Execution module and soft mechanical arm with same

Abstract

The invention relates to an execution module and a soft mechanical arm with the same, and belongs to the technical field of mechanical arms, the execution module comprises at least one soft actuator, the soft actuator comprises a dielectric layer and a conductive layer, the dielectric layer is connected with the conductive layer, the dielectric layer is used for generating charge transfer when a human body touches the soft actuator, and the conductive layer is connected with the dielectric layer; the conductive layer is used for detecting the charge change of the dielectric layer and generating an electric signal. The soft actuator is constructed through the dielectric layer and the conductive layer, the dielectric layer transfers charges when the human body touches the soft actuator, the conductive layer detects the charge change of the dielectric layer when the charges are transferred and generates the electric signal, and therefore the problem that the soft mechanical arm is difficult to accurately recognize the human body contact is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of robotic arms, and in particular relates to an execution module and a software robotic arm having the same. Background Art

[0002] A soft robotic arm is a robotic arm designed with flexible materials or structures. It has high flexibility, multiple degrees of freedom, and good environmental adaptability. It can safely interact with humans or other objects in complex environments.

[0003] There are many ways to drive soft robotic arms, including pneumatic drive, hydraulic drive, shape memory alloy drive, electroactive polymer drive, etc. These drive methods have their own advantages and disadvantages. For example, pneumatic drive has the characteristics of fast response and low cost, but the control accuracy is relatively low; while electroactive polymer drive has the advantages of high precision and high flexibility, but the cost is currently high.

[0004] For example, Chinese patent publication number CN114516070B discloses a variable stiffness soft robotic arm, which includes two connecting seats and a plurality of bellows modules arranged between the two connecting seats, the plurality of bellows modules are arranged in parallel, the bellows module includes an inner bellows, an outer bellows and a variable stiffness body, a main ventilation cavity is formed in the inner bellows, a variable stiffness cavity is formed between the inner bellows and the outer bellows, and the variable stiffness body is arranged in the variable stiffness cavity; the variable stiffness body has two or more hard particle layers, the hard particle layer includes a flexible connecting layer and a plurality of hard particles uniformly arranged on the flexible connecting layer, and adjacent hard particle layers are connected together; the hard particle layer located on the inner side is connected to the outer wall of the inner bellows; thereby, the overall stiffness of the robotic arm can be actively adjusted, the load capacity of the robotic arm is improved, and the application occasions of the robotic arm are expanded.

[0005] At present, traditional rigid robots in complex and unstructured environments require complex control strategies to achieve efficient interaction with human users. In contrast, soft robots, due to their flexible structure and excellent deformation ability, show higher adaptability in unknown and unstructured environments, and have broad development space in application fields such as flexible manipulation, rehabilitation medicine, and rescue.

[0006] However, currently some soft robotic arms can only obtain contact information from the surrounding environment and cannot accurately identify human contact. Therefore, it is urgent to develop an execution module and a soft robotic arm having the same to solve the problems in the prior art. Summary of the invention

[0007] The purpose of the present invention is to provide an execution module and a soft robotic arm having the same, wherein the soft actuator is constructed by a dielectric layer and a conductive layer, and the dielectric layer undergoes charge transfer when touched by a human body, and the conductive layer detects the charge change during the charge transfer of the dielectric layer and generates an electrical signal, so as to solve the problem that the soft robotic arm is difficult to accurately recognize human body contact raised in the above-mentioned background technology.

[0008] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0009] An execution module, comprising:

[0010] A soft actuator, wherein at least one soft actuator is provided, and the soft actuator comprises a dielectric layer and a conductive layer, wherein the dielectric layer is connected to the conductive layer, the dielectric layer is used for charge transfer when touched by a human body, and the conductive layer is used for detecting charge changes in the dielectric layer and generating an electrical signal.

[0011] Furthermore, the preparation of the dielectric layer comprises the following steps:

[0012] constructing a bellows; wherein the bellows is made of a photopolymer resin;

[0013] Forming terminal hydroxyl groups on the surface of the bellows;

[0014] The corrugated tube with terminal hydroxyl groups formed on the surface was immersed in a HDFS solution dissolved in hexane to form a self-assembled monolayer.

[0015] Furthermore, the method for forming the terminal hydroxyl groups on the surface of the bellows is plasma treatment.

[0016] Furthermore, the conductive layer is formed by photocuring, and the precursor solution of the conductive layer includes acrylamide, lithium chloride, lithium phenyl-2,4,6-trimethylbenzoylphosphonate, N,N-methylenebisacrylamide and ethylene glycol.

[0017] Furthermore, it also includes a processing module, which includes a memory, a processor and a computer program stored in the memory, and the processor is electrically connected to the conductive layer.

[0018] Furthermore, the execution module further includes:

[0019] An air pressure sensor is used to detect the air pressure in the soft actuator and generate air pressure data, and the air pressure sensor is communicatively connected with the processor; the processor executes the computer program to implement the steps of the touch detection method.

[0020] Furthermore, the touch detection method comprises the following steps:

[0021] Get some conventional air pressure data;

[0022] Calculating a first local outlier factor based on a number of conventional air pressure data;

[0023] Get changing air pressure data;

[0024] Calculate the second local outlier factor according to the normal air pressure data and the variable air pressure data;

[0025] It is determined whether a touch event occurs according to the first local outlier factor and the second local outlier factor.

[0026] Furthermore, the local outlier factors are obtained by the following formula:

[0027] ;

[0028] in, is the local outlier factor, For a given point, is the neighbor point corresponding to a given point, is the number of elements in the set, is the local reachable density;

[0029] The local reachable density is obtained by the following formula:

[0030] ;

[0031] in, is the local reachable density, is the number of elements in the set, is the reachable distance;

[0032] The reachable distance is obtained by the following formula:

[0033] ;

[0034] in, is the reachable distance, For a given point, is the neighbor point corresponding to a given point, Yes and Point The distance between, k-dist(p) is to a given point The k-th minimum distance.

[0035] Further, the air pressure sensor is arranged inside the soft actuator;

[0036] Alternatively, the air pressure sensor is disposed in an isolated air cavity, and the isolated air cavity is communicated with the interior of the soft actuator through a manifold.

[0037] A soft robotic arm comprises the execution module.

[0038] The present invention has the following advantages:

[0039] (1) The soft actuator of the present application is constructed by a dielectric layer and a conductive layer. When the dielectric layer is touched by a human body, charge transfer occurs, and the conductive layer detects the charge change of the dielectric layer during charge transfer and generates an electrical signal, thereby enabling the soft robotic arm with the soft actuator of the present application to accurately recognize human contact and prevent the soft robotic arm from being affected by environmental collisions or non-human touch in the environment.

[0040] (2) The present application also provides an air pressure sensor for detecting the air pressure in the soft actuator and generating air pressure data, and a touch detection method for performing touch detection based on air pressure changes according to changes in the air pressure data. The method is combined with the soft actuator constructed of a dielectric layer and a conductive layer to more accurately identify non-human contact object contact events, thereby further improving the robustness and versatility of the robotic arm.

[0041] Other features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the overall structure of the software robotic arm of this application.

[0043] Explanation of the markings in the figure: 10, suction cup; 20, connecting pipe; 30, pneumatic actuator; 40, ventilation pipe; 50, soft actuator; 60, control board. DETAILED DESCRIPTION

[0044] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0045] Embodiment 1

[0046] An execution module, such as Figure 1 As shown, including:

[0047] The soft actuator 50 is provided with at least one soft actuator 50, and the soft actuator 50 includes a dielectric layer and a conductive layer, the dielectric layer is connected to the conductive layer, the dielectric layer is used to transfer charge when touched by a human body, and the conductive layer is used to detect the charge change of the dielectric layer and generate an electrical signal according to the charge change of the dielectric layer.

[0048] Specifically, the dielectric layer undergoes charge transfer when touched by a human body, so that the contact surface is charged; when the charge transfer occurs in the dielectric layer, the conductive layer senses the charge change of the dielectric layer, generates a potential difference, and generates an electrical signal.

[0049] In this embodiment, the preparation of the dielectric layer includes the following steps:

[0050] constructing a bellows; wherein the bellows is made of a photopolymer resin;

[0051] Forming terminal hydroxyl groups on the surface of the bellows;

[0052] The corrugated tube with terminal hydroxyl groups formed on the surface was immersed in a HDFS solution dissolved in hexane to form a self-assembled monolayer; wherein the mixing ratio of HDFS to hexane was 1:300.

[0053] In this embodiment, the bellows is 3D printed from Elastic50A material provided by Formlabs, with a minimum Shore hardness of 50A and a maximum strain of 160%, so as to meet the softness requirements for direct physical contact or interaction between humans and robots. It can also withstand sufficiently large strains without failure during repeated operations, and also shows a fast shape recovery speed after driving.

[0054] The method for forming terminal hydroxyl groups on the surface of the bellows is plasma treatment, specifically, air plasma treatment for 30 seconds under vacuum conditions to form terminal hydroxyl groups on the surface of the bellows.

[0055] The conductive layer is formed by photocuring, and a precursor solution of the conductive layer includes acrylamide (AAm), lithium chloride (LiCl), lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP), N,N-methylenebisacrylamide (MBAAm) and ethylene glycol (EG).

[0056] Specifically, the precursor solution includes 3.5 M acrylamide (AAm), 1.5 M lithium chloride (LiCl), 0.17 mM lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP), and 8 mM N,N-methylenebisacrylamide (MBAAm).

[0057] Among them, acrylamide (AAm) is the monomer, N,N-methylenebisacrylamide (MBAAm) is the cross-linker, lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) is the photoinitiator, ethylene glycol (EG) is the liquid component, lithium chloride (LiCl) is the ionic charge carrier, and trichlorosilane is the surface perfluorination agent.

[0058] In this embodiment, after the precursor solution is coated inside the corrugated tube, the conductive layer is polymerized and formed by irradiating with 400 nanometer ultraviolet light in a curing device for 10 minutes.

[0059] When a human body touches the soft actuator 50, the dielectric layer contacts the human body, and charge transfer occurs, causing the contact surface to be charged. When the contact surface is charged, the conductive layer made of ionic hydrogel senses the change in charge, thereby generating a potential difference. This potential difference generates an electrical signal, which can be detected and used to identify external touch.

[0060] When the conductive layer and the dielectric layer come into contact and separate, due to their different electron affinities, charge transfer occurs at the contact surface, causing one material to be positively charged and the other to be negatively charged. This charge separation phenomenon is called the triboelectric effect. When a finger touches the surface of the corrugated actuator, due to the triboelectric effect, charge transfer occurs between the finger and the dielectric layer, causing the dielectric layer to be negatively charged and the finger to be positively charged. This charge separation induces opposite charges in the conductive layer, resulting in an instantaneous voltage signal. The sensor extracts contact information, such as the size of the contact, the intensity of pressure, and the duration of the touch, by monitoring the changes in these voltage signals. When a human operator touches the soft actuator 50, the processor detects the contact signal and uses it as a trigger signal to control the movement of the robotic arm, such as grasping an object or bending the robotic arm.

[0061] Optionally, a processing module is further included, wherein the processing module includes a memory, a processor and a computer program stored in the memory, and the processor is electrically connected to the conductive layer.

[0062] The present application converts the structure of the bellows-type soft actuator 50 into a dielectric layer for charge transfer when touched by the human body and a conductive layer for detecting the charge change during charge transfer of the dielectric layer and generating an electrical signal. When the user touches the dielectric layer arranged on the outside, the conductive layer arranged on the inside generates an electrical signal due to the charge transfer of the dielectric layer. After the processor receives the electrical signal generated by the conductive layer, it controls the soft robotic arm to perform corresponding actions. The human body touch recognition is more accurate and the soft robotic arm can be prevented from being affected by environmental collisions or non-human touches in the environment.

[0063] A soft robotic arm, such as Figure 1 As shown, including:

[0064] Soft actuator 50;

[0065] A control board 60, wherein a control circuit is disposed in the control board 60, and the control circuit is electrically connected to the processing module;

[0066] A pneumatic actuator 30, wherein the pneumatic actuator 30 is connected to the soft actuator 50;

[0067] a vent pipe 40, wherein the vent pipe 40 is connected to the pneumatic actuator 30;

[0068] A connecting pipe 20, one end of which is connected to the pneumatic actuator 30;

[0069] The suction cup 10 is connected to the other end of the connecting tube 20 .

[0070] In this embodiment, the processing module is arranged on the control board 60, and the control circuit also includes a solenoid valve, a current driver of the solenoid valve, various sensors, a microcontroller, a power supply circuit and a communication unit, etc. This is the prior art and will not be described in detail in this application. Among them, the power supply circuit is responsible for providing a stable power supply for the entire system to ensure that all electronic components obtain appropriate voltage and current during operation. The current driver of the solenoid valve is responsible for providing appropriate current to the solenoid valve to control its switching state. The solenoid valve is used to adjust the air pressure to drive the movement of the soft robotic arm. The communication unit is a wireless communication unit, which is responsible for wireless communication with the external control system.

[0071] In this embodiment, the surface of the suction cup 10 includes a soft layer, which is a soft material obtained by demolding Ecoflex 00-30. In this embodiment, the suction cup 10 uses a silicone suction cup 10, and the bottom surface of the soft layer suction cup 10 is cleaned by vacuum plasma. The suction cup 10 also includes a rigid shell, which is 3D printed with PLA material to enhance the sealing performance on the rough surface, minimize gas leakage, and achieve smart grasping on rough and inclined surfaces and safe attachment in position.

[0072] Optionally, the soft robotic arm may also be other existing soft robotic arms replaced with the soft actuator 50 of the present application. The specific soft actuator 50 is replaced with the existing technology and will not be described in detail in this application.

[0073] Embodiment 2

[0074] Although the structure of the soft actuator 50 composed of a dielectric layer for charge transfer when touched by a human body and a conductive layer for detecting the charge change during charge transfer of the dielectric layer and generating an electrical signal can directly detect human touch events, the soft actuator 50 may give false alarms or missed alarms in certain situations, such as changes in humidity or material properties, resulting in misjudgment by the processor. Based on this, the present embodiment provides a touch detection method for realizing touch detection based on changes in air pressure in a bellows-type soft actuator 50, so as to provide additional verification, reduce the possibility of misjudgment, and enhance the robustness of the system.

[0075] The difference between this embodiment and the first embodiment is that the execution module further includes:

[0076] An air pressure sensor is communicatively connected to the processor, and is used to detect the air pressure in the soft actuator 50, generate air pressure data and transmit it to the processor, and the processor executes the computer program to implement the steps of the touch detection method.

[0077] In this embodiment, the touch detection method includes the following steps:

[0078] Get some conventional air pressure data;

[0079] Calculating a first local outlier factor based on a number of conventional air pressure data;

[0080] Get changing air pressure data;

[0081] Calculate the second local outlier factor according to the normal air pressure data and the variable air pressure data;

[0082] It is determined whether a touch event occurs according to the first local outlier factor and the second local outlier factor.

[0083] The first local outlier factor and the second local outlier factor are both obtained by the following formula:

[0084] ;

[0085] in, is the local outlier factor, For a given point, is the neighbor point corresponding to a given point, For the collection, is the number of elements in the set, is the local reachable density.

[0086] The local reachable density is obtained by the following formula:

[0087] ;

[0088] in, is the local reachable density, is the number of elements in the set, is the reachable distance.

[0089] The reachable distance is obtained by the following formula:

[0090] ;

[0091] in, is the reachable distance, For a given point, is the neighbor point corresponding to a given point, Yes and Point The distance between, k-dist(p) is to a given point The k-th minimum distance.

[0092] In this embodiment, the air pressure data is detected by the air pressure sensor in the bellows, wherein, in the initial state, each air pressure sensor collects 40 data as normal air pressure data.

[0093] Taking the air pressure sensor model XGZP6847040KPG as an example, the pressure of the three bellows is set to 10 kPa, and 40 data samples of the air pressure sensor of a bellows are collected as normal air pressure data. The 40 data points are evenly distributed between 9.999 kPa and 10.001 kPa.

[0094] For example, take k=1, including the given point A and its neighboring points B, C and D.

[0095] Among them, the air pressure value at point A is 9.9995kPa, the air pressure value at point B is 9.9998kPa, the air pressure value at point C is 10.0004kPa, and the air pressure value at point D is 9.9997kPa.

[0096] For point A, reach-dist(A,D)=0.0002, reach-dist(A,B)=0.0003, reach-dist(A,C)=0.0009; in this embodiment, the reachable distance is the difference in air pressure between a given point and a neighboring point.

[0097] lrd3(A)=3 / (0.0002+0.0003+0.0009)=2142.86;

[0098] For point B, reach-dist(B,D)=0.0001, reach-dist(B,A)=0.0003, reach-dist(B,C)=0.0006;

[0099] (B)=3 / (0.001+0.003+0.006)=3000.

[0100] For point C, reach-dist(C,B)=0.0006, reach-dist(C,D)=0.0007, reach-dist(C,A)=0.0009;

[0101] (C)=3 / (0.0006+0.0007+0.0009)=1363.64;

[0102] For point D, reach-dist(D,B)=0.0001, reach-dist(D,A)=0.0002, reach-dist(D,C)=0.0007;

[0103] (D)=3 / (0.001+0.002+0.007)=3000.

[0104] lof(A)=(3000+1363.64+3000) / (3*2142.86)=1.145.

[0105] Similarly, the LOF values ​​of the remaining given points are calculated, and their LOF mean is about 1.00, which indicates that when there is no contact event, the LOF values ​​are concentrated around 1.00, and the standard deviation is very small, indicating that the LOF value is very stable when there is no contact event.

[0106] When a contact event occurs, the reading of the air pressure sensor will change suddenly, causing the local density of the data point to decrease significantly and the LOF value to increase.

[0107] For example, taking point M as the given point, the air pressure value of point M is 10.0030 kPa, and points A, B, and C are neighboring points, then lof(M)=2.168.

[0108] For example, taking point N as the given point, the air pressure value at point N is 10.0100 kPa, and points A, B, and C are neighboring points, then lof(N)=2.68.

[0109] In this embodiment, the air pressure sensor is arranged inside the soft actuator; optionally, the air pressure sensor can also be arranged in an isolated air cavity, and the isolated air cavity is connected to the inside of the soft actuator through a manifold to realize air pressure detection.

[0110] Optionally, an air pressure sensor is disposed in each of the soft actuators, or each of the soft actuators is connected to an isolated air cavity in which an air pressure sensor is disposed.

[0111] In this embodiment, the touch detection method further includes:

[0112] receiving a conductive layer signal;

[0113] The type of the touch event is determined based on the conductive layer signal and whether a touch event occurs. The types of touch events include human touch, object touch, etc. For example, if there is a conductive layer signal and a touch event is determined based on the air pressure data, it is a human touch; if there is no conductive layer signal and a touch event is determined based on the air pressure data, it is an object touch; if there is a conductive layer signal and a touch event is determined based on the air pressure data, it is not a touch event, then a false alarm may occur or the touch event may be close to the human body.

[0114] A touch detection device, comprising:

[0115] A touch occurrence detection module is used to obtain a number of normal air pressure data; calculate a first local outlier factor based on the number of normal air pressure data; obtain variable air pressure data; calculate a second local outlier factor based on the normal air pressure data and the variable air pressure data; and determine whether a touch event occurs based on the first local outlier factor and the second local outlier factor;

[0116] The touch type detection module is used to receive the conductive layer signal and determine the type of the touch event according to the conductive layer signal and whether the touch event occurs.

[0117] This embodiment combines an air pressure sensor for detecting the air pressure within a soft actuator and generating air pressure data, and a touch detection method for performing touch detection based on air pressure changes according to changes in air pressure data, with a soft actuator constructed of a dielectric layer and a conductive layer, so as to more accurately identify the type of contact events and further improve the robustness and versatility of the robotic arm.

[0118] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

[0119] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An execution module, characterized in that: include: A soft actuator, wherein at least one soft actuator is provided, and the soft actuator comprises a dielectric layer and a conductive layer, wherein the dielectric layer is connected to the conductive layer, the dielectric layer is used for charge transfer when touched by a human body, and the conductive layer is used for detecting charge changes in the dielectric layer and generating an electrical signal.

2. The execution module according to claim 1, characterized in that: The preparation of the dielectric layer comprises the following steps: constructing a bellows; wherein the bellows is made of a photopolymer resin; Forming terminal hydroxyl groups on the surface of the bellows; The corrugated tube with terminal hydroxyl groups formed on the surface was immersed in a HDFS solution dissolved in hexane to form a self-assembled monolayer.

3. The execution module according to claim 2, characterized in that: The method for forming the terminal hydroxyl group on the surface of the bellows is plasma treatment.

4. The execution module according to any one of claims 1 to 3, characterized in that: The conductive layer is formed by photocuring, and the precursor solution of the conductive layer includes acrylamide, lithium chloride, lithium phenyl-2,4,6-trimethylbenzoylphosphonate, N,N-methylenebisacrylamide and ethylene glycol.

5. The execution module according to claim 1, characterized in that: The invention also comprises a processing module, wherein the processing module comprises a memory, a processor and a computer program stored in the memory, and the processor is electrically connected to the conductive layer.

6. The execution module according to claim 5, characterized in that: The execution module also includes: An air pressure sensor is used to detect the air pressure in the soft actuator and generate air pressure data, and the air pressure sensor is communicatively connected with the processor; the processor executes the computer program to implement the steps of the touch detection method.

7. The execution module according to claim 6, characterized in that: The touch detection method comprises the following steps: Get some conventional air pressure data; Calculating a first local outlier factor based on a number of conventional air pressure data; Get changing air pressure data; Calculate the second local outlier factor according to the normal air pressure data and the variable air pressure data; It is determined whether a touch event occurs according to the first local outlier factor and the second local outlier factor.

8. The execution module according to claim 7, characterized in that: The first local outlier factor and the second local outlier factor are both obtained by the following formula: ； in, is the local outlier factor, For a given point, is the neighbor point corresponding to a given point, is the number of elements in the set, is the local reachable density; The local reachable density is obtained by the following formula: ； in, is the local reachable density, is the number of elements in the set, is the reachable distance; The reachable distance is obtained by the following formula: ； in, is the reachable distance, For a given point, is the neighbor point corresponding to a given point, Yes and Point The distance between, k-dist(p) is the distance to a given point The k-th minimum distance.

9. The execution module according to any one of claims 6 to 8, characterized in that: The air pressure sensor is arranged inside the soft actuator; Alternatively, the air pressure sensor is disposed in an isolated air cavity, and the isolated air cavity is communicated with the interior of the soft actuator through a manifold.

10. A soft robotic arm, comprising the execution module according to any one of claims 1 to 9.

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