A Compact Adjustable Stiffness Rotary Actuator Based on Linear Springs: Working Principle, Design, and Experimental Verification

Inspired by improving the adaptive capability of the robot to external impacts or shocks, the adjustable stiffness behavior in joints is investigated to ensure conformity with the safety index. This paper proposes a new soft actuation unit, namely Adjustable Stiffness Rotary Actuator (ASRA), induced by a novel optimization of the elastic energy in an adjusting stiffness mechanism. Specifically, a stiffness transmission is configured by three pairs of antagonistically linear springs with linkage bars. The rotational disk and link bars assist the simplified stiffness control based on a linear transmission. To enhance the elastic energy efficiency, the force compressions of the linear springs are set to be perpendicular to the three-spoke output element, i.e., the output link direction. Besides, the ASRA model is also formed to investigate the theoretical capabilities of the stiffness output and passive energy. As a simulated result, a high passive energy storage ability can be achieved. Then, several experimental scenarios are performed with integral sliding mode controllers to verify the physical characteristics of the ASRA. As trial results, the fast transient response and high accuracy of both the position and stiffness tracking tests are expressed, in turn, independent and simultaneous control cases. Moreover, the real output torque is measured to investigate its reflecting stiffness.

Coalescence as autosegmental spreading and delinking

Phonological coalescence, understood as a type of synchronic alternation in which two phonological elements seem to fuse into one, presents a prima facie challenge for versions of Optimality Theory that assume the principle of containment. If all underlying material has to be present in the output form, replacing two input elements with a single output element is not straightforward. I argue that, under the assumptions of Autosegmental Coloured Containment Theory, a distinct operation of coalescence is unnecessary, as all major types of coalescence patterns can be analysed in terms of (i) adding new association lines between some autosegmental nodes, and (ii) the underparsing of other nodes, leading to their phonetic non-realisation. The proposed analysis accurately reflects the heterogeneity of coalescence alternations, which are shown to fall into three different types.

A measurement method of fifth-generation multiple-input multiple-output antenna based on microwave imaging

An increase in the quantity and density of antenna elements increases the mismatched failure rate and measurement difficulty of the multiple-input multiple-output. To simplify the measurement method of the S11 parameter utilizing the traditional vector network analyzer, this article proposes a multiple-input multiple-output measurement method based on microwave imaging. The multiple-input multiple-output element was designed, and then the existence of mismatched scattering of the mismatched state through microwave one-dimensional and two-dimensional imaging simulations was verified. A wideband Vivaldi antenna was designed for measurement imaging verification. The research results show that the proposed method is capable of detecting the mismatched scattering of mismatched elements as well as accurately locating the mismatched elements and mismatched position of circuits behind the element, which improves the measurement efficiency.

Determination of Kinematic Parameters of Rotary Transmission Tooled with Hydraulic Cylinders

The paper considers mathematical model developed by the authors which determines the relation of design factors of transmission tooled with hydraulic cylinders to kinematic parameters of output element movement. The paper also provides description of methods to determine pumping unit efficiency for rotary transmission tooled with hydraulic cylinders.

High Power Microwave Compressor with Two Output Units for Synchronous Energy Extraction

The compressor contains the oversized cylindrical cavity with two interference output units each in the figure of a circular waveguide H-tee. The H-tees are coupled by a waveguide section and the energy is extracted synchronously through two output ports. The synchronism is provided through using a single microwave switch mutual for both H-tees. Simulation and experimental study of the X-band microwave compressor were carried out. The simulation made it possible to optimize the configuration of the oversized storage cavity and the output element. The amplification factor was 14 dB when the energy was extracted though one output unit at the output pulsewidth of 6...7 ns. Amplification factor and the output power were increased by 2dB and the pulsewidth was decreased down to 3...3.5 ns when the energy was extracted synchronously through two output units.

Modelling and Testing of a Toroidal CVT

This paper deals with the design and testing of a miniature CVT prototype. The CVT under study is a special toroidal-type, which is able to maintain a quasi-constant power at the output element by automatically changing the transmission ratio function of the torque applied to the output element. The power-transmitting elements of the device have been built by modifying rolling element bearings.

Analysis of the Experimental Torque Characteristic of a Magnetorheological Clutch Using Neural Networks

In this paper the dependence of the torque characteristic of a magnetorheological clutch on several working parameters is analysed by means of a feedforward neural network. The clutch was envisaged to have the possibility to disengage the vacuum pump in diesel engine vehicles, in order to increase the overall vehicle efficiency. A large set of test was carried out following different protocols in order to obtain a detailed characterization of the clutch. Results showed how, due to the characteristics of MR fluids and to the complex mechanism of torque transmission, the torque characteristics (both the yield torque and the torque-slip behaviour) is function of the relative speed between the primary and secondary clutch groups and also function of the dissipated energy during the clutch slip and of the rest time between consecutive slippages. The data acquired during all tests were used to train a neural network with five input elements and one output element. The developed neural network was proved to satisfactorily reproduce the actual clutch properties and can be used in the future in an engine-vehicle simulator in order to model the torque characteristic of the clutch subjected to different operating cycles.

Kinematic Analysis of a Belt Mechanism with a Circular Eccentric Output Element

The paper proposes two methods for kinematic analysis of a belt mechanism with circular eccentric output element (link). One of them is based on the mechanisms geometry and the second on its kinematics in order to obtain the transmission functions of different order. Both approaches are based on a imaginary cam mechanism instantaneous isokinetic with the given belt mechanism. The transmission functions obtained by means of proposed procedures are in a numerical form due to the finite incremental method used in solving the problem.