Inter-robot relative positions are crucial for executing various multirobot missions, such as formation maneuvering and collaborative inspection. However, the current sensing technology usually provides part of relative position information, such as inter-robot distances, bearings and angles. This prompts the study of determining inter-robot relative positions, i.e., relative localization, from these partial measurements. Based on the existing results of static networks' localizability and mobile robots' relative localization, we propose a novel concept,relative localizabilityto describe whether a multirobot system isrelatively localizable. Given each robot's self-displacement measurements and inter-robot partial measurements in$d$($d\leq 4$) sampling instants, we show that a multirobot system's relative localization can be achieved in a purelyalgebraicanddistributedmanner, in which the multirobot system is said to be$d$-step relatively localizable. To make the results more general, we consider that the multirobot system consists of landmarks, leaders, and followers, and that the inter-robot measurements can be distances, bearings or angles. When robots' coordinate frames have different orientations, we show that the given local measurements can be used to determine robots' relative positions and their coordinate frames' relative orientations simultaneously. Simulations and experiments of relative localization for ground robots are conducted to validate the obtained results.

Based on the different types of input and output filters, the single-phase high-frequency link matrix rectifier is divided into voltage source and current source. Respectively, for the voltage and current source circuit proposed de-re-coupling coupled PWM modulation strategy, and the working state of voltage and current source topology in a high frequency period is analyzed in detail. Finally, the simulation results verify the correctness and feasibility of the proposed method.

Aiming at the topology of single-phase current source high-frequency link matrix rectifier, a novel unipolar frequency doubling de-re-coupling SPWM method is proposed. The basic idea and the corresponding logic combination are used to control the matrix converter. And the working state of the circuit topology in a high frequency period is analyzed. The proposed new modulation method eliminates the voltage spikes generated by the leakage current of the transformer, and it realizes the natural commutation. Finally, the simulation results verify the correctness and feasibility of the proposed modulation method.

There are many methods for detecting harmonic current in grid, which have different characteristics. Ip-iqdetection method based on instantaneous reactive power theory is complex and various link, when the grid voltage is unbalanced, the grid synchronization signal error will appear, and low-pass filter (LPF) in harmonic detection link brings influence about rapidity. In order to detect the harmonic current accurately and rapidly, realize the compensation of full current harmonics, this article presents a harmonic detection method based on sinusoidal amplitude integrators (SAI), which is not only suitable for balanced grid, but also can detect the harmonic current accurately when the grid is unbalanced. The harmonic current detection method based on sinusoidal amplitude integrator is used to extract the positive sequence fundamental current based on the positive sequence SAI structure. The simulation of the proposed method is carried out under the condition of balanced and unbalanced grid, which verifies the feasibility and effectiveness of the proposed method.

In this paper, on the basis of single phase high frequency link matrix inverter and Z source network, a single-phase Z source high frequency link matrix inverter is proposed. And use a modulation strategy named pre and post coordinated SPWM. which using boost pulse width modulation as the former, and the matrix converter work in an all `1' state when the former direct connection. Z source inverter overcomes the alternating current waveform distortion caused by the need of dead time in traditional inverter's same bridge arm. And the Z source inverter has the function of boost and buck, can achieve a wide range of voltage output. The matrix converter adopts bidirectional switch, which can realize the bidirectional flow of energy, and can adjust the power factor flexibly. In this paper, the operating mode of single phase Z source high frequency link inverter is analyzed. Secondly, the mathematical model of Z source high frequency link matrix inverter system is established. Finally, the MATLAB software is used to simulate and verify the single-phase Z source high frequency link inverter.