The main focus of the article is an advanced actuator, designed and optimized for small dynamic legged robots. The presented actuator prototype is unique, as the market lacks similar solutions when dimensions and weight of the module are considered. The actuator has a modular structure, which makes it easy to replace in case of malfunction and simplifies the overall structure of the robot. High torque bandwidth, achieved by the module, is crucial to agile locomotion, obstacle avoidance and push recovery of the quadrupedal robot. The Authors have conducted a solution review aimed at similar small-size modules. It was found that there are no advanced actuators suitable for sub 5 kg quadruped robots. The unique design presented in this paper is described in all three aspects: mechanical, electrical and software. The mechanical section depicts the solutions implemented in the module, especially the low gear ratio gearbox. The custom brushless motor driver is presented in the electrical section, together with detailed diagrams and hardware descriptions. The last section depicts solutions implemented in the software, the main motor control algorithm and auxiliary modules such as automatic motor parameter identification and encoder misalignment correction. Tests performed in the last part of this paper validated the design goals established for the actuator. The results confirmed the high torque capability and exhibited the motor saturation region. Continuous and peak torque were measured based on the thermal characteristics of the module. Moreover, the automatic motor parameter identification process carried out by the controller itself was validated by manual measurements.

Doping is one of the possible ways to significantly increase the thermoelectric properties of many different materials. It has been confirmed that by introducing bismuth atoms into Mg sites in the Mg2Si compound, it is possible to increase career concentration and intensify the effect of phonon scattering, which results in remarkable enhancement in the figure of merit (ZT) value. Magnesium silicide has gained scientists’ attention due to its nontoxicity, low density, and inexpensiveness. This paper reports on our latest attempt to employ ultrafast selfpropagating high-temperature synthesis (SHS) followed by the spark plasma sintering (SPS) as a synthesis process of doped Mg2Si. Materials with varied bismuth doping were fabricated and then thoroughly analyzed with the laser flash method (LFA), X-ray diffraction (XRD), scanning electron microscopy (SEM) with an integrated energy-dispersive spectrometer (EDS). For density measurement, the Archimedes method was used. The electrical conductivity was measured using a standard four-probe method. The Seebeck coefficient was calculated from measured Seebeck voltage in the sample subjected to a temperature gradient. The structural analyses showed the Mg2Si phase as dominant and Bi2Mg3 located at grain boundaries. Bismuth doping enhanced ZT for every dopant concentration. ZT = 0:44 and ZT=0.38 were obtained for 3wt% and 2wt% at 770 K, respectively.

Discrete two-dimensional orthogonal wavelet transforms find applications in many areas of analysis and processing of digital images. In a typical scenario the separability of two-dimensional wavelet transforms is assumed and all calculations follow the row-column approach using one-dimensional transforms. For the calculation of one-dimensional transforms the lattice structures, which can be characterized by high computational efficiency and non-redundant parametrization, are often used. In this paper we show that the row-column approach can be excessive in the number of multiplications and rotations. Moreover, we propose the novel approach based on natively two-dimensional base operators which allows for significant reduction in the number of elementary operations, i.e., more than twofold reduction in the number of multiplications and fourfold reduction of rotations. The additional computational costs that arise instead include an increase in the number of additions, and introduction of bit-shift operations. It should be noted, that such operations are significantly less demanding in hardware realizations than multiplications and rotations. The performed experimental analysis proves the practical effectiveness of the proposed approach.