Method for designing a software grasping robot

Abstract

The application provides a design method of a soft grabbing robot, which comprises the following steps: firstly, different hybrid variable stiffness mechanisms are designed, and corresponding hybrid variable stiffness soft actuators are prepared; then, a pneumatic driving test platform and a variable stiffness performance test platform are built; then, the bending performance test and the stiffness test are performed on each hybrid variable stiffness soft actuator; finally, the bending performance and the variable stiffness capacity of the hybrid variable stiffness soft actuators are compared and analyzed, and the hybrid variable stiffness soft actuator with the best comprehensive performance is selected. Three different actuators are prepared, the pneumatic driving test platform and the variable stiffness performance test platform are built, and the bending performance test and the stiffness test are performed on the three prepared hybrid variable stiffness soft actuators, so that the bending performance and the variable stiffness performance are simultaneously considered.

Description

Technical Field

[0001] This invention belongs to the field of variable stiffness soft actuator technology, and particularly relates to a design method for a soft grasping robot. Background Technology

[0002] Soft gripping robots are widely used in industrial applications, often in industrial production lines to grasp fragile and easily damaged objects, thus replacing rigid gripping robots in this role. The main requirements for soft gripping robots in industrial applications are adaptability, bending motion capability, and load-bearing capacity. Strong adaptability allows soft gripping robots to better conform to objects, while good bending motion capability helps them wrap around and grasp objects. Summary of the Invention

[0003] The purpose of this invention is to provide a design method for a soft grasping robot that simultaneously achieves both bending performance and variable stiffness performance. To achieve the above objective, the following technical solution is adopted:

[0004] A design method for a soft grasping robot includes the following steps:

[0005] Step 1: Design different hybrid variable stiffness mechanisms and fabricate corresponding hybrid variable stiffness software actuators;

[0006] Step 2: Build a pneumatic drive test platform and a variable stiffness performance test platform;

[0007] Step 3: Perform bending performance and stiffness tests on each hybrid variable stiffness software actuator;

[0008] Step 4: Conduct comparative analysis of the bending performance and variable stiffness capability of the hybrid variable stiffness software actuators, and select the hybrid variable stiffness software actuator with the best overall performance.

[0009] Preferably, step 1, the process of designing the hybrid variable stiffness mechanism specifically includes:

[0010] Design of a hybrid variable stiffness mechanism 1: The particles and the sheet are coupled vertically within the film, and there are three layers of material from top to bottom within the film;

[0011] Design of hybrid variable stiffness mechanism 2: The thin sheet and the particle are coupled to the same thin film from front to back, and the particle and the thin sheet are stacked on top of each other at the end of the variable stiffness structure;

[0012] Design of Hybrid Variable Stiffness Mechanism 3: The particles and sheets are coupled in segments within different thin films, and each thin film is connected to a vacuum pump;

[0013] Hybrid variable stiffness software actuators include:

[0014] Hybrid variable stiffness soft actuator 1: includes a hybrid variable stiffness mechanism 1 and a pneumatic drive structure bonded to the hybrid variable stiffness mechanism 1; the pneumatic drive structure includes a confinement layer and a strain layer, the lower end of the strain layer is bonded to the confinement layer; the strain layer includes several spaced airbags, and the airbags are connected to the air chambers in the confinement layer.

[0015] Hybrid variable stiffness soft actuator II: Hybrid variable stiffness mechanism II, pneumatic drive structure bonded to hybrid variable stiffness mechanism II;

[0016] Hybrid variable stiffness soft actuator 3: Hybrid variable stiffness mechanism 3, pneumatic drive structure bonded to the hybrid variable stiffness mechanism 3.

[0017] Preferably, in step 2, the pneumatic drive test platform includes:

[0018] Support 1, used to hold the end of the hybrid variable stiffness software actuator;

[0019] An air compressor and a pneumatic controller are connected. The output end of the air compressor is connected to the air inlet of the pneumatic controller, and the air outlet of the pneumatic controller is connected to the air chamber in the confinement layer.

[0020] The host computer is connected to the communication interface of the pneumatic controller;

[0021] Wherein, the bending angle θ is defined as the angle between the axis from the end point of the software driver to the fixed end point, the axis passing through the fixed end point, and the two axes.

[0022] The variable stiffness performance testing platform includes:

[0023] Support 2 is used to clamp one end of the hybrid variable stiffness software actuator and its height is adjustable; the end of the hybrid variable stiffness software actuator is attached to the pressure sensor on the linear guide rail; the pressure sensor is set on the slider on the linear guide rail and is connected to the host computer 2 for signal transmission.

[0024] The vacuum pump and vacuum pressure gauge are used to provide negative pressure to the cavity in the confinement layer. Its input end is connected in sequence to the vacuum pressure gauge and the cavity in the confinement layer. The vacuum pressure gauge is used to display the vacuum level of the vacuum pump and is connected to the host computer via a signal connection.

[0025] The guide rail controller controls the horizontal movement of the linear guide rail and is connected to the host computer via two signals.

[0026] The pressure indicator is connected to the host computer via two signals.

[0027] The stiffness of the soft actuator tip to be measured is defined as the ratio of the pressure at the soft actuator tip to the distance the tip moves.

[0028] Preferably, step 3 includes:

[0029] Bending performance test: Inflatable bending tests were conducted on three types of variable stiffness soft actuators, one without embedded plugging material and the other with embedded material.

[0030] First, set the input air pressure in the pneumatic controller to 0 kPa-60 kPa, with an interval of 10 kPa each time;

[0031] For each input air pressure, the experiment was repeated 5 times, and the average value of the bending angle θ was taken. The experimental data were then fitted into an input air pressure-bending angle curve.

[0032] Stiffness testing includes:

[0033] First, use a vacuum gauge to set the vacuum level, increasing it by 20 kPa each time between 0 kPa and 80 kPa.

[0034] Then, the slider is moved by controlling the guide rail controller, moving 2mm at a time between 0mm and 20mm, and the pressure corresponding to each movement position is recorded;

[0035] For each vacuum level, moving from 0mm to 20mm constitutes one experiment. Repeat the experiment 5 times and take the average pressure corresponding to each moving position.

[0036] Finally, based on the definition of stiffness... By measuring the average pressure at each moving position and the sliding distance at each moving position, the stiffness value can be obtained, and finally, a sliding distance-stiffness diagram under different vacuum levels can be obtained.

[0037] Preferably, step 4 includes:

[0038] Based on the input air pressure-bending angle curve and the sliding distance-stiffness curve under different vacuum levels, the bending performance and variable stiffness performance of each soft actuator are compared with the other two soft actuators. The soft actuator with the best bending performance and variable stiffness performance is selected as the soft grasping robot.

[0039] Compared with the prior art, the advantages of the present invention are:

[0040] Prototypes of hybrid variable stiffness soft actuators were fabricated using 3D printing and silicone casting techniques. Three different actuators were created based on different variable stiffness structures. Furthermore, a pneumatic drive testing platform and a variable stiffness performance testing platform were built to conduct bending performance and stiffness tests on the three fabricated hybrid variable stiffness soft actuators. This was to study the different coupling methods of the two materials in the cavity, aiming to obtain the hybrid variable stiffness structure with the strongest variable stiffness performance, bending capability, and anti-interference ability. This structure will serve as the variable stiffness structure for a soft grasping robot. Attached Figure Description

[0041] Figure 1 This is a structural diagram of a hybrid variable stiffness software actuator;

[0042] Figure 2 This is a structural diagram of the pneumatic drive test platform;

[0043] Figure 3 This is a structural diagram of the variable stiffness performance testing platform;

[0044] Figure 4 A schematic diagram of four types of actuator bending;

[0045] Figure 5 A comparison chart of the relationship between input air pressure and bending angle for four types of software actuators;

[0046] Figure 6 Slip distance-stiffness diagrams for a hybrid variable stiffness soft actuator under different vacuum conditions;

[0047] Figure 7 The slip distance-stiffness diagrams for the hybrid variable stiffness soft actuator II under different vacuum conditions;

[0048] Figure 8 The slip distance-stiffness diagrams for a hybrid variable stiffness soft actuator III under different vacuum conditions;

[0049] Figure 9 A comparison of the stiffness of the three actuators at 80 kPa;

[0050] Figure 10 This is a structural diagram of a hybrid variable stiffness mechanism.

[0051] Figure 11 This is a structural diagram of the hybrid variable stiffness mechanism II;

[0052] Figure 12 Here is a structural diagram of the hybrid variable stiffness mechanism three;

[0053] Figure 13 A cross-sectional view of the robotic arm in a soft grasping robot;

[0054] Figure 14 This is a structural diagram of the pneumatic controller. Detailed Implementation

[0055] The design method of the soft grasping robot of the present invention will be described in more detail below with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving the advantageous effects of the invention. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0056] like Figures 1-14 A design method for a soft grasping robot includes the following steps:

[0057] Step 1: Design different hybrid variable stiffness mechanisms and create corresponding hybrid variable stiffness software drivers.

[0058] The process of designing a hybrid variable stiffness mechanism specifically includes:

[0059] Design of a hybrid variable stiffness mechanism 1: The particles and the thin sheet are coupled vertically within the film, and there are three layers of material in the film from top to bottom.

[0060] This involves placing two materials on top of each other on the same thin film.

[0061] There is a layer of particles sandwiched between two thin sheets or a layer of thin sheets sandwiched between two layers of particles. Inside the film, there are three layers of material from top to bottom. When a vacuum is drawn inside the film, friction is generated between the particles, between the particles and the thin sheets, and between the thin sheets, thus exhibiting high overall rigidity.

[0062] The advantage of this coupling method lies in enhancing the variable stiffness capability of the overall blocking mechanism while maintaining the fluidity of the particle blockage. It allows for greater stiffness and stronger load-bearing capacity. Compared to traditional particle blockage, layered blockage mechanisms have greater overall stiffness. Particle blockage is not limited by shape, and the fluidity of the particles makes it more adaptable to external objects. Therefore, sandwiching a thin sheet between two layers of particles can effectively improve the overall stiffness of the mechanism and separate the two particle layers, reducing instability after particle rearrangement.

[0063] Design of Hybrid Variable Stiffness Mechanism 2: This involves coupling a thin sheet and particles together on the same film, with the particles and thin sheet stacked one on top of the other at the end of the variable stiffness structure.

[0064] Two materials are placed one after the other in a thin film. From left to right, they are granules and sheets, with the granules and sheets stacked one on top of the other at the end of the variable stiffness structure. When a vacuum is applied to the entire variable stiffness structure, the granules change from a fluid state to a near-solid state and rub against the compressed sheets. The sheets exhibit a "collapse" phenomenon, being compressed from the height of the granules before the vacuum pressure to a height difference with the granule stack, increasing the friction between the layers and thus increasing the overall stiffness.

[0065] The advantages of this hybrid variable stiffness structure lie in its integration of single-particle blocking and layer blocking, with thin sheets embedded at the bottom. Layer blocking offers stable arrangement, effectively ensuring the stability of the overall stiffness improvement. Embedding granular material at the ends maintains particle flowability while increasing stiffness; without vacuum, this flowability allows for better contact between the actuator and the object. Simultaneously, the thin sheet layers below and to the right of the particles enclose them, confining them within a space and reducing the instability of particle rearrangement. After vacuuming, the rapid compression of the thin sheets creates a height difference between the compressed particles and the contacting objects, effectively locking them in place. Furthermore, because the main body of the variable stiffness mechanism is thin sheets, it requires less granular material, making it lighter and reducing material costs compared to particle-blocking mechanisms. However, the arrangement of the embedded materials in this hybrid variable stiffness mechanism is relatively complex, and the manufacturing and embedding process is more cumbersome. Therefore, the overall stiffness improvement is not as significant as that of a three-layer stacked hybrid variable stiffness structure.

[0066] Design of Hybrid Variable Stiffness Mechanism 3: The particles and sheets are coupled in segments within different thin films, and each thin film is connected to a vacuum pump.

[0067] The two materials are placed in segments on a thin film. As shown in the figure, the hybrid variable stiffness mechanism is divided into four segments from left to right, consisting of individual layers, particles, layers, and particles. When a vacuum is applied to the blocking mechanism within different thin films, frictional forces are generated between the thin films and between the particles, thereby changing the stiffness of that segment.

[0068] The advantage of this coupling method lies in its ability to control stiffness in segments, unlike traditional variable stiffness mechanisms that control overall stiffness within a single thin film. Furthermore, the rearrangement instability caused by particle transitions between solid and fluid states can be mitigated to some extent, preventing uneven distribution due to random particle flow. Additionally, when controlling the stiffness of a blockage module segment, the inconsistency in stiffness between segments causes deformation and bending, altering the overall bending shape. This provides greater flexibility and control over the bending shape, a capability unattainable by other traditional single-blocking methods.

[0069] Hybrid variable stiffness software actuators include:

[0070] Hybrid variable stiffness soft actuator 1: includes a hybrid variable stiffness mechanism 1 and a pneumatic drive structure bonded to the hybrid variable stiffness mechanism 1; the pneumatic drive structure includes a confinement layer and a strain layer, the lower end of the strain layer is bonded to the confinement layer; the strain layer includes several spaced airbags, and the airbags are connected to the air chambers in the confinement layer.

[0071] Hybrid variable stiffness soft actuator II: Hybrid variable stiffness mechanism II, pneumatic drive structure bonded to hybrid variable stiffness mechanism II;

[0072] Hybrid variable stiffness soft actuator 3: Hybrid variable stiffness mechanism 3, pneumatic drive structure bonded to the hybrid variable stiffness mechanism 3.

[0073] Step 2: Build a pneumatic drive test platform and a variable stiffness performance test platform.

[0074] The pneumatic drive test platform includes:

[0075] Support 1, used to hold the end of the hybrid variable stiffness software actuator;

[0076] An air compressor and a pneumatic controller are used. The output of the air compressor is connected to the input of the pneumatic controller, and the output of the pneumatic controller is connected to the air chamber in the confinement layer. The pneumatic controller is the SCB-18PRO multi-functional pneumatic controller developed by Beijing SRT Company. Its air pressure adjustment range is -70KPa to 100KPa, which meets the needs of this experiment. The inflation is mainly completed by the air compressor, and the pneumatic controller is used to control the air intake volume.

[0077] The host computer is used to control the inflation and deflation of the pneumatic controller and to adjust the input air pressure.

[0078] The bending angle θ is defined as the angle between the axis from the end point of the software driver to the fixed end point, the axis passing through the fixed end point, and the two axes.

[0079] Specifically, the support bracket secures the end of the soft actuator, which can then bend or bend when air pressure is supplied. Furthermore, the software provides effective feedback on the input air pressure, allowing for timely recording and adjustment.

[0080] The variable stiffness performance testing platform includes:

[0081] The second bracket is used to hold one end of the hybrid variable stiffness soft actuator; the end of the hybrid variable stiffness soft actuator is attached to the pressure sensor on the linear guide rail; the pressure sensor is set on the slider on the linear guide rail and is connected to the host computer second signal; since the guide rail only moves 20mm in total, the displacement is small, so it is only necessary to lower the soft actuator to a suitable height through the second bracket to ensure that its end always acts on the pressure sensor.

[0082] The vacuum pump and vacuum pressure gauge are used. The vacuum pressure gauge controls the negative pressure through the host computer. The vacuum pump is used to provide negative pressure to the cavity in the confinement layer. Its input end is connected to the vacuum pressure gauge and the cavity in the confinement layer in sequence to ensure that the internal air in the soft-actuator mixed variable stiffness structure can be extracted in time under the control of the air pressure regulator, so that it can exhibit high stiffness. The vacuum pressure gauge is used to set the vacuum level of the vacuum pump and is connected to the host computer via two signals.

[0083] The guide rail controller controls the horizontal movement of the linear guide rail and is connected to the host computer via two signals.

[0084] The pressure indicator is connected to the host computer via two signals.

[0085] The stiffness of the soft actuator tip to be measured is defined as the ratio of the pressure at the soft actuator tip to the distance the tip moves.

[0086] Specifically, the guide rail controller is model CM36L with a maximum accuracy of 0.01cm, and the pressure indicator is model BF754H with a maximum accuracy of 0.01N and a maximum measurable force of 20N.

[0087] Step 3: Perform bending performance and stiffness tests on each hybrid variable stiffness software actuator. This includes:

[0088] Bending performance test: Inflatable bending tests were conducted on three types of variable stiffness soft actuators, one without embedded blocking material and the other with embedded material.

[0089] First, set the input air pressure in the pneumatic controller to 0 kPa-60 kPa, with an interval of 10 kPa each time;

[0090] For each input air pressure, the experiment was repeated 5 times, and the average value of the bending angle θ was taken. The experimental data were then fitted into an input air pressure-bending angle curve.

[0091] Stiffness testing includes:

[0092] Select corundum particles with a radius of 3 mm, and copy paper with a length, width, and height of 130 mm, 22 mm, and 0.5 mm, respectively. Embed 10 layers of variable stiffness mechanism and perform stiffness tests on the three types of variable stiffness software actuators that have been fabricated.

[0093] First, use a vacuum gauge to set the vacuum level, increasing it by 20 kPa each time between 0 kPa and 80 kPa.

[0094] Then, the slider is moved by the guide rail controller, moving 2mm at a time between 0mm and 20mm, and the pressure corresponding to each moving position is recorded. The software driver is adjusted to the correct height and fixed in place. The slider's starting point is the position where the pressure is exactly 0. For example, the first 2mm movement forms a moving position, and the pressure value at this point is recorded; the next 2mm movement forms a second moving position (with a corresponding sliding distance of 4mm), and the pressure value at this point is also recorded.

[0095] For each vacuum level, moving from 0mm to 20mm constitutes one experiment. Repeat the experiment 5 times and take the average pressure corresponding to each moving position.

[0096] Finally, based on the definition of stiffness... By measuring the average pressure at each moving position and the sliding distance at each moving position, the stiffness value can be obtained, and finally, a sliding distance-stiffness diagram under different vacuum levels can be obtained.

[0097] Step 4: Conduct comparative analysis of the bending performance and variable stiffness capability of the hybrid variable stiffness software actuators, and select the hybrid variable stiffness software actuator with the best overall performance. This includes:

[0098] Based on the input air pressure-bending angle curve and the slip distance-stiffness curve under different vacuum levels, the bending performance and variable stiffness performance of each soft actuator are compared with the other two soft actuators, and the soft actuator with the best bending performance and variable stiffness performance is selected.

[0099] Specifically, such as Figure 5The soft actuators were pressurized with air pressures ranging from 0 kPa to 60 kPa under four different conditions. The bending angles of all four actuators gradually increased with increasing air pressure, with the multi-bladder soft actuator showing a consistently rapid increase. The other three variable stiffness soft actuators exhibited more pronounced angle changes starting at 30 kPa. This is because the variable stiffness soft actuators incorporate embedded particles and thin sheets, resulting in a higher stiffness compared to a simple multi-bladder pneumatic actuator structure. The confinement layer is also thicker, thus the angle increase is not rapid before 30 kPa. As the air pressure increases, the bending force also increases, leading to a faster increase in the bending angle. The variable stiffness soft actuators 1, 2, and 3 in the figure represent actuators with embedded materials stacked vertically, actuators with embedded materials placed front-to-back, and actuators with embedded materials placed in segments, respectively. It is evident that the bending angle of variable stiffness actuator 1 is significantly smaller than the other two, with a maximum angle of 85.98°, which is 5.35° and 8.14° lower than the other two actuators, respectively. This is because the form of its embedded material makes its stiffness much greater than the other two, which limits the bending performance of the actuator.

[0100] like Figures 6-8 As the vacuum level increases, the end stiffness of the three variable stiffness soft actuators also increases, indicating that the vacuum level has a significant impact on stiffness. Furthermore, as the guide rail moves, the force borne by the actuator end also increases, thus exhibiting greater stiffness. When the sliding distance is 0 mm, since the actuator end is not subjected to pressure, the stiffness is displayed as 0, which is consistent with the definition of stiffness. In the figure, variable stiffness actuator 1, variable stiffness actuator 2, and variable stiffness actuator 3 represent actuators with embedded materials stacked vertically, embedded materials placed front and back, and embedded materials placed in segments, respectively.

[0101] like Figure 9 It can be seen that when the particles and sheets are stacked one on top of the other, the end stiffness is the greatest under a vacuum of 80 kPa, reaching 0.0697 N / mm, which is 0.0089 N / mm and 0.014 N / mm greater than the end stiffness of the other two actuators, respectively.

[0102] After conducting bending performance and variable stiffness capability tests on the three types of variable stiffness soft actuators that were manufactured, it was found that the soft actuator with embedded materials stacked vertically had the best variable stiffness performance, but its bending performance was the worst due to stiffness limitations; the soft actuator with embedded materials placed in segments had the best bending performance, but its variable stiffness capability was the worst compared to the other two; the soft actuator with embedded materials placed front and back had the best overall bending and variable stiffness performance, with a maximum bending angle of 91.33° and a maximum stiffness of 0.0467 N / mm under a vacuum of 80 kPa.

[0103] like Figure 13 As shown in Table 1, the dimensions of the soft robotic arm are as follows.

[0104] Table 1 Dimensions of Soft Robotic Arms

[0105]

[0106] Furthermore, the bending performance of actuator 2 can reach a maximum of 91.33° under a pressure of 60 kPa, which is only 2.79° less than that of actuator 3. However, its stiffness can reach a maximum of 0.0467 N / mm under a vacuum of 80 kPa, which is only 0.0064 N / mm lower than that of actuator 1.

[0107] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A design method for a soft grasping robot, characterized in that, Includes the following steps: Step 1: Design different hybrid variable stiffness mechanisms and fabricate corresponding hybrid variable stiffness software actuators; The process of designing a hybrid variable stiffness mechanism specifically includes: Design of a hybrid variable stiffness mechanism 1: The particles and the sheet are coupled vertically within the film, and there are three layers of material from top to bottom within the film; Design of hybrid variable stiffness mechanism 2: The thin sheet and the particle are coupled to the same thin film from front to back, and the particle and the thin sheet are stacked on top of each other at the end of the variable stiffness structure; Design of Hybrid Variable Stiffness Mechanism 3: The particles and sheets are coupled in segments within different thin films, and each thin film is connected to a vacuum pump; Hybrid variable stiffness software actuators include: Hybrid variable stiffness soft actuator 1: includes a hybrid variable stiffness mechanism 1 and a pneumatic drive structure bonded to the hybrid variable stiffness mechanism 1; the pneumatic drive structure includes a confinement layer and a strain layer, the lower end of the strain layer is bonded to the confinement layer; the strain layer includes several spaced airbags, and the airbags are connected to the air chambers in the confinement layer. Hybrid variable stiffness soft actuator II: Hybrid variable stiffness mechanism II, pneumatic drive structure bonded to hybrid variable stiffness mechanism II; Hybrid variable stiffness soft actuator three: Hybrid variable stiffness mechanism three, pneumatic drive structure bonded to hybrid variable stiffness mechanism three; Step 2: Build a pneumatic drive test platform and a variable stiffness performance test platform; Step 3: Perform bending performance and stiffness tests on each hybrid variable stiffness software actuator; Step 4: Conduct comparative analysis of the bending performance and variable stiffness capability of the hybrid variable stiffness software actuators, and select the hybrid variable stiffness software actuator with the best overall performance.

2. The design method of the soft grasping robot according to claim 1, characterized in that, In step 2, the pneumatic drive test platform includes: Support 1, used to hold the end of the hybrid variable stiffness software actuator; An air compressor and a pneumatic controller are connected. The output end of the air compressor is connected to the air inlet of the pneumatic controller, and the air outlet of the pneumatic controller is connected to the air chamber in the confinement layer. The host computer is connected to the communication interface of the pneumatic controller; Wherein, the bending angle θ is defined as the angle between the axis from the end point of the software driver to the fixed end point, the axis passing through the fixed end point, and the two axes. The variable stiffness performance testing platform includes: Support 2 is used to clamp one end of the hybrid variable stiffness software actuator and its height is adjustable; the end of the hybrid variable stiffness software actuator is attached to the pressure sensor on the linear guide rail; the pressure sensor is set on the slider on the linear guide rail and is connected to the host computer 2 for signal transmission. The vacuum pump and vacuum pressure gauge are used to provide negative pressure to the cavity in the confinement layer. Its input end is connected in sequence to the vacuum pressure gauge and the cavity in the confinement layer. The vacuum pressure gauge is used to display the vacuum level of the vacuum pump and is connected to the host computer via a signal connection. The guide rail controller controls the horizontal movement of the linear guide rail and is connected to the host computer via two signals. The pressure indicator is connected to the host computer via two signals. The stiffness of the soft actuator tip to be measured is defined as the ratio of the pressure at the soft actuator tip to the distance the tip moves.

3. The design method of the soft grasping robot according to claim 1, characterized in that, Step 3 includes: Bending performance test: Inflatable bending tests were conducted on three types of variable stiffness soft actuators, one without embedded plugging material and the other with embedded material. First, set the input air pressure in the pneumatic controller to 0 kPa-60 kPa, with an interval of 10 kPa each time; For each input air pressure, the experiment was repeated 5 times, and the average value of the bending angle θ was taken. The experimental data were then fitted into an input air pressure-bending angle curve. Stiffness testing includes: First, use a vacuum gauge to set the vacuum level, increasing it by 20 kPa each time between 0 kPa and 80 kPa. Then, the slider is moved by controlling the guide rail controller, moving 2mm at a time between 0mm and 20mm, and the pressure corresponding to each movement position is recorded; For each vacuum level, moving from 0mm to 20mm constitutes one experiment. Repeat the experiment 5 times and take the average pressure corresponding to each moving position. Finally, based on the definition of stiffness... By measuring the average pressure at each moving position and the sliding distance at each moving position, the stiffness value can be obtained, and finally, a sliding distance-stiffness diagram under different vacuum levels can be obtained.

4. The design method of the soft grasping robot according to claim 1, characterized in that, Step 4 includes: Based on the input air pressure-bending angle curve and the sliding distance-stiffness curve under different vacuum levels, the bending performance and variable stiffness performance of each soft actuator are compared with the other two soft actuators. The soft actuator with the best bending performance and variable stiffness performance is selected as the soft grasping robot.

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