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The expert assessment method underlies most decision-making methods in the technical field of activity, from the search for rational design solutions to issues of industrial safety of hazardous production facilities, which is embodied in the form of regulatory documents governing the implementation of a risk-oriented approach to problem solving in the specified areas. The subjectivity of the expert assessment method can often lead to decisions that are objectively not rational in a specific design situation. This article considers a modification of the superstructure of the criteria weight assessment level of the hierarchy analysis method based on statistical processing of a set of possible combinations of criteria priorities using the example of choosing a rational option for a belt conveyor drive system, which is a direct replacement for the expert assessment method and paired comparisons at this hierarchy level. It is shown that when taking into account the proposed modification and paired comparison at the first level of the hierarchy of clearly defined values of options within each criterion (characteristics of technical objects), the method of paired comparisons is excluded from the structure of the methodological apparatus of the hierarchy analysis method, which makes it possible to single out the obtained set of results into a separate decision-making method.

The creation of new and improvement of existing machines and mechanisms requires the development of drive engineering and the creation of new drive systems capable of competing with currently known circuit solutions. Under these conditions, the creation of combined pneumatic-mechanical drives is an important scientific and technical task. The purpose of this work is to increase the speed at a given accuracy of auxiliary movements of the target mechanisms of technological machines by creating a pneumatic-mechanical drive with improved energy and dynamic characteristics. The technical solution of a positioning pneumatic-mechanical drive of executive movements of technological equipment is presented, mathematical and computer models are developed. In this case, the method of solving the differential equation in the SimInTech program is used. As a result, an oscillogram of transients is obtained. The developed models allow for dynamic analysis of pneumatic-mechanical systems.

Introduction. The problem of the load on an electric drive system in a parallel kinematic structure is considered. The task of developing a fault-tolerant system that provides performing a given process in case of a failure of one or more drives is described. The work objective is to create a method for estimating the current and additional load on each drive of the mechanism of a parallel kinematic structure. The solution enables to correct the operating mode when performing a given process without compromising serviceable drives.Materials and Methods. Previously, a diagnostic method was developed. It is based on the calculation and analysis of the coefficients of straight lines that approximate the envelopes of the values of the wavelet transform coefficients of electric motor current signals, taking into account the characteristic scales. This makes it possible to determine the current technical condition of the electric motor and find malfunctions. The logical continuation of this approach is the proposed method for assessing the current and additional load. It provides finding the current load on the drive based on the coefficients of the lines approximating the envelopes of the wavelet coefficients of the current signal. To calculate the additional load, the number and location of faulty drives are taken into account.Results. For each scale of the wavelet coefficients, the relative coefficients and the current load on each drive are determined. The possibility of redistributing the load to two adjacent jacks was checked; the behavior of the system in this case was investigated. The load moved by the faulty jack is redistributed to two adjacent jacks in equal shares — 14.76 % each. The total load on the drives is 44.28 %, which is safe for the servo. The load on the drive of the fourth jack does not change (29.52 %). The drives have a sufficient safety margin. It is established that all three operating modes are acceptable for the studied servo drive, and they do not cause dynamic overloads and premature failure.Discussion and Conclusions. The experimental studies on the method of assessing the current and additional load have shown its adequacy and high efficiency. It was found that when the drives were disconnected from one of the racks of the mechanism, the system performed a load redistribution on the drives. Thus, it was possible to avoid their dynamic overloads and premature failure. This means that the solution is able to ensure the reliable functioning of the complex at the time of renovation work.

The paper contains the results of theoretical studies of loading parameters of carrying and tractive belts of a multidrive belt conveyor in case of accidental sliding deviations of electric motor drives. The direct effect of a random combination of sliding deviations on the working life value of the carrying belt is shown. The justification for taking into account the actual parameters of belt loading cycles when calculating their working life during the process of designing multidrive belt conveyor within each combination of sliding deviations is given. The paper demonstrates inconsistency of the approach regulating the determination of the skewness ratio of loading cycles as a value inverse to the drives traction factor.

The paper contains the results of the probabilistic modelling of joint operation of multidrive belt conveyors in case of their full load as well as without cargo. As a result, modelling demonstrates the need of additional reservation of drive power when designing multidrive belt conveyors. On the basis of the modelling, operational principles of joint operation of belt conveyors are established when there are random slide deviations of their engines. These deviations represent specific conditions of electric motors distribution between the drives as well as the influence features of their parameters on the distribution of the carrying and tractive belts.

The paper is aimed at specifying and summarizing system-wide and internal slide variations of electric motors in the structures of multimotor drives of multidrive belt conveyors. The accounting principle of the indicated variations is formulated in the form of the hierarchic structure when building a probabilistic mathematical model of tractive effort distribution in the multidrive belt conveyor. A system of the obligatory internal combinations of slide variations of electric motors in the multidrive belt conveyor is suggested. Taking into account the recommendations of the given system, the dependencies enabling one to estimate the labour coefficient of the probabilistic modelling and give detailed and qualitative descriptions of every design case are suggested.

There was suggested a probabilistic mathematical model of tractive effort distribution among the drives of multidrive belt conveyors. This model takes into account (in an inverted way) speed variations of different points of tractive and carrying belt forms using an artificial increase in probabilistic interval boundaries of slide departures of drive engines. Taking into consideration the given mathematical model, an integrated approach to traction calculation of belt conveyor of conventional construction and random configuration is formulated. This approach is based on presentation of units of the traction calculation process in the form of classifying characteristics with the corresponding mathematical description. The set of these classifying characteristics for each unique engineering case forms the corresponding specific equation systems of traction calculation.

This paper provides substantiation of selection method of preferred alternative of belt conveyor drive systems on the basis of the analytic hierarchy process. Conditions for the correct application of the proposed method in the selection process of preferred alternative of technical objects were worked out. The set of criteria of system effectiveness evalua-tion and the corresponding hierarchical structure in accordance with the developed conditions was proposed.

Method of determination of relative immobile and sliding areas between carrying and tractive belts in places of mount-ing of belt conveyor intermediate drives made in the form of tractive contours is proposed. The example shows potential of this method in multidrive belt conveyor design process.