This paper analyses the movement of piezoelectric actuator. The goal of this work was to create an algorithm for trajectory planning of piezorobot, create a system for trajectory control, develop software and verify the functioning of the algorithm in practice. Movements of piezorobot are very small and very frequent therefore it is difficult to measure trajectories using standard equipment. Design of a novel measurement system and trajectory adjustment was created in this paper. An experimental system for control and trajectory movement tracking of piezorobot was developed. It consists of cylindrical piezorobot, control signal forming and image processing system for trajectory tracking. The cylindrical piezorobot moves in specific trajectories on the plane and is controlled with sinusoidal signals. They are generated by trajectory forming and control software using MATLAB and LabVIEW. The control signals are monitored using a system with oscilloscope. The trajectory of piezorobot was monitored and measured using video camera and video processing software developed by LabVIEW. The software contains image processing and object path tracking, and is implemented using LabVEW and MATLAB. Experimental results showed that trajectories forming algorithm and developed control software is suitable for controlling robots moving on plane.

There is an ever-increasing demand for small-size, low-cost, and high-precision positioning systems. Therefore, investigation in this field is performed to search for various solutions that can meet technical requirements of precise multi-degree-of-freedom (DOF) positioning systems. This paper presents a new design of a piezoelectric cylindrical actuator with two active kinematic pairs. This means that a single actuator is used to create vibrations that are transformed into the rotation of the sphere located on the top of the cylinder and at the same time ensure movement of the piezoelectric cylinder on the plane. Numerical and experimental investigations of the piezoelectric cylinder have been performed. A mathematical model of contacting force control was developed to solve the problem of positioning of the rotor when it needs to be rotated or moved according to a specific motion trajectory. The numerical simulation included harmonic response analysis of the actuator to analyze the trajectories of the contact points motion. A prototype actuator has been manufactured and tested. Obtained results confirmed that such a device is suitable for both positioning and movement of the actuator in the plane.

This paper presents results on the development and investigation of new miniature robots with increased number of degrees of freedom, based on the application of piezoelectric kinematic pairs with multi-DOF. The schematics of technologically advanced multi-DOF active kinematic pairs are presented and the details of their control are explained. The structure control of multi-DOF active kinematic pairs is based on sectioning of electrodes of the piezoelectric actuators and allows selecting desirable types of oscillations and speeds of links. Three modifications of piezoelectric robots with 6 and 15 DOFs are provided, together with their resolutions and responses to step inputs. Modal and harmonic analyses were performed and displacements of contact points were obtained. Trajectory planning algorithms are developed based on the numerical results.

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The operational problem of container unloading from the ship is analyzed in this paper. Dynamic “crane-cargo-ship” system was investigated, and a mathematical model was created. In the model, the gap between the container and the ship’s cargo hold, the mass of the cargo, the container’s center of the mass, and the frictional forces that may occur during lifting from the cargo hold were estimated. Numerical analysis of the system was performed. Results of numerical analysis were compared with experimental measurements of containers unloading process in port. Requirement of lifting power was modelled depending on mass of cargo. Additional power needs in case of contact forces between container and wall of the ship’s cargo hold were calculated. Rational lifting conditions could be deduced using a created mathematical model and the reliability of the container and cargo during lifting could be deduced.