The invention concerns a method and a device for deformation control of structures, especially deformation control through a position change or a variable deformation as a result of a structure oscillation influenced by temperature or rotational speed or pressure, occurring in particular in machine tools and aircraft structures.

State-of-the-art

Some of the cases are temperature deformations resulting from heat generation in spindle drives, mechanism drives, friction in joints forming kinematic pairs and the very technological process, e.g. machining, changing the mechanism dimensions to a great extent.

A consequence of these changes is a loss of a tool positioning accuracy.

The aim is to eliminate or compensate the temperature deformations by acting upon a mechanism structure through some actuator in order to achieve an opposite deformation to the temperature deformation.

There are many arrangements for reducing and removing these temperature deformations. There are structural designs involving a structure symmetry, where a structure is deformed evenly and includes a mutual compensation, or, on the other side, a structure asymmetry, where a structure is deformed in an expected direction without affecting a manufacturing process.

Other measures involve intensive cooling of components where heat generation occurs.

Actuators for temperature deformation reducing are used as well.

Eventually a machine is equipped with temperature measuring sensors and based on foregoing tests a temperature deformation of a tool position is predicted on the basis of values on these temperature sensors and the deformation is compensated in a tool positioning control system.

All of these actions either reduce temperature deformations only partly or predict their values from indirect measurements, thus a complete compensation of these deformations cannot be achieved or a controlled intervention is needed for a compensation of temperature deformations.

Other cases are demanded structure deformations resulting from a temperature of a structure environment or interior. Aircraft engines may be an example, where according to a temperature passages heed to be opened or closed, clearances or shapes need to be changed. Here the aim is to produce temperature deformations for a better function of a machine or a structure.

Controlled actuators or thermal expansivity in a structure are used for this purpose. Controlled actuators are typically computer controlled and they require an external power source. However, actuators based on shape memory alloys - SMA - are used, too. The advantage of SMA actuators is that the external environment heat is their power source. Their disadvantage is that they have only two states so far. Other cases are demanded time- variable deformations (oscillations) of a structure as a result of a pressure and actions of force of a structure environment or interior. Example of this can be airplane wings, where according to the wing circumfluence and excitation there is a need to damp or, reversely, induce a motion, or to change a shape. So the aim is to accomplish a dynamic change of a structure deformation in order to achieve its better function or a better function of a machine using such a structure.

Other demanded structure deformation is a deformation occurring depending on different structure conditions than its temperature is. These may be rotational speed, velocity, flow rate and pressure or conditions of other machine parts.

Actuators for reducing or producing a deformation have a common problem that they require application of multiplicatively higher force than necessarily needed for a structure deformation.

The aim of this invention is such a structure arrangement where a universal actuator or a temperature actuator produces a deformation in a required way so that a necessary actuator force is of a value as minimal as possible needed for affecting the structure.

Subject Matter of the Invention

A subject matter of the method for a carrying structure deformation control according to this invention consists in creating an auxiliary structure connected to a frame, parallel to the basic carrying structure, and connecting both of the structures one to another through at least one actuator.

For a change of the basic carrying structure deformation, a position of actuator connecting points to the basic carrying structure towards a frame is determined and a force effect needed for acting through an actuator upon the basic carrying structure for a change of its deformation is determined according to the basic carrying structure deformation found out on the basis of measurements of a change of the position of actuator connecting points to the basic carrying structure towards a frame.

A relative position of actuator connecting points to the basic carrying structure and to the auxiliary parallel structure is determined by measuring positions of connecting points to the basic carrying structure towards a frame and to the auxiliary parallel structure towards a frame, and/or by measuring relative positions of actuator connecting points to the basic carrying structure and to the auxiliary parallel structure.

An actuator is controlled according to a position and/or a deformation and/or a motion of the basic carrying structure and/or of the auxiliary parallel structure and/or their relative position and/or a deformation and/or a motion and/or the environment condition.

A subject matter of a device for a carrying structure deformation control according to the invention consists in an auxiliary structure parallel to the basic carrying structure and connected to the basic carrying structure through at least one actuator, whereas the auxiliary parallel structure and the basic carrying structure are connected to a frame. An actuator is alternatively arranged between the auxiliary parallel structure and the basic carrying structure and connected to the auxiliary parallel structure and the basic carrying structure by means of drawbars and rotational joints.

The basic carrying structure is fitted with a position sensor of the basic carrying structure and/or a sensor of the environment condition and the auxiliary parallel structure is fitted with a position sensor of the auxiliary parallel structure. An actuator can be a thermal actuator and this actuator can be begirded by an electrical resistance wire connected to a computer controlled electrical voltage source connected to the basic carrying structure position sensor and/or the auxiliary parallel structure position sensor and/or the environment condition sensor.

The advantage of the solutions described above is that the actuators have to generate a force only necessarily needed for a demanded deformation of a shape of the basic carrying structure, even for different and complicated shape deformations. The application of drawbars is advantageous for placing actuators off the structure, having larger place for construction of actuators.

Overview of Figures in Drawings

In the Figures below there are schematic depictions of arrangements of actuators for producing a structure deformation, where

Figs. 1 and 2 show an embodiment for producing a deformation by tensile or compressive forces according to the state-of-the-art

Fig. 3 shows an embodiment for producing a deformation by tensile or compressive forces according to this invention

Figs. 4 and 5 show an embodiment for producing a deformation by bending according to the state-of-the-art

Figs. 6 and 7 show an embodiment for producing a deformation by bending according to this invention

Fig. 8 shows an alternative arrangement for a deformation by bending Fig. 9 shows an alternative arrangement for producing a deformation by bending according to the state-of-the-art

Figs. 10 and 11 show an embodiment for producing a deformation of an alternative structure by bending according to this invention

Fig. 12 shows an embodiment for producing a structure deformation by torsion

Fig. 13 shows an alternative arrangement for producing a structure deformation by torsion

Fig. 14 shows an embodiment for producing a deformation of an object shape

Fig. 15 shows a transverse section through the structure bodies depicted in Fig. 14

Fig. 16 shows two alternatives of a carrying structure

Fig. 17 shows an embodiment for producing a deformation of the carrying structure depicted in Fig. 16

Fig. 18 shows an embodiment for producing a deformation of an airplane wing Fig. 19 shows an embodiment for producing a general type of a deformation of an object shape

Fig. 20 shows an embodiment similar to the one depicted in Fig. 19

Examples of Embodiments of the Invention

Figs. 1 to 3 show an arrangement of actuators for producing a structure deformation by tensile or compressive forces. Fig. 1 depicts a disadvantageous solution existing up to now of an actuator acting to produce tensile or compression deformation 9 of a body of the basic carrying structure \ by acting of actuators 3, which are piezoelectric actuators in this case. The disadvantage is that there is a difficult transmission of a force acting of these actuators 3 for producing a deformation at a surface contact upon a body of basic carrying structure L

Fig. 2 depicts another disadvantageous solution existing up to now of an actuator acting to produce tensile or compression deformation 9 of a body of the basic carrying structure I by acting of actuator 3 based on piezo actuators again. The disadvantage is that actuator 3 carries basic carrying structure l and the whole load acting upon the body of basic carrying structure 1 , in this case the weight.

Fig. 3 depicts a solution of actuators acting to produce tensile or compression deformation 9 of a body of basic carrying structure 1 by acting of actuators 3 according to this invention. There are piezo actuators used, too. Auxiliary parallel structure 2 attached to frame 10 is arranged in parallel with basic carrying structure 1 and actuators 3 are located between the end of auxiliary parallel structure 2 and the body of basic carrying structure L Achieving a required deformation (a motion) is measured by position sensor IT of basic carrying structure \ towards frame 10. Sensor JT can consist of a laser interferometer. The advantage of this solution is that actuators 3 in this case do not carry the basic loading, they only act by demanded deformation forces. Actuators 3 can consist of piezo actuators, hydraulic actuators, electrodynamic actuators, other electric actuators or temperature actuators (shape memory alloys acting according to a reached temperature).

Figs. 4 to 7 show an arrangement of actuators for producing a structure deformation by bending force.

Fig. 4 depicts a disadvantageous solution existing up to now of an actuator 3 acting to produce bending deformation 9 of a body of basic carrying structure i_by acting of actuator 3. The disadvantage is that there is a disadvantageous ratio of the force of actuator 3 to the force needed for the bending deformation of the body of basic carrying structure T This ratio is determined by equality of a force momentum of actuator 3 and a momentum of the demanded force acting in the direction of deformation 9. The force of actuator 3 is needlessly high, namely L/d-times higher than the force necessarily needed for bending a beam of basic carrying structure L

Fig. 5 depicts another disadvantageous solution existing up to now of an actuator 3 acting to produce bending deformation 9 of a body of basic carrying structure l by acting of piezo- based actuator 3 or shape memory alloy actuator 3. Again, the disadvantage is that there is a disadvantageous ratio of the force of actuator 3 to the force needed for the bending deformation of the body of basic carrying structure L This ratio is again determined by equality of a force momentum of actuator 3 and a momentum of the demanded force acting in the direction of deformation 9. The force of actuator 3 is needlessly high, namely L/d-times higher than the force necessarily needed for bending a beam of basic carrying structure L

Fig. 6 depicts a solution of an actuator 3 acting to produce bending deformation 9 of a body of basic carrying structure i by acting of piezo-based actuator 3 or shape memory alloy actuator 3 according to this invention. Auxiliary parallel structure 2 attached to frame 10 is arranged in parallel with basic carrying structure 1 and actuator 3 is located between the end of auxiliary parallel structure 2 and the body of basic carrying structure i. Achieving a required deformation (a motion) is measured by position sensor JT of basic carrying structure i. Auxiliary parallel structure 2 is deformed by actuator 3 force acting, therefore for the control of actuator 3 a position of auxiliary parallel structure 2 needs to be measured; this is carried out by position sensor 12 of auxiliary parallel structure 2, which measures a relative position of auxiliary parallel structure 2 towards basic carrying structure L Sensors ϋ and 12 can consist of a laser beam and CCD element. The advantage of the solution is that actuators 3 in this case act by only a necessarily needed deformation force for achieving demanded bend 9 of the body of basic carrying structure L

Fig. 7 depicts an alternative solution of an actuator 3 acting to produce bending deformation 9 of a body of basic carrying structure I by acting of piezo-based actuator 3 or shape memory alloy actuator 3 according to this invention. A certain problem of the solution depicted in Fig. 6 is that for developing a force necessarily needed for bending the beam of basic carrying structure \ an actuator with such dimensions is needed which cannot be accommodated within the space between basic carrying structure \ and auxiliary parallel structure 2. This issue has been solved in a solution depicted in Fig. 7. Actuator 3 acting between basic carrying structure l and auxiliary parallel structure 2 in Fig. 6 is replaced by actuator 3 acting between frame JO and drawbars 6 in Fig. 7. This actuator 3 acts in parallel with structures l and 2, having enough space for its arrangement. It could be even taken out as far as the frame off structures J, and 2. Drawbars 6 are connected to basic carrying structure l and to auxiliary parallel structure 2 and to actuator 3 through rotational joints 7. If an angle between drawbars 6 and structures J_ and 2 is 45 degrees, then actuator 3 force will be equal to the force acting upon structures 1 and 2 in the direction of bending deformation 9.

Figs. 8 to 11 show another case of a structure deformation by bending force.

Fig. 8 shows basic carrying structure l attached to frame 10; the structure is deformed in the direction of deformation 9 owing to temperature acting. The demand is to compensate the deformation by force acting of an actuator.

Fig. 9 depicts a disadvantageous solution existing up to now of actuators acting to produce compensating bending deformation 9 of a body of basic carrying structure I by acting of piezo- based actuators 3 or hydraulic-type actuators or shape memory alloy actuators. The disadvantage is that there is a disadvantageous ratio of the force of actuators 3 to the force needed for the bending deformation of the body of basic carrying structure I, similar as in Figs. 4 and 5.

Fig. 10 depicts a solution of an actuator 3 acting to produce bending deformation 9 of a body of basic carrying structure J_ by acting of actuator 3, e.g. a piezo-based actuator, a hydraulic- type actuator, an electric-type actuator or a shape memory alloy actuator according to this invention for a case of insufficient stiffness of frame 10. Auxiliary parallel structure 2 attached to frame 10 is arranged in parallel with basic carrying structure ! and actuators 3 are located between the end of auxiliary parallel structure 2 and the body of basic carrying structure L Achieving a required deformation (a motion determined by bending of basic carrying structure 1) is measured by sensor 1_1 of a position of basic carrying structure i. Auxiliary parallel structure 2 is deformed by actuator 3 force acting, therefore for the control of actuator 3 a position of auxiliary parallel structure 2 needs to be measured; this is carried out by position sensor 12 of auxiliary parallel structure 2, which measures a relative position of auxiliary parallel structure 2 towards basic carrying structure i. Sensors J_1 and 12 can consist of a laser interferometer. The advantage of the solution is that actuators 3 in this case act by only a necessarily needed deformation force for achieving demanded bend 9 of the body of basic carrying structure 1.

Fig. 11 depicts a solution of an actuator 3 acting to produce bending deformation 9 of a body of basic carrying structure I by acting of shape memory alloy actuator 3 according to this invention. Auxiliary parallel structure 2 je very simple here and actuator 3 is located between structure 2 and basic carrying structure L Shape memory alloy actuator 3 has a given deformation and action of force depending on the temperature, so measurements for achieving the demanded deformation of basic carrying structure 1 need not to be carried out, unlike as depicted in Fig. 10 through sensors ϋ and 12. According to the environment temperature basic carrying structure I is deformed and according to this temperature shape memory alloy actuator 3 is deformed as well, thus compensating by its acting the deformation of basic carrying structure 1. This way undeformed basic carrying structure ! is achieved, such as a machining device.

Figs. 12 to 13 show another case of a structure deformation by torsion (rotation).

Fig. 12 depicts a solution of an actuator acting to produce a torsional (rotational) deformation 9 of a body of basic carrying structure 1 by acting of shape memory alloy actuator 3 according to this invention. In parallel with basic carrying structure consisting of a cylinder there is auxiliary parallel structure 2 attached to frame 10 arranged; auxiliary parallel structure 2 consists of parallel beams or a parallel tube (a cross-section in Fig. 12) and actuator 3 firmly fixed to structures 1 and 2 is located between the end of auxiliary parallel structure 2 and the body of basic carrying structure 1. The actuator consists of a spiral-wound spring of shape memory alloy, which can be controlled by heat of an electrical resistance wire controlled by electric current. Achieving a required deformation (a motion) is measured by position sensor 11 of basic carrying structure L In spite of the fact that auxiliary parallel structure 2 is deformed by actuator 3 force acting, it is not always necessary to measure a position of auxiliary parallel structure 2. To control the acting of actuator 3 in such a way that demanded deformation 9 is achieved will suit the purpose. Sensor IT can consist of a laser beam and CCD element. The advantage of the solution is that actuator 3 in this case acts by only a necessarily needed deformation force for achieving the demanded rotational motion of the body of basic carrying structure 1.

Fig. 13 depicts an alternative solution of actuator 3 acting to produce torsional (rotational) deformation 9 of a body of basic carrying structure 1 by acting of actuator 3 according to this invention. The body of basic carrying structure \ consists of a tube and auxiliary parallel structure 2 consisting of a cylinder (or a tube) is located inside this tube. Actuators 3 acting between basic carrying structure i and auxiliary parallel structure 2 consist of drawbars, which exert a torsional moment upon the body of basic carrying structure 1.

Figs. 14 to 15 show a general case of an object shape deformation, the so-called object shape morphing.

Fig. 14 depicts a solution of actuator 3 acting to produce demanded shape deformation 9 of a body of basic carrying structure \ by acting of actuator 3 according to this invention. The body of basic carrying structure i is hollow and auxiliary parallel structure 2 is located in its cavity. Fig. 14 depicts a longitudinal section though the bodies of structures 1 and 2. Actuators 3 are located between auxiliary parallel structure 2 and basic carrying structure i. Actuators 3 prop against the body of auxiliary parallel structure 2 and cause the demanded shape deformation 9 of the body of basic carrying structure L The deformation of both structures 1 and 2 is measured by position sensors ϋ and 12; the values read on the sensors determine the deformation. The sensors can be laser-type or tensometric-type.

Fig. 15 shows the solution as depicted in Fig. 14, but as a transverse cross-section through bodies of structures 1 and 2. The bodies of basic carrying structure 1 in Fig. 14 and 15 can be for example rotating machine blades.

Fig. 16 shows an example of a rotating blade as basic carrying structure 1. The blade is located on rotor 13, which rotates around a fixed rotor creating frame 10. The blade on the left-hand side is full, the blade on the right-hand side is hollow. The demand is to change a shape of the rotating blade, and/or to modify its shape after its deformation.

Fig. 17 depicts a solution of actuator 3 acting to produce demanded shape deformation 9 of a body of basic carrying structure 1 by acting of actuator 3 according to this invention. The body of basic carrying structure 1 in a form of a blade is hollow and auxiliary parallel structure 2 is located in its cavity. The aim is to change the rotating blade shape in a controlled way. Fig. 17 depicts a longitudinal section through the bodies of structures 1 and 2. Actuators 3 are located between auxiliary parallel structure 2 and basic carrying structure L Actuators 3 prop against the body of auxiliary parallel structure 2 and cause the demanded shape deformation 9 of the body of basic carrying structure I. The deformation of both structures 1 and 2 is measured by position sensors IT and 12; the values read on the sensors determine the deformation. The sensors can be laser-type or tensometric-type. In this example the blade representing basic carrying structure i is fixed on rotor 13, which is not stressed by deformations. Then rotor F3 of blade 1 replaces frame 10, to which auxiliary parallel structure 2 is attached as well. Demanded shape deformation 9 of basic carrying structure 1 consisting of the blade is determined by the environment condition, e.g. rotational speed of rotor 13, flow rate around blades, pressure and temperature at the inlet into the rotating machine using basic carrying structure 1 consisting of the blade, etc. Control computer 18 and sensor 19 monitoring the environment condition are not depicted in Fig. 17.

Fig. 18 shows a solution of actuators 3 acting to control a deformation of wing 15 of airplane 14 according to this invention. Wing 5 of airplane 14 is depicted with three cross-sections. The body of basic carrying structure 1 in a form of wing 15 is hollow and auxiliary parallel structure 2 in a form of a beam is located in its cavity. There can be more objectives of control for acting of actuators 3. One of the objectives can be a change of a profile shape of wing 15 in a longitudinal or transversal direction in cross-sections, as with blades depicted in Fig. 17. Another objective can be oscillation damping and/or a change of frequencies and shapes of oscillation of wing 15 in order to suppress fluttering of wing 15. Another objective can be inducing vibrations of wing 15 surface, influencing a behavior of the boundary layer of circumfluence of the wing profile. These objectives of actuators 3 acting can be also used in other cases, e.g. for the blades in Fig. 17. Actuators 3 are located between auxiliary parallel structure 2 and basic carrying structure 1. Actuators 3 prop against the body of auxiliary parallel structure 2 and cause the demanded time-variable deformation of the body of basic carrying structure 1. Fig. 18 does not show a direction of deformation 9 of wing 15, as there may be many different directions. Also, measurements of a position and a deformation and oscillation of both of structures 1 and 2 using position sensors H and 12 are not depicted in Fig. 18 in order to keep the illustration well-arranged. The measurements can be carried out by tensiometers, accelerometers, pressure or laser sensors etc. Based on these measurements actuators 3 are controlled; they act by force upon basic carrying structure 1 of wing 15 for the purpose of time-variable control of its deformation. Demanded deformation 9 of basic carrying structure 1 consisting of wing 5 is determined by the environment condition, e.g. a flight speed and altitude of airplane 14, airflow around wing 15, oscillation of wing 15, etc. Control computer 18 and sensor 19 monitoring the environment condition are not depicted in Fig. 18.

In this example wing 15 representing basic carrying structure 1 is fixed on a fuselage of airplane 14, which is not stressed by deformations. Then airplane 14 fuselage replaces frame 10, to which auxiliary parallel structure 2 inside wing 15 profile is attached as well.

Fig. 19 shows a general case of an object shape deformation, the so-called object shape morphing. A body of auxiliary parallel structure 2 is arranged next to a body of basic carrying structure L Structures 1 and 2 are interconnected through a needed number of actuators 3 for achieving the demanded shape deformation of the body of basic carrying structure 1. Actuators can be piezo-types, hydraulic, electric, shape memory alloys and others. The deformation (position) of both structures 1 and 2 is measured by position sensors IT and 12. The sensors can be laser-type, optic or tensometric etc. It is obvious here that auxiliary parallel structure 2 was created by reproducing basic carrying structure 1 in an equidistant distance.

Fig. 19 also shows that the deformation of basic carrying structure 1 can be determined from measurements using position sensor 12 of auxiliary parallel structure 2 by measuring positions of connecting points of actuators 3 to auxiliary parallel structure 2 towards frame 10 and from measurements using another position sensor IT of basic carrying structure 1 by measuring a relative position of connecting points of actuator 3 to basic carrying structure 1 and to auxiliary parallel structure 2.

In Fig. 20 an embodiment as depicted in Fig. 19 is shown, where actuator 3 consists of thermal actuator made of shape memory alloys (SMA) here. Thermal actuator 3 is either controlled by the environment temperature without an interconnection with a sensor and computer or it is begirded by an electrical resistance wire 16 connected to electrical voltage source 17 controlled by computer 18. Computer 18 is controlled by information from environment condition sensor 19, e.g. an environment temperature sensor or a sensor of airflow around the structure or a rotational speed sensor etc. This is a sensor monitoring such parameters in the environment that influence the control of the deformation of basic carrying structure 1 or auxiliary parallel structure 2. However, position sensor H of the basic carrying structure and/or position sensor 12 of the auxiliary parallel structure can also be used for the control by computer 18. But this is not shown in Fig. 18.

Auxiliary parallel structure 2 is usually created in a way that next to basic carrying structure I the basic carrying structure is reproduced once more in parallel (collaterally) in an equidistant distance towards basic carrying structure L This new independent structure is simplified as needed or further modified and after this modification auxiliary parallel structure 2 has been created. An only condition is that a direction in which action of force of actuator 3 has to act for a demanded deformation of basic carrying structure 1 can be achievable from auxiliary parallel structure 2 so that an unacceptable deformation of this auxiliary parallel structure 2 does not occur by effect of actuator 3 acting. A requirement is that a direction in which actuator 3 acts is such that a value of the action of force in this direction is only necessarily needed for achieving the demanded deformation of basic carrying structure L Then actuators 3 are located between basic carrying structure 1 and auxiliary parallel structure 2; actuators 3 produce the demanded deformation of basic carrying structure ! by their acting. The acting of actuators 3 is controlled by measuring the deformation of basic carrying structure ! using position sensors IT of basic carrying structure L If actuators 3 require a feedback control according to their deformation determined from the mutual (relative) position of basic carrying structure l and auxiliary parallel structure 2, then they are complemented by position sensors ϋ and 12. Demanded deformation 9 of basic carrying structure 1 is typically determined on the basis of measurements using environment condition sensor 19.

The deformation of basic carrying structure ! can also be determined by measuring positions of connecting points of the actuator to auxiliary parallel structure 2 towards frame 10 and by measuring a relative position of connecting points of the actuator to basic carrying structure 1 and to auxiliary parallel structure 2.

All variants described above can be combined one with another.

Frame 10, to which carrying structure 1 and auxiliary parallel structure 2 is attached, represents such a part of the device that is not subjected to deformations and can even take a function of the auxiliary parallel structure. And vice versa, a part of stationary, but also movable structures, which are not subjected to deformations, can perform a function of frame 10, from which auxiliary parallel structure 2 is led.

The use of sensors IT for a position (deformation) of basic carrying structure 1 is usually necessary. The use of sensors 12 for a position (deformation) of auxiliary parallel structure 2 is applicable, especially for dynamic (fast) changes of a deformation (shape) of structures in order to eliminate or reduce their oscillation.

Actuators cause a static or a time-variable deformation of the basic carrying structure by their action of force. The time-variability of the action of force enables to change by a deformation a lot of dynamic properties of the basic carrying structure, such as damping, own frequencies and own shapes or an interaction with flowing medium (external or internal circumfluence).

Actuators 3 can be computer controlled. In all the cases, a computer can use for its control the information from position sensors ϋ of basic carrying structure 1 and/or position sensors 12 of auxiliary parallel structure 2 and/or environment condition sensors 19.

The advantage of the solutions described above is that actuators 3 have to exert a force only necessarily needed for the required static or time-variable deformation of a shape (morphing) of basic carrying structure I, even for different and complicated shape deformations. The application of drawbars 6 is advantageous for placing actuators 3 off structures 1 and 2, having larger place for construction of actuators 3.