Coordination of Movements of Two-Handed 12-DOF Robot Manipulators at Their Joint Manipulation

The study focuses on a two-handed robot with twelve degrees of freedom, six for each arm, and gives an example of calculating generalized coordinates for the two-armed robot limbs at their joint manipulation. The initial data for obtaining generalized coordinates are represented by the location of the work object, which is a cube. When solving the problem, the last arm links reach the faces of the work object with a given orientation. To obtain generalized coordinates, we used a hierarchical approach, which is based on an algorithm for solving the inverse problem of kinematics, and developed a control flow chart. The values ??of generalized robot coordinates were obtained for each location of the object of work, taking into account the kinematic constraints in the joints of the robot actuator. Findings of research show that it is possible to obtain generalized coordinates for the coordinated movement of the robot actuators with tree-like kinematic scheme.

Mechanisms of power distribution: principles of kinematic and force analysis

The article considers the features of performing kinematic and power analysis of a controlled power mechanism for the transmission of wheeled transport and transport-technological machines. Such mechanisms are currently used mainly on cars in order to improve handling, stability, traction and dynamic properties in severe road conditions. Such mechanisms are not produced in Russia, but theoretical studies are currently being conducted, the results of which will allow determining the main parameters of the mechanism and synthesizing its kinematic scheme. The proposed approaches are based on the methods used in the kinematic and force analysis of planetary gears, but it is taken into account that the mechanism of power distribution during operation has two degrees of freedom. It is indicated that there is a structural and functional similarity between the power distribution mechanism of the car and the turning mechanism of the tracked vehicle. A method is proposed for calculating the gear ratio of the power distribution mechanism according to the condition of matching the minimum possible turning radius provided by the steering trapezoid kinematics and the calculated turning radius.

ANALYSIS OF OPERABILITY OF THE SPECIAL VEHICLE TRANSMISSION

The work is devoted to the analysis of the transmission of a special vehicle (SV) for moving on various surfaces, in particular on stepped ones, designed for people with disabilities. Based on the analysis of various vehicles for the movement of people with disabilities, a model of a SV was created. The main difference of proposed SV is the possibility of using the movement of the passenger՚s center of mass relative to the chassis of a SV for stabilization of the movement. A kinematic scheme of the SV transmission which includes the planetary reducer was created. The reducer provides movement of SV at various modes. Also SV transmission was modeled in the Solidworks software. The analysis of the performance of this transmission when moving a SV on various surfaces was made on base of created 3D-model. Based on the analysis, the efficiency of the transmission of a SV was proved both when moving on a straight surface, and in walking mode when overcoming steps.

Selection and calculation of traction elements of the elevator lifting mechanism

The correct choice of elements of the elevator lifting mechanism and their parameters ensures its reliability, durability, energy and economic efficiency. The paper contains recommendations for the selection of the traction elements of the elevator lifting mechanism and the sequence of determining their parameters based on a multivariate calculation. The purpose of the proposed sequence is to obtain the most rational parameters of the traction elements of the elevator lifting mechanism. The initial data for the calculation are the lifting capacity of the elevator, the nominal speed of movement, the height of the lift of the car. It is also necessary to consider the purpose of the elevator. At the first stage of the calculation, the masses of the cab and the counterweight are determined. In this case, the existing data on analogue lifts should be used. In the absence of such data, the approximate dependences proposed by the authors of the article can be used. At the second stage, the kinematic scheme of the elevator is selected. At the third stage, the type of traction element is selected. On the basis of domestic and foreign experience in elevator engineering and well-known literature, recommendations are formulated for choosing the type of traction element. The final stage is a multivariate calculation of traction elements. It is proposed to evaluate the calculation results taking into account the minimum value of the safety factor in accordance with the EN 81-1: 1998 standard. The calculation of the traction elements considered in the work is only a small part of the process of determining the optimal parameters of the elements of the elevator lifting mechanism. At the same time, already at this stage, variability is introduced, which makes the calculation quite laborious to perform it manually. Obviously, a multivariate calculation method that allows you to analyze many different combinations of parameters of the elements of the elevator lifting mechanism and choose the optimal ones is impossible without the use of a computer.

Changing the technical characteristics of conveyors with a suspended belt in case of failures in the power supply system of drive suspensions

The results of the research presented in the article relate to a fundamentally new type of continuous transport machines-conveyors with a suspended load-carrying belt and a distributed drive. The main advantages of which are due to the features of the kinematic scheme, in which the load-bearing conveyor belt is held by the sides by means of roller suspensions on rolling guides closed along the route and does not interact with its base with supporting supports, and the drive is implemented according to the distributed scheme by the equipment of individual suspensions with individual motor-gear drives. A feature of such a kinematic scheme is the nature of the failures associated with the operation of highly loaded drive suspensions, the influence of which affects the main technical characteristics of the conveyor with a sufficiently increased number. The paper presents a mathematical model designed to calculate the dynamic characteristics of a conveyor with a suspended belt and a distributed drive when the types of failures characteristic of this conveyor design occur, associated with a break in the supply electrical circuit of the motor-gear drive of the suspensions. Based on the developed mathematical model for the reference design of a conveyor with a suspended belt and a distributed drive, a series of numerical calculations of dynamic characteristics in the event of failures of drive suspensions is performed. The obtained results allowed us to establish that with a reduction in the number of groups of consistently failed drive suspensions located with an equal step along the route, the technical characteristics of the conveyor deteriorate: the speed of movement of the load-bearing belt and the total power of the drives are reduced, and the longitudinal tensile stresses in the belt are increased. With an increase in the number of consistently failed drive suspensions within one group, the power and speed of the conveyor decrease non-linearly, and the longitudinal stresses in the conveyor belt increase linearly. In general, the results of calculations of the technical characteristics of the reference idealized design demonstrated the possibility of the conveyor operation in case of failure of 90% of the drive suspensions. The actual performance indicators are determined by the technical characteristics of the used gear motor drives.

ON THE ACCURACY OF POSITIONING OF MOBILE ROBOT'S WALKING PROPULSION DEVICES

The problems of the influence of the choice of the kinematic scheme of the walking mechanism on the positioning accuracy of its foot with the same small positioning errors are considered. The relationships between the laws of changing the coordinates of the foot of the walking mechanism as a material point and the change in the position of the output elements of the motors of the drives of the orthogonal mover and the mover with a parallel chain of drives are established.

STUDY OF THE DYNAMICS OF THE EXOSKELETON ACTUATING UNIT

A person has more than 300 degrees of mobility, but it is practically impossible to recreate such a kinematic scheme. In this article, a kinematic scheme of the exoskeleton is proposed that is most necessary for human movement. A 3D model of the exoskeleton actuating unit with an electrohydraulic drive has been developed in the CAD system and the values of masses, coordinates of mass centers, inertia tensors of the links of the exoskeleton actuating unit have been calculated. A launch file has been developed in the MATLAB environment for modeling the dynamics of the exoskeleton actuating unit. The control laws in the degrees of mobility of the actuating unit of the exoskeleton are selected. As a result of the theoretical study, the ranges of changes in the generalized coordinates for the joints under study are determined. The dependences of the power and the moment in the joints 9, 10 on time are obtained. The conducted studies have shown that lifting the leg will require more energy and this makes it necessary to develop power plants, explore various types of drives and ways to control them energy-efficiently. The obtained data can serve in the development of a medical exoskeleton.

Force analysis of the two-satellite planetary mechanism with elliptical gears

Non-circular gears can be used in modern machines and mechanisms for the implementation of various types of motion and have high strength and compactness compared to linkage mechanisms. This article presents the force analysis of non-circular gear on the example of the planetary mechanism with elliptical gears, providing the rotationally reciprocating motion of the impeller of the stirred tank. Based on the calculation schemes of the links, kinetostatic balance equations for each link of the mechanism are compiled and solved. Reaction forces in kinematic pairs and balancing moment on the input shaft of the mechanism are found. The results can be used in the synthesis and analysis of various machines with the proposed kinematic scheme of the mechanism.

Power Plant for a 0.6­0.8 Class Mobile Vehicle Based on the T­16 Self­Propelled Tractor Chassis

The authors showed the necessity to develop a rear-wheel drive hybrid mobile agricultural vehicle with electric drive and power plant. (Research purpose) To develop and study a new kinematic scheme of a mobile vehicle based on a self-propelled tractor T-16 chassis, which provides increased reliability, comfortable working conditions for the operator, a significant improvement in the environmental situation, and better economic efficiency. (Materials and methods) The authors listed the advantages of the new hybrid vehicle kinematic scheme. They gave the comparative technical characteristics of a diesel engine and an asynchronous electric motor. They developed a new methodology for calculating gas turbine engine technical parameters and described the production process of an electric drive with a capacity of 11 kilowatts to drive the driving wheels. The authors gave a thermal design of the compressor parameters, turbine. They calculated the excess air ratio. According to the parameters obtained, a K27-145 turbocharger was chosen, which simultaneously served as a turbine and a compressor of a gas turbine engine. A kinematic diagram was created with a gas turbine electric generator, storage batteries, an asynchronous frequency-controlled motor and a mechanical gearbox. (Results and discussion) The authors proposed to use a mobile vehicle as a mobile power plant: an output socket with a voltage of 220-230 volts operated from an inverter connected to batteries; the second socket – with a three-phase voltage of 400 volts – from the generator of the power gas turbine plant. (Conclusions) It was proved that the proposed hybrid mobile vehicle design on a battery and a gas turbine was capable of operating throughout the entire working day, and to provide 16 horsepower of a diesel engine, it was enough to install an asynchronous electric motor with a capacity of 7.5 kilowatts. The authors calculated the compressor performance of the gas turbine engine, which was 0.178 kilograms per second. The geometric parameters of the combustion chamber and the technical characteristics of the turbocharger were determined.

Use of electromechanical analogies in the construction and calculation of a simulation model of the process of torsional oscillations of the shaft line of an internal combustion engine

The purpose of the article is to substantiate the possibility of using electromechanical analogies in the construction and calculation of parameters of the simulation model of the process of torsional oscillations of the internal combustion engine shaft, which will allow to move from mechanical models of shafts to their electrical counterparts. Results of the research. The article clarifies the relationship between phenomena occurring in mechanical and electrical systems, mechanical and electrical analogues are established, namely force is considered as electromotive force or voltage, velocity as current, moment of inertia as inductance, spring flexibility as capacitance, coefficient friction as electrical resistance, and the kinematic scheme of the shaft line is presented in the form of a diagram of a reactive bipolar, the parameters of which are determined during analytical calculations of the kinematic scheme of the elastic system. The concept of dynamic stiffness is introduced, which is similar to the concept of reactive resistance of a bipolar. The initial data for the calculation of a linear system in which it is assumed that the pliability of the shock absorber is zero. Conclusions. According to the results of the analogies, the parameters of the simulation model were obtained. The calculation of the elastic system using the method of electromechanical analogies allowed to build a simulation model of the shaft line of an internal combustion engine.