Coupling tunable D-band directional coupler for millimeter-wave applications

A coupling tunable D-band directional coupler is designed based on a novel coupling grid structure proposed in this letter. The designed directional coupler has excellent performance with ultra-wideband. The coupling can be tuned from -28.2 dB to -33.2 dB at 140 GHz by changing the angle of the coupling grid, and the dynamic range of the coupling is about 5 dB. The return loss is smaller than -15 dB in the whole D-band from 110 GHz to 170 GHz. A 3-dB coupler use the similar coupling structure is also designed. The coupling is 3.3144 dB at the center frequency of 140 GHz.Comment: 2 pages, 6figure

Design of Millimeter-wave Detector for Gyrotron Power Monitoring

The real-time power monitoring of gyrotron is one of the key issues in the operation of electron cyclotron resonance heating system. The detector can be used for real-time power monitoring. We analyzed the principle of diode detection and designed a D-band wideband detector based on Schottky diode in this paper. The detector includes a waveguide-to-microstrip transition, a matching circuit, a diode, and a low pass filter. A novel waveguide-to-microstrip transition was developed based on probe coupling. A wideband lossy matching circuit was developed based on tapered-line and series matching resistor. The simulation results show that when the input power is -30dBm at 140 GHz, the detection sensitivity is about 1600V/W.Comment: 12 pages, 19 figure

Hybrid Task Constrained Planner for Robot Manipulator in Confined Environment

Trajectory generation in confined environment is crucial for wide adoption of intelligent robot manipulators. In this paper, we propose a novel motion planning approach for redundant robot arms that uses a hybrid optimization framework to search for optimal trajectories in both the configuration space and null space, generating high-quality trajectories that satisfy task constraints and collision avoidance constraints, while also avoiding local optima for incremental planners. Our approach is evaluated in an onsite polishing scenario with various robot and workpiece configurations, demonstrating significant improvements in trajectory quality compared to existing methods. The proposed approach has the potential for broad applications in industrial tasks involving redundant robot arms

Safety Index Synthesis with State-dependent Control Space

This paper introduces an approach for synthesizing feasible safety indices to derive safe control laws under state-dependent control spaces. The problem, referred to as Safety Index Synthesis (SIS), is challenging because it requires the existence of feasible control input in all states and leads to an infinite number of constraints. The proposed method leverages Positivstellensatz to formulate SIS as a nonlinear programming (NP) problem. We formally prove that the NP solutions yield safe control laws with two imperative guarantees: forward invariance within user-defined safe regions and finite-time convergence to those regions. A numerical study validates the effectiveness of our approach