ABSTRACT
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.
ABSTRACT
A multifunctional device to transfer graphical or text information for blind or visually impaired is presented. The prototype using tactile perception has been designed where information displayed on the screen of electronic device (mobile phone, PC) is transferred by oscillating needle, touching the fingertip. Having the aim to define optimal parameters of the fingertip excitation by needle, the computational analysis of different excitation modes has been carried out. A 3D solid computational finite element model of the skin segment, comprising four main fingertip skin layers (stratum corneum, epidermis, dermis and hypodermis) was built by using ANSYS Workbench FEA software. Harmonic analysis of its stress-strain state under excitation with different frequency (up to 10000 Hz) and harmonic force (0.01 N), acting outer stratum corneum layer in normal direction at one, two or three points has been performed. The influence of the mode of dynamic loading of skin was evaluated (in terms of the tactile signal level) on the basis of the normal and shear elastic strain in dermis, where mechanoreceptors are placed. It is shown that the tactile perception of information, delivered by three vibrating pins, may be influenced by configuration of excitation points (their number and phase of loading) and the frequency of excitation.
