3D printing of robot end effectors with progressively changing functions

Abstract

A robotic end effector includes: at least two fingers connected by joints; and a deformable pad on the exterior of the at least two fingers, wherein the deformable pad includes a functionally graded hardness. A method for 3D printing a deformable pad for a robotic end effector includes the steps of: depositing a first material on the exterior of the at least two fingers connected by joints; and depositing a second material on the exterior of the at least two fingers connected by joints to create the deformable pad, wherein the first material and the second material have different hardnesses and the deformable pad includes a functionally graded hardness.

Description

Technical Field

[0001] This disclosure relates to a 3D additive manufacturing method and a robot end effector. This application also relates to a robot end effector fabricated by 3D additive manufacturing. Background Technology

[0002] Fused filament fabrication (FFF)—also known in the art as thermoplastic extrusion, plastic jet printing (PJP), fused filament method (FFM), or fused deposition modeling—is an additive manufacturing process that extrudes material in continuous layers onto a platform to form a three-dimensional (3D) product. Typically, FFF uses molten thermoplastic material extruded onto the platform. 3D printing sometimes uses support structures that are easily dissolved or removed from the part after printing.

[0003] The drawbacks of existing FFF (Fluorescent Forming) techniques using thermoplastics include single-material-property printing, limited print orientation strength, limited durability, and limited flexibility. Thermosetting materials are generally not used in FFF because the monomers are low-viscosity liquids before curing, and during deposition, the curing liquid flows or breaks into droplets, resulting in low-quality finished parts with undesirable low resolution. Attempts to print with thermosetting materials require the addition of fillers (such as inorganic powders or polymers) to induce thixotropic behavior in the resin before it fully cures. These solutions adversely affect the final properties of the printed parts. Other problems include poor resolution control in the printed parts and frequent clogging of the mixing system.

[0004] Manufacturers use robots equipped with robotic end effectors. These end effectors are used to grasp, pick up, move, and place objects. End effectors typically have complex, expensive, and difficult-to-design multi-joint structures and sophisticated actuation mechanisms. These robots equipped with robotic end effectors are designed to repeatedly grasp, pick up, move, and place the same object. End effectors often struggle to grasp objects of varying sizes. Summary of the Invention

[0005] This disclosure relates to robotic end effectors, 3D printing methods, and 3D printed objects.

[0006] In some embodiments, this disclosure relates to a robotic end effector comprising: at least two fingers connected by joints; and a deformable pad on the exterior of the at least one finger, wherein the deformable pad comprises a material with functionally graded hardness.

[0007] In some embodiments, the functional gradient hardness includes a soft-hard material on the exterior of the at least two fingers and a hard-hard material on the exterior of the hard-hard material. In some embodiments, the functional gradient hardness includes a hard-hard material region and a soft-hard material region on the exterior of the at least two fingers.

[0008] In some embodiments, the functional gradient hardness includes a plurality of hard material regions and a plurality of soft material regions on the exterior of the at least two fingers. In some embodiments, the functional gradient hardness includes a soft material at the tips of the at least two fingers and a hard material at the bases of the at least two fingers. In some embodiments, the functional gradient hardness includes a hard material at the tips of the at least two fingers and a soft material at the bases of the at least two fingers.

[0009] In some embodiments, the hardness region and the softness region are uniformly distributed on the at least two fingers. In some embodiments, the hardness region and the softness region are non-uniformly distributed on the at least two fingers. In some embodiments, the robot end effector comprises a linearly functionally graded hardness material. In some embodiments, the robot end effector comprises a non-linearly functionally graded hardness material.

[0010] In some embodiments, the robotic end effector includes one or more sensors. In some embodiments, the one or more sensors are located within the deformable pad. In some embodiments, the one or more sensors provide tactile feedback.

[0011] In some embodiments, the robotic end effector includes at least three fingers. In some embodiments, the robotic end effector includes at least four fingers. In some embodiments, the robotic end effector includes at least five fingers.

[0012] In some embodiments, the exterior of the deformable pad includes a corrugated surface.

[0013] In some embodiments, the deformable pad comprises a thermosetting material. In some embodiments, the thermosetting material used to form the thermosetting material includes isocyanates, isocyanate prepolymers, urethane, urea-containing polymers, polyol prepolymers, amine prepolymers, polyols containing at least one terminal hydroxyl group, polyamines containing at least one amine comprising the reactive hydrogen of isocyanates, or mixtures thereof.

[0014] In some embodiments, the deformable pad comprises foam and solid elastomer. In some embodiments, the deformable pad comprises urethane or silicone.

[0015] In some embodiments, the functional gradient hardness is in the range of Shore A 10 to Shore D 100. In some embodiments, the functional gradient hardness is in the range of about Shore A 40 to 90 or about Shore 00 20 to Shore D 80, or in the range of about 15 psi to about 70 psi (as determined by indentation load deflection testing). In some embodiments, the soft hardness is about Shore A 10 and the hard hardness is about Shore D 100.

[0016] In some embodiments, this disclosure relates to a method for creating a deformable pad for a 3D printed robot end effector, the method comprising the steps of: depositing a first material on the exterior of at least two fingers connected by a joint; and depositing a second material on the exterior of the at least two fingers connected by a joint to create a deformable pad, wherein the first material and the second material have different hardnesses and the deformable pad includes a functionally graded hardness.

[0017] In some embodiments, the deposition of the first material completely surrounds the at least two fingers, and the deposition of the second material is on the first material. In some embodiments, the deposition of the first material is on a region of the at least two fingers, and the deposition of the second material is on a different region of the at least two fingers. In some embodiments, the deposition of the first material is on the bottom of the at least two fingers, and the deposition of the second material is on the top of the at least two fingers.

[0018] In some embodiments, the deposition of the first material and the deposition of the second material are uniformly distributed on the exterior of the at least two fingers. In some embodiments, the deposition of the first material and the deposition of the second material are non-uniformly distributed on the exterior of the at least two fingers. In some embodiments, the first material comprises hardness and the second material comprises softness. In some embodiments, the first material comprises softness and the second material comprises hardness. In some embodiments, the method includes linear functionally graded hardness. In some embodiments, the method includes a non-linear functionally graded hardness material.

[0019] In some embodiments of the method, the deformable pad includes one or more sensors. In some embodiments of the method, the one or more sensors are located within the deformable pad. In some embodiments of the method, the one or more sensors provide tactile feedback.

[0020] In some embodiments of the method, the robotic end effector includes at least three fingers. In some embodiments of the method, the robotic end effector includes at least four fingers. In some embodiments of the method, the robotic end effector includes at least five fingers.

[0021] In some embodiments of the method, the exterior of the deformable pad includes a corrugated surface.

[0022] In some embodiments of the method, the first material and / or the second material comprises a thermosetting material. In some embodiments of the method, the thermosetting material comprises isocyanate, isocyanate prepolymer, urethane, urea-containing polymer, polyol prepolymer, amine prepolymer, polyol containing at least one terminal hydroxyl group, polyamine containing at least one amine comprising the reactive hydrogen of isocyanate, or mixtures thereof.

[0023] In some embodiments of the method, the first material and / or the second material independently comprise a foam or solid elastomer. In some embodiments of the method, the first material and / or the second material independently comprise urethane or silicone resin.

[0024] In some embodiments of the method, the functional gradient hardness is in the range of Shore A 10 to Shore D 100. In some embodiments of the method, the functional gradient hardness is in the range of about Shore A 40 to 90 or about Shore 00 20 to Shore D 80, or in the range of about 15 psi to about 70 psi (e.g., as determined by indentation load deflection testing). In some embodiments of the method, the soft hardness is about Shore A 10 and the hard hardness is about Shore D 100. Attached Figure Description

[0025] Figure 1 A deformable pad with functional gradient hardness is described, featuring three materials with different hardnesses and two built-in sensors.

[0026] Figure 2 A deformable pad with functional gradient hardness, featuring three materials of different hardnesses and two built-in sensors, is depicted, as well as the ability to conform to the shape of an apple using the deformable pad. Detailed Implementation

[0027] Embodiments of this disclosure relate to a robotic end effector comprising: at least two fingers connected by joints; and a deformable pad on the exterior of the at least two fingers, wherein the deformable pad comprises a functionally graded hardness.

[0028] Embodiments of this disclosure also relate to a method for a deformable pad for a 3D printed robot end effector, the method comprising the steps of: depositing a first material on the exterior of at least two fingers connected by joints; and depositing a second material on the exterior of at least two fingers connected by joints to create a deformable pad, wherein the first material and the second material have different hardnesses and the deformable pad includes a functionally graded hardness.

[0029] In some embodiments, this disclosure relates to a deformable pad comprising a first material and a second material, wherein the first material and the second material have different hardnesses and the deformable pad comprises a functionally graded hardness.

[0030] In some embodiments, this disclosure relates to a method for 3D printing a deformable pad, the method comprising the steps of: depositing a first material and depositing a second material to fabricate a deformable pad, wherein the first material and the second material have different hardnesses and the deformable pad comprises a functionally graded hardness.

[0031] In some embodiments, this disclosure relates to a method for fabricating a robotic end effector, the method comprising the steps of: 3D printing a deformable pad comprising a first material and a second material, wherein the first material and the second material have different hardnesses and the deformable pad comprises a functionally graded hardness; and adhering the deformable pad to one or more fingers of a robotic structure.

[0032] In some embodiments, the deformable pad of the end effector can have selective flexibility. The pad can conform to the shape of the object to be manipulated to maximize the surface area in contact with the object, minimize surface pressure, and prevent slippage. The deformable pad according to embodiments of this disclosure can minimize potential damage or deformation to the object to be lifted.

[0033] In some implementations, increasing the hardness of the pad depth can prevent deformation of the deformable pad and can provide pressure transmission to the sensor while also providing strength to the deformable pad.

[0034] Surprisingly and unexpectedly, it was found that robotic end effectors with functionally graded stiffness can reduce the number of joints required to achieve the same or superior level of grasping compared to end effectors without functionally graded stiffness.

[0035] Surprisingly and unexpectedly, it was discovered that robotic end effectors with functionally graded stiffness can grasp, pick up, move, and place objects of various sizes. Because the disclosed end effectors can grasp, pick up, move, and place objects of various sizes, they can make robots more efficient and enhance their usability.

[0036] For example, the disclosed end effector can be used to grasp, pick up, move, and place fruits or vegetables that naturally come in a variety of sizes and shapes. As another example, the disclosed end effector can be used in a warehouse to grasp, pick up, move, and place boxes or objects of various sizes and shapes.

[0037] In some implementations, to further enhance selective flexibility and allow the deformable pad to conform to the manipulated object, the deformable pad may be constructed using an open structure. In some implementations, these open structures may be designed to selectively deform under pressure, which further increases the clamping pressure across the surface of the irregularly shaped object.

[0038] In some implementations, an end effector with functionally graded stiffness can allow for a reduction in the number of finger bones necessary to deform into the shape of an object and move the object without breaking it, while increasing the force that can be used to lift and manipulate the object.

[0039] It has been found that the deformable pads according to this disclosure are surprisingly durable and resilient. In some embodiments, the deformable pad can return to its original shape after a single use. In some embodiments, the deformable pad exhibits less than 10% change in hardness or sensitivity after 10, 100, or 1000 cycles of repeated use, or does not tear. In some embodiments, a built-in sensor can be used to detect when it is time to replace the used deformable pad with a new one. In some embodiments, the sensor can detect whether the deformable pad needs to be replaced when the sensor closest to the surface detects pressure at the same level as the deeper sensor.

[0040] In view of the benefits of this disclosure, various examples and implementations of the disclosed subject matter are possible and will be apparent to those skilled in the art. Throughout this disclosure, references to “some implementations,” “certain implementations,” “certain exemplary implementations,” and similar phrases are intended to mean that those implementations are non-limiting examples of the subject matter of the invention, and that alternative implementations may exist without exclusion.

[0041] This article uses the articles “a,” “one,” and “the” to indicate one or more (i.e., at least one) grammatical objects of an item. For example, “element” means one element or more elements.

[0042] As used herein, the term “about” means ±10% of the value. For example only, “about 50% harder” can include anything from at least 45% harder to at least 55% harder.

[0043] The word “comprising” is used in a manner consistent with its open-ended meaning, that is, it means that a given product or process may optionally have additional features or elements in addition to those explicitly described. It should be understood that wherever the language “comprising” is used to describe an embodiment, other similar embodiments described in relation to “consisting of” and / or “substantially consisting of” can be contemplated within the scope of this disclosure.

[0044] As used in this article, the term "additive manufacturing" refers to the extrusion printing of thermoset materials.

[0045] As used herein, “exterior” of at least two fingers means at least a portion of the outermost exposed part of the finger, any part of one or more faces of the finger, any location on the finger that may be exposed to air or liquid in a cavity, and any outer portion of the finger. The exterior can be regular, irregular, or complex in shape, have sides of equal or unequal dimensions, and include cavities, gaps, or holes on the finger.

[0046] As used herein, the term "finger" is a portion of an end effector that, when used as a robotic end effector, grasps, picks up, moves, and / or places an object. A "finger" can also be considered a finger bone or a gripper. The tip of a finger is located near or at the end of the finger and is the furthest part of the finger from the robotic arm. The base of a finger is located near or at the bottom of the finger and is the closest part of the finger to or from the robotic arm. The tip or bottom is not a single point but may instead be a general area (i.e., the area around the tip or the area around the bottom). Fingers can be multi-jointed, fingers can be single-jointed, and fingers can be non-jointed.

[0047] As used herein, the terms “thermoset,” “thermoset product,” and “thermoset material” are used interchangeably and refer to the reaction product of at least two chemicals that form a covalently bonded crosslinked or polymeric network. Unlike thermoplastics, the thermoset products described herein can be irreversibly cured or solidified.

[0048] As used herein, the term "thermosetting material" refers to a covalently bonded crosslinked or polymeric network that still exhibits reactive properties; for example, it may still possess hydroxyl, amine, and / or isocyanate functional groups that provide measurable hydroxyl, NH, or NCO values ​​in titration. In one embodiment, the thermosetting material may have a viscosity of less than 3,000,000 cp. In one embodiment, the thermosetting material may have a molecular weight of no more than 100,000 g / mol.

[0049] Robot end effector

[0050] In some embodiments, this disclosure relates to a robotic end effector comprising: at least two fingers connected by joints; and a deformable pad on the exterior of the at least one finger, wherein the deformable pad comprises a material with functionally graded hardness.

[0051] In some embodiments, the functionally graded hardness material may include two, three, four, five, or six materials. In some embodiments, each material may include a mixture of different materials. In some embodiments, the mixture of different materials can achieve a gradual transition from one hardness to different hardnesses.

[0052] In some embodiments, the functional gradient hardness includes a soft-hard material on the exterior of at least two fingers and a hard-hard material on the exterior of the hard-hard material.

[0053] In some embodiments, the functional gradient hardness includes a hard material on the exterior of at least one finger and a soft material on the exterior of the soft material.

[0054] In some embodiments, the functional gradient hardness includes a hard material region and a soft material region on the exterior of at least two fingers. In some embodiments, the functional gradient hardness includes multiple hard material regions and multiple soft material regions on the exterior of at least two fingers.

[0055] In some embodiments, hard and soft material regions are uniformly distributed on at least two fingers. In some embodiments, hard and soft material regions are non-uniformly distributed on at least two fingers. In some embodiments, one or more fingers may be dexterous fingers. In some embodiments, one or more fingers may be fixed fingers. In some embodiments, one or more fingers include deformable pads, and one or more fingers do not include deformable pads.

[0056] In some implementations, the functional gradient hardness includes a soft-hard material at the tips of at least two fingers and a hard-hard material at the base of at least two fingers.

[0057] In some implementations, the functional gradient hardness includes a hard material at the tips of at least two fingers and a soft material at the base of at least two fingers.

[0058] In some implementations, the robotic end effector includes one or more sensors. In some implementations, one or more sensors are located within a deformable pad. In some implementations, one or more sensors provide tactile feedback. In some implementations, one or more sensors can guide the robotic end effector to improve grasping, picking up, moving, and placing objects.

[0059] In some embodiments, the robotic end effector includes at least three fingers. In some embodiments, the robotic end effector includes at least four fingers. In some embodiments, the robotic end effector includes at least five fingers.

[0060] In some implementations, the exterior of the deformable pad includes a corrugated surface.

[0061] In some embodiments, the deformable pad comprises a thermosetting material. In some embodiments, the thermosetting material used to form the thermosetting material includes isocyanates, isocyanate prepolymers, urethane, urea-containing polymers, polyol prepolymers, amine prepolymers, polyols containing at least one terminal hydroxyl group, polyamines containing at least one amine comprising the reactive hydrogen of isocyanates, or mixtures thereof.

[0062] In some embodiments, the deformable pad comprises foam and solid elastomer. In some embodiments, the deformable pad comprises urethane or silicone.

[0063] In some embodiments, the softness is about Shore A 10 and the hardness is about Shore D 100.

[0064] In some embodiments, the functional graded hardness can be in the range of about Shore A 40 to 90, or about Shore 00 20 to Shore D 80. In some embodiments, the functional graded hardness can be in the range of foam hardness from about 15 pounds to about 70 pounds (as determined by indentation load deflection testing).

[0065] In some embodiments, the deformable pad can constitute the entire finger. In other words, apart from the deformable pad, there are no additional objects representing the finger (except for potentially mechanically controlled joints or sensors) (i.e., there are no objects separate from the thermosetting material and no potentially mechanically controlled joints or sensors present in the finger). In some embodiments, the finger is 3D printed, and then the deformable pad is 3D printed onto the 3D-printed finger.

[0066] In some embodiments, the fingers may comprise an object separate from the thermosetting material, such as a metal or polymer. In some embodiments, the fingers are not objects created by 3D printing.

[0067] Functional Gradient Hardness

[0068] As used herein, the term "functional gradient" refers to an increase in hardness from one value to another. In some embodiments, the gradient may be smooth and / or continuous. In some embodiments, the gradient may be discrete and / or gradual. In some embodiments, the gradient may be from the tip of the finger to the bottom of the finger. In some embodiments, the gradient may be within the depth and / or thickness of the material. In some embodiments, the gradient rate may be low or high. In some embodiments, the gradient may be linear. In some embodiments, the gradient may be non-linear. In the context of "functionally gradient" hardness, the phrase means that the hardness increases from one value to another.

[0069] Hardness refers to the amount of pressure required to deform a material to a certain distance. In some embodiments, the material may have a Shore A hardness from about 20 to about 120. In some embodiments, the hardness may be a Shore A value of at least about 20, at least about 30, at least about 40, at least about 50, at least about 60, at least about 70, at least about 80, at least about 90, at least about 100, at least about 110, or at least about 120. In some embodiments, the hardness may be a Shore A value not greater than about 120, not greater than about 110, not greater than about 100, not greater than about 90, not greater than about 80, not greater than about 70, not greater than about 60, not greater than about 50, not greater than about 40, not greater than about 30, or not greater than about 20.

[0070] In some embodiments, the material may have a hardness of about Shore 00 20 to Shore D 100. In some embodiments, the material may have a hardness of about Shore 00 20 to Shore A 90. In some embodiments, the material may have a hardness of about Shore A 40 to Shore A 90. In some embodiments, the material may have a hardness of about Shore A 50 to Shore D 100.

[0071] In some embodiments, the material may have a Shore D hardness from about 3 to about 120. In some embodiments, the hardness may be a Shore D value of at least about 30, at least about 40, at least about 50, or at least about 60. In some embodiments, the hardness may be a Shore D value of no more than about 120, no more than about 110, no more than about 90, no more than about 80, or no more than about 70.

[0072] Hardness can be measured using a hardness tester such as the ASTM D2240 hardness tester. While a Shore hardness tester can be used to measure the hardness of non-foam materials, foam may be too soft for a Shore hardness tester. The unit of hardness for foam can be indentation force deflection (IFD), and the standard is specified by the Polyurethane Foam Association (United Industrial Foam Standards and Guidelines, Section 4.0, available at www.pfa.org / jifsg / jifsgs4.html), requiring a force (in pounds) of 50 square feet (referred to as 25% IFD) indented by 25% of its thickness. In some embodiments, the hardness can be at least about 15 pounds, at least about 20 pounds, at least about 30 pounds, or at least about 35 pounds of about 25% IFD. In some embodiments, the hardness can be no more than about 60 pounds, no more than about 50 pounds, or no more than about 40 pounds of about 25% IFD. In some embodiments, a more rigid foam can be characterized by compressive strength at 10% flexural strength as defined in ASTM D1621 or flexural strength as defined in EN 12089. In some embodiments, a rigid foam can have compressive strength ranging from about 25 kPa to about 200 kPa or flexural strength between about 150 kPa and about 2000 kPa.

[0073] Method for Deformable Pads in End Effectors of 3D Printed Robots

[0074] In some embodiments, this disclosure relates to a method for creating a deformable pad for a 3D-printed robotic end effector, the method comprising the steps of: depositing a first material on the exterior of at least two fingers connected by joints; and depositing a second material on the exterior of the at least two fingers connected by joints to create a deformable pad, wherein the first material and the second material have different hardnesses and the deformable pad includes a functionally graded hardness.

[0075] In some implementations, the deposition of the first material completely surrounds at least two fingers, and the deposition of the second material is on the first material.

[0076] In some implementations, the first material is deposited over regions of at least two fingers, and the second material is deposited over different regions of at least two fingers.

[0077] In some embodiments, the deposition of the first material and the deposition of the second material are uniformly distributed on the exterior of at least two fingers. In some embodiments, the deposition of the first material and the deposition of the second material are non-uniformly distributed on the exterior of at least two fingers.

[0078] In some embodiments, the first material has a hardness and the second material has a softness.

[0079] In some embodiments, the deformable pad includes one or more sensors. In some embodiments, one or more sensors are located within the deformable pad. In some embodiments, one or more sensors provide tactile feedback.

[0080] In some embodiments, the robotic end effector includes at least three fingers. In some embodiments, the robotic end effector includes at least four fingers. In some embodiments, the robotic end effector includes at least five fingers.

[0081] In some implementations, the exterior of the deformable pad includes a corrugated surface.

[0082] In some embodiments, the first material and / or the second material comprises a thermoset material. In some embodiments, the thermoset material comprises isocyanate, isocyanate prepolymer, urethane, urea-containing polymer, polyol prepolymer, amine prepolymer, polyol containing at least one terminal hydroxyl group, polyamine containing at least one amine comprising the reactive hydrogen of isocyanate, or a mixture thereof.

[0083] In some implementations, the first material and / or the second material independently comprise foam or solid elastomer.

[0084] In some embodiments, the first material and / or the second material independently comprise urethane or silicone resin.

[0085] In some implementations, the functional gradient hardness is in the range of Shore A 10 to Shore D 100.

[0086] In some embodiments, the functional graded hardness can be in the range of about Shore A 40 to 90, or about Shore 00 20 to Shore D 80. In some embodiments, the functional graded hardness can be in the range of foam hardness from about 15 pounds to about 70 pounds (as determined by indentation load deflection testing).

[0087] In some embodiments, the deformable pad can constitute the entire finger. In other words, apart from the deformable pad, there are no additional objects representing the finger (except for potentially mechanically controlled joints or sensors) (i.e., there are no objects separate from the thermosetting material and no potentially mechanically controlled joints or sensors present in the finger). In some embodiments, the finger is 3D printed, and then the deformable pad is 3D printed onto the 3D-printed finger.

[0088] In some embodiments, the fingers may comprise an object separate from the thermosetting material, such as a metal or polymer. In some embodiments, the fingers are not objects created by 3D printing.

[0089] thermosetting materials

[0090] The thermosetting material according to the embodiments of the claim can be composed of any number of materials.

[0091] In some embodiments, the thermosetting material may be an isocyanate, an isocyanate prepolymer, urethane, a urea-containing polymer, a polyol prepolymer, an amine prepolymer, a polyol containing at least one terminal hydroxyl group, a polyamine containing at least one amine comprising the reactive hydrogen of an isocyanate, or a mixture thereof.

[0092] In some embodiments, the thermosetting material may be an isocyanate. In some embodiments, the thermosetting material may be an isocyanate prepolymer. In some embodiments, the thermosetting material may be urethane. In some embodiments, the thermosetting material may be a urea-containing polymer. In some embodiments, the thermosetting material may be a polyol prepolymer. In some embodiments, the thermosetting material may be an amine prepolymer. In some embodiments, the thermosetting material may be a polyol containing at least one terminal hydroxyl group. In some embodiments, the thermosetting material may be a polyamine containing at least one amine comprising the reactive hydrogen of an isocyanate.

[0093] In some embodiments, the thermosetting material may be urethane and / or a urea-containing polymer. In some embodiments, the urethane and / or urea-containing polymer may be a polymer containing urethane groups (-NH-(C=O)-O-) as part of the polymer chain. The urethane bond can be formed by reacting an isocyanate group (-N=C=O) with a hydroxyl group (-OH). Polyurethane can be produced by reacting an isocyanate containing at least two isocyanate groups per molecule with a compound having terminal hydroxyl groups. In some embodiments, an isocyanate having an average of two isocyanate groups per molecule can react with a compound having an average of at least two terminal hydroxyl groups per molecule.

[0094] In some embodiments, urethane and / or urea-containing polymers may be polymers comprising urea groups (-NH-(C=O)-NH-) as part of the polymer chain. Urea bonds can be formed by reacting isocyanate groups (-N=C=O) with amine groups (e.g., -N(R')2), wherein each R' is independently hydrogen or an aliphatic and / or cyclic group (typically (C1-C4)alkyl). Polyureas can be prepared by reacting an isocyanate containing at least two isocyanate groups per molecule with a compound having terminal amine groups.

[0095] In some embodiments, the aliphatic group may be a saturated or unsaturated straight-chain or branched hydrocarbon group. For example, the term may include alkyl (e.g., -CH3) (or alkylene, if in-chain such as -CH2-), alkenyl (or alkenyl, if in-chain), and ynyl (or ynylene, if in-chain) groups. In some embodiments, the alkyl group may be a saturated straight-chain or branched hydrocarbon group including, for example, methyl, ethyl, isopropyl, tert-butyl, heptyl, dodecyl, octadecyl, pentyl, 2-ethylhexyl, etc. In some embodiments, the alkenyl group may be an unsaturated straight-chain or branched hydrocarbon group having one or more carbon-carbon double bonds, such as vinyl. In some embodiments, the ynyl group may be an unsaturated straight-chain or branched hydrocarbon group having one or more carbon-carbon triple bonds. Unless otherwise indicated, aliphatic groups typically contain 1 to 30 carbon atoms. In some embodiments, the aliphatic group may contain 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms.

[0096] In some embodiments, the cyclic group may be a closed-ring hydrocarbon group classified as an alicyclic group, an aromatic group, or a heterocyclic group, and may optionally include an aliphatic group. In some embodiments, the alicyclic group may be a cyclic hydrocarbon group having properties similar to those of an aliphatic group. In some embodiments, the aromatic group or aryl group may be a mononuclear or polynuclear aromatic hydrocarbon group. In some embodiments, the heterocyclic group may be a closed-ring hydrocarbon in which one or more atoms in the ring are elements other than carbon (e.g., nitrogen, oxygen, sulfur, etc.). Unless otherwise specified, the aliphatic group may have 6 to 20 carbon atoms, 6 to 18 carbon atoms, 6 to 16 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms.

[0097] In some embodiments, the urethane and / or urea-containing polymers may be polymers comprising urethane and urea groups as part of the polymer chain. Polyurethane / polyurea can be produced by reacting an isocyanate containing at least two isocyanate groups per molecule with a compound having terminal hydroxyl groups and a compound having terminal amine groups. In some embodiments, polyurethane / polyurea can be produced by reacting an isocyanate containing at least two isocyanate groups per molecule with a compound having terminal hydroxyl and terminal amine groups (e.g., a hydroxylamine such as 3-hydroxy-n-butylamine (CAS114963-62-1)). The reaction to produce polyurethane, polyurea, or polyurethane / polyurea may include other additives, including but not limited to catalysts, chain extenders, curing agents, surfactants, pigments, or combinations thereof.

[0098] Isocyanates that can be considered polyisocyanates can have the structure R-(N=C=O). n Wherein, n can be at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, or at least 8, and where R can be an aliphatic and / or cyclic group. In some embodiments, the isocyanate may have an n equivalent to that in methylene diphenyl diisocyanate (MDI). In some embodiments, the isocyanate may be a diisocyanate (e.g., R-(N=C=O)2 or (O=C=N)-R-(N=C=O)).

[0099] Examples of isocyanates may include, but are not limited to, methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI). Examples of MDI may include, but are not limited to, monomeric MDI, polymeric MDI, and their isomers. [The last part, "having the chemical formula C," appears to be incomplete and requires further context.] 15 H 10 Examples of MDI isomers of N2O2 may include, but are not limited to, 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI. Examples of TDI isomers having the chemical formula C9H6N2O2 may include, but are not limited to, 2,4-TDI and 2,6-TDI. In some embodiments, examples of isocyanates may include, but are not limited to, monomeric diisocyanates and capped polyisocyanates. In some embodiments, examples of monomeric diisocyanates may include, but are not limited to, hexamethylene diisocyanate (HDI), methylene dicyclohexyl diisocyanate or hydrogenated MDI (HMDI) and isophorone diisocyanate (IPDI). In some embodiments, an example of HDI may be hexamethylene-1,6-diisocyanate. In some embodiments, an example of HMDI may be dicyclohexylmethane-4,4'-diisocyanate. Capped polyisocyanates may be based on HDI or IDPI. In some embodiments, examples of capped polyisocyanates may include, but are not limited to, HDI trimer, HDI biuret, HDI diuret, and IPDI trimer.

[0100] In some embodiments, examples of isocyanates may include, but are not limited to: mixtures of 2,4- and 2,6-toluene diisocyanate (TDI), diphenylmethane-4,4'-diisocyanate (MDI), naphthalene-1,5-diisocyanate (NDI), 3,3'-dimethyl-4,4'-biphenyl diisocyanate (TODI), crude TDI, polymethylene polyphenyl isocyanurate, crude MDI, xylene diisocyanate (XDI), and phenyl diisocyanate, such as aromatic diisocyanates; aliphatic diisocyanates such as 4,4'-methylene-dicyclohexyl diisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), and cyclohexane diisocyanate (hydrogenated XDI); and modified products such as isocyanurates, carbodiimides, and ureaformamides.

[0101] In some embodiments, a terminal hydroxyl group (R-(OH)) is present. n The compound can be a "polyol" wherein n is at least 2 (referred to herein as "difunctional"), at least 3 (referred to herein as "trifunctional"), at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, and 10, and wherein R is an aliphatic and / or cyclic group. In some embodiments, the polyol mixture may include a small amount of a monofunctional compound having a single terminal hydroxyl group.

[0102] In some embodiments, examples of polyols may include, but are not limited to, polyester polyols and polyether polyols. In some embodiments, examples of polyester polyols may include, but are not limited to, those formed by the condensation of an acid and an alcohol. In some embodiments, examples may include those formed by phthalic anhydride and diethylene glycol, phthalic anhydride and dipropylene glycol, adipic acid and butane, and succinic acid and butane or hexanediol. In some embodiments, polyester polyols may be semi-crystalline. In some embodiments, examples of polyether polyols include, but are not limited to, those formed by the polymerization of oxides such as ethylene oxide, propylene oxide, or butane oxide from initiators such as glycerol, dipropylene glycol, TPG (tripropylene glycol), castor oil, sucrose, or sorbitol.

[0103] In some embodiments, examples of polyols may include, but are not limited to, polycarbonate polyols and lactone polyols such as polycaprolactone. In some embodiments, compounds having terminal hydroxyl groups (R-(OH)) n It can have a molecular weight of about 200 Daltons to about 20,000 Daltons (calculated before incorporating the compound with terminal hydroxyl groups into the polymer).

[0104] In some embodiments, compounds having terminal amine groups (e.g., R-(N(R')2) n The compound may be referred to as a "polyamine," wherein n may be at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, and 10, wherein R may be an aliphatic and / or cyclic group, and wherein each R' may independently be hydrogen or an aliphatic and / or cyclic group (e.g., (C1-C4)alkyl). In some embodiments, the polyamine mixture may include a small amount of a monofunctional compound having a single terminal amino group.

[0105] In some embodiments, a suitable polyamine may be a diamine or a triamine, and may be a primary or secondary amine. In some embodiments, the compound having a terminal amino group may have a molecular weight of about 30 Daltons to about 5000 Daltons (calculated before incorporating the compound having a terminal hydroxyl group into the polymer), such as from about 40 Daltons to about 400 Daltons.

[0106] In some embodiments, examples of polyamines may include, but are not limited to, diethyltoluenediamine, di-(methylthio)toluenediamine, 4,4'-methylenebis(2-chloroaniline), and chain extenders available under the trade names LONZACURE L15, LONZACURE M-CDEA, LONZACURE M-DEA, LONZACURE M-DIPA, LONZACURE M-MIPA, and LONZACURE DETDA.

[0107] In some embodiments, suitable examples of polyamines may include, but are not limited to, ethylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, 1,6-diaminohexane, 2,5-diamino-2,5-dimethylhexane, 2,2,4-and / or 2,4,4-trimethyl-1,6-diaminohexane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,3-and / or 1,4-cyclohexanediamine, and 1-amino-3,3,5-trimethyl-5-aminomethylamine. 2,4- and / or 2,6-hexahydrotoluene diamine, 2,4'- and / or 4,4'-diaminodicyclohexylmethane and 3,3'-dialkyl-4,4'-diaminodicyclohexylmethane such as 3,3'-dimethyl-4,4-diaminodicyclohexylmethane and 3,3'-diethyl-4,4'-diaminodicyclohexylmethane; aromatic polyamines such as 2,4- and / or 2,6-diaminotoluene and 2,4'- and / or 4,4'-diaminodiphenylmethane; and polyoxyethylene polyamines.

[0108] In some embodiments, the term polyol and / or polyamine mixture can be a mixture of one or more polyols with different molecular weights and functionalities, one or more polyamines with different molecular weights and functionalities, or a combination of one or more polyols and one or more polyamines.

[0109] In some embodiments, this disclosure also provides the components described herein, as well as thermosetting systems that include components (e.g., a first reactive component and a second reactive component) and one or more optional reactive components such as a third reactive component.

[0110] In some embodiments, the thermoset material may include at least one reactive component. In some embodiments, the thermoset material may include at least two reactive components. In some embodiments, the thermoset material may include at least three reactive components. In some embodiments, the thermoset material may include at least four reactive components.

[0111] In some embodiments, the thermoset material can be prepared by the methods disclosed in WO 2018 / 106822 and PCT / US2018 / 064323, both of which are incorporated herein by reference in their entirety. In some embodiments, a method for preparing a thermoset material (such as urethane and / or urea-containing polymer thermoset products) may include introducing a first reactive component and a second reactive component into a mixing chamber. In some embodiments, the first reactive component may include an isocyanate, and the second reactive component may include a mixture of polyols and / or polyamines. In some embodiments, the first reactive component may include an isocyanate, and the second reactive component may include a polyol. In some embodiments, the first reactive component may include an isocyanate, and the second reactive component may include a polyamine. In some embodiments, the first reactive component may include an isocyanate, and the second reactive component may include both a polyol and a polyamine. The first and second reactive components may have certain properties, including but not limited to viscosity, reactivity, and chemical compatibility.

[0112] In some implementations, the thermoset material may be a solid thermoset material.

[0113] In some implementations, the thermosetting material may be a foam thermosetting material.

[0114] In some implementations, the thermosetting material can be a solid thermosetting material or a foam thermosetting material.

[0115] Although the following description is given in the context of foam, it can be applied to thermoset materials, including conventional urethane and / or urea-containing polymers, both non-foam and foam. Foams with a range of stiffness and elasticity are available. Urethane and / or urea-containing polymers can be very durable, allowing the foam to be reused without altering its properties. This range of properties allows these materials to be used in clinical settings where ideal rigid positioning or, more ideally, pressure distribution is desired.

[0116] Foams of urethane and / or urea-containing polymers can be the product of a reaction between two reactant components. A range of foam properties can be achieved by varying the relative weights of the formulation components to balance the reaction rate, the interfacial tension of the reaction mixture, and the elasticity of the polymer scaffold. In 3D printing, an extrusion nozzle can deposit material (e.g., thermoset material) layer by layer onto a substrate following a 3D computer model of the desired 3D object.

[0117] In some embodiments, foam precursor formulations enable high-resolution 3D deposition to form customized 3D foam objects. In some embodiments, thermoset materials can be deposited while maintaining the desired predetermined resolution and mechanical integrity of the foam by partially advancing the reaction of a precursor such as a polyurethane precursor and adjusting the levels of catalysts and surfactants.

[0118] The production of foams from urethane and / or urea-containing polymers can differ from the production of non-foaming urethane and / or urea-containing polymers due to the presence of water. Foams from urethane and / or urea-containing polymers can be formed by the simultaneous reaction of isocyanate and water to form urea bonds and generate gas, and by the reaction of isocyanate with a polyfunctional high molecular weight alcohol to form a cross-linked elastomeric foam scaffold.

[0119] In some embodiments, the foam can be formed using the following reactive monomers: diisocyanate, water, and a polyfunctional alcohol (e.g., a polyol) or a polyfunctional amine. The amount of water in the formulation can affect the foam density and the strength of the foam scaffold. The molecular weight of the polyol and / or polyamine mixture can determine the crosslinking density of the foam scaffold and the elasticity, resilience, and hardness of the resulting foam. In some embodiments, a near-stoichiometric amount of diisocyanate can be used to completely react with water and the polyol and / or polyamine mixture.

[0120] In some embodiments, prepolymer synthesis can be used to modify the curing profile of a polyurethane or polyurea system. In prepolymer synthesis, a stoichiometric excess of diisocyanate can react with a mixture of polyols and / or polyamines. The resulting prepolymer can have a higher molecular weight than the starting diisocyanate, and the molecules in the prepolymer can possess isocyanate functionality, thus remaining reactive. Due to the higher molecular weight, hydrogen bonds, and / or urea bonds, the prepolymer can also have a higher viscosity. This prepolymer can then be reacted with a mixture of polyols and / or polyamines and water to produce a foam with substantially the same foam support composition achievable without prepolymer synthesis. However, the viscosity growth profile can be altered, typically starting high and increasing more slowly, thus foam morphological characteristics such as pore size and pore stability can lead to foams with drastically different appearances.

[0121] Supported foams are not simply a matter of density, hardness, or resilience, but can span a wide range of properties. This disclosure extends the entire range of foam properties. Foam density and hardness can be interrelated: low-density foams can be softer foams. A range of foam densities and hardnesses can be achieved first by varying the content of a blowing agent such as water in the formulation and by adjusting the content of excess isocyanate in the formulation. Increasing the functional groups of components in a polyol and / or polyamine mixture (e.g., incorporating certain 4- or 6-functional polyols) can increase the hardness and viscosity growth rate during curing. Foam resilience can be altered by varying the polyols and / or polyamines incorporated into the formulation. Memory foams can be achieved by reducing the molecular weight of the polyols and polyamines; high resilience can be achieved by incorporating grafted polyols. In some embodiments, the foam density range can be less than 0.3 g / cm³. 3 The hardness ranges from 30-50 ILFD, and the resilience ranges from 10-50%. Foam properties can also include open-cell and closed-cell content. Open-cell foams can be porous structures formed by struts, with windows in the pore walls that allow air or liquid to flow between the pores. Closed-cell foams can be advantageous, for example, in insulation applications by preventing airflow.

[0122] Example

[0123] The purposes and methods described herein will now be described in further detail with reference to the following examples. These examples are provided for illustrative purposes only, and the embodiments described herein should in no way be construed as limiting to these examples. Rather, embodiments should be interpreted to encompass any and all variations that become apparent as a result of the teachings provided herein.

[0124] Example 1: Deformable Multi-Material Pad and its Manufacturing Method

[0125] The following describes how to construct a deformable multi-material pad using 3D printing:

[0126] 1) Shore A 90 material on the substrate layer.

[0127] 2) Place the sensor on top of the Shore 90 material.

[0128] 3) Print circular Shore 60 material on the pad, with Shore 90 material printed on the periphery.

[0129] 4) Place the sensor on top of the layer.

[0130] 5) Print a final layer of Shore 40 material with a central circle, followed by a ring of Shore 60 material, and then the periphery of Shore 90 material.

[0131] The pad is attached to the robotic arm. The second finger has a single material pad or a similar deformable multi-material pad.

[0132] When the end effector lifts or lowers an object, the sensor closest to the surface signals when the object makes contact, and the sensor deepest in the field signals when compression should stop so that the object is not damaged.

[0133] Example 2: 3D printing and property analysis of an end effector with built-in sensors

[0134] Material Description: The soft material is a two-component polyurethane with a Shore hardness of 40. The isocyanate mixture has an isocyanate weight percentage of 9% as determined by titration. The polyol mixture is stoichiometrically matched to the isocyanate mixture at a 1:1 weight ratio. The hard material is a two-component polyurethane with a Shore hardness of 60. The isocyanate mixture has an isocyanate weight percentage of 12% as determined by titration. The polyol mixture is stoichiometrically matched to the isocyanate mixture at a 1:1 weight ratio.

[0135] The pressure sensor is named Interlink Model 402. The printer is a German RepRap X400 model. The Viscotec pump is a ViscoDuo-FDD 4 / 4 model.

[0136] Print shape, size, and fill type:

[0137] Printed shape: rectangular prism

[0138] Size: 45mm × 45mm × 6.48mm (Max: 6.48mm - Minimum: 5.40mm)

[0139] Fill: Linear, solid fill (100% density)

[0140] Print settings:

[0141] Indicator (ratio of quality on side A to quality on side B): 1.20

[0142] Bead width: 0.5mm

[0143] Linear extrusion density: 0.75E / mm

[0144] Linear speed: F1000

[0145] Initial layer height: 1.05mm (hard resin)

[0146] Second layer height: 1.15mm (hard resin)

[0147] Third layer height: 1.10mm (soft resin)

[0148] Fourth layer height: 1.15mm (soft resin)

[0149] Printing steps:

[0150] a. Print a layer of hard resin onto a clean silicone pad.

[0151] b. Place sensor 2 on top of the first layer of resin, so that the circular part of the sensor is in the center of the printing material.

[0152] c. Gently touch the sensor with the tongue depressor so that the sensor lies flat on the polyurethane.

[0153] d. Print a second layer of hard resin on the top of the sensor.

[0154] e. Replace the syringe.

[0155] f. Use soft resin to print a third layer on the top of the part.

[0156] g. Place sensor 1 on top of the third layer, so that the sensor is directly above sensor 2.

[0157] h. Print the fourth and final layer on top of the sensor.

[0158] i. If necessary, squeeze out a small amount of material and use a thin wooden stick to move and wipe the cured material into any gaps on the fourth layer.

[0159] Material conditioning (curing, heating, etc.) time

[0160] Curing time: 48 hours

[0161] Curing chamber temperature: approximately 80°F (26.67°C)

[0162] Humidity in the curing chamber: 30% to 40%

[0163] Sensor Connections: Connect the interconnect force-sensitive resistors to the Arduino UNO. In each sensor, connect the sensor to +5V on the Arduino. Connect the other end of the sensor to a 10K ohm pull-down resistor and an analog input pin on the Arduino. Then, connect the other end of the pull-down resistor to ground on the Arduino.

[0164] Touch Test Experiment: The first test of the sensor is a basic touch test, in which a block is placed on a hard stone counter and then pressed very gently; then, increasing force is applied directly to the tip of the sensor with a finger. The sensor output is a value from 0 to 1023, where 0 is the force the sensor cannot pick up and 1023 is the maximum theoretical force reading that the Arduino can receive from the sensor. The sensor output initially corresponds to a low reading for the sensor built into the soft material at light contact. As the applied pressure increases, the reading of the sensor built into the soft material increases. Eventually (for example, a value of around 500 from the soft sensor), the sensor built into the hard material responds and the sensor output value increases. The touch test experiment demonstrates the ability to detect both soft and hard pressure over a wide range, essential to the manipulator's construction.

[0165] MTS Insight Electromechanical Testing System (MTS) Test: The second test involved using an MTS device with a 5kN load cell, which had two parallel plates, where an object could be placed on top of an end effector flush with the base plate. The MTS could be finely moved up and down to press the object against the end effector. This was to replicate the end effector picking up objects at different force levels. The MTS was then incrementally moved within the range of sensor values ​​for each object, demonstrating the end effector's ability to pick up a wide range of force measurements. Before each new reading, the experimenter allowed one minute to control stress relaxation and ensure consistent results, as relaxation effects can influence the force applied to the object. For the tomato test, a five-second relaxation time was used because the tomato dissipates force too quickly to measure pressure. Contact surface area was estimated using digital caliper measurements. It was assumed that the contact surface area of ​​all objects remained constant, except for stress spheres with visible large deformation.

[0166] The results of the MTS test are shown in Table 1:

[0167] Table 1: MTS Test Results

[0168]

[0169] * The relaxation time is 5 seconds instead of 1 minute because the force dissipates too quickly for the pressure to be measured.

[0170] Example 2 and Table 1 demonstrate that the end effector according to this disclosure can surprisingly pick up objects with a wide range of sizes, shapes and force levels, and that the built-in sensor can be used to detect force when it is built into materials of different hardness (e.g., soft and hard materials).

Claims

1. A method for an end effector of a 3D printing robot, the method comprising: Deposit a first thermosetting material with a first hardness; as well as A second thermosetting material having a second hardness different from the first thermosetting material is deposited, such that the first thermosetting material is attached to the second thermosetting material, thereby forming at least a portion of the finger of the robot end effector, wherein at least a portion of the first thermosetting material and the second thermosetting material form a deformable pad of the finger. In this process, the first thermosetting material and the second thermosetting material are deposited layer by layer. In this configuration, at least one layer of the first thermosetting material is deposited on top of the first sensor, and the second sensor is placed on top of the at least one layer of the first thermosetting material, with the second thermosetting material deposited on top of the second sensor. The first and second sensors provide tactile feedback. Both the first sensor and the second sensor are pressure sensors.

2. The method according to claim 1, wherein, At least one of the first thermosetting material and the second thermosetting material includes foam.

3. The method according to claim 1 or 2, wherein, The first thermosetting material is deposited on the exterior of the finger-shaped substrate.

4. The method according to claim 1 or 2, wherein, The second thermosetting material is deposited on the outer surface of the first thermosetting material.

5. The method according to claim 1 or 2, wherein, The first thermosetting material is foam, and the second thermosetting material is solid thermosetting material.

6. The method according to claim 1 or 2, wherein, The second hardness is greater than the first hardness.

7. The method according to claim 1 or 2, wherein, The first hardness is greater than the second hardness.

8. The method according to claim 1 or 2, wherein, The first thermosetting material and the second thermosetting material are unevenly distributed on the outside of the finger.

9. The method according to claim 1 or 2, wherein, At least a portion of the first thermosetting material and the second thermosetting material are deposited to form a linear functional gradient hardness from the first hardness to the second hardness.

10. The method according to claim 1 or 2, wherein, At least a portion of the first thermosetting material and the second thermosetting material are deposited to form a nonlinear functional gradient hardness from the first hardness to the second hardness.

11. The method according to claim 1 or 2, wherein, The robot end effector includes at least two fingers.

12. The method according to claim 4, wherein, The robot end effector includes at least two fingers.

13. The method according to claim 6, wherein, The robot end effector includes at least two fingers.

14. The method according to claim 1 or 2, wherein, The deformable pad has a corrugated surface.

15. A robot end effector manufactured by the method according to any one of claims 1 to 14.

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