In this paper, a balanced-to-balanced (BTB) inphase filtering power divider (FPD) is proposed, which can realize a two-way equal power division with high selectivity and isolation. The design of the proposed FPD is primarily based on microstrip/slotline transition structures and slotline T-junction. A U-type microstrip feed line integrated with a stepped-impedance slotline resonator is adopted at the input and output ports, which makes the differential-mode (DM) responses independent of the common-mode (CM) ones. Meanwhile, superior DM transmission and CM suppression are achieved intrinsically, thereby simplifying the design procedure significantly. By employing slotline resonators loaded with resistors, the isolation between the two output ports can be improved greatly. In addition, a DM passband with a sharp filtering performance is realized by introducing the microstrip stub-loaded resonators (SLRs). By changing the electrical length of the open-stub of the SLR, the fractional bandwidth (FBW) is controllable. In order to verify the feasibility of the proposed design method, two prototype circuits of the proposed FPDs with different bandwidths are fabricated and measured. Good agreement between the simulation and measurement results is observed.
This work intends to enhance the mobility and flexibility of a tracked mobile robot through changing its shape in unstructured environments. A shape-shifting mobile robot, AMOEBA-I, has been developed. With three tracked modules, AMOEBA-I has nine locomotion configurations and three of them are symmetrical configurations. The key advantage of this design over other mobile robots is its adaptability and flexibility because of its various configurations. It can change its configuration fluently and automatically to adapt to different environments or missions. A modularized structure of the control system is proposed and designed for AMOEBA-I to improve the fault tolerance and substitutability of the system. The strategies of cooperative control, including cooperative shape shifting, cooperative turning and cooperative obstacle negotiation, have been proposed to improve the capability of shape shifting, locomotion and obstacle negotiation for AMOEBA-I. A series of experiments have been carried out, and demonstrated that such a structure possesses excellent mobility and high flexibility under various urban environments including stairs, a narrow space, an obstacle, uneven debris and an underground garage. Being small, portable, and remotely controlled, AMOEBA-I has potential applications in areas such as urban search and rescue and environment reconnaissance.
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