110  are etched, it may be easier to fold along the fold lines  100  in one direction. Therefore, in an embodiment, etched fold lines  100  can be used to define a direction in which the template should be folded. For example, if the fold line  112  is etched into the top of the template  100 , then it may be easier to fold the square structure  114  up and over the remainder of the template  100 . On the other hand, if the fold line  112  is etched into the bottom of the template  100 , then it may be easier to fold the square structure  114  down and under the remainder of the template  100 . These etched fold lines can help guide a user as to which way the template  100  should be folded. 
     In an embodiment, the template  100  may be machined from a substrate material. For example, the raw substrate material may be exposed to a laser cutting tool, or any other type of tool, that can cut the template  100  out from the raw substrate material. The cutting tool may also cut out cutouts such as cutout  104  and cut out holes such as hole  106 . The cutting tool may also perforate or etch fold lines in the template  100 , such as fold line  110 . 
     In operation, the cutting tool may receive a cutting pattern from a foldable machine database that defines the template and its features, as will be discussed below. The cutting tool may then automatically cut and etch the template  100  from the stock substrate material. 
     Circuitry 
     Once the template has been formed, a circuit may be printed and populated on the template. Referring to  FIGS. 2A-2F , a process for printing a populating circuitry onto the template  100  is shown. As shown, in  FIGS. 2A and 2B , a printed circuit mask on a copper foil  202  and/or  204  may be defined. The masks  202  and  204  may define circuit traces  205  that will be formed on the template  100 . The foil  202  and/or  204  may then be applied to the template, and the excess copper (i.e. the copper not covered by the mask material) may be chemically etched away, leaving the circuit traces defined by the mask behind as shown in  FIG. 2C  and  FIG. 2D . The masking and etching process is a subtractive process (i.e. a process that removes material by etching) and can be used to create conductive traces and planes on the template  100 . The circuit can be printed with a solid ink printer and the material can be etched away using a chemical etching process, such as a ferric-chloride etch. 
     In an embodiment, an additive process can also be used to create conductive traces and planes. For example, processes known in the art that sputter or add conductive material to the template in desired locations can be used to create the circuit traces and planes. 
     In some instances, the conductive traces and planes may cross over the fold lines  110  so that, when the template  100  is folded, the conductive traces and planes are also folded. Accordingly, a conductive material (e.g. a copper foil or the like) that is resistant to folding can be used so that the traces do not break when the template  100  is folded into its final form. 
     Once the conductive traces are formed, the circuit can be populated with electronic components as shown in  FIGS. 2E and 2F . As shown, surface mount components such as chip  206 , resistor  208 , or voltage regulator  210  can be mounted on the template  100 . In an embodiment, a pick and place machine can place the components, then a soldering process (e.g. wave soldering and the like) can solder the components onto the surface of the template  100 . Other processes can also be used place and solder the components, such as manual placing and soldering, or other automated manufacturing processes that place and solder electronic components. 
     As shown in  FIG. 2F , components such as a potentiometer  212  and an actuator (shown as a motor  214 ) can also be added to the template  100 . These components can also be soldered in place, or can be mounted in place with screws, tacks, adhesive, or any other method of mounting. Although not shown, through hole components can also be added and soldered to the template  100 . 
     Final Assembly 
     Referring now to  FIG. 3 , a final assembly of a foldable machine  300  is shown. After the circuitry has been populated, the two-dimensional template  100  can be folded along the fold lines  110  to form a three-dimensional body  302  of the machine  300 . As shown, the template  100  of  FIG. 1  can be folded to form a six-legged crawler machine  300 . The circuitry  304  may control the movement of the crawler machine  300 , and may be able to move the legs (e.g. leg  306 ) of the crawler machine  300  so that the crawler machine  300  propels itself forward or backward, turns in place, and/or steers and turns as desired. 
     In an embodiment, the circuitry  304  can include a processor (e.g. a microprocessor or the like), a volatile or non-volatile memory, and computer readable instructions stored in the memory which, when executed by the processor, cause the machine  300  to perform functions such as walking, taking sensor readings, etc. 
     The crawler machine  300  can also include linear actuators  308  for moving the legs  306  back and forth. In an embodiment, these linear actuators may be wire that is coiled around the shaft of a motor so that the motor, when activated, can pull on the leg  306 . In another embodiment, these linear actuators may be NiTi SMA coil springs that are actuated by a phase transition based on temperature. In other words, when the linear actuator is heated, it may retract. By providing an electrical current through the actuator  308 , the actuator  308  may heat up and retract, thus pulling the leg  306 . 
     As shown, each leg  306  may have two actuators  308  connected so that the leg  306  can be pulled forward, when one actuator  308  is retracted, and backward, when the other actuator  308  is retracted. The circuitry  304  can control the actuators  308  attached to each leg  306  so that the crawler machine  300  can move. 
     Although the circuitry  304  is shown on the outside surface of the crawler machine  300 , the circuitry  304  can alternatively or additionally be located on an inside surface of the crawler machine  300 . Also, although the crawler machine is shown with reference to a penny  310 , the crawler machine  300  (or other foldable machines) can be produced in any desired size. 
     Referring now to  FIG. 4 , diagrams of the final assembly of a crawler machine  300  are shown to illustrate articulation and movement of the legs  306 . As shown in diagram  400 , the actuators  308  can pull the legs  306  forward and backward to allow the crawler machine  300  to move. The legs can be moved individually or simultaneously. Depending upon the sequence of leg movement, the crawler machine  300  can move forward, backward, or can turn. For example, if the legs on only one side of the crawler machine  300  are actuated, the crawler machine  300  may move in an arc. Alternatively, if the legs  306  on one side of the crawler machine  300  are actuated in a forward pattern, and the legs  306  on an opposing side of the crawler machine  300  are actuated in a reverse pattern, the crawler machine  300  may spin so that it is facing a new direction. 
     As shown by the images in  FIG. 4 , the crawler machine  300  can also climb over obstacles. 
     Referring to  FIG. 5  and  FIGS. 6A-6C , an additional embodiment of a foldable machine for gripping objects is shown. A template  500  may be cut from stock substrate material in a similar manner to the process described above. The template  500  may include circuitry  502  that can be printed and populated on the surface of the template  500 , as described above. However, the template  500  may have a shape and folding pattern designed to form a gripping tool, rather than a crawler machine. 
       FIGS. 6A-6C  are perspective views that illustrate the final assembly of the gripping tool. As shown, the gripping tool  600  has pincers  602  that can be opened and closed by circuitry  604 . The pincers  600  can be used to grasp objects and may be useful, for example, to grab objects that are dangerous to touch, such as hot or acidic objects. The gripping tool  600  may also be useful to grab hard-to-reach objects where a human hand cannot reach, and may also be useful as a tool for manufacturing. For example, the gripping tool  600  could be installed in a pick and place machine where it is used to select and place electronic components onto a printed circuit board. 
     Modeling 
     In various embodiments, methods of fabricating machines by printing and/or folding processes may utilize a database of system components such as actuators, sensors, processors, materials, final assemblies, folding patterns, cutout patterns, substrates, and user-specified constraints. The database can include parameterized expert-designed components (e.g. a crawler machine body shape with a variable number of legs, a leg with variable size, etc.). Each component within the database may be represented by a class where some of its properties can vary. The physical characteristics of each component (e.g., its mechanical properties, weight, and power consumption) can be determined and included in the class. The database can be updated as users design and fabricate new robots. 
     A modeling engine may be associated with each component in the database. This engine can be used to select the approximate desired parameters that match the user specification. For example, the modeling engine can be used to select materials and/or patterns to create a crawler machine having 6 legs capable of carrying a radon sensor and covering a 200 m2 space within 24 hours. 
     In an embodiment, the database may include a library of models that provide fundamental robotic capabilities such as locomotion or manipulation. In an embodiment, the library can be stored in a database. 
     Turning to  FIG. 7 , a block diagram of a computer architecture  700  for storing a library of models is shown. In an embodiment, a computer  702  (or a series of computers connected by a network) includes a processor or series of processors  704  and a volatile or non-volatile memory or series of memories  706 . Computer readable instructions stored in the memory  704  may be executed by the processor  702 . 
     The computer  702  may also include a database or series of databases  708  that can be stored on a hard drive or other storage device. The database  708  may be any database, relational or otherwise, known in the art that can store data such as model data for foldable machines. 
     The models sometimes include engineering trade-offs between system specifications that may be different for every application. Using a model database  808 , a user can request a design that meets high-level specifications without requiring a detailed technical design. A high-level specification may include information such as: “a crawling robot to map radon levels in a basement.” 
     Referring now to  FIG. 8 , a diagram of a model  800  is shown. In an embodiment, the model  800  may be represented by data stored in the database  707 . The data may represent a pattern, such as that shown in  FIG. 8 , that represents a model of a foldable machine and can be used to fabricate the folded machine. The model  800  may include borders, cutouts, shapes, circuit locations, circuit components, folding patterns, or any other information that can be used to define a foldable machine. 
     Fabrication Process 
     In an embodiment, a process for fabricating a foldable machine includes storing models for folding machines in a database. A user may then specify high level goals to be achieved, such as “detect radon gas in a basement.” The database may then select a model that can be fabricated into a foldable machine to perform the task. 
     In certain circumstances, the model can be modified based on specific task needs. For example, a user can specify the weight of a radon detector to be carried by the machine, the size of the basement to be traversed, the height of obstacles that the machine must walk over, etc. These requirements can be used to modify the model prior to fabrication. For example, if the basement to be traversed is large, the model may be modified to include a power source (e.g. battery) that has enough stored power so that the foldable machine can traverse the large basement. As another example, if the radon detector has a particular weight, the model can be modified so that the material and/or the folding pattern used is sufficiently strong to carry the radon detector. 
     Once the model is chosen, the model may be fed into a cutting tool, such as an automated laser cutting machine, which will cut a template for the machine out of a stock sheet of material. Holes, folding patterns, and other features can also be cut into the template. 
     A circuit can then be formed on one or more surfaces of the template, through a subtractive or additive process, as described above. Circuit components and actuators can be populated and mounted on the template to complete the circuit. 
     Once populated, the template can be folded into the final form of the foldable machine. The final form can be a two- or three-dimensional machine tailored to perform the specific task identified by the user. After the machine is folded, additional electrical components can be added to the machine if needed or desired. The machine can then be put into use to complete the specified task. 
     Having described various embodiments, which serve to illustrate various concepts, structures and techniques, which are the subject of this patent, it will now become apparent to those of ordinary skill in the art that other embodiments incorporating these concepts, structures and techniques may be used. Accordingly, the scope of the patent should not be limited to the described embodiments but rather should be limited only by the spirit and scope of the following claims.