CN117823595A - Multilayer composite flexible gear type harmonic reducer and flexible industrial robot - Google Patents
Multilayer composite flexible gear type harmonic reducer and flexible industrial robot Download PDFInfo
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Abstract
The invention relates to the field of industrial robots, and discloses a multi-layer composite flexible gear with memory alloy embedded therein, a harmonic reducer using the flexible gear, and an industrial robot using the harmonic reducer. The multilayer composite flexible wheel comprises a wheel body made of high damping materials, a shape memory alloy wire layer is embedded in the inner side of the wheel body along the circumferential direction, the shape memory alloy wire layer is connected with a power supply, and the shape memory alloy wire layer comprises a plurality of shape memory alloy wire sections which are arranged side by side along the axial direction on the inner side of a wheel surface. The invention provides the self-driven harmonic reducer flexible gear integrating the flexible gear and the wave generator, the harmonic reducer and the flexible industrial robot, which are provided by adopting the embedded shape memory alloy material without affecting the service performance of the harmonic reducer, so that the volume of the harmonic reducer is greatly reduced, the weight is reduced, flexible deformable endless transmission is realized, and the application requirement of the flexible robot in a non-structural environment is met.
Description
Technical Field
The invention relates to the field of industrial robots, in particular to a multi-layer composite flexible gear type harmonic reducer and a flexible industrial robot.
Background
At present, a harmonic gear reducer is widely applied to the field of industrial robots due to small size and light weight, but for industrial robots operating in a non-structural environment, as the working environment is variable and unfixed at any time and is complex and changeable, the traditional rigid non-deformable industrial robot cannot meet the operating conditions of the non-structural environment, the required reducer also requires variable transmission ratio motion and can flexibly change the volume, and the main structure of the traditional harmonic gear reducer consists of a rigid gear, a flexible gear and a wave generator, is a rigid member and cannot adaptively change the volume along with the environmental change.
Meanwhile, as the working load moment changes at any time in the non-structural environment, the industrial robot needs to continuously output different output moments under the rated input moment to meet the requirements of the working environment, and therefore the joint reducer is required to realize stepless speed change transmission. The existing harmonic speed reducer has large transmission ratio and wide transmission ratio range, and the transmission ratio which can be realized by adopting the harmonic speed reducer with different stages is between 50 and 140000. However, the common harmonic speed reducer is driven by a fixed transmission ratio, and can not realize endless transmission, the transmission ratio of the common harmonic speed reducer is determined after the rigid gear, the flexible gear and the wave generator are designed and selected, and the transmission ratio can not be changed any more unless the parts are replaced.
The above makes the existing harmonic reducer unable to meet the application requirements of flexible industrial robots in non-structural environments.
Disclosure of Invention
The invention aims to provide a multi-layer composite flexible gear with embedded memory alloy and a multi-layer composite flexible gear type harmonic reducer, so that the size of the harmonic reducer is greatly reduced, the weight is reduced, the flexible structure is deformable, and stepless speed change transmission is realized while the service performance of the harmonic reducer is not affected.
In order to achieve the above purpose, the invention adopts the following technical scheme: a multi-layer composite flexible wheel comprises a wheel body made of high damping materials, wherein a plurality of sections of shape memory alloy wire layers are embedded in the wheel body along the circumferential direction, each section of shape memory alloy wire layer is connected with a power supply, and the length of the shape memory alloy wire layer is less than or equal to one half of the inner circumference of the wheel body.
Preferably, as a modification, the shape memory alloy wire layer comprises a plurality of shape memory alloy wire segments arranged side by side in the axial direction inside the tread.
Preferably, as a modification, a plurality of shape memory alloy wire segments within the shape memory alloy wire layer are connected in series in the same circuit.
Preferably, as a modification, a plurality of shape memory alloy wire segments in the shape memory alloy wire layer are connected in parallel in the same circuit.
Preferably, as a modification, the shape memory alloy wire layer is a single shape memory alloy wire segment.
Preferably, as an improvement, the high damping material is a modified polymer composite material with nitrile rubber as a base material.
Preferably, as an improvement, the wheel body is composed of a plurality of high damping material layers, and the shape memory alloy wire layer is positioned between the two high damping material layers.
Preferably, as an improvement, the flexible wheel can be driven to periodically and radially stretch and creep at multiple points in the circumferential direction by inputting current with phase difference to the shape memory alloy wire layer through a power supply.
Preferably, as a modification, the shape memory alloy wire segments are shape memory alloy wires that are machined into a spring shape.
Preferably, as a modification, the wheel body of the flexspline is ring-shaped or spherical shell-shaped.
The principle and the advantages of the scheme are as follows: the thin-wall flexible wheel is made of high damping alloy materials such as rubber alloy, and the shape memory alloy spring wires are embedded in the flexible wheel in parallel in the circumferential direction, so that the Shape Memory Alloy (SMA) has the characteristics of self damping and viscous damping, has the functions of high power density, large output force, flexibility, shape memory effect expansion and contraction and the like, is deformed by heating the SAM through current output, can replace a motor, and realizes self driving; the self-sensing and self-sensing functions similar to skeletal muscle and muscle shuttles are shown by the change rule of 'resistance-length' of the SMA instead of a displacement sensor. Therefore, the SMA spring wire is integrated in the toothless transmission system, so that the transmission system has self-driving and self-sensing characteristics, and the super elasticity of the transmission system can be utilized, so that the rigidity and the large volume of the traditional electromechanical integrated system are overcome, and the flexible and small-volume space arrangement and operation are realized.
On one hand, the self-driven deformation of the flexible gear can cause the flexible gear to directly change the circumference of the radial section in situ, so that the pitch circumference of a contact transmission pair between the flexible gear and the rigid gear is changed, the transmission ratio of the flexible gear and the rigid gear is changed, and compared with the conventional friction type stepless speed change transmission, the toothless transmission system integrated with the SMA material has the advantages of simple structure, small volume, compactness and flexible change of the appearance shape.
On the other hand, the factors influencing the bearing capacity are the torsional rigidity of the flexspline and the transmission rigidity of the toothless contact interface, the torsional rigidity is determined by the integral torsional rigidity change caused by the deformation of the SMA spring wires of the multi-layer flexspline, the transmission rigidity is influenced by the size of the contact area, the size of the contact area is changed, the number of radial support fluctuation of the wave generator and the change of the amplitude and the circumference size of the flexspline are regulated through the self-driving and self-sensing deformation of the SMA material, and the change of the contact area of the toothless transmission pair is caused, so that the change of the contact transmission rigidity is caused. The self-driving/self-sensing deformation of the SMA integrated in the flexible gear realizes the elastic deformation of the multi-layer material driving the rubber alloy high damping alloy material layer in the flexible gear, thereby adjusting the torsional rigidity of the multi-layer flexible gear and forming the self-adaptive variable rigidity output.
The bionic peristaltic gearless transmission system has the advantages of increased bearing capacity, increased contact transmission area and contribution to realizing high transmission precision and low return difference. While ensuring the bearing capacity, the contact transmission rigidity is properly increased and the torsional rigidity is properly reduced. The reduction of torsional rigidity enables the elastic deformation of the high damping material multi-layer composite flexible gear based on rubber alloy to be recovered properly. The multiple flexible gear which is properly recovered has the controllable elastic deformation of buffering and tolerance, shows good nonlinear rigidity and hysteresis behavior, can well weaken, homogenize, reduce and store high-frequency random alternating impact load or instantaneous peak load in the transmission process and damage energy fluctuation caused by high-frequency transmission error components, thereby preventing external impact load and external disturbance, ensuring that a transmission part does not generate rigid impact, well solving the problems of large dynamic transmission error, low sensitivity, poor repeated positioning precision and low rigidity of a transmission mechanism, ensuring high-precision transmission and realizing coordination and unification between high precision and high rigidity, high reliability and high sensitivity under extreme/abrupt change working conditions and external impact load environments, and ensuring that the flexible gear has vibration damping and noise reduction, high rigidity bearing capacity, high precision and high sensitivity.
The embedded shape memory alloy wire is adopted and is electrified to be controlled, the process that the motor driving wave generator drives the flexible gear in the prior art is replaced, the self-driving shape change of the flexible gear is realized, the multilayer composite flexible gear of the scheme integrates the functions of the traditional flexible gear and the wave generator, the use performance of the harmonic reducer is not influenced, and meanwhile, the structure of the traditional wave generator is omitted, so that the volume of the harmonic reducer is greatly reduced. Compared with the conventional friction type stepless speed change transmission, the flexible gear integrated with the SMA material can form toothless transmission with the rigid gear, the toothless transmission system is simple in structure, small in size and compact, the rigid gear can be not limited to a round rigid structure in the prior art, the rigid gear can be in various shapes, and the appearance shape of the rigid gear can be flexibly changed as long as the rigid gear and the flexible gear keep multipoint friction transmission. Furthermore, the limitation on the application scene is weakened, and the method can be applied to special micro robots and other unconventional application scenes.
The utility model provides a compound flexspline of multilayer harmonic reducer, includes rigid gear and flexspline, and the rigid gear cover is established in the flexspline outside, and flexspline part and rigid gear friction contact, flexspline adopt foretell compound flexspline of multilayer, make shape memory alloy wire layer warp through the electric current that lets in to the shape memory alloy wire layer of flexspline that has the phase difference, drive flexspline produces periodic radial flexible peristaltic motion in the circumferencial direction, forms normal vector between flexspline and the rigid gear and moves at the curved surface of two-dimensional plane or three-dimensional space arbitrary direction, and then flexspline rotation through friction drive rigid gear in the circumferencial direction.
Preferably, as an improvement, the inner wall of the rigid wheel is a circular arc curved surface, the macroscopic surface of the wheel surface of the flexible wheel is a wedge-shaped texture which is continuous along the circumferential direction, the microscopic surface of the wheel surface of the flexible wheel is a plurality of suckers, the suckers have gradient elastic modulus in the radial direction of the flexible wheel, and the friction contact point between the wheel surface of the flexible wheel and the inner wall of the rigid wheel is two points, three points, four points or more. Thus, the wheel surface of the flexible wheel microscopically adopts the composite bionic texture of the octopus sucking disc and the frog finger tips, and the groove shape of the octopus sucking disc surface is beneficial to improving the adhesion; the modulus of the tree frog sole gradually decreases from the surface to the inside, and the gradient modulus is favorable for improving the adhesion and the friction and the wear resistance of the structure, and is inspired by the adhesion and the friction structural characteristics of the two animals, so that the scheme combines the surface microstructures and the performances of the octopus sucker and the tree frog sole to carry out coupling bionic design, constructs a novel gradient modulus composite bionic micro sucker texture, improves the adhesion, the friction and the wear resistance of the structure and resists alternating fatigue failure, and can greatly enhance the friction coefficient contacted with the inner wall of the rigid wheel. The wheel surface macroscopically adopts a wedge-shaped texture, and the toothless transmission contacts with a working wedge-shaped texture interface, when the wedge-shaped extrusion effect generated by the transmission is exhibited on the inclined surface, the wedge-shaped extrusion effect can be enhanced to increase the contact pressure, so that the contact friction force of a transmission mechanism is improved, the extrusion force contacted with the inner wall of a rigid wheel can be enhanced after the deformation acting force of the shape memory alloy is applied, the friction force contacted between a flexible wheel and the rigid wheel is greatly enhanced, the stable and reliable friction transmission between the flexible wheel and the rigid wheel is ensured, and the alternating fatigue failure is resisted.
Preferably, as an improvement, the shape memory alloy wire layer is deformed by introducing current with phase difference into the shape memory alloy wire layer of the flexible wheel, so as to drive the circumference change of the flexible wheel, so that variable transmission ratio transmission can be formed between the flexible wheel and the rigid wheel, the circumference of the contact transmission interface of the rigid wheel and the flexible wheel is non-circular, and the contact transmission interface of the rigid wheel and the flexible wheel is a flexible deformable interface.
The bionic peristaltic gearless transmission system has the advantages of increased bearing capacity, increased contact transmission area and contribution to realizing high transmission precision and low return difference. While ensuring the bearing capacity, the contact transmission rigidity is properly increased and the torsional rigidity is properly reduced. The reduction of torsional rigidity enables the elastic deformation of the high damping material multi-layer composite flexible gear based on rubber alloy to be recovered properly. The multiple flexible gear which is properly recovered has the controllable elastic deformation of buffering and tolerance, shows good nonlinear rigidity and hysteresis behavior, can well weaken, homogenize, reduce and store high-frequency random alternating impact load or instantaneous peak load in the transmission process and damage energy fluctuation caused by high-frequency transmission error components, thereby preventing external impact load and external disturbance, ensuring that the transmission part does not generate rigid impact, well solving the problems of large dynamic transmission error, low sensitivity, poor repeated positioning precision and low rigidity of the transmission mechanism, and realizing coordination and unification between high precision and high rigidity, high reliability and high sensitivity under extreme/abrupt change working conditions and external impact load environments while guaranteeing high-precision transmission.
The harmonic reducer of this scheme is flexible harmonic reducer, through adopting embedded shape memory alloy on the flexbile gear to the change girth of flexbile gear direct in radial cross section normal position is realized to the mode control shape memory alloy's of circular telegram, thereby realizes the toothless friction transmission between flexbile gear and the rigid gear, through the change of shape memory alloy's the strain change flexbile gear and the rigid gear under the phase difference current between contact transmission pair pitch circumference, realizes the transmission of change transmission ratio between flexbile gear and the rigid gear. The harmonic reducer omits the traditional wave generator structure, greatly reduces the whole volume, has adjustable and changeable transmission ratio, and can effectively meet the application requirements on special micro robots. The contact transmission interface between the flexible wheel and the rigid wheel is circular or non-circular, is different from the traditional rigid non-deformable interface, can be a rigid interface or a flexible variable interface, and can be used for unstructured application scenes. For example, when the bionic snake moves and shuttles in unstructured environments with different-size apertures in the ground, the flexible deformation of the joints can adapt to the sizes of the different apertures.
A flexible industrial robot adopts the harmonic reducer. The joint of the industrial robot has high motion sensitivity, high motion precision, small volume and light weight, and the joint structure can flexibly deform so as to meet the flexible and changeable requirements of the industrial robot in the non-structural complex and changeable environment; the transmission ratio of the joint part is adjustable, so that the requirements of operation and application under special unconventional scenes and non-structural environments can be met, the requirements of high-load output moment matching of rated power self-adaptive stepless speed change are ensured, and high-efficiency and high-quality work is ensured.
Drawings
Fig. 1 is a schematic structural diagram of embodiment 1 of the present invention.
Fig. 2 is a schematic structural diagram of embodiment 3 of the present invention.
Fig. 3 is a schematic structural diagram of embodiment 2 of the present invention.
Fig. 4 is a schematic structural diagram of embodiment 6 of the present invention.
Fig. 5 is a partial view of the macro texture of the surface of the flexspline in example 6 of the present invention.
Fig. 6 is a partial view of the micro texture of the surface of the flexspline in example 6 of the present invention.
Fig. 7 is a schematic contact diagram of a flexspline and a rigid spline in embodiment 8 of the present invention.
Fig. 8 is a partial cross-sectional view of the flexspline in contact with the rigid spline in example 9 of the present invention.
Detailed Description
The following is a further detailed description of the embodiments:
reference numerals in the drawings of the specification include: wheel body 1, shape memory alloy wire layer 2, steel wheel 3.
Example 1, substantially as shown in figure 1: a multi-layer composite flexible gear comprises a wheel body 1 made of a plurality of layers of high damping materials, wherein the high damping materials are modified polymer composite materials taking nitrile rubber as a base material, and rubber alloy is preferable in the embodiment. A plurality of sections of shape memory alloy wire layers 2 are embedded in the wheel body 1 along the circumferential direction, each section of shape memory alloy wire layer 2 is connected with a power supply, the length of the shape memory alloy wire layer 2 is equal to one half of the inner circumference of the wheel body 1, the shape memory alloy wire layer 2 comprises a plurality of shape memory alloy wire sections which are arranged side by side along the axial direction inside a wheel surface, the shape memory alloy wire sections are shape memory alloy wires processed into a spring shape, and the plurality of shape memory alloy wire sections in the shape memory alloy wire layer 2 are connected in series in the same circuit.
The current with phase difference is input to the shape memory alloy wire layer 2 through a power supply, so that the flexible wheel can be driven to generate periodic radial expansion and creeping motion at multiple points in the circumferential direction.
Embodiment 2, as shown in fig. 3, differs from embodiment 1 only in that the length of the shape memory alloy wire layer 2 is equal to one third of the inner circumference of the wheel body 1.
Embodiment 3, as shown in fig. 2, differs from embodiment 1 only in that the length of the shape memory alloy wire layer 2 is equal to one-fourth of the inner circumference of the wheel body 1.
Example 4, which differs from example 1 only in that the shape memory alloy wire layer 2 is a single length of shape memory alloy wire.
Embodiment 5 differs from embodiment 1 only in that several segments of the shape memory alloy wire within the shape memory alloy wire layer 2 are connected in parallel in the same circuit.
Embodiment 6, a multilayer composite flexspline type harmonic reducer, as shown in fig. 4, includes rigid gear and flexspline, the rigid gear inner wall is circular arc curved surface, the rigid gear cover is established in the flexspline outside, the flexspline adopts one kind of multilayer composite flexspline of embodiment 1 or embodiment 3, the flexspline is inboard to have no wave generator, as shown in fig. 5, the wheel face macroscopic surface texture of flexspline is the wedge texture along circumference continuously, as shown in fig. 6, the wheel face microscopic surface texture of flexspline is a plurality of sucking discs, the sucking disc has the gradient elasticity modulus that gradually reduces from the surface inwards in the flexspline radial direction, shape memory alloy wire layer 2 warp through letting in the electric current that has the phase difference to the shape memory alloy wire layer 2 of flexspline, drive the flexspline produces periodic radial flexible peristaltic motion in the circumferencial direction, the wheel face of flexspline and the rigid gear inner wall friction contact point of flexspline are two-point, form normal vector between flexspline and the rigid spline in the curved surface motion of two-dimensional plane, and then the flexspline rotates through friction drive rigid spline in the circumferencial direction. The shape memory alloy wire layer 2 of the flexible wheel is deformed by introducing current with phase difference into the shape memory alloy wire layer 2 of the flexible wheel, so that the circumference of the flexible wheel is driven to change, and the variable transmission ratio transmission can be formed between the flexible wheel and the rigid wheel.
Embodiment 7, a multi-layer composite flexspline type harmonic reducer, the difference between this embodiment and embodiment 6 is only that a multi-layer composite flexspline of embodiment 2 is adopted, and the friction contact point between the face of the flexspline and the inner wall of the rigid gear is three points.
In embodiment 8, a multi-layer composite flexible gear type harmonic reducer is different from embodiment 6 only in that, as shown in fig. 7, the wheel body 1 of the flexible gear is annular, the rigid gear 3 is of a flexible structure, the circumference of the contact transmission interface between the wheel body 1 of the flexible gear and the rigid gear 3 is non-circular, and the friction contact point between the wheel surface of the flexible gear and the inner wall of the rigid gear 3 is four points.
In embodiment 9, a multi-layer composite flexspline type harmonic reducer is different from embodiment 6 only in that, as shown in fig. 8, the flexspline wheel 1 and the rigid gear 3 are both spherical, and the contact transmission interface perimeter between the flexspline wheel 1 and the rigid gear 3 is non-circular.
Embodiment 10, a flexible industrial robot, using any one of the harmonic reducers of embodiments 6-9 as a transmission member for joint portions between mechanical arms. The joint structure can flexibly deform to meet flexible variable multiple requirements of the operation multi-robot in a non-structural complex and variable environment, the transmission ratio of the joint part is adjustable, the requirement of the rated power self-adaptive infinitely variable speed matching large load output moment is ensured, and the operation application requirement in a special non-conventional scene and a non-structural environment can be met.
In embodiment 11, aiming at the problems that the flexible gear deformation of the harmonic reducer in embodiment 6 needs feedback control, but the volume space of the harmonic reducer is small, and a position sensor cannot be installed to sense the deformation of the flexible gear so as to control the Shape Memory Alloy (SMA), the invention also provides a neural network PID control method based on a resistance self-sensing model. The generated control signal is amplified by power and then is input into the SMA to realize the adjustment of the heating power of the driver and obtain the actual output strain, so that the position tracking control of the driver on the Shape Memory Alloy (SMA) is realized, and finally, the periodic change is generated through a multi-head (flexible wheel) with a phase difference current control wave generator.
In practical applications, the change of the SMA resistance is used as a feedback signal of a control system, so that the cost of using a sensor can be reduced and the increase of the volume and the weight of the device can be avoided. Before the resistance self-sensing model is built, the basic resistance characteristics of the SMA are first studied. The resistivity of the SMA is next analyzed, and the SMA resistance can be expressed as:
where R represents the resistance of the SMA, L and S are the length and cross-sectional area of the SMA, respectively, and ρ represents the resistivity of the SMA. The change in resistivity with temperature T can be expressed as:
ρ＝ρ 0 (1+aT)(1.2)
wherein 0 represents the resistivity at 0 ℃, and a is the temperature coefficient of resistance.
SMA can be divided into three phases, a martensite phase, an austenite phase, and an R phase, which differ in their crystal structure and exhibit different electrical and mechanical properties. The R-phase makes the resistance analysis more complex, so for ease of analysis, it is assumed that the resistance characteristics of SMA are mainly determined by the volume fractions of martensite and austenite. Therefore, the SMA resistivity calculation formula is known from the Brinson constitutive model as follows:
ρ＝ρ M +(ξ AT -ξ AS )(ρ A -ρ M ) (1.3)
wherein, xi A And xi M Austenite volume fraction and martensite volume fraction, ρ, respectively A And ρ M Austenite resistivity and martensite resistivity, respectively, ζ AT And xi AS Temperature-affected austenite volume fraction and stress-affected austenite volume fraction, respectively. Therefore, the resistance self-sensing model deduced based on the formula has numerous and complex parameters, and is difficult to build an accurate resistance self-sensing model mechanically and needs to be determined through experiments. Converting resistance to strain signal in feedback control systemIt is necessary to build a self-sensing model based on the resistance-strain curve. But similar to the apparent hysteresis gap exhibited by the current-strain curve, to better build a resistive self-sensing model of the SMA, the hysteresis width can be reduced by prestressing the SMA to improve model accuracy. In order to quantitatively study the influence of prestress on the hysteresis width of the curve, a calculation formula of the hysteresis width is defined as follows:
wherein H is gap Is the hysteresis width s hi Sum s ci Is the strain value of the heating and cooling path s max Is the maximum strain value.
The high order polynomial fitting of the data helps to improve the accuracy of the self-sensing modeling. In order to facilitate the use of a self-sensing model in an embedded program, the resistor is normalized, and the resistor normalization formula is as follows:
wherein R is max ，R min And R is the maximum resistance, the minimum resistance and the actual resistance, respectively, and R is the normalized resistance calculation result.
Six degree polynomial fits were used on the stabilization data 50 th degree after training, and the resulting polynomial equation was fitted as follows:
where r is the resistance value and s (r) is the corresponding calculated strain.
The essence of the resistive self-sensing model is to estimate the strain by means of the resistance, and to replace the displacement signal measured by the actual sensor with the calculated strain during position control as a feedback signal to the control system.
The position control algorithm of the SMA driver consists of a traditional proportional-integral-derivative (PID) controller and a BP neural network. The discrete form of the incremental PID is given by:
wherein e (k), k p (k)、k i (k) And k d (k) The error at time k, the proportional gain, the integral gain, and the differential gain, respectively.
The PID parameters are automatically adjusted by the neural network according to error feedback, and the expression is as follows:
neural network PIDs are more suitable for control of nonlinear objects than traditional PIDs due to their parameter automatic tuning capabilities. The process of the BP neural network is mainly divided into two stages: forward propagation and backward propagation. Where forward propagation is the process of computing network output, input data is passed from the input layer to the output layer by layer. Each layer of neurons performs a weighted summation on the input data and then generates the next layer of input by activating a function. Counter-propagating is the process of optimizing the network weights, propagating the errors forward layer by calculating the errors between the output layer and the actual target, updating the weights to reduce the errors. The two processes are cycled until the network converges.
The forward propagation is mainly used for calculating the output of a network, and an S function is used as an activation function, and the calculation formula is as follows:
wherein the upper corner mark (1) represents the input layer, and the upper corner mark (2) after the same represents the hidden layer.X i (k) The output of the input layer and the output of the input layer respectively. />Input and output of hidden layer respectively, +.>For the weight on the line from the ith neuron of the layer to the jth neuron of the hidden layer at the moment of k-1, m neurons are totally input to the hidden layer.
The back propagation is mainly used for realizing weight adjustment and update among layers of the neural network, a delta learning algorithm is adopted, and meanwhile, in order to increase the convergence rate, an inertia term is introduced to enable weight coefficient adjustment to be more stable, and a calculation formula is as follows:
wherein alpha is an inertia coefficient, and alpha is more than or equal to 0 and less than 1.
The weight between layers is repeatedly corrected through the steps, and the PID parameters which are adjusted in real time are obtained and applied to a position control algorithm.
In the method, a resistance self-sensing model and neural network control technology is adopted to realize closed-loop control of the whole flexible harmonic reducer. According to the resistance change characteristic research analysis resistance-strain curve of the SMA material, apply appropriate prestressing force in order to improve the influence of hysteresis width, and then utilize the polynomial fitting of the higher order to set up the unified resistance self-perception model of SMA material heating cooling path, have reached the purpose of eliminating the position sensor through detecting the resistance as feedback signal. And a feedback control scheme is researched based on the resistance self-sensing model, so that closed-loop position control of the shape memory alloy is formed, hysteresis nonlinearity of the SMA is compensated, and good control performance is shown for a nonlinear system.
The foregoing is merely exemplary of the present invention, and specific technical solutions and/or features that are well known in the art have not been described in detail herein. It should be noted that, for those skilled in the art, several variations and modifications can be made without departing from the technical solution of the present invention, and these should also be regarded as the protection scope of the present invention, which does not affect the effect of the implementation of the present invention and the practical applicability of the patent. The protection scope of the present application shall be subject to the content of the claims, and the description of the specific embodiments and the like in the specification can be used for explaining the content of the claims.
Claims (10)
1. The utility model provides a compound flexbile gear of multilayer which characterized in that: the wheel body is made of high damping materials, a plurality of sections of shape memory alloy wire layers are embedded in the wheel body along the circumferential direction, each section of shape memory alloy wire layer is connected with a power supply, and the length of the shape memory alloy wire layer is less than or equal to one half of the inner circumference of the wheel body.
2. The multi-layer composite flexspline of claim 1 wherein: the shape memory alloy wire layer comprises a plurality of shape memory alloy wire segments which are arranged side by side along the axial direction inside the wheel surface.
3. The multi-layer composite flexspline of claim 2 wherein: the plurality of shape memory alloy wire segments in the shape memory alloy wire layer are connected in parallel in the same circuit.
4. The multi-layer composite flexspline of claim 1 wherein: the wheel body is ring-shaped or spherical shell-shaped.
5. The multilayer composite flexspline of claim 3 or 4 wherein: the high damping material is a modified polymer composite material with nitrile rubber as a base material.
6. The multi-layer composite flexspline of claim 1 wherein: the current with phase difference is input to the shape memory alloy wire layer through a power supply, so that the flexible wheel can be driven to generate periodic radial expansion and creep at multiple points in the circumferential direction.
7. The utility model provides a compound flexbile gear formula harmonic reducer of multilayer, includes rigid gear and flexbile gear, its characterized in that: the rigid gear is sleeved on the outer side of the flexible gear, the part of the flexible gear is in friction contact with the rigid gear, the flexible gear adopts the multilayer composite flexible gear according to any one of claims 1-6, the shape memory alloy wire layer is deformed by introducing current with phase difference into the shape memory alloy wire layer of the flexible gear, the flexible gear is driven to generate periodical radial telescopic peristaltic motion in the circumferential direction, a normal vector is formed between the flexible gear and the rigid gear to move in a two-dimensional plane or a curved surface of any direction of a three-dimensional space, and the flexible gear is further driven to rotate in the circumferential direction through friction.
8. The multi-layer composite flexspline type harmonic reducer according to claim 7, characterized in that: the inner wall of the rigid wheel is an arc curved surface, the macroscopic surface texture of the wheel surface of the flexible wheel is a wedge-shaped texture which is continuous along the circumferential direction, the microscopic surface texture of the wheel surface of the flexible wheel is a plurality of suckers, the suckers have gradient elastic modulus in the radial direction of the flexible wheel, and the friction contact points between the wheel surface of the flexible wheel and the inner wall of the rigid wheel are multiple points.
9. The multi-layer composite flexspline type harmonic reducer according to claim 8, characterized in that: the shape memory alloy wire layer is deformed by introducing current with phase difference into the shape memory alloy wire layer of the flexible wheel, the circumference of the flexible wheel is driven to change, variable transmission ratio transmission can be formed between the flexible wheel and the rigid wheel, the circumferences of the contact transmission interface of the rigid wheel and the flexible wheel are non-circular, and the contact transmission interface of the rigid wheel and the flexible wheel is a flexible deformable interface.
10. A flexible industrial robot, characterized by: flexible industrial robot using a multi-layer composite flexspline type harmonic reducer according to any of claims 7-9.
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| CN202410120438.7A CN117823595A (en) | 2024-01-29 | 2024-01-29 | Multilayer composite flexible gear type harmonic reducer and flexible industrial robot |
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