Hybrid Beamforming Transmitter Modeling for Millimeter-Wave MIMO Applications

<div>Hybrid digital and analog beamforming is an</div><div>emerging technique for high-data-rate communication at</div><div>millimeter-wave (mm-wave) frequencies. Experimental evaluation</div><div>of such techniques is challenging, time-consuming, and costly.</div><div>This article presents a hardware-oriented modeling method for</div><div>predicting the performance of an mm-wave hybrid beamforming</div><div>transmitter. The proposed method considers the effect of active</div><div>circuit nonlinearity as well as the coupling and mismatch in the</div><div>antenna array. It also provides a comprehensive prediction of</div><div>radiation patterns and far-field signal distortions. Furthermore,</div><div>it predicts the antenna input active impedance, considering</div><div>the effect of active circuit load-dependent characteristics. The</div><div>method is experimentally verified by a 29-GHz beamforming</div><div>subarray module comprising an analog beamforming integrated</div><div>circuit (IC) and a 2 × 2 subarray microstrip patch antenna.</div><div>The measurement results present good agreement with the</div><div>predicted ones for a wide range of beam-steering angles. As a</div><div>use case of the model, far-field nonlinear distortions for different</div><div>antenna array configurations are studied. The demonstration</div><div>shows that the variation of nonlinear distortion versus steering</div><div>angle depends significantly on the array configuration and beam</div><div>direction. Moreover, the results illustrate the importance of</div><div>considering the joint operation of beamforming ICs, antenna</div><div>array, and linearization in the design of mm-wave beamforming</div><div>transmitters.</div>

Hybrid Beamforming Transmitter Modeling for Millimeter-Wave MIMO Applications

<div>Hybrid digital and analog beamforming is an</div><div>emerging technique for high-data-rate communication at</div><div>millimeter-wave (mm-wave) frequencies. Experimental evaluation</div><div>of such techniques is challenging, time-consuming, and costly.</div><div>This article presents a hardware-oriented modeling method for</div><div>predicting the performance of an mm-wave hybrid beamforming</div><div>transmitter. The proposed method considers the effect of active</div><div>circuit nonlinearity as well as the coupling and mismatch in the</div><div>antenna array. It also provides a comprehensive prediction of</div><div>radiation patterns and far-field signal distortions. Furthermore,</div><div>it predicts the antenna input active impedance, considering</div><div>the effect of active circuit load-dependent characteristics. The</div><div>method is experimentally verified by a 29-GHz beamforming</div><div>subarray module comprising an analog beamforming integrated</div><div>circuit (IC) and a 2 × 2 subarray microstrip patch antenna.</div><div>The measurement results present good agreement with the</div><div>predicted ones for a wide range of beam-steering angles. As a</div><div>use case of the model, far-field nonlinear distortions for different</div><div>antenna array configurations are studied. The demonstration</div><div>shows that the variation of nonlinear distortion versus steering</div><div>angle depends significantly on the array configuration and beam</div><div>direction. Moreover, the results illustrate the importance of</div><div>considering the joint operation of beamforming ICs, antenna</div><div>array, and linearization in the design of mm-wave beamforming</div><div>transmitters.</div>

High-Bandwidth Active Impedance Control of the Proprioceptive Actuator Design in Dynamic Compliant Robotics

Dynamic compliant robotics is a fast growing field because of its ability to widen the scope of robotics. The reason for this is that compliant mechanisms may ensure safe/compliant interactions between a robot and an external element—for instance, a human operator. Active impedance control may widen the scope even further in relation to passive elements, but it requires high-bandwidth robust torque and active impedance control which induces high-noise issues even if high-end sensors are used. To address these issues, a complete controller design scheme, including Field-Oriented Control (FOC) of a Brushless Direct Current (BLDC) motor, is proposed. In this paper, controller designs for controlling the virtual impedance, motor torque and field are proposed which enables high-bandwidth robust control. Additionally, a novel speed and angle observer is proposed that aims to reduce noise arising in the angle sensor (typically a 12-bit magnetic encoder) and a Kalman/Luenberger based torque observer is proposed that aims to reduce noise arising in the phase current sensors. Through experimental tests, the combination of the controller designs and observers facilitated a closed-loop torque bandwidth of 2 . 6 k Hz and a noise reduction of 13 . 5 (in relation to no observers), at a sample rate and Pulse Width Modulation (PWM) frequency of 25 k Hz . Additionally, experiments verified a precise and high performing controller scheme both during impacts and at a variety of different virtual compliance characteristics.