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The development of vision-based navigation algorithms using a camera is becoming more important. The vision-based navigation can be categorized into two types. The first is to use sequential camera images as relative navigation. The second is to estimate the absolute navigation solution using a camera image and database. In absolute navigation, the difference between the database and the camera image is a major obstacle to image registration. One of the factors that make a lot of difference is the shadow effect. This shadow increases the inconsistency between the two images and eventually degrades the localization accuracy. This means that shadows have a significant impact when measuring the similarity of the two templates. To mitigate this effect, we inherited and developed the Monte Carlo Localization (MCL) algorithm based on a new similarity cost function, which is a key contribution to this article. We have established the importance of information with information reallocation logic that considers shadow areas. The proposed algorithm allocates the importance of the information considering a portion of the shaded area in the camera image. First of all, we analyzed the effects of shadows on the camera. To compare the performance of the algorithm, we used not only the shadow restoration algorithm but also various template-based matching algorithms. The proposed algorithm is validated through various simulations and real flight experiments as well.

We present a new navigation structure using dual databases for aerial vehicle, which include the simple switching technique. It is possible to use the various database for an alternative navigation system. We utilize the terrain referenced navigation (TRN) and image-based navigation (IBN). The TRN has been researched for fighter aircraft or cruise missiles. And the IBN is widely researched recently during the computer science technologies are rapidly grown up. Generally, the TRN is very effective on the environment with high altitude fluctuation with uniqueness. However, the IBN provides a very accurate pose of the vehicle for the environment with a lot of features in the input camera image. However, both algorithm has disadvantages that are greatly influenced by the operating environment. We propose a fusion structure using both algorithms with adaptive logic based on decision making logic. The decision variable includes the roughness and uniqueness of the environment. We use a stochastic linearization (SL) method in TRN also, which is widely known as an essential method on TRN using digital elevation map (DEM). In the case of the IBN, we use the speed up robust feature point (SURF) algorithm for the matching process, which is invariant to translation, rotation, scale, and illumination. Both measurement models are fused with the extended Kalman filter(EKF). We conducted simulations to validate the proposed structure using DEM and aerial projective map. Two kinds of databases are provided by the Ministry of Land, Infrastructure and Transport in the Republic of Korea.

Nano-satellite has payload limitation to minimize weight and cost then minimum number of attitude sensors can be loaded which are sun sensor, magnetometer and gyroscope. However, The sun sensor cannot be used during eclipse, nano-satellite keeps estimating attitude with model propagator. Which contains the uncertainty, torque disturbance. For small satellite has too low moment of inertia to vulnerable to disturbance relatively. In this reason torque disturbance can be critical point to estimate attitude using propagator. The recursive attitude determination algorithm using Kalman filter is very widely used. For this reasons, attitude determination algorithms based on adaptive extended Kalman filter with disturbance torque are introduced. Which are P-scaling, Q-scaling and Q-estimation technic. In this paper, it is assumed disturbance torque represents the model uncertainty. This research shows it is possible to estimate the disturbance, angular rate and attitude of the satellites through the simulation. To solve the attitude determination problem for nano-satellite, It is possible to estimate not only attitude but also disturbance through the adaptive algorithms.

We formulated a cubic spline trajectory planner with arc-length parameter which is estimated by summing up to the 3rd order in Taylor's expansion. The PVAJT motion planning is presented to reduce trajectory calculation time at every cycle time of servo control loop so that it is able to generate cubic spline trajectory in real time. These method can be used to more complex spline trajectory. We executed 3 case studies with different values of Tc and Ts, and showed the advantages of PVAJT motion planner. DSP-based motion controller is designed to implement The PVAJT motion planning.

The excess inductance of the conductor connecting the ground pins of the MMIC and the ground plane is extracted from a simplified procedure of measurement and optimization. The method is applied to a digital attenuator chip with a positive bias circuit. The addition of bypass capacitors with the value compensating the extracted excess inductance of the conductor clearly improves the performance of the chip.

This paper describes switch network architecture for Synchronous Digital Hierarchy BDCS (Broadband Digital Cross-Connect System), automatic detection of connection matrix status for AU3/4 of switching unit under it, detection of transmission error between unit switches and transmission error for switching routing path. It expands T switch spatially in existing T-S-T switch to make switch network architecture simple and makes strictly non-blocking switch network demanded by most of BDCS. The switch network is composed of unit switch, capable of switching to time and space and being applied to T switch and S switch in T-S-T switch.

A practical method to adapt TU signals is proposed for the TU switch in SDH (synchronous digital hierarchy)-based BDCS (broadband digital cross-connect system) because the SDH network is likely to incorporate two types of TUs, such as TU11 and TU12. Due to the SDH mapping structure, it is not possible for TUs to be directly connected with the switch. To solve this, signal processors were implemented to handle overhead, pointer and signal rate conversion. In particular, the VC3 signal processor makes a new frame format to carry the mixed TU traffic. The frame rate is still maintained at VC3 without added signalling bits.

We review the functions required for TU unit switching and explain the design of TUSM (TU11/TU12 frame alignment and supervisory monitoring), TUTW (TU1n time switch) and TUSW (TU1n space switch) which executes these functions. The VC3 signal termination, and the TUT11/TU12 signal frame alignment and supervisory monitoring function are essential to execute the TU11/TU12 unit switching in the BDCS (broadband digital cross-connect system) with the 50M/150M level and 1.5M/2M level cross-connection function. The TU switch ASIC, applied to a multistage strictly nonblocking switch network, has the merits of transmission bus error detection, combined use of pre/post time switch unit, elevation of system stability using sync memory and provision of a simple switch using 3 port memory. Even though the TU11 and TU12 signals are mixed, it supplies the switching function without any restriction. On the implementation of the switch, we have a serious problem of placement and layout because it includes many networks. However, it prevents any problems to occur at the layout by reducing the available network after memory grouping and makes the entire operation system simple by grouping the connection matrix memory to be controlled and converting the many memory operations into a single memory operation.

In this paper we will go over the functions required for TU unit switching and explain the design of TUSM(TU11/TU12 frame alignment and supervisory monitoring) which executes these functions. VC3 signal termination, TUT11/TU12 signal frame alignment and supervisory monitoring function are essential to execute the TU11/TU12 unit switching in the BDCS (Broadband Digital Cross-connect System) with the 50 M/150 M level and 1.5 M/2 M level cross-connection function. The connection rate of the chip is set to 19.44 Mb/s and it is designed to have signal release/forming, de-multiplexing/muitiplexing of 7 TUG2, frame alignment of 28 TU11 or 21 TU12, VC11/VC12 signal path monitoring function and the monitoring function of signal connection located at the pre/post time switch.