Study on unified hydraulic drive module with self-adaptation by power and kinematic parameters

. When improving technological drives of machines and equipment, an important role is given to unified self-adapting subsystems and modules under the conditions of stochastic loads due to environmental resistance. The objective of this work is to study the principles of performance commonality and self-adaptation of a patented process hydraulic drive module with a working body that carries out the feed movement and the primary motion. At that, the design options of the module are considered. The principle of module performance commonality is discovered in the presented methodology for its study and conservation. This considers the law, purpose, internal adaptive relationships and the self-adaptation algorithm, which are confirmed by a physical experiment. The process of self-adaptation is presented by a functional block diagram and adaptive relationship equations. The equalities take into account the features of different versions of the module. The results of comparative experimental studies have confirmed that the presence of internal adaptive communications in the module hydraulic system structure provides the principle of its self-adaptation and functional efficiency. A function-unified module can be used in the technological hydraulic systems of machines and equipment to stabilize power and to adapt the kinematic parameters of these movements under the conditions of non-stationarity of values of the power parameters of the environmental resistance.


Introduction
When improving technological drives of machines and equipment, an important role is given to unified self-adapting subsystems and modules under the conditions of stochastic loads due to environmental resistance.The objective of this work is to study the principles of performance commonality and self-adaptation of a patented process hydraulic drive module with a working body that carries out the feed movement and the primary motion.At that, the design options of the module are considered.
The principle of module performance commonality is discovered in the presented methodology for its study and conservation.This considers the law, purpose, internal adaptive relationships and the self-adaptation algorithm, which are confirmed by a physical experiment.The process of self-adaptation is presented by a functional block diagram and adaptive relationship equations.The equalities take into account the features of different versions of the module.
The results of comparative experimental studies have confirmed that the presence of internal adaptive communications in the module hydraulic system structure provides the principle of its self-adaptation and functional efficiency.
A function-unified module can be used in the technological hydraulic systems of machines and equipment to stabilize power and to adapt the kinematic parameters of these movements under the conditions of non-stationarity of values of the power parameters of the environmental resistance.

Study Objective and Concept
The purpose of the scientific paper is a system study of the principles of performance commonality, modularity and self-adaptation of the hydraulic drive due to load of technological machines and equipment subject to the parameter matching of technological movements of the executive body.
The research concept consists in the theoretical and experimental validation of the following statement: a hydraulic actuator module offers the properties of self-adaptation and performance commonality, if mathematical models of the goal, law, algorithm and internal adaptive communications under the adaptive load control and working movements on the executive body of technological machines and equipment, are equivalent and functionally similar in its possible modifications.

Conditions, Materials and Methods
The scientific novelty and practical feasibility of the proposed concept is studied on the example of the device according to the patent of the Russian Federation No. 2582691 in Fig. 1.This allows for adaptive speed variation of the feed and rotation of the executive body to achieve compliance of the parameters of its power actions with the given values under the conditions of variable values of the medium resistance parameters [9].Modularity of the device.The principle of self-adaptation incorporated in the device in Fig. 1 is also used in other devices [10,11].All three devices are united through the concept of modularity [5,12,13] and commonality [14].They, as well as modules of other modifications, may differ in the following: instead of a flow control valve, they can have an adjustable throttle and another combination of different types of hydraulic motors (hydraulic motor -hydraulic motor, hydraulic cylinder -hydraulic cylinder, etc.).Analysis of the performance commonality of a self-adaptive module.The analysis methodology of demands and the studies on performance commonality of the module with self-adaptation due to load and coordination of movements on the executive body includes the following: − technological and parametric analysis of the machines and equipment stock according to the criterion of the demand for load self-adaptive drive under the conditions of stochastic change in environmental parameters perceived by the executive body and the requirement to coordinate its working movements; Fig. 1 Basic diagram of device with self-adaptation due to power parameters of drilling rocks with variable properties. 1 is hydraulic pump (hp); 2 is release valve; 3 is filter; 4, 7, 8 are hydraulic distributors; 5, 10 are chokes; 6 is hydraulic motor; 9 is flow control valve (Cv);11 is feed hydraulic cylinder; 12, 13, 14 are pressure gauges; 15 is tank − formulation of the law and the goal of the adaptive regulation of the power and kinematic impact of the executive body on the resistance medium: efforts (torques), linear (angular) speeds (accelerations); − study on internal adaptive communications between parameters and module performance indices; − definition of a generalized algorithm and criteria for assessing the level of module selfadaptation; − experimental assessment of the conformity of laws and self-adaptation algorithms for unified modules of the same design and functionality, as well as their compliance with the laws and algorithms of standard adaptive systems; − development of the control principles in the life cycle criteria for achieving and evaluating the performance commonality of a self-adaptive module of various design; − analysis of the implementation of the principle of maximum commonality [15] of selfadaptive modules of the same dimension range and design (horizontal commonality of a module of one design); − analysis of the implementation of the principle of maximum commonality of selfadaptive technical systems of different design according to the type of combinations of feed hydraulic motors and primary motion (vertical commonality).− During operation of the load self-adaptive module, in order to stabilize it and coordinate movements on the executive body, to maintain the principles of performance commonality, it is necessary: − up to schedule or as required, to verify compliance with the current values of the parameters and indicators of self-adaptation and performance commonality of the technical systems using either known methods or the similarity principle of the PFTS technical systems performance [16] according to standard criteria and indicators of performance similarity; − to perform the self-adaptive module setup according to the functional and constructive parameters using nomographs of performance similarity.

Results and Discussion
Engineering and parametric analysis of the machines and equipment stock according to the criterion of demand for self-adaptation of the drive is carried out through analyzing their technological purpose, possible operating conditions and modes without self-adaptation and the required modes with self-adaptation.
One of the laws of adaptive control (for example, for ACC systems [2]) involves the stabilization of power (or kinematic) output parameters of a technical system through continuous adaptive changes in kinematic (power) parameters.For the considered option of the device with a combination of the hydraulic cylindermotor as hydraulic motors for supply and primary motion, the control law in relative coordinates has the form: where βi is indicator of relative change in the experimental variable; rpm , rmf , pm , f are, respectively, the incremental moments of resistance on the hydraulic motors of the primary motion and on the feed motion, the angular velocity of the shaft of the primary motion and the feed speed of the cylinder rod.The purpose of self-adaptation in Fig. 2 is the load control perceived by the executive body subject to the fulfillment of agreed working movements.
hm = k ( pm ), k = const Thus, the load regulation on the executive body of the technical system is performed by the module through changing the feed with the sign opposite to the sign of the change in the total moment (force) of the environmental resistance (load).
In Fig. 2, there are the following agreed notations: Р 1 , Р 2 , Р hp is oil pressure in the hydraulic system after the primary motion hydraulic motor, mode regulator Ch 1 and after the pump, respectively; Cv is flow regulator, Ch 10 is choke; M pm , F mf , M rpm , F rmf , ΔM rpm , ΔF rmf are the driving moments on the shafts of the hydraulic motors of the primary motion and feed, the resistance moments perceived by the shaft of the hydraulic motor of the primary motion and the feed hydraulic-cylinder rod, as well as their deviations from the nominal, given values; Q pm , Q mf , Q Ch1 ,Q cv , Q ch2 , ΔQ hf are oil consumption (excluding leaks) through hydraulic motors of the primary motion and feed, mode controller, flow controller, throttle, change in oil flow through the hydraulic cylinder in the process of selfadaptation; ω pm , V mf are angular velocities of the main motor hydraulic shaft and the feed hydraulic cylinder rod.
The above reasoning allows us to formulate an algorithm for continuous self-adaptation of a module.The continuous algorithm scheme (Fig. 2) of self-adaptation (with a constantflow pump and flow regulator in the hydraulic system) is determined through the following mathematical model: The scheme of the continuous self-adaptation algorithm (with a constant-flow pump and an adjustable throttle (C h3 instead of the flow regulator in the hydraulic system) is determined through the following mathematical model:

Analytical study of the device self-adaptation principle
In [17], the rationale for the presence and implementation of the device with direct positive and negative feedback adaptive communications, providing the self-adaptation principle is given.
It is known [18] that the mathematical model for describing adaptive systems can contain, beyond the equations of adaptive communications, target conditions, a control law, a criterion for the preference of a law, insensitivity estimates, continuous or discrete adaptation algorithms, local or integral accuracy figures of parameter identification, and other conditions and criteria for the quality of adaptation.
The internal negative feedback of the module [17] is described by the equations: − with a two-line flow regulator in the module in Fig. 1, #  !hf = −" /# rhf [± / ($ rpm0 + С rmf0 )] / ($ rpm0 + С rmf0 ) 0,5 ; (5) − with an adjustable throttle instead of a flow regulator: where: − μ Ch3 , f Ch3 , ρ are, respectively, the flow coefficient and the area of the working window of the throttle C h1 , as well as the oil density; − # vh = 2)*г are velocity gain factors of hydraulic motors; − φ hf , rmf0 , rmf0 , & Ch30 are, respectively, angular acceleration of the hydraulic drive shaft of the feed motion, increment of the environmental resistance moments relative to their specified values perceived by the working body; − A, B, C are coefficients: "=−1,8% Ch3 ; − i gpm , i gmf , η gmf , η gpm are gear ratios of the primary motion and feed chains, efficiency of gears of the primary motion ;and feed mechanisms The internal direct positive communication is described by the equations: − with a two-line flow regulator in the module in Fig. 1, # 9: − with the adjustable throttle (C h3 ) instead of a flow regulator: Ch3 ±'(∆& 0 Ch3 )) 0,5 ] (8) The equation (5 and 6) determines negative feedback between the change in the feed rate of the machine executive body to the object (environment) of the impact and the change in the total resistance moment to this effect relative to the specified value.This equation reveals the self-regulation principle of the module hydraulic system, the principle of its adaptation when changing the input parameters of the environment: under constant loads on the working body, corresponding to a given mode when there is no change in flow.Under the value variation of the total resistance moment relative to the given value, a change in supply with a sign opposite to the sign of change in moment is observed.
The equations for positive direct ( 7), ( 8) and negative feedback ( 5), ( 6) communications are obtained under the condition that the hydraulic system of the module contains hydraulic motors.In this case, features of these communications were considered when equipping the module with a flow regulator or an adjustable throttle.In principle, other combinations of hydraulic motors can be used in modules of other design [5]: hydraulic motor -hydraulic cylinder, hydraulic cylinder -hydraulic motor, hydraulic cylinder -hydraulic cylinder.However, even with these combinations of hydraulic motors, the principle of selfadaptation will occur.The difference will take place, for example, in numerical values of the performance indicators, stability.Therefore, the practical choice of a particular combination of hydraulic motors, in addition to the design and technological expediency, should be accompanied by an analysis of the possible values of indicators and the nature of static, kinematic and dynamic characteristics.Then, the practical choice of a particular combination of hydraulic motors, in addition to design and technological expediency, should be accompanied by an analysis of the possible values of indicators and the nature of static, kinematic and dynamic characteristics.

Experimental evaluation of the principle of module self-adaptation
In order to practically verify the principle of module self-adaptation, a physical experiment was performed.
The task was set: to study the degree of stabilization of the power parameters of the feed and rotation forces of the drill (resistance moments) when drilling a package made of plates of various materials and when drilling deep holes in a homogeneous material.
The experiments were conducted on the bench that was a 2N125 drilling machine with a conventional electromechanical drive (without adaptation) and, then, a converted hydraulic module with self-adaptation.The hydraulic equipment of the module was set up through setting certain values of the flow cross sections in the throttles 5, 10, and in the flow regulator 9 in Fig. 1.To determine these values, the previously obtained mathematical dependences were used, as well as calibration charts and nomographs.Throughout the experiment, the system setup was not changed.
Before the experiment began, air had been removed from the hydraulic system, and the installation itself had been brought to the operating temperature regime (oil t ≃ 45° С).For the experiment, the stand -machine system was set to an operating mode corresponding to drilling holes with a diameter of dсв = 12 mm.In all experiments, normal taper-shank HSS drills were used.When drilling a package of materials, the effect of the self-adaptation principle on the stabilization of the axial force and the drilling moment with variable resistance of the processable medium was studied in Fig. 3, 4. The package was made up of plates with different physical and mechanical properties: aluminum (AD1 type according to GOST 21488-97), steel (St.Z type according to GOST 380-2005) and copper (M1 type according to GOST 859-2001).The experimental results are presented in the graphs in (Fig. 3) and in (Fig. 4).
A change in the torque value of resistance to the drilling of a package of plates of different materials (Fig. 3) without adaptation is: 36% for plates of aluminum and copper; 68% for a combination of aluminum and steel; 106% for the combination of steel and copper.When drilling with adaptation, these ratios, respectively, make up for the combinations: aluminum -copper 5%; aluminum -steel 12%; steel -copper 18%.
A similar comparative analysis of the axial force of the drill feed in Fig. 4 shows that the maximum variation in the force value under drilling without adaptation is (35 -200)%, and with adaptation -(5.6 -12)%.Thus, the experiment shows the presence and efficiency of self-adaptation.
Comparing the experiment results of drilling deep holes graphs in Fig. 5 and 6 it can be stated that when changing the hole depth from 6.0 to 75 mm under drilling steel with selfadaptation (Fig. 5), the drilling resistance has changed from 14.6 to 15.3 Nm, which is 3.4%.In this case, the value of angular velocity of the feed motor shaft decreased from 29 to 10 rad/s, i.e. by 66%.The angular velocity of the primary motion of the hydraulic motor shaft decreased from 65 to 55 rad/s.As expected, a decrease in the speed of the main motor shaft φ hf occurs simultaneously with a decrease in the speed of the feed motor shaft φ ͠ , which verifies the presence of a direct positive communication in the system.When drilling deep holes using a regular hydraulic drive without self-adaptation (Fig. 6), these results are as follows: if angular velocities of the feed motor shafts and the primary motion are constant, the change in the drilling moment varies from 14.2 to 19.0 Mn, i.e. by 27%.When drilling with adaptation (Fig. 5), the change in torque is only 3.4%.This confirms the presence of an internal negative feedback module in the hydraulic system.
Thus, the task of studying the module when drilling holes was to establish the possibility of implementing the functions inherent in the constraint-type systems by the hydraulic drive, i.e. establishing the possibility of implementation of the operation algorithms (3) and ( 4) by the hydraulic drive module, as well as the control law (1) and the law of achieving goal (2).The experiment performed verifies the theoretical evidence of the module self-adaptation due to the presence and efficiency of adaptive communications in the module hydraulic system.

Conclusions
With regard to findings of the analytical and experimental studies on the principles of performance commonality and self-adaptation of a hydraulic drive module, it is reasonable to conclude the following: − the hydraulic devices noted in the article are united through the feature of a unified module, since they have a common functional purpose, structure, internal adaptive communications; they differ in performance targeted at the use in specific machines and equipment; Angular velocity of shaft of primary motion, rad/s − a structurally unified module is a hydraulic actuator with two output links of the feed and the primary motion whose hydraulic equipment is combined according to a differential circuit, which enables to obtain direct positive and negative feedback by adaptive selfregulation of the kinematic and force parameters of the movements relative to the given values at running variables of the environmental resistance parameters; − with different design of the modules, the self-adaptation feature survives; however, the type of device (throttle or flow regulator) on the drain line of the hydraulic motor primary motion differently affects the performance, rigidity of adaptive communications, which determines the application of the module in specific technological machines and equipment; − the experimental studies results verify the correctness of theoretical studies on the selfadaptation principle of the hydraulic drive module of technological machines.

Fig. 2 .
Fig. 2. Functional-structural diagram of self-adaptation of hydraulic drive power module under load regulation on executive bodyThis goal is determined by the relations: