Kinematics of trunk-like robots with piezo actuators

This paper presents the investigation of direct and inverse kinematics for piezo robot with spherical actuators. Two different actions of spherical piezo actuators are intro-duced. Several methods to solve inverse kinematics were analyzed. A geometric approach is chosen for solving the inverse kinematics, because it has a lot of advantages in ac-cordance to other methods. A theory and a concise algo-rithm to find the solutions of the inverse kinematics using the global projections of robot links is presented

Kinematic characteristics of hollow ball under different braking conditions

The purpose of this article is to evaluate smart fluids influence on braking properties for spherical piezo actuator and to determine the functions for rheological experimental graphs of chosen smart fluids. Braking action and motion are modeled using numerical method, which can also be called a stepped approximation. It can be done using Excel program, which can be found in typical Microsoft Office suite

Piezoelectric cantilevers for energy harvesting with irregular design of the cross sections

Results of the numerical and experimental investi-gations of the piezoelectric rectangular cantilevers with ir-regular design of the cross section area are presented in this paper. The aim of the investigation was to analyse how mod-ification of the cross section area by periodical gaps acts on power density of the piezoelectric energy harvesting sys-tems based on a rectangular cantilever. It was found out, that modifications of the cross section area ensure higher strain values and allows to improve strain distribution in piezo ce-ramic layer and by this way to improve power density of the energy harvesting systems. Numerical investigations of the piezoelectric cantilevers with irregular design of the cross section area were performed in order to analyse strain dis-tribution and predict electrical characteristics of the im-proved energy harvesting systems. Experimental investiga-tions of the prototypes were performed and results of the numerical modelling were validated. Results of the numeri-cal and experimental investigation are discussed as well

Analysis of planned motion trajectories for scalable micro-robots

Prototypes of micro-robots and geometric path planning algorithms are presented in this paper. Geometric motion trajectories are generated by switching contacts, control points and tangents methods. Analysis of high-speed formation of trajectories using switching contacts method revealed that the geometric path depends on orientation angle of a micro-robot. Investigation of formation of high-precision trajectories demonstrated that there is minimal deviation from the given motion trajectory at which micro-robot stops. This paper presents methodologies for evaluation of optimal orientation angle of a micro-robot and minimum deflection from the given trajectory. The methodologies are verified by experiments

Control features of 3D deflector under different braking conditions

The purpose of this article is to accurately evaluate the stopping distances of 3D deflector using tunable rheological features of smart fluids. Experimental characteristics of the chosen fluids are changed into smooth polynomial functions in accordance to the form of experimental graph and small total difference of ordinate values. Braking action and motion are modeled using a stepped approximation method, which is simple to use. This method was performed with Microsoft Excel program

Research and development of piezoelectric active supports for precise shafts

Design and investigation of active piezoelectric block, having a precise V-shaped groove for checking the roundness or concentricity of precise shafts is presented. Piezoelectric V-block realizes the rotation and translational motion of the precise shaft and is characterized by zero base errors of motion generation system. Numerical modeling based on finite element method is performed to find resonant frequencies and modal shapes of the piezoelectric actuator. The trajectories of the contacting points for shaft – piezoelectric actuator is defined. Results of numerical and experimental studies are presented

Manipulators with two levels of friction control between links, implemented using piezoelectric transducers, oscillating in burst type excitation mode

The paper discusses the results of development and investigation of the new class of multi-degree-of-freedom robots, based on new concept. Classical rule of Robotics – the number of degree-of-freedom of robot should be equal to the number of applied actuators – is questioned here. This concept is realized by using kinematic pairs with alternating degree-of-freedom, controlled by a solitary force or moment, changing its direction in space. The number of degree-of-freedom of kinematic pair is controlled from 0 to 3, exploiting the dependence of friction forces upon oscillation in the contact zone of links

Methodology of calibration of vertical angle measurements

At the moment in Lithuanian there is no existing reglamentation dealing with calibration or testing of geodetic angle measuring instrumentation (as theodolites, tacheometers, laser scanners, laser trackers etc.) in full range of its angular measurements. Though calibration and testing of horizontal angle measurements can be performed by multiple methods, calibration of vertical angle measurements still is a serious problem. In the paper a review on possible methodology of calibration and testing of vertical angle measuring instrumentation (like tacheometers, laser scanners etc.) is given together with proposed principles and technical solutions for the calibration

Polynomial error approximation of a precision angle measuring system

The paper deals with the calibration of a flat angle measuring system. The article describes a comparative method for using a multi-angular prism (polygon) with autocollimator along with an angle measuring system. The components of angle measuring system is analysed in the paper. The article also presents polynomial error approximation and the obtained results of calibrating the precision angle measuring system as well as discusses preliminary assumptions for further research

Cylindrical piezorobot’s trajectory planning and control

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