An execution module and a soft robotic arm having the same

Abstract

An execution module and a soft robotic arm having the same belong to the technical field of robotic arms. An execution module includes: a soft actuator, at least one soft actuator is provided, the soft actuator includes a dielectric layer and a conductive layer, the dielectric layer is connected to the conductive layer, the dielectric layer is configured to have charge transfer when touched by a human body, and the conductive layer is configured to detect the charge change of the dielectric layer and generate an electrical signal. In this application, a soft actuator is constructed by the dielectric layer and the conductive layer, and the dielectric layer has 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 to solve the problem that it is difficult for a soft robotic arm to accurately recognize human contact.

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 soft robotic arm having the same. Background Art

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

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

[0004] For example, Chinese Patent Publication No. 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. Each 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. Each hard particle layer includes a flexible connection layer and a number of hard particles evenly arranged on the flexible connection layer. Adjacent hard particle layers are connected together; the hard particle layer located inside is connected to the outer wall of the inner bellows; thus, it can actively adjust the overall stiffness of the robotic arm, improve the load capacity of the robotic arm, and expand the application scenarios of the robotic arm.

[0005] Currently, due to the need for complex control strategies for traditional rigid robots in complex and unstructured environments to achieve efficient interaction with human users, in contrast, soft robots, due to their flexible structures and excellent deformation capabilities, 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 about the surrounding environment and cannot accurately identify human contact. Therefore, there is an urgent need 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 object of the present invention is to provide an execution module and a soft robotic arm having the same. A soft actuator 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 during the charge transfer of the dielectric layer and generates an electrical signal, so as to solve the problem that it is difficult for the soft robotic arm to accurately recognize human contact in the above-mentioned background art.

[0008] To solve the above technical problems, the specific technical solution of the present invention is as follows:

[0009] An execution module, comprising:

[0010] A soft actuator, at least one soft actuator is provided. The soft actuator includes a dielectric layer and a conductive layer. 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 the charge change of the dielectric layer and generating an electrical signal.

[0011] Further, the preparation of the dielectric layer includes the following steps:

[0012] Construct a corrugated pipe; wherein, the corrugated pipe is made of a photopolymer resin;

[0013] Form a terminal hydroxyl group on the surface of the corrugated pipe;

[0014] Immerse the corrugated pipe with a terminal hydroxyl group formed on its surface into an HDFS solution dissolved in hexane to form a self-assembled monolayer.

[0015] Further, the method of forming a terminal hydroxyl group on the surface of the corrugated pipe is plasma treatment.

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

[0017] Further, it further includes a processing module. The processing module includes a memory, a processor, and a computer program stored on the memory. The processor is electrically connected to the conductive layer.

[0018] Further, the execution module further includes:

[0019] A barometric pressure sensor, the barometric pressure sensor is used for detecting the barometric pressure inside the soft actuator and generating barometric pressure data. The barometric pressure sensor is communicatively connected to the processor; the processor executes the computer program to implement the steps of the touch detection method.

[0020] Further, the touch detection method includes the following steps:

[0021] Obtain a number of conventional barometric pressure data;

[0022] Calculate the first local outlier factor based on a number of conventional barometric pressure data;

[0023] Obtain the changing barometric pressure data;

[0024] Calculate the second local outlier factor based on the conventional barometric pressure data and the changing barometric pressure data;

[0025] Judge 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 all obtained through the following formula:

[0027] ;

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

[0029] The local reachability density is obtained through the following formula:

[0030] ;

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

[0032] The reachability distance is obtained through the following formula:

[0033] ;

[0034] wherein, is the reachability distance, is the given point, is the neighbor point corresponding to the given point, is the point and the point the distance between, k-dist(p) is the k-th minimum distance to the given point .

[0035] Furthermore, the barometric pressure sensor is arranged inside the soft actuator;

[0036] Or, the barometric pressure sensor is arranged in an isolation air cavity, and the isolation air cavity is communicated with the inside of the soft actuator through a manifold.

[0037] A soft robotic arm includes the execution module described above.

[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 human body touches it, the dielectric layer undergoes charge transfer, and the conductive layer detects the charge change during the charge transfer of the dielectric layer and generates an electrical signal, so that the soft robotic arm with the soft actuator of the present application can accurately recognize human contact and avoid being affected by environmental collisions or non-human touches in the environment.

[0040] (2) The present application is also provided with a pressure sensor for detecting the air pressure in the soft actuator and generating pressure data, and a touch detection method that can perform touch detection based on the change in air pressure according to the change in pressure data. Combined with the soft actuator constructed by the dielectric layer and the conductive layer, it can more accurately identify the object contact event of non-human contact, and further improve 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 It is a schematic diagram of the overall structure of the soft robotic arm of the present application.

[0043] Marking description in the figure: 10, suction cup; 20, connecting pipe; 30, pneumatic device; 40, ventilation pipe; 50, soft actuator; 60, control board. Detailed Description of the Invention

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

[0045] Embodiment 1

[0046] An execution module, as Figure 1 shown, includes:

[0047] A soft actuator 50, at least one soft actuator 50 is provided, 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 for charge transfer when touched by the human body, and the conductive layer is used for detecting the charge change of the dielectric layer and generating an electrical signal according to the charge change of the dielectric layer.

[0048] Specifically, when the human body touches the dielectric layer, charge transfer occurs, making the contact surface 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] Construct a corrugated pipe; wherein, the corrugated pipe is made of a photocurable resin;

[0051] Form a terminal hydroxyl group on the surface of the corrugated pipe;

[0052] Immerse the corrugated pipe with a terminal hydroxyl group formed on its surface in an HDFS solution dissolved in hexane to form a self-assembled monolayer; wherein, the mixing ratio of HDFS to hexane is 1:300.

[0053] In this embodiment, the corrugated pipe is 3D printed from the 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, and can also withstand a large enough strain during repeated operations without malfunction, and also shows a fast shape recovery speed after actuation.

[0054] The method for forming a terminal hydroxyl group on the surface of the corrugated pipe is plasma treatment, specifically, it is treated with air plasma for 30 s under vacuum conditions to form a terminal hydroxyl group on the surface of the corrugated pipe.

[0055] The conductive layer is formed by photocuring, and the 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 of acrylamide (AAm), 1.5 M of lithium chloride (LiCl), 0.17 mM of lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP), and 8 mM of N,N-methylenebisacrylamide (MBAAm).

[0057] Among them, acrylamide (AAm) is a monomer, N,N-methylenebisacrylamide (MBAAm) is a crosslinking agent, lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) is a photoinitiator, ethylene glycol (EG) is a liquid component, lithium chloride (LiCl) is an ionic charge carrier, and trichlorosilane is used as a surface perfluorinating agent.

[0058] In this embodiment, after the precursor solution is coated inside the corrugated pipe, the conductive layer is formed by polymerization after being irradiated with 400 nm ultraviolet light in a curing device for 10 minutes.

[0059] When the human body touches the soft actuator 50, the dielectric layer comes into contact with the human body, and charge transfer occurs, resulting in the charged contact surface. After 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 touches.

[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, thereby generating an instantaneous voltage signal. The sensor extracts contact information, such as the size of the contact point, the pressure intensity, 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 actions of the robotic arm, such as grasping an object or bending the robotic arm.

[0061] Optionally, it further includes a processing module, where 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] In this application, by converting 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 the charge transfer of the dielectric layer and generating an electrical signal, after the user touches the dielectric layer arranged outside, the conductive layer arranged 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, with a relatively high accuracy in identifying human touches, and can also prevent the soft robotic arm from being affected by environmental collisions or non-human touches in the environment.

[0063] A soft robotic arm, as Figure 1 shown, includes:

[0064] A soft actuator 50;

[0065] A control board 60, where a control circuit is arranged inside the control board 60, and the control circuit is electrically connected to the processing module;

[0066] An air actuator 30, where the air actuator 30 is connected to the soft actuator 50;

[0067] An air pipe 40, where the air pipe 40 is connected to the air actuator 30;

[0068] Connecting pipe 20, one end of the connecting pipe 20 is connected to the pneumatic device 30;

[0069] Suction cup 10, the suction cup 10 is connected to the other end of the connecting pipe 20.

[0070] In this embodiment, the processing module is arranged on the control board 60. The control circuit also includes a solenoid valve, a current driver of the solenoid valve, various sensors, a microcontroller, a power supply circuit, a communication unit, etc. This is prior art and will not be elaborated in this application. Among them, the power supply circuit is responsible for providing 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 on-off state. The solenoid valve is used to regulate air pressure so as to drive the movement of the soft robotic arm. The communication unit is a wireless communication unit and is responsible for wireless communication with an external control system.

[0071] In this embodiment, the surface of the suction cup 10 includes a soft layer, and the soft layer is made of a soft material and obtained by demolding Ecoflex 00-30. In this embodiment, the suction cup 10 used is 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 further includes a rigid shell, and the rigid shell is 3D printed with PLA material, so as to enhance the sealing performance for rough surfaces, minimize gas leakage, and achieve dexterous grasping and secure attachment in position on rough and inclined surfaces.

[0072] Optionally, the soft robotic arm can also be an existing soft robotic arm replaced with the soft actuator 50 of the present application. The specific replacement of the soft actuator 50 is prior art and will not be elaborated in this application.

[0073] Embodiment Two

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

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

[0076] A barometric pressure sensor, which is communicatively connected to the processor. The barometric pressure sensor is configured to detect the barometric pressure inside the soft actuator 50, generate barometric 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] Obtain a number of conventional barometric pressure data;

[0079] Calculate the first local outlier factor based on the number of conventional barometric pressure data;

[0080] Obtain variable barometric pressure data;

[0081] Calculate the second local outlier factor based on the conventional barometric pressure data and the variable barometric pressure data;

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

[0083] Among them, both the first local outlier factor and the second local outlier factor are obtained through the following formula:

[0084] ;

[0085] Wherein, is the local outlier factor, is the given point, is the neighbor point corresponding to the given point, is the set, is the number of elements in the set, is the local reachability density.

[0086] The local reachability density is obtained through the following formula:

[0087] ;

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

[0089] The reachability distance is obtained through the following formula:

[0090] ;

[0091] Wherein, is the reachability distance, is the given point, is the neighbor point corresponding to the given point, is the point and the point The distance between, k-dist(p) is the minimum distance to the k-th of a given point among them.

[0092] In this embodiment, the air pressure data is detected by the air pressure sensors inside the corrugated pipes. Among them, in the initial state, each air pressure sensor collects 40 data as the regular air pressure data.

[0093] Taking the air pressure sensor with the model number XGZP6847040KPG as an example, the pressures of the three corrugated pipes are all set to 10 kPa, and 40 data samples of the air pressure sensor of a certain corrugated pipe are collected at this time as the regular air pressure data. The 40 data points are evenly distributed between 9.999 kPa and 10.001 kPa.

[0094] For example, when k = 1, it includes the given point A and the neighbor points B, C, and D.

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

[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 the given point and the neighbor points.

[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, calculate the LOF values of the remaining given points. The average LOF value 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 values are very stable when there is no contact event.

[0106] When a contact event occurs, the reading of the pressure sensor will change suddenly, resulting in a significant decrease in the local density of this data point and an increase in the LOF value.

[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 neighbor points, then lof(M) = 2.168.

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

[0109] In this embodiment, the pressure sensor is disposed inside the soft actuator; alternatively, the pressure sensor may also be disposed in the isolation air cavity, and the isolation air cavity is communicated with the inside of the soft actuator through a manifold to realize air pressure detection.

[0110] Alternatively, a pressure sensor is disposed in each soft actuator, or each soft actuator is communicated with an isolation air cavity provided with a pressure sensor.

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

[0112] Receiving a conductive layer signal;

[0113] According to the conductive layer signal and the judgment of whether a touch event occurs, judge the type of the touch event that occurs. The types of the touch event include human touch, object touch, etc. For example, if there is a conductive layer signal and it is judged that a touch event occurs according to the air pressure data, it is a human touch; if there is no conductive layer signal and it is judged that a touch event occurs according to the air pressure data, it is an object touch; if there is a conductive layer signal and it is judged that no touch event occurs according to the air pressure data, there may be a false alarm or a close contact with a human body.

[0114] A touch detection device, comprising:

[0115] A touch occurrence detection module, configured to obtain a plurality of conventional air pressure data; calculate a first local outlier factor according to the plurality of conventional air pressure data; obtain variable air pressure data; calculate a second local outlier factor according to the conventional air pressure data and the variable air pressure data; and determine whether a touch event occurs according to the first local outlier factor and the second local outlier factor;

[0116] A touch type detection module, configured to receive a conductive layer signal; and determine the type of the touch event that occurs according to the conductive layer signal and the determination of whether a touch event occurs.

[0117] In this embodiment, a pressure sensor for detecting the air pressure inside the soft actuator and generating air pressure data, and a touch detection method capable of performing touch detection based on air pressure changes according to changes in air pressure data are combined with the soft actuator composed of a dielectric layer and a conductive layer, so as to more accurately identify the type of contact event, and further improve the robustness and versatility of the robotic arm.

[0118] It can be understood that the present invention is described through some embodiments. Those skilled in the art know that, without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations 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 belong to the scope protected by the present invention.

[0119] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An execution module, characterized in that, Comprising: A soft actuator, at least one soft actuator is provided, the soft actuator includes a dielectric layer and a conductive layer, 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 the charge change of the dielectric layer and generating an electrical signal; The preparation of the dielectric layer includes the following steps: Constructing a corrugated pipe; wherein, the corrugated pipe is made of a photopolymer resin; Forming a terminal hydroxyl group on the surface of the corrugated pipe; Immersing the corrugated pipe with a terminal hydroxyl group formed on its surface into an HDFS solution dissolved in hexane to form a self-assembled monolayer; 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; The minimum Shore hardness of the corrugated pipe is 50A, and the maximum strain is 160%; It further includes a processing module, the processing module includes a memory, a processor, and a computer program stored on the memory, and the processor is electrically connected to the conductive layer; The execution module further includes: A pressure sensor, the pressure sensor is used for detecting the air pressure inside the soft actuator and generating air pressure data, and the pressure sensor is communicatively connected to the processor; the processor executes the computer program to implement the steps of the touch detection method; The touch detection method includes the following steps: Obtaining a number of conventional air pressure data; Calculating a first local outlier factor according to a number of conventional air pressure data; Obtaining variable air pressure data; Calculating a second local outlier factor according to the conventional air pressure data and the variable air pressure data; Judging whether a touch event occurs according to the first local outlier factor and the second local outlier factor; Both the first local outlier factor and the second local outlier factor are obtained through the following formula: ； Among them, is the local outlier factor, is the given point, is the neighbor point corresponding to the given point, is the number of elements in the set, is the local reachability density; The local reachability density is obtained through the following formula: ； Among them, is the local reachability density, is the number of elements in the set, is the reachability distance; The reachable distance is obtained through the following formula: ； wherein, is the reachable distance, is the given point, is the neighbor point corresponding to the given point, is the point and the point is the distance between, k-dist(p) is the k-th smallest distance to the given point .

2. The execution module according to claim 1, wherein The method for forming a terminal hydroxyl group on the surface of the corrugated pipe is plasma treatment.

3. The execution module according to claim 1, wherein The pressure sensor is arranged inside the soft actuator; Or, the pressure sensor is arranged in an isolation air cavity, and the isolation air cavity is communicated with the inside of the soft actuator through a manifold.

4. A soft robotic arm, comprising the execution module according to any one of claims 1-3.

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