WO2021082520A1 - Model building method for variable-stiffness soft robot - Google Patents
Model building method for variable-stiffness soft robot Download PDFInfo
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- WO2021082520A1 WO2021082520A1 PCT/CN2020/100791 CN2020100791W WO2021082520A1 WO 2021082520 A1 WO2021082520 A1 WO 2021082520A1 CN 2020100791 W CN2020100791 W CN 2020100791W WO 2021082520 A1 WO2021082520 A1 WO 2021082520A1
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- film tube
- particles
- spherical particles
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- soft robot
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- 238000000034 method Methods 0.000 title claims abstract description 26
- 239000002245 particle Substances 0.000 claims abstract description 151
- 239000012798 spherical particle Substances 0.000 claims abstract description 95
- 239000012530 fluid Substances 0.000 claims abstract description 18
- 239000010409 thin film Substances 0.000 claims abstract description 16
- 239000000945 filler Substances 0.000 claims abstract description 6
- 239000010408 film Substances 0.000 claims description 87
- 239000012528 membrane Substances 0.000 claims description 31
- 230000007246 mechanism Effects 0.000 claims description 23
- 238000004364 calculation method Methods 0.000 claims description 22
- 230000003068 static effect Effects 0.000 claims description 20
- 238000006073 displacement reaction Methods 0.000 claims description 17
- 230000000903 blocking effect Effects 0.000 claims description 14
- 229910003460 diamond Inorganic materials 0.000 claims description 9
- 239000010432 diamond Substances 0.000 claims description 9
- 239000008188 pellet Substances 0.000 claims description 8
- 238000007789 sealing Methods 0.000 claims description 8
- 230000009471 action Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- QNRATNLHPGXHMA-XZHTYLCXSA-N (r)-(6-ethoxyquinolin-4-yl)-[(2s,4s,5r)-5-ethyl-1-azabicyclo[2.2.2]octan-2-yl]methanol;hydrochloride Chemical group Cl.C([C@H]([C@H](C1)CC)C2)CN1[C@@H]2[C@H](O)C1=CC=NC2=CC=C(OCC)C=C21 QNRATNLHPGXHMA-XZHTYLCXSA-N 0.000 claims 1
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- 238000004088 simulation Methods 0.000 abstract description 4
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- 238000005516 engineering process Methods 0.000 description 2
- 230000033001 locomotion Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 238000000844 transformation Methods 0.000 description 2
- 230000001154 acute effect Effects 0.000 description 1
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- 210000003437 trachea Anatomy 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1602—Programme controls characterised by the control system, structure, architecture
- B25J9/1605—Simulation of manipulator lay-out, design, modelling of manipulator
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1615—Programme controls characterised by special kind of manipulator, e.g. planar, scara, gantry, cantilever, space, closed chain, passive/active joints and tendon driven manipulators
Definitions
- the invention relates to the technical field of driving travel, in particular to a modeling method of a variable stiffness soft robot.
- the mechanism needs to have better variable stiffness performance, that is, better flexibility and rigidity.
- it Before coming into contact with the object, it needs to have good flexibility and be able to realize its own movement through active deformation, so as to better adapt to external objects and obtain a larger contact area.
- After full contact with the object it needs to have good rigidity to increase the pressure between the objects in contact, and then increase the friction between the objects in contact.
- Pneumatic structure has good position control performance, but due to the characteristics of its material itself, the stiffness of the mechanism made of it is not high, and the introduction of a blocking system can increase the stiffness of the soft robot to adapt to more applications.
- the pneumatic drive has the characteristics of fast response, high power density, and high switching speed.
- the materials constituting the soft robot are usually flexible, the pressure is always maintained at a low level when driven by air pressure, which enables the soft robot to achieve corresponding motions and at the same time has high safety.
- Variable stiffness is an effective way for soft structures (natural or man-made) to interact with the environment.
- the inherent flexibility of the software structure deforms itself to adapt to the external environment, and the safe interaction prevents the external environment from damaging the entity. But at the same time, it also needs to strengthen its own rigidity to increase the force applied to the external environment.
- variable stiffness method based on particle clogging is a more effective method of using vacuum pressure to control stiffness.
- Particle blockage is to cause a large number of particles to undergo a phase change, transitioning between a fluid state and a solid state. If the particles are placed in a sealing film under normal conditions, due to the large gaps between the particles and the small friction between the particles, they can flow arbitrarily, thus exhibiting a fluid-like behavior. At this time, a large number of particles are wrapped.
- the sealing film can be changed in any shape. When the air in the sealing film is discharged, a large number of particles are compressed together. At this time, due to the increase of the contact surface pressure between the particles, the friction between the particles rises sharply. At this time, the particles are restricted and cannot flow freely. , So that the filling particles present a solid state, and the sealing film and the particles as a whole show a certain degree of rigidity.
- variable stiffness software driver software arm and software platform based on blocking mechanism
- the application is The author discloses a variable stiffness soft drive based on the blocking mechanism, which is mainly composed of a flexible frame, a trachea, an outer flexible layer, a blocking mechanism, a deformable plug and a blocking plug.
- the blocking mechanism is mainly composed of a supporting frame, an elastic connecting rope, and a large ball. It is composed of particles, small ball particles, tightening spring and sealing film, which can have greater flexibility and rigidity through the principle of variable stiffness.
- the technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art, and provide a modeling method of a variable stiffness soft robot.
- the modeling method of the variable stiffness soft robot takes all the filling particles and the film tube in the film tube into consideration. As a whole particle block, the small spherical particles are equivalent to fluid, the film tube is equivalent to a closed space, the sphere-plane Hertz contact model is established, and the locking force is established based on the Hertz contact theory and the Hertz contact model of two spheres. And the model of the locking torque, so as to control the stiffness of the variable stiffness soft robot as required.
- a modeling method of a variable stiffness soft robot includes the following steps.
- Step 1 the design of the locking force FL between the filling particles, includes the following steps.
- Step 11 support frame selection.
- the support frame in the blocking mechanism is selected as a rhombus frame, and the sealing film is selected as a film tube.
- the large spherical particles and small spherical particles in the film tube are collectively referred to as filler particles.
- Step 12 Establish a particle block model.
- all the filling particles in the film tube are rigid and are restricted as a whole, that is, all the filling particles in the film tube and the film tube, When taken as a whole piece of pellets.
- Step 13 the design of the locking force FL between the filling particles.
- the particle block receives an external force
- the small spherical particles in the filled particles are equivalent to a fluid.
- the calculation formula of the locking force FL between the filled particles is obtained as follows.
- P′ is the equivalent pressure in the film tube
- R 1 is the radius of the diamond-shaped skeleton
- ⁇ is the sharp apex angle of the diamond-shaped skeleton
- R 2 is the radius of the large spherical particles
- ⁇ 1 is the friction coefficient between the small spherical particles and the diamond-shaped skeleton
- ⁇ 2 is the friction coefficient between small spherical particles and large spherical particles.
- Step 2 Calculate the equivalent pressure P'in the film tube.
- the radius of the small spherical particles is much smaller than the radius of the film tube, and the area of the film tube facing the single small spherical particle is small. Therefore, the film tube in contact with the single small spherical particle can be regarded as a flat surface.
- the sphere-plane Hertz contact model according to the Hertz contact theory and the Hertz contact model of two spheres, the calculation formula for the equivalent pressure P′ in the membrane tube is obtained as follows.
- R 3 is the radius of the small spherical particles
- v 1 is the Poisson's ratio of the diamond-shaped framework
- v 2 is the Poisson's ratio of the small spherical particles
- E 1 is the Young's modulus of the diamond-shaped framework
- E 2 is the Young's ratio of the small spherical particles.
- Modulus P is the vacuum pressure in the film tube.
- Step 3 Establish the corresponding relationship between the locking force FL and the vacuum pressure P in the film tube. Substituting the equivalent pressure P'in the membrane tube calculated in step 2 into the locking force FL designed in step 1, the corresponding relationship between the locking force FL and the vacuum pressure P in the membrane tube is obtained as shown in the following formula.
- Step 4 Design the locking torque ML of the particle block.
- the design formula is shown below.
- d is the radius of the film tube.
- step 5 establishing the corresponding relationship between the locking torque M L and the hardness S 1 of the pellets.
- the corresponding relationship between the Young's modulus value and the Shore hardness value the corresponding relationship between the locking torque M L and the hardness S 1 of the small spherical particles is established as follows.
- the stiffness of the variable stiffness soft robot is adjusted.
- step 6 the design of the deformation angle ⁇ of the film tube.
- the film tube will deform in contact with the small spherical particles, and the deformation angle ⁇ of the film tube is calculated using the following formula.
- the calculation method of the deformation angle ⁇ of the film tube includes the following steps.
- Step 61 Calculate the relative radial deformation displacement ⁇ of the thin film tube. According to the sphere-plane Hertzian contact model established in step 2, and then according to the Hertzian contact theory and the two-sphere Hertzian contact model, the relative radial deformation displacement ⁇ of the membrane tube is obtained to satisfy the following calculation formula.
- Step 62 Establish a corresponding relationship between the deformation angle ⁇ of the membrane tube and the relative radial deformation displacement ⁇ of the membrane tube.
- the corresponding relationship between the deformation angle ⁇ of the membrane tube and the relative radial deformation displacement ⁇ of the membrane tube is calculated as follows.
- Step 63 Calculate the deformation angle ⁇ of the film tube. Substituting the relative radial deformation displacement ⁇ of the thin film tube calculated in step 61 into step 62, it is obtained that the deformation angle ⁇ of the thin film tube satisfies the following formula.
- step 13 according to the static balance equation and Pascal's law, the method of calculating the locking force FL between the filled particles includes the following steps.
- the particle block includes an upper particle block and a lower particle block, wherein the lower particle block is located on the side of the object to be locked and the bottom is in contact with the object to be locked, and the upper particle is located on the side away from the object to be locked.
- the locking force of the lower particle block needs to resist the external moment. Therefore, the upper particle block and the lower particle block slide relative to each other in the horizontal direction. According to the static balance equation of the particle block, the locking force F L described as.
- f L is the friction force of the particle block in the contact area with the diamond-shaped skeleton
- f P is the static force of the particle block on the locking area
- f U is the friction force of the lower particle block and the large spherical particles in the horizontal direction.
- Step 13b f P is calculated.
- the small spherical particles are equivalent to fluid, and the film tube is equivalent to a closed space.
- Several small spherical particles are filled in the closed space to form a static fluid model. Then the static force f P applied by the particle block in the horizontal direction of the locking area , Will be provided by the pressure between the particle block and the diamond skeleton, specifically.
- R 1 is the radius of the rhombus skeleton
- ⁇ is the apex angle of the rhombus skeleton
- P′ is the equivalent pressure in the film tube.
- Step 13c f L is calculated.
- the frictional force f L of the particle block in the contact area with the diamond-shaped skeleton is.
- ⁇ 1 is the friction coefficient between the particle block and the diamond-shaped skeleton.
- Step 13d f U is calculated.
- the frictional force f U between the lower layer of particles and the large spherical particles in the horizontal direction is.
- ⁇ 2 is the friction coefficient between small spherical particles and large spherical particles.
- step 13e the f P , f L and f U calculated in steps 13b, 13c, and 13d are substituted into step 13a respectively to obtain the calculation formula of the locking force FL between the filling particles.
- the vacuum pressure P in the membrane tube is adjusted by the vacuum pump, and then the stiffness of the variable stiffness soft robot is adjusted.
- the vacuum pressure P in the membrane tube increases, the deformation angle ⁇ and the locking torque M L of the membrane tube will increase, and the stiffness of the variable stiffness soft robot will increase.
- the stiffness of the variable stiffness soft robot is adjusted.
- the radius R 3 of the small ball particle is larger, the locking torque M L is smaller, and the rigidity of the variable-rigidity soft robot will decrease.
- the stiffness of the variable stiffness soft robot is adjusted.
- the radius R 1 of the rhombus skeleton is larger, the locking torque M L is larger, and the rigidity of the variable-rigidity soft robot will increase.
- the stiffness of the variable stiffness soft robot is adjusted.
- the radius R 2 of the large ball particle is larger, the locking torque M L is larger, and the rigidity of the variable-rigidity soft robot will increase.
- the invention has the following beneficial effects: the particles are quickly divided into upper and lower layers, and the locking force of the lower layer of particle blocks resists the external moment.
- the upper and lower layers of particle blocks slide relatively in the horizontal direction.
- the small spherical particles are equivalent to a fluid
- the film tube is equivalent to a closed space.
- the inside of the tube is filled with small spherical particles.
- the locking force is obtained according to the static balance equation of the particle block.
- the film area where a single particle is facing If the area is small, it can be regarded as a plane, then the film and particle block are analyzed using the Hertzian contact theory, the sphere-plane Hertzian contact model is established, and the relationship between the hardness of the small ball and the locking torque is obtained.
- the apex angle and radius of the rhombus skeleton By adjusting the apex angle and radius of the rhombus skeleton, the radius of the large spherical particles, the radius of the small spherical particles, the hardness, the vacuum pressure and other parameters, the required stiffness of the variable stiffness soft robot can be obtained.
- the model established by the invention is simulated through variable stiffness characteristics, and the simulation result is consistent with the established model, so the reliability is high and it is convenient for popularization and utilization.
- Figure 1 shows a schematic structural diagram of a blocking mechanism in a variable stiffness soft robot of the present invention.
- Figure 2 shows a longitudinal cross-sectional view of a blocking mechanism in a variable stiffness soft robot of the present invention.
- Fig. 3 shows an exploded analysis diagram of the force on the end of the blocking mechanism in a variable stiffness soft robot of the present invention.
- Figure 4 shows a cross-sectional view of the longitudinal plane where all the large spherical particles connected by the same tightening spring are located.
- Figure 5 shows a schematic diagram of the force analysis of the lower particle block.
- Figure 6 shows a schematic diagram of the fluid pressurization model.
- Figure 7 shows a schematic diagram of the force analysis of the blocking mechanism in the present invention.
- Figure 8 shows the Hertz model of two balls in contact.
- Figure 9 shows the particle-plane Hertz contact model of the small spherical particles in contact with the film tube.
- Figure 10 shows the simplified model diagram of Figure 9.
- Figure 11 shows the corresponding relationship between the deformation angle ⁇ and the vacuum pressure P.
- Figure 12 shows the corresponding relationship between the locking torque M L and the vacuum pressure P.
- Figure 13 shows the corresponding relationship between the locking torque M L and the radius R 3 of the small spherical particles.
- Figure 14 shows the corresponding relationship between the locking torque M L and the radius R 1 of the diamond skeleton.
- Figure 15 shows the corresponding relationship between the locking torque M L and the radius R 2 of the large spherical particles.
- Figure 16 shows the corresponding relationship between the locking torque M L and the hardness S 1 of the pellets.
- variable stiffness soft robot For details, please refer to the invention patent application filed on August 31, 2017 with the application number CN201710768485.2.
- the name of the invention is "variable stiffness soft driver, soft arm and software platform based on clogging mechanism.” "This application does not improve the structure of the blocking mechanism itself, but selects the support frame in the blocking mechanism as the diamond-shaped frame 32, and the sealing film as the film tube 31.
- the large spherical particles 34 and the small spherical particles 35 in the film tube are collectively referred to as filling particles.
- the elastic connecting rope is selected as a flexible rope 33, and vacuum pressure is provided into the film tube through a vacuum pump 40.
- the specific structure is shown in Figs. 1 and 2.
- a modeling method of a variable stiffness soft robot includes the following steps.
- Step 1 the design of the locking force FL between the filling particles, includes the following steps.
- Step 11 support frame selection.
- Step 12 Establish a particle block model.
- all the filling particles in the film tube are rigid and are restricted as a whole, that is, all the filling particles in the film tube and the film tube, When taken as a whole piece of pellets.
- Step 13 the design of the locking force FL between the filling particles.
- the particle block When the particle block receives an external force, the small spherical particles in the filled particles are equivalent to a fluid. According to the static balance equation and Pascal's law, the calculation formula of the locking force FL between the filled particles is obtained as follows.
- P′ is the equivalent pressure in the film tube
- R 1 is the radius of the diamond-shaped skeleton
- ⁇ is the sharp apex angle of the diamond-shaped skeleton
- R 2 is the radius of the large spherical particles
- ⁇ 1 is the friction coefficient between the small spherical particles and the diamond-shaped skeleton
- ⁇ 2 is the friction coefficient between small spherical particles and large spherical particles.
- the above method for calculating the locking force FL between filled particles according to the static balance equation and Pascal's law includes the following steps.
- the particle block includes an upper particle block 51 and a lower particle block 52, wherein the lower particle block is located on the side of the object to be locked and the bottom is in contact with the object to be locked, and the upper particle is located on the side away from the object to be locked.
- the particle block receives an external force F E
- the locking force of the lower particle block needs to resist the external moment. Therefore, the upper particle block and the lower particle block slide relative to each other in the horizontal direction.
- the static balance equation of the particle block, then the locking force FL is described as.
- f L is the friction force of the particle block on the contact area 10 with the diamond-shaped skeleton
- f P is the static force of the particle block on the locking area 60
- f U is the horizontal friction between the lower particle block and the large spherical particles. force.
- Step 13b f P is calculated.
- the static force f P of the particle block on the locking area can be estimated by the fluid pressure model.
- the fluid in a confined space exerts pressure on the fluid, can be transferred from the fluid to all directions in the space with the same magnitude.
- Figure 6 and Pascal's law we can get:
- the small spherical particles are equivalent to a fluid, and the film tube is equivalent to a closed space, and its interior is filled with small spherical particles, which constitutes a static fluid model as shown in Figure 7.
- the force applied on each side It can be calculated by the above formula.
- FN2 is the positive pressure of the particle block on the diamond-shaped skeleton, as shown in Figure 7, R 1 is the radius of the diamond-shaped skeleton, ⁇ is the apex angle of the diamond-shaped skeleton, and P'is the equivalent pressure applied by the particle block to the diamond-shaped skeleton and the big sphere. , Which is the equivalent pressure in the film tube.
- the above-mentioned diamond-shaped skeleton radius R 1 refers to the radius of the radial large circle in the diamond-shaped skeleton in Fig. 3, which is infinitely close to the radius d of the film tube and can be approximately equal.
- the apex angle ⁇ of the rhombus skeleton refers to the apex angle on the flexible rope, which is an acute angle.
- Step 13c f L calculation: the friction force f L of the particle block in the contact area with the diamond-shaped skeleton is:
- ⁇ 1 is the friction coefficient between the particle block and the diamond-shaped skeleton
- a 1 is the equivalent area of the contact area between the particle block and the diamond-shaped skeleton.
- Step 13d the frictional force f U between the lower layer of particles and the large spherical particles in the horizontal direction is:
- F N1 is the positive pressure of the particle block on the large spherical particle
- R 2 is the radius of the large spherical particle
- ⁇ 2 is the friction coefficient between the small spherical particle (filling particle) and the large spherical particle
- a 2 is the particle block and the large spherical particle. The equivalent area of particle contact.
- step 13e the f P , f L and f U calculated in steps 13b, 13c, and 13d are substituted into step 13a respectively to obtain the calculation formula of the locking force FL between the filling particles.
- Step 2 Calculate the equivalent pressure P'in the film tube.
- Ra is the radius of the ball a in Figure 8
- R b is the radius of the ball b
- v a is the Poisson's ratio of the ball a
- v b is the Poisson's ratio of the ball b
- E a is the Young's modulus of the ball a
- E b is b Ball Young's modulus.
- the radius of the small spherical particle is much smaller than the radius of the film tube, and the area of the film tube facing the single small spherical particle is small. Therefore, the film tube in contact with the single small spherical particle can be regarded as a flat surface.
- the relative radial deformation displacement of the ⁇ film tube R 3 is the radius of the small spherical particles
- v 1 is the Poisson's ratio of the diamond-shaped framework
- v 2 is the Poisson's ratio of the small spherical particles
- E 1 is the Young's modulus of the diamond-shaped framework
- E 2 is the Young's modulus of the small spherical particles
- P is the vacuum pressure in the film tube.
- Step 3 Establish the corresponding relationship between the locking force FL and the vacuum pressure P in the film tube. Substituting the equivalent pressure P'in the membrane tube calculated in step 2 into the locking force FL designed in step 1, the corresponding relationship between the locking force FL and the vacuum pressure P in the membrane tube is obtained as shown in the following formula.
- Step 4 Design the locking torque ML of the particle block.
- the design formula is shown below.
- d is the radius of the film tube.
- Step 5 Establish the corresponding relationship between the locking torque M L and the hardness S 1 of the small ball particles.
- E is the Young's modulus in MPa
- S is the hardness in accordance with ASTM D2240. This formula is suitable for materials with a hardness of 20 to 80, which is close to the material properties of small spherical particles.
- the corresponding relationship between the Young's modulus value and the Shore hardness value is established as follows.
- the stiffness of the variable stiffness soft robot is adjusted.
- Step 6 the design of the deformation angle ⁇ of the film tube.
- the film tube When the particle block is subjected to an external force, the film tube will deform in contact with the small spherical particles, and the deformation angle ⁇ of the film tube is calculated using the following formula.
- the calculation method of the deformation angle ⁇ of the film tube includes the following steps.
- Step 61 Calculate the relative radial deformation displacement ⁇ of the thin film tube. According to the sphere-plane Hertzian contact model established in step 2, and then according to the Hertzian contact theory and the two-sphere Hertzian contact model, the relative radial deformation displacement ⁇ of the membrane tube is obtained to satisfy the following calculation formula.
- step 2 the above calculation formula can be obtained, which is only for reference here.
- Step 62 Establish a corresponding relationship between the deformation angle ⁇ of the membrane tube and the relative radial deformation displacement ⁇ of the membrane tube.
- Step 63 Calculate the deformation angle ⁇ of the film tube. Substituting the relative radial deformation displacement ⁇ of the thin film tube calculated in step 61 into step 62, it is obtained that the deformation angle ⁇ of the thin film tube satisfies the following formula.
- the relationship between the locking torque M L and the vacuum pressure P as shown in Fig. 12 is obtained. It can be seen from the figure that the greater the vacuum pressure P, the greater the locking torque M L. Therefore, the stiffness of the mechanism can be controlled by adjusting the vacuum pressure.
- the relationship between the locking torque M L and the radius R 3 of the small spherical particles shown in Fig. 13 is obtained. It can be seen from the figure that the larger the radius R 3 of the pellets, the smaller the locking torque M L. And as the size of small particles decreases, the decrease of the locking torque M L becomes smaller and smaller under the same size reduction.
- the relationship between the locking torque M L and the radius size R2 of the large spherical particles shown in Fig. 15 can be obtained. It can be seen that the larger the radius of the large spherical particles, the larger the locking torque M L. And with the increase of the radius of the large spherical particles, the increase of the locking torque M L becomes larger and larger under the same size increment.
- the invention first theoretically studies and analyzes the principle of variable stiffness of the plugging variable stiffness structure, first simplifying the modeling, and applying the Pascal model and Hertz contact theory to establish the mechanical model of the plugging mechanism, and derive the locking torque and vacuum at the end of the mechanism
- the relationship between the pressure, the hardness of the small spherical particles and the radius of the large spherical particles The relationship between the stiffness of the mechanism and the degree of vacuum, the radius of the diamond skeleton and the size of the large spherical particles is obtained, and the simulation analysis is performed. It is convenient for the subsequent design of the cavity shape and wall thickness of the driver to have better bending performance and better meet the design requirements.
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Claims (10)
- 一种变刚度软体机器人的建模方法,其特征在于:包括如下步骤:A modeling method for a variable stiffness soft robot, which is characterized in that it comprises the following steps:步骤1,填充颗粒间的锁紧力F L设计,包括如下步骤: Step 1, the design of the locking force FL between the filling particles, including the following steps:步骤11,支撑骨架选择:堵塞机构中的支撑骨架选择为菱形骨架,密封薄膜选择为薄膜管;薄膜管中的大球颗粒和小球颗粒均统称为填充颗粒;Step 11, support frame selection: the support frame in the blocking mechanism is selected as a diamond frame, and the sealing film is selected as a film tube; the large spherical particles and small spherical particles in the film tube are collectively referred to as filler particles;步骤12,建立颗粒块模型:为分析填充颗粒对变刚度软体机器人刚度的影响,在真空压力作用下,假定薄膜管内的所有填充颗粒都是刚性的,且被限制为一个整体,也即将薄膜管内的所有填充颗粒和薄膜管,当作为一个整体的颗粒块;Step 12: Establish a particle block model: In order to analyze the effect of the filling particles on the stiffness of the variable stiffness soft robot, under the action of vacuum pressure, it is assumed that all the filling particles in the film tube are rigid and restricted as a whole, that is, the inside of the film tube All the filled particles and film tubes are treated as a whole particle block;步骤13,填充颗粒间的锁紧力F L设计:当颗粒块受到外力时,将填充颗粒中的小球颗粒等效成流体,根据静力平衡方程和帕斯卡定律,得到填充颗粒间锁紧力F L的计算公式如下: Step 13, the locking force F L between the design of filler particles: when the external force is applied grain block, pellets equivalent granular fill fluid particles, according to the static equilibrium equations and Pascal's law, the locking force between the filler particles to give The calculation formula of FL is as follows:其中,P′为薄膜管内等效压强,R 1为菱形骨架半径,α为菱形骨架的锐形顶角,R 2为大球颗粒半径,μ 1为小球颗粒与菱形骨架之间的摩擦系数,μ 2为小球颗粒与大球颗粒之间的摩擦系数; Among them, P′ is the equivalent pressure in the film tube, R 1 is the radius of the diamond skeleton, α is the sharp apex angle of the diamond skeleton, R 2 is the radius of the large spherical particles, and μ 1 is the friction coefficient between the small spherical particles and the diamond skeleton. , Μ 2 is the friction coefficient between small spherical particles and large spherical particles;步骤2,薄膜管内等效压强P′计算:自然状态下,小球颗粒半径远小于薄膜管半径,单个小球颗粒正对着的薄膜管区域面积较小,因而,能将与单个小球颗粒接触的薄膜管近似看成是一块平面,建立球体-平面赫兹接触模型,根据赫兹接触理论和两圆球赫兹接触模型,得到薄膜管内等效压强P′的计算公式如下:Step 2. Calculate the equivalent pressure P′ in the film tube: In the natural state, the radius of the small spherical particle is much smaller than the radius of the film tube, and the area of the film tube facing the single small spherical particle is small. Therefore, it can be compared with the single small spherical particle. The contacting membrane tube is approximately regarded as a plane, and the sphere-plane Hertz contact model is established. According to the Hertz contact theory and the two-sphere Hertz contact model, the calculation formula of the equivalent pressure P′ in the membrane tube is obtained as follows:其中,R 3为小球颗粒半径,v 1为菱形骨架的泊松比,v 2为小球颗粒的泊松比,E 1为菱形骨架杨氏模量,E 2为小球颗粒的杨氏模量,P为薄膜管内的真空压力; Among them, R 3 is the radius of the small spherical particles, v 1 is the Poisson's ratio of the diamond-shaped framework, v 2 is the Poisson's ratio of the small spherical particles, E 1 is the Young's modulus of the diamond-shaped framework, and E 2 is the Young's ratio of the small spherical particles. Modulus, P is the vacuum pressure in the film tube;步骤3,建立锁紧力F L与薄膜管内真空压力P的对应关系:将步骤2中计算的薄膜管内等效压强P′代入步骤1设计的锁紧力F L中,得到如下式所示的锁紧力F L与薄膜管内真空压力P的对应关系: Step 3. Establish the corresponding relationship between the locking force FL and the vacuum pressure P in the membrane tube: Substitute the equivalent pressure P′ in the membrane tube calculated in step 2 into the locking force FL designed in step 1, and obtain the following formula Corresponding relationship between locking force F L and vacuum pressure P in the film tube:步骤4,颗粒块的锁紧力矩M L设计,设计公式如下所示: Step 4. Design the locking torque ML of the particle block. The design formula is as follows:其中,d为薄膜管半径。Among them, d is the radius of the film tube.
- 根据权利要求1所述的变刚度软体机器人的建模方法,其特征在于:还包括步骤5,建立锁紧力矩M L与小球颗粒硬度S 1的对应关系:根据杨氏模量值与肖氏硬度值的对应关系,建立锁紧力矩M L与小球颗粒硬度S 1的对应关系如下: The modeling method of a variable stiffness soft robot according to claim 1, characterized in that it further comprises step 5, establishing the corresponding relationship between the locking torque M L and the hardness S 1 of the small spherical particles: according to the Young's modulus value and the Shore Corresponding relationship of the hardness value, the corresponding relationship between the locking torque M L and the hardness S 1 of the small ball particles is established as follows:
- 根据权利要求2所述的变刚度软体机器人的建模方法,其特征在于:通过调整小球颗粒的硬度S 1,进而调整变刚度软体机器人的刚度;小球颗粒的硬度S 1越大,变刚度软体机器人的刚度越大。 The modeling method of the variable stiffness soft robot according to claim 2, characterized in that: the stiffness of the variable stiffness soft robot is adjusted by adjusting the hardness S 1 of the small spherical particles ; the greater the hardness S 1 of the small spherical particles, the change Stiffness The greater the stiffness of the soft robot.
- 根据权利要求2所述的变刚度软体机器人的建模方法,其特征在于:还包括步骤6,薄膜管变形角β的设计:颗粒块受到外力时,薄膜管将与小球颗粒发生接触变形,则薄膜管的变形角β采用如下公式进行计算得出:The modeling method of a variable stiffness soft robot according to claim 2, characterized in that it further comprises step 6, the design of the deformation angle β of the film tube: when the particle block receives an external force, the film tube will deform in contact with the small spherical particles, Then the deformation angle β of the film tube is calculated using the following formula:
- 根据权利要求4所述的变刚度软体机器人的建模方法,其特征在于:薄膜管变形角β的计算方法,包括如下步骤:The modeling method of a variable stiffness soft robot according to claim 4, wherein the method for calculating the deformation angle β of the film tube includes the following steps:步骤61,薄膜管的相对径向形变位移δ的计算:根据步骤2中建立的球体-平面赫兹接触模型,再根据赫兹接触理论和两圆球赫兹接触模型,得到薄膜管的相对径向形变位移δ满足如下计算公式:Step 61: Calculation of the relative radial deformation displacement δ of the membrane tube: According to the sphere-plane Hertz contact model established in step 2, and then according to the Hertz contact theory and the two-sphere Hertz contact model, the relative radial deformation displacement of the membrane tube is obtained. δ satisfies the following calculation formula:步骤62,建立薄膜管变形角β与薄膜管相对径向形变位移δ的对应关系:根据球体-平面赫兹接触模型,计算得出薄膜管变形角β与薄膜管相对径向形变位移δ的对应关系如下:Step 62: Establish the corresponding relationship between the deformation angle β of the membrane tube and the relative radial deformation displacement δ of the membrane tube: According to the sphere-plane Hertz contact model, the correspondence relationship between the deformation angle β of the membrane tube and the relative radial deformation displacement δ of the membrane tube is calculated as follows:步骤63,薄膜管变形角β的计算:将步骤61中计算得到的薄膜管相对径向形变位移δ代入步骤62中,得出薄膜管变形角β满足如下公式:Step 63: Calculation of the deformation angle β of the thin film tube: Substituting the relative radial deformation displacement δ of the thin film tube calculated in step 61 into step 62, it is obtained that the deformation angle β of the thin film tube satisfies the following formula:
- 根据权利要求1所述的变刚度软体机器人的建模方法,其特征在于:步骤13中,根据静力平衡方程和帕斯卡定律,计算填充颗粒间锁紧力F L的方法,包括如下步骤: The modeling method of a variable stiffness soft robot according to claim 1, characterized in that: in step 13, according to the static balance equation and Pascal's law, the method of calculating the locking force FL between the filled particles includes the following steps:步骤13a,锁紧力描述:颗粒块包括上层颗粒块和下层颗粒块,其中,下层颗粒块位于待锁紧物体一侧且底部与待锁紧物体相接触,上层颗粒则位于背离待锁紧物体的一侧;当颗粒块受到外力时,下层颗粒块的锁紧力需抵抗外力矩,因而,上层颗粒块和下层颗粒块沿水平方向发生相对滑动,根据颗粒块的静力平衡方程,则锁紧力F L描述为: Step 13a, description of locking force: the particle block includes an upper particle block and a lower particle block, where the lower particle block is located on the side of the object to be locked and the bottom is in contact with the object to be locked, while the upper particle is located away from the object to be locked When the particle block is subjected to an external force, the locking force of the lower particle block needs to resist the external moment. Therefore, the upper particle block and the lower particle block slide relative to each other in the horizontal direction. According to the static balance equation of the particle block, the lock The tightening force FL is described as:F L=2f U+f p+f L F L =2f U +f p +f L其中,f L是颗粒块在与菱形骨架接触区域上的摩擦力,f P是颗粒块在锁紧区域上的静态力,f U是下层颗粒块与大球颗粒在水平方向上的摩擦力; Among them, f L is the friction force of the particle block in the contact area with the diamond-shaped skeleton, f P is the static force of the particle block on the locking area, and f U is the friction force of the lower particle block and the large spherical particles in the horizontal direction;步骤13b,f P计算:将小球颗粒等效成流体,薄膜管等效为一个密闭空间,密闭空间内填充若干小球颗粒,从而构成一个静态流体模型,则颗粒块作用在锁紧区域水平方向上的静态力f P,将由颗粒块与菱形骨架间的压力提供,具体为: Step 13b, f P calculation: the small spherical particles are equivalent to a fluid, and the film tube is equivalent to a closed space, and a number of small spherical particles are filled in the closed space to form a static fluid model, and the particle block acts on the level of the locked area The static force f P in the direction will be provided by the pressure between the particle block and the diamond skeleton, specifically:f P=πR 1 2P′sinα f P =πR 1 2 P′sinα其中,R 1为菱形骨架半径,α为菱形骨架顶角,P′为薄膜管内等效压强; Among them, R 1 is the radius of the diamond-shaped framework, α is the apex angle of the diamond-shaped framework, and P′ is the equivalent pressure in the film tube;步骤13c,f L计算:颗粒块在与菱形骨架接触区域上的摩擦力f L为: Step 13c, f L calculation: the friction force f L of the particle block in the contact area with the diamond-shaped skeleton is:f L=πR 1 2P′μ 1 f L =πR 1 2 P′μ 1其中,μ 1为颗粒块与菱形骨架之间的摩擦系数; Among them, μ 1 is the friction coefficient between the particle block and the diamond-shaped skeleton;步骤13d,f U计算:下层颗粒块与大球颗粒在水平方向上的摩擦力f U为: Step 13d, f U calculation: the frictional force f U between the lower layer of particles and the large spherical particles in the horizontal direction is:其中,μ 2为小球颗粒与大球颗粒之间的摩擦系数; Among them, μ 2 is the friction coefficient between small spherical particles and large spherical particles;步骤13e,将步骤13b、13c和13d计算的f P、f L和f U,分别代入步骤13a中,即得到填充颗粒间锁紧力F L的计算公式。 In step 13e, the f P , f L and f U calculated in steps 13b, 13c, and 13d are substituted into step 13a respectively to obtain the calculation formula of the locking force FL between the filling particles.
- 根据权利要求5所述的变刚度软体机器人的建模方法,其特征在于:通过真空泵调整薄膜管内的真空压力P,进而调整变刚度软体机器人的刚度;当薄膜管内的真空压力P增大时,薄膜管的变形角β和锁紧力矩M L均将增大,变刚度软体机器人的刚度增大。 The modeling method of the variable stiffness soft robot according to claim 5, characterized in that: the vacuum pressure P in the membrane tube is adjusted by a vacuum pump, thereby adjusting the stiffness of the variable stiffness soft robot; when the vacuum pressure P in the membrane tube increases, Both the deformation angle β and the locking moment M L of the membrane tube will increase, and the stiffness of the variable stiffness soft robot will increase.
- 根据权利要求5所述的变刚度软体机器人的建模方法,其特征在于:通过调整小球颗粒半径R 3,进而调整变刚度软体机器人的刚度;当小球颗粒半径R 3越大,锁紧力矩M L越小,变刚度软体机器人的刚度将减小。 The modeling method of the variable stiffness soft robot according to claim 5, characterized in that: the rigidity of the variable stiffness soft robot is adjusted by adjusting the radius R 3 of the small spherical particle; when the radius R 3 of the small spherical particle becomes larger, the locking The smaller the torque M L, the lower the stiffness of the variable stiffness soft robot.
- 根据权利要求5所述的变刚度软体机器人的建模方法,其特征在于:通过调整菱形骨架半径R 1,进而调整变刚度软体机器人的刚度;当菱形骨架半径R 1越大,锁紧力矩M L越大,变刚度软体机器人的刚度将增大。 The method for modeling a variable stiffness soft robot according to claim 5, characterized in that: the rigidity of the variable stiffness soft robot is adjusted by adjusting the radius R 1 of the rhombic skeleton; when the radius R 1 of the rhombus becomes larger, the locking torque M The larger L is, the rigidity of the variable rigidity soft robot will increase.
- 根据权利要求5所述的变刚度软体机器人的建模方法,其特征在于:通过调大球颗粒半径R 2,进而调整变刚度软体机器人的刚度;当大球颗粒半径R 2越大,锁紧力矩M L越大,变刚度软体机器人的刚度将增大。 The modeling method of claim 5 variable stiffness software robot as claimed in claim wherein: the ball transfer large particle radius R 2, and further adjusted by varying the stiffness of the software robot; when large spherical particles larger radius R 2, the locking The greater the torque M L, the greater the stiffness of the variable stiffness soft robot.
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