CN110315571B - Soft actuator control method for correcting robot assembly posture - Google Patents

Soft actuator control method for correcting robot assembly posture Download PDF

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CN110315571B
CN110315571B CN201910468268.0A CN201910468268A CN110315571B CN 110315571 B CN110315571 B CN 110315571B CN 201910468268 A CN201910468268 A CN 201910468268A CN 110315571 B CN110315571 B CN 110315571B
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soft actuator
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CN110315571A (en
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陈教料
王佳才
张立彬
胥芳
鲍官军
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Zhejiang University of Technology ZJUT
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J15/00—Gripping heads and other end effectors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
    • B25J19/0004—Braking devices
    • 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
    • B25J9/1674—Programme controls characterised by safety, monitoring, diagnostic

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Abstract

A robot assembles the software actuator control method that the posture rectifies, to the pneumatic software actuator of multicavity room that can deflect to the arbitrary direction, adopt a method of combining deflection direction vector and deflection angle to express the deformation condition of the software actuator; according to the characteristics of pneumatic control and elastic deformation of the pneumatic soft actuator, the assembly posture deviation rectifying control process is divided into two stages of assembly posture sensing and assembly posture adjustment: an assembling posture sensing stage and an assembling posture adjusting stage. The invention realizes the assembly attitude sensing and the assembly attitude deviation correction in the assembly process of the robot for the heterogeneous non-rigid parts.

Description

Soft actuator control method for correcting robot assembly posture
Technical Field
The invention relates to a soft actuator control method, in particular to a soft actuator control method for correcting the assembly posture of a robot.
Background
In the automatic assembly of the parts, the assembly actions of clamping, positioning and mounting performed by the traditional rigid end effector usually cause the damage of the parts due to the manufacturing error, the positioning error, the over-rigidity of an assembly execution system and the like. In the current field of robotic automated assembly, rigid end grippers are often used to grip parts in order to ensure efficient assembly of such heterogeneous, non-rigid parts. A force feedback sensor is installed at a tail end joint of the robot, the assembly attitude of the part is sensed through assembly contact force feedback, and then the assembly robot is controlled to adjust the assembly attitude according to the sensed assembly attitude of the part. The robot assembly attitude deviation rectifying control method needs to additionally install a force sensor and needs to add a specific assembly attitude deviation rectifying algorithm in a robot operation control program, so that the cost is increased, the adaptability of the attitude deviation rectifying method to different robots is reduced, and the operation efficiency of robot automatic assembly is also reduced.
Compared with a rigid clamping mechanism, the pneumatic soft actuator made of the rubber material has the characteristics of multiple degrees of freedom and high adaptability to complex force action environments, so that the pneumatic soft actuator has good potential for assembly posture correction. However, the existing deformation control of the elastic pneumatic software only controls the large deformation in a single deformation direction, and is not suitable for the conditions of multiple deformation directions and small deformation during assembly posture deviation correction.
Disclosure of Invention
In order to overcome the defects of high hardware cost and poor adaptability of the existing assembly posture deviation rectifying control method, the invention provides a soft actuator control method for rectifying the assembly posture of a robot, which realizes the assembly posture sensing and assembly posture deviation rectifying in the assembly process of a robot for heterogeneous non-rigid parts.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a robot assembles the software actuator control method that the posture rectifies, to the pneumatic software actuator of multicavity room that can deflect to the arbitrary direction, adopt a method of combining deflection direction vector and deflection angle to express the deformation condition of the software actuator; according to the characteristics of pneumatic control and elastic deformation of the pneumatic soft actuator, the assembly posture deviation rectifying control process is divided into two stages of assembly posture sensing and assembly posture adjustment:
in the assembly attitude sensing stage, the pneumatic soft robot is regarded as a bending deformation sensor, the deflection direction vector of the soft deformation can be obtained according to the air pressure value of each chamber, the volume change of the soft deformation process is calculated according to the air pressure value feedback of each chamber and an ideal gas state equation, and then the bending angle under the current volume change is calculated according to the curvature continuous criterion of the elastic material deformation;
in the stage of adjusting the assembly attitude, the multi-chamber soft body is taken as a pneumatic bending actuator, the relation between air pressure acting work and a bending angle can be obtained according to a Yeoh constitutive model of the elastic body and a virtual work principle, and the air pressure of each chamber is controlled to bend the soft body to a specified direction at a specified angle, so that the deviation correction of the assembly attitude is realized.
Further, for a soft actuator with n chambers, the soft actuator control method comprises the following steps:
the method comprises the following steps: determining the bending direction vector of each chamber of a soft actuator
Selecting the bottom section of the soft actuator as a projection reference surface, selecting the bottom center point of the soft actuator as an origin, establishing a plane coordinate system on the projection reference surface to enable the control air pressure of each chamber of the pneumatic soft actuator to be equal, then increasing the control air pressure of the ith (i is 1-n) chamber of the soft actuator to enable the soft actuator to bend, and enabling the unit vector of the axis of the pneumatic actuator in the projection direction of the projection reference surface
Figure GDA0002650091700000033
As the bending direction vector of the ith chamber;
step two: collecting the air pressure change condition of each chamber in the standard assembly process
Collecting air pressure data P of each chamber of n.k groups of soft actuators at the same time interval in the process of completing standard assembly by the roboti,jWherein, i is 1 to n to represent different chambers of the soft actuator, and j is 1 to k to represent the serial number of the air pressure value of each chamber acquired when the assembly action is executed;
step three: judging the assembly deviation condition
When the robot performs an assembly task, acquiring an air pressure feedback value P 'of the ith chamber of the soft actuator at different moments at the same time as the step I'i,jComparison of Pi,jAnd P'i,jA difference value if
|Pi,j-P’i,j|>(1) Considering that an error occurs in the assembly process, recording the current air pressure value P 'of each chamber'iAnd informing the robot to stop the assembling action and retreat to a safe position, wherein the safe position is a set allowable error range;
step four: soft body attitude sensing in the presence of assembly errors
When errors are generated in the assembling process, the soft actuator bends under the action of external force, and the bending direction is the external forceThe direction is used, according to the interaction of the force, the external force acting on the soft actuator at the moment is opposite to the resultant force of the air pressure of each chamber to the soft actuator; according to the bending direction vector of each chamber determined in the step one and the air pressure value P 'of each chamber under the bending condition'iThe bending direction vector of the resultant force of the air pressure of each chamber to the soft actuator under the error condition can be obtained as
Figure GDA0002650091700000031
The bending direction of the soft actuator under the error condition is opposite to the direction vector, i.e.
Figure GDA0002650091700000032
The analysis is simplified by assuming the bending deformation process of the soft actuator under the condition of assembly error, and the relationship between the gas volume V and the gas pressure P is as follows according to an ideal gas state equation
Figure GDA0002650091700000041
Wherein n is the mass of the gas, R is the constant of the gas, and T is the temperature, the volume V of the gas cavity of the soft actuator after the deformation is obtained according to the volume and the gas pressure of the cavity before the soft actuator is bent and deformed, the gas pressure value after the bending and the deformation and the formula (4)m；
Further, the bending angle theta after bending deformation and the volume V of the soft actuator are obtained according to the cross-sectional shape of the soft actuatormIn relation to (2)
θ＝f(Vm) (5)
Determining the soft actuator assembling posture during assembling error according to the bending direction of the soft actuator provided by the formula (3) and the bending angle provided by the formula (5);
step five: soft actuator assembly attitude adjustment
Analyzing the contact force and the matching type according to the part assembling process and step fourSensing the assembly posture during the middle assembly deviation to obtain the correct assembly posture under the current error condition, namely the deflection direction vector of the soft actuator during the correct assembly
Figure GDA0002650091700000043
And a deflection angle thetac；
The bending direction vector of the resultant force of the air pressure of each chamber to the soft actuator expressed by the formula (2) has
Figure GDA0002650091700000042
Wherein P isin,iInputting gas pressure for each gas cavity;
based on the assumption in step four and equation (5), the bending angle of the soft actuator is θcVolume of each air cavity
Vm,i＝gi(θc)(i＝1～n) (7)
Wherein n is the number of air chambers of the soft actuator, gi() Is a bending angle thetacVolume V of each air cavitym,iFunctional relationship between;
during the process of adjusting the assembly attitude of the soft actuator, the work done by the compressed gas is completely used for overcoming the external constraint force and the work done by the internal stress of the rubber material, and a balance expression is established according to the virtual work principle
Figure GDA0002650091700000051
Wherein dVc,iVolume change of air cavity before and after posture adjustment, Vr，iVolume of rubber material of each air cavity, WouIn order to overcome the work of external constraint, W is the energy density function of the rubber material, and a second-order Yeoh constitutive model strain energy density function is adopted, so that
Figure GDA0002650091700000052
Wherein, C10，C20Is a material parameter, and lambda is an actuator axial main elongation ratio;
simultaneous formulas (6) - (9) are substituted into the known quantity of each part to obtain the input gas pressure P of each air cavity required by the attitude deviation rectifying control of the soft actuatorin,iAnd adjusting the pneumatic soft actuator to a correct assembly posture by controlling the pressure of the input gas to reach a required value, and returning to the step for carrying out assembly again.
In the fourth step, for the bending deformation process of the soft actuator under the condition of assembly error, the following assumptions are made to simplify the analysis:
4.1) the pneumatic soft actuator has no radial expansion, namely the external contour dimension of the cross section is not changed;
4.2) the rubber material of the outer wall of the air cavity of the pneumatic soft actuator is uniformly changed;
4.3) the mechanical influence of the strain limiting layer on the whole deformation process is not considered;
4.4) the total volume of the elastic matrix is kept unchanged before and after deformation;
4.5) the curvature of the multi-chamber pneumatic soft actuator is changed uniformly in the bending deformation process.
The main technical conception of the invention is as follows: the bending direction of the pneumatic soft actuator is expressed as the acting direction of the air pressure force of each air cavity by adopting a projection method, the air pressure feedback of each air cavity of the pneumatic soft actuator is utilized to realize the assembly posture sensing in the automatic assembly process of the robot, and the pneumatic soft actuator is bent and deformed in an appointed mode through the air pressure control of the soft actuator, so that the aim of deviation correction and adjustment of the assembly posture is fulfilled.
The invention has the following beneficial effects: compared with other assembly posture recognition correction, the software actuator control method applied to robot assembly posture correction can reduce hardware cost and improve the assembly efficiency and applicability of the robot for heterogeneous non-rigid parts.
Drawings
FIG. 1 is a flow chart of a soft actuator control method for correcting the assembly attitude of a robot.
FIG. 2 is an example of a soft pneumatic actuator application.
Fig. 3 is a sectional view taken along line a-a of fig. 2, in which 1 is a bottom plate of the end effector, 2 is a movable ejector bead mounting rod, 3 is an ejector bead mounting rod, 4 is a three-chamber cylindrical pneumatic soft device, 5 is a clamping mechanism mounting rod, 6 is a fixed ejector bead, 7 is a puller cylinder, 8 is a cylinder mounting plate, 9 is an ejector bead spring, 10 is a clamping mechanism fixing plate, and 11 is a clamping mechanism.
FIG. 4 is a schematic diagram of the deflection of a soft pneumatic actuator.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Referring to fig. 1 to 4, a method for controlling a soft actuator for correcting a robot assembly posture, which represents the deformation of the soft actuator by combining a deflection direction vector and a deflection angle for a multi-chamber pneumatic soft actuator capable of deflecting in any direction. According to the characteristics of pneumatic control and elastic deformation of the pneumatic soft actuator, the assembly posture deviation rectifying control process is divided into two stages of assembly posture sensing and assembly posture adjusting. In the stage of sensing the assembly posture, the pneumatic soft robot is regarded as a bending deformation sensor, the deflection direction vector of the soft deformation can be obtained according to the air pressure value of each chamber, the volume change of the soft deformation process is calculated according to the air pressure value feedback of each chamber and an ideal gas state equation, and then the bending angle under the current volume change is calculated according to the curvature continuous criterion of the elastic material deformation. In the stage of adjusting the assembly attitude, the multi-chamber soft body is taken as a pneumatic bending actuator, the relation between air pressure acting work and a bending angle can be obtained according to a Yeoh constitutive model of the elastic body and a virtual work principle, and the soft body can be bent to a specified direction at a specified angle by controlling the air pressure of each chamber, so that the deviation correction of the assembly attitude is realized.
The invention is further described by taking a rigid-flexible composite robot end effector applying a three-chamber flexible pneumatic actuator (part 4 in figure 3) as an object, and the control method of the flexible actuator comprises the following steps:
the method comprises the following steps: determining the bending direction vector of each chamber of a soft actuator
Selecting the bottom section of the soft actuator as a projection reference surface, selecting the bottom center point of the soft actuator as an origin, and establishing a plane coordinate system on the projection reference surface. The control air pressure of each chamber of the pneumatic soft actuator is equal, then the control air pressure of one chamber of the soft actuator is increased to bend the soft actuator (as shown in figure 4), and because the air chambers of the three-air-chamber soft pneumatic actuator are arranged at intervals of 120 degrees, the unit vector of each air chamber on the projection reference surface
Figure GDA0002650091700000071
Are respectively as
Figure GDA0002650091700000072
(as shown in fig. 4).
Step two: collecting the air pressure change condition of each chamber in the standard assembly process
Collecting air pressure data P of each chamber of n.k groups of soft actuators at the same time interval in the process of completing standard assembly by the roboti,j. Wherein, i is 1-3 for different chambers of the soft actuator, and j is 1-k for the serial number of the air pressure value of each chamber collected during the assembly operation.
Step three: judging the assembly deviation condition
When the robot performs an assembly task, acquiring an air pressure feedback value P 'of the ith chamber of the soft actuator at different moments at the same time as the step I'i,jComparison of Pi,jAnd P'i,jA difference value if
|Pi,j-P’I,j|>0.1Pa (1)
Considering that an error occurs in the assembly process, recording the current air pressure value P 'of each chamber'iAnd the robot is informed to stop the assembly action and move back to the safe position.
Step four: soft body attitude sensing in the presence of assembly errors
When an error occurs in the assembly process, the soft actuator bends under the action of an external force (as shown in fig. 4), the bending direction is the direction of the external force,according to the force interaction, the external force acting on the soft actuator is opposite to the resultant force of the air pressure of each chamber to the soft actuator. According to the bending direction vector of each chamber determined in the step one and the air pressure value P of each chamber under the bending conditioniThe bending direction vector of the resultant force of the air pressure of each chamber to the soft actuator under the error condition can be obtained as
Figure GDA0002650091700000081
The bending direction of the soft actuator under the error condition is opposite to the direction vector, i.e.
Figure GDA0002650091700000082
For the soft actuator bending deformation process in case of assembly errors, the following assumptions can be made to simplify the analysis:
4.1) the pneumatic soft actuator has no radial expansion, namely the external contour dimension of the cross section is not changed;
4.2) the rubber material of the outer wall of the air cavity of the pneumatic soft actuator is uniformly changed;
4.3) the mechanical influence of the strain limiting layer on the whole deformation process is not considered;
4.4) the total volume of the elastic matrix is kept unchanged before and after deformation;
4.5) the curvature of the multi-chamber pneumatic soft actuator is changed uniformly in the bending deformation process.
Based on the above assumptions, the relationship between the gas volume V and the gas pressure P is as follows from the ideal gas equation of state
Figure GDA0002650091700000083
Where n is the gas mass, R is the gas constant, and T is the temperature. The volume V of the air cavity of the soft actuator after deformation can be obtained according to the volume and the air pressure of the air cavity before the soft actuator is bent and deformed, the air pressure value after the soft actuator is bent and deformed and the formula (4)m. Further, based onThe above assumption 4.1), 4.4), 4.5) obtaining the bending angle theta after bending deformation and the volume V of the soft actuator according to the sectional shape of the soft actuatormIn relation to (2)
θ＝f(Vm) (5)
The soft actuator assembly attitude at the time of assembly error can be determined based on the soft actuator bending direction provided by equation (3) and the bending angle provided by equation (5).
Step five: soft actuator assembly attitude adjustment
According to the contact force and the matching type analysis in the part assembling process and the assembly posture perception in the assembly deviation in the step four, the correct assembly posture under the current error condition can be obtained, namely the deflection direction vector of the soft actuator in the correct assembly
Figure GDA0002650091700000093
And a deflection angle thetac。
The bending direction vector of the resultant force of the air pressure of each chamber to the soft actuator expressed by the formula (2) has
Figure GDA0002650091700000091
Wherein P isin,iThe gas pressure is input for each gas cavity.
Based on the assumptions 4.1) -4.5 in step four) and equation (5), the bending angle θ of the soft actuator can be obtainedcVolume of each air cavity
Vm,i＝gi(θc)(i＝1～3) (7)
Wherein g isi() Is a bending angle thetacVolume V of each air cavitym,iFunctional relationship between;
during the process of adjusting the assembly attitude of the soft actuator, the work done by the compressed gas is completely used for overcoming the external constraint force and the work done by the internal stress of the rubber material, and a balance expression is established according to the virtual work principle
Figure GDA0002650091700000092
Wherein dVc,iVolume change of air cavity before and after posture adjustment, Vr，iVolume of rubber material of each air cavity, WouIn order to overcome the work of external constraint, W is the energy density function of the rubber material, and a second-order Yeoh constitutive model strain energy density function is adopted, so that
Figure GDA0002650091700000101
Wherein, C10，C20Taking C as the material parameter from the rubber material10＝0.11MPa，C20And λ is the actuator axial main elongation ratio, which is 0.02 MPa.
In the example of application, the three-air-chamber pneumatic actuator is attached to the clamp mounting rod, and the attached clamp mounting rod is restrained by the spring force (as shown in fig. 2), so that there is a possibility that the attitude adjustment process will be performed
Figure GDA0002650091700000102
Wherein m is the number of springs, ki，liThe spring coefficient of each jacking spring and the deformation amount during the posture adjustment are respectively, and G and h are respectively the weight of an object fixedly connected on the soft actuator and the displacement of the object in the posture adjustment process.
Simultaneous formulas (6) - (10) are substituted into the known quantity of each part to obtain the input gas pressure P of each air cavity required by the attitude deviation rectifying control of the soft actuatorin,iAnd the pneumatic soft actuator can be adjusted to a correct assembly posture by controlling the pressure of the input gas to reach a required value.

Claims (2)

1. A robot assembles the software actuator control method that the posture rectifies, characterized by that, to the multi-chamber software actuator that can deflect to the arbitrary direction, adopt a method of combining deflection direction vector and deflection angle to express the deformation situation of the software actuator; according to the characteristics of pneumatic control and elastic deformation of the soft actuator, the assembly posture deviation rectifying control process is divided into two stages of assembly posture sensing and assembly posture adjusting:
in the stage of sensing the assembly posture, the soft actuator is taken as a bending deformation sensor, the deflection direction vector of the deformation of the soft actuator can be obtained according to the air pressure value of each chamber, the volume change of the soft actuator in the deformation process is calculated according to the air pressure value feedback of each chamber and an ideal gas state equation, and then the bending angle under the current volume change is calculated according to the curvature continuous criterion of the deformation of the elastic material;
in the stage of adjusting the assembly posture, the multi-chamber soft actuator is regarded as a pneumatic bending soft actuator, the relation between air pressure acting work and a bending angle can be obtained according to a Yeoh constitutive model of the elastic body and a virtual work principle, and the air pressure of each chamber is controlled to enable the soft actuator to bend towards a specified direction at a specified angle, so that the deviation correction of the assembly posture is realized;
for a soft actuator with n chambers, the soft actuator control method comprises the following steps:
the method comprises the following steps: determining the bending direction vector of each chamber of a soft actuator
Selecting the bottom section of the soft actuator as a projection reference surface, selecting the bottom center point of the soft actuator as an origin, establishing a plane coordinate system on the projection reference surface to equalize the control air pressure of each chamber of the soft actuator, increasing the control air pressure of the ith (i is 1-n) chamber of the soft actuator to bend the soft actuator, and forming a unit vector of the axis of the soft actuator in the projection direction of the projection reference surface
Figure FDA0002650091690000011
As the bending direction vector of the ith chamber;
step two: collecting the air pressure change condition of each chamber in the standard assembly process
Collecting air pressure data P of each chamber of n.k groups of soft actuators at the same time interval in the process of completing standard assembly by the roboti,jWherein i-1-n represent soft actuators each differentlyThe chamber j is 1-k and represents the serial number of the air pressure value of each chamber acquired when the assembly action is executed;
step three: judging the assembly deviation condition
When the robot performs an assembly task, acquiring an air pressure feedback value P 'of the ith chamber of the soft actuator at different moments at the same time as the step I'i,jComparison of Pi,jAnd P'i,jA difference value if
|Pi,j-P’i,j|>(1)
Considering that errors occur in the assembly process, recording the air pressure value of each current chamber, and informing the robot to stop the assembly motion and retreat to a safe position, wherein the range is a set allowable error range;
step four: soft actuator attitude sensing in the presence of assembly errors
When errors are generated in the assembling process, the soft actuator bends under the action of external force, the bending direction is the action direction of the external force, and the external force acting on the soft actuator is opposite to the resultant force of the air pressure of each chamber on the soft actuator according to the interaction of the forces; according to the bending direction vector of each chamber determined in the step one and the air pressure value P 'of each chamber under the bending condition'iThe bending direction vector of the resultant force of the air pressure of each chamber to the soft actuator under the error condition can be obtained as
Figure FDA0002650091690000021
Where n is the number of pneumatic chambers of the actuator,
Figure FDA0002650091690000022
is the bending direction vector of the ith chamber,
the bending direction of the soft actuator under the error condition is opposite to the direction vector, i.e.
Figure FDA0002650091690000023
The analysis is simplified by assuming the bending deformation process of the soft actuator under the condition of assembly error, and the relationship between the gas volume V and the gas pressure P is as follows according to an ideal gas state equation
Figure FDA0002650091690000031
Wherein n is the mass of the gas, R is the constant of the gas, and T is the temperature, the volume V of the gas cavity of the soft actuator after the deformation is obtained according to the volume and the gas pressure of the cavity before the soft actuator is bent and deformed, the gas pressure value after the bending and the deformation and the formula (4)m；
Further, the bending angle theta after bending deformation and the volume V of the soft actuator are obtained according to the cross-sectional shape of the soft actuatormIn relation to (2)
θ＝f(Vm) (5)
Determining the soft actuator assembling posture during assembling error according to the bending direction of the soft actuator provided by the formula (3) and the bending angle provided by the formula (5);
step five: soft actuator assembly attitude adjustment
Obtaining the correct assembly posture under the current error condition according to the contact force and the fit type analysis in the part assembly process and the assembly posture perception in the assembly deviation in the step four, namely obtaining the deflection direction vector of the soft actuator in the correct assembly
Figure FDA0002650091690000032
And a deflection angle thetac；
The bending direction vector of the resultant force of the air pressure of each chamber to the soft actuator expressed by the formula (2) has
Figure FDA0002650091690000033
Wherein P isin,iThe pressure of the gas is input into each gas cavity, n is the number of pneumatic cavities of the actuator,
Figure FDA0002650091690000034
is the bending direction vector of the ith chamber;
based on the assumption in step four and equation (5), the bending angle of the soft actuator is θcVolume V of each air cavitym,i
Vm,i＝gi(θc) (i＝1～n) (7)
Wherein n is the number of air chambers of the soft actuator, gi() Is a bending angle thetacVolume V of each air cavitym,iFunctional relationship between;
during the process of adjusting the assembly attitude of the soft actuator, the work done by the compressed gas is completely used for overcoming the external constraint force and the work done by the internal stress of the rubber material, and a balance expression is established according to the virtual work principle
Figure FDA0002650091690000041
Wherein dVc,iVolume change of air cavity before and after posture adjustment, Vr，iVolume of rubber material of each air cavity, WouIn order to overcome the work of external constraint, W is the energy density function of the rubber material, and a second-order Yeoh constitutive model strain energy density function is adopted, so that
Figure FDA0002650091690000042
Wherein, C10，C20Is a material parameter, and lambda is an actuator axial main elongation ratio;
simultaneous formulas (6) - (9) are substituted into the known quantity of each part to obtain the input gas pressure P of each air cavity required by the attitude deviation rectifying control of the soft actuatorin,iAnd adjusting the soft actuator to a correct assembly posture by controlling the pressure of the input gas to reach a required value, and returning to the step three.
2. The soft actuator control method for robot assembly attitude deviation rectification according to claim 1, wherein in the fourth step, for the soft actuator bending deformation process under the assembly error condition, the following assumptions are made to simplify the analysis:
4.1) the soft actuator has no radial expansion, namely the external contour dimension of the cross section is not changed;
4.2) the rubber material on the outer wall of the air cavity of the soft actuator is uniformly changed;
4.3) the mechanical influence of the strain limiting layer on the whole deformation process is not considered;
4.4) the total volume of the elastic matrix is kept unchanged before and after deformation;
4.5) the curvature of the multi-chamber soft actuator is changed uniformly in the bending deformation process.
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