This paper presents an optimized design and motion planning method of a hydraulically driven leg for jumping. The knee joint range was enlarged, and the desired torque profile was achieved using a ...four-bar linkage. The dynamics of the robot were considered during the motion planning, and the optimal trajectory was obtained by linear programming. Simulations and experiments showed that the leg could jump 1 m under a load of 50 kg.
AUV docking devices have the ability to achieve homing of the AUV, supply the AUV with energy, and exchange data with it, thus improving the endurance and ensuring the continuous long-term and ...large-scale operation of the AUV. To improve the successful docking rate of the AUV, a funnel-shaped underwater docking device with multi-degree freedom based on a deep-sea platform was designed in this paper. The heading angle, pitch angle, and roller angle of the docking device could be adjusted in a timely manner according to the current flow direction and the position of the AUV. In order to realize the timely adjustment of the heading angle, pitch angle, and roll angle of the docking device, a set of underwater hydraulic systems was developed as the power source to drive the corresponding hydraulic cylinders, hydraulic motors, and other executive components. The model of the heading angle adjustment circuit of the hydraulic system was established and the open-loop transfer function of the heading angle adjustment circuit was derived. The dynamic response performance of the hydraulic circuit was simulated and the optimized PID algorithm was used to improve the dynamic response performance. Finally, the accuracy of the heading angle adjustment circuit model and the effectiveness of the control algorithm were validated by experiment of the docking device in a water pool.
Problem. The choice of the machine drive type at the design stage is a complex and multifaceted task, the correct solution of which largely depends on its technical level and operational qualities. ...The aim of the study is to identify the ways to increase the energy efficiency of technological machine drives and to develop an algorithm for selecting the drive type. Methodology. System analysis made it possible to analyze the environmental parameters in which it is appropriate to use a drive of one type or another, to develop criteria for comparing their application efficiency. The theory of automatic control methods made it possible to establish the drive characteristics. The theory of mechanisms and machines methods made it possible to determine the mass, size, and energy parameters of drives. Results. The main actions to improve the energy efficiency of technological machine drives are considered, an algorithm for choosing the drive type has been developed and a table has been created to compare the main consumer properties of drives. It has been established that the electrical drive of the executive elements is currently the main one in the area of mechatronic systems. It provides good control, easy feedback organization, high efficiency, and the best mass-dimensional efficiency. Originality. Considering the maximum number of factors, an algorithm for choosing the drive type has been developed. Criteria for com-paring the efficiency of different drive types are proposed. Areas of effective application of electrical, hydraulic, pneumatic, and mechanical drives and their limiting output parameters are given. Practical value. Application of the developed algorithm reduces the time for selecting the drive type. In the future, it is necessary to supple-ment the existing database on the use of various drive types, based on the latest developments of their elements and circuit solutions, to develop new criteria for comparing drives of various types.
The high work rate, quick reversibility, and step-less gear ratio are some key features for designing efficient hydraulic mobile equipment. In this article overall performances as well the losses ...associated with the hydro-motor under variable displacement conditions have been investigated. The performance analyses have been carried out over a wide range of speed and load demands. The effect of the displacement conditions of the motor is taken into account consideration for the performance evaluation of the motor in an in-house fabricated closed-circuit hydrostatic drive system. For the present study, a variable displacement bent axis hydro-motor of capacity 28 cc has been used. From the rigorous experimentation, data are recorded under different operating conditions and at different motor displacements. The effect of losses on hydro-motor performance is characterized. The results obtained in the present study are likely to be helpful in the preliminary selection of similar hydraulic components as well as in optimizing their performance working in underground mining operations under adverse working conditions.
This paper presents a proposed strategy for improving the position-tracking accuracy of force-based impedance control in hydraulic single-leg robots. Initially, the mechanical structure and drive ...system of the single-leg robot are introduced. Subsequently, a kinetic and dynamic model is developed to determine the desired position and force for each joint based on the given action. The proposed strategy, called equivalent stiffness impedance control, is then presented. It combines a penalty function and the stiffness of each joint near the desired position to calculate the equivalent stiffness. Simulations and experiments are conducted to evaluate the performance of the control strategy. The results demonstrate that the proposed strategy achieves fast response speed and high position tracking accuracy. Moreover, the mechanical characteristics near the desired position are comparable to traditional impedance control. This research provides valuable insights for impedance control in bionic-legged robots.
In order to comply with agrotechnical requirements and reduce fuel consumption when performing tillage operations, various methods of controlling the depth of plowing are used: position, draft, ...height and mixed. The choice of the method is carried out subjectively by the operator in the presence of appropriate technical means and visual assessment of the results of the work, therefore, substantiation of the rational controlling method is an urgent task. The results of theoretical studies of the process of controlling the depth of tillage by the working bodies of the plowing unit are given. Taking into account the elastic and damping properties of tires, the parameters of power wiring, as well as the compressibility of the working fluid in the nodes of the hydraulic system and the pliability of pipelines, a mathematical description of the process of functioning of the plowing unit equipped with an electrohydraulic drive of the attachment is compiled. Using mathematical modelling with force and kinematic disturbances from the soil, comparative statistical estimates are obtained on the accuracy of the tillage depth and energy consumption for the control process with various methods of regulation. Based on the numerical implementations of the model for the given conditions of the agrophone, a rational method of regulation is determined which satisfies the specified requirements. It is noted that with the altitude-force method of control, the smallest deviation of the tillage depth from the specified one is achieved with a decrease in energy consumption in comparison with the power method by 1.2 times.
The dynamic processes of the system of stabilization of the speed of the conveyor belt with a built-in hydraulic drive on the basis of an improved mathematical model, which takes into account the ...physical phenomena occurring in the hydraulic system during the action of alternating load. The influence of the main parameters of the hydraulic system and the magnitude of the load on the course of dynamic processes is analyzed and recommendations for their selection are formulated. The proposed scheme of the built-in hydraulic drive of a conveyor belt with system of stabilization of speed of movement automatically provides its uninterrupted work. The use of an additional hydraulic pump allowed to stabilize the speed of the conveyor belt to 7.8%, provided that the load on the working link is 2.3 times.
This paper presents a method to solve the kinematics of a rigid-flexible and variable-diameter continuous manipulator. The multi-segment underwater manipulator is driven by McKibben water hydraulic ...artificial muscle (WHAM). Considering the effect of elasticity and friction, we optimized the static mathematical model of WHAM. The kinematic model of the manipulator with load is established based on the hypothesis of piecewise constant curvature (PCC). We developed an optimization algorithm to calculate the length of the WHAMs according to the principle of minimum strain energy and obtain the configuration space parameters of the kinematic model. Based on the infinitesimal method, the homogeneous transformation matrices of the variable-diameter bending sections are computed, and the terminal position and attitude are obtained. In this paper, we studied the working space of the manipulator by quantitative analysis of the impact factors including pressure and load. A deep neural network (DNN) with six hidden layers is designed to solve inverse kinematics. The forward kinematic results are used to train and test the DNN, and the correlation coefficient between the output and target samples reaches 0.945. We carried out an underwater experiment and verified the effectiveness of the kinematic modeling and solution method.
The work presents a segmented pump-motor control scheme of a closed-loop hydraulic drive used in mining equipment. It analyses the dynamics of the drive through modeling and simulation. The system ...model integrates a control scheme for modulating the displacement of the pump and the hydro-motor of the hydraulic drive. The model also considers the state-dependent non-linear losses as well as the transient behaviors of the pump and the hydro-motor. The experimental results validate the model for various working conditions of the equipment. The model simulation also analyses the perturbation of critical parameters and control gain on the system's performance for a wide range of operating conditions of the mining equipment. The study performed in this research work will be expedient for the preliminary design and assortment of similar hydraulic drive used in the mobile equipment.
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