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This paper presents a reference-free readout method for the phase-change memory (PCM) that compensates for the temperature drift of the cell resistance. The proposed method reconfigures the sense amplifier (SA) array into flash analog-to-digital converters (ADCs) in order to extract the optimum decision threshold for the given temperature from the distribution of the data output therefrom. The resolution of the reconfigured flash ADC, the number of flash ADCs for data averaging, and the required number of samples are determined for a target bit error rate of 1 ppm. The proposed SA drives a bit line (BL) rapidly with switchable current sources. A proof-of-concept prototype chip is fabricated via the 180-nm CMOS process. A single-channel readout path occupies $137 \times 27\,\,\mu \text{m}^{\mathbf {2}}$ and consumes $305~\mu \text{W}$ under a 3.3-V supply, with readout latency less than 100 ns.

This paper proposes an adaptive output feedback control for trajectory tracking of underactuated surface vessels (USVs). For the realistic dynamical model of USVs, we consider the USV model, where the mass and damping matrices are not diagonal. Moreover, except the mass matrix, the system parameters and nonlinearities of the USV are all assumed to be unknown. Despite this uncertain circumstance, we develop an adaptive observer based on the neural networks to estimate the velocity data of USVs. Then, an output feedback control law is designed by simultaneously considering the input saturation and underactuated problems.

This paper presents a power-saving readout scheme for CMOS image sensors (CISs) that utilizes the image properties. The proposed delta-readout ( $\Delta $ -readout) scheme reads the signal difference between two pixels located next to each other ( $\Delta _{\mathrm {pixel}}$ ) by utilizing the most significant bits (MSBs) information of the previous pixel. By effectively reducing the dynamic range of the signal, compensated by the $\Delta $ -window checking, the proposed $\Delta $ -readout scheme can reduce the effective number of decision cycles in a successive-approximation register (SAR) analog-to-digital converter (ADC) and reduce the power consumption while preserving the ADC performance. A prototype QQVGA CIS with ten 10-bit SAR ADCs in a multi-column-parallel (MCP) configuration was fabricated in a $0.18~\mu \text {m}~1$ P4M CIS process with a $4.4~\mu \text {m}$ pixel pitch, where each single ADC occupies an area of $70\,\,\mu \text {m}\,\,\times \,\,500\,\,\mu \text {m}$ . The measurement results of the implemented prototype CIS showed a maximum power-saving of 26% with a figure-of-merit (FoM) for ADC of 15 fJ/conversion-step.

This paper proposes a low-power logarithmic resistance sensor for multi-level cell phase-change memory readout. The proposed sensor is composed of a resistance-to-current converter (R2I) and a current-to-digital converter (I2D). A simple bleeding current source pair added to the R2I enhances the current settling speed and the sensing accuracy. The two-step I2D with a time-to-digital converter-configured fine ADC could be designed with low-power consumption and small size owing to the time-reference generator that is shared by multiple channels and incorporates interpolation and size-scaling techniques. The total conversion time of the readout sensor, including the R2I conversion, is 100 ns, and the power consumption of a single-channel readout sensor is 60 μW under a 1.2 V supply. The ratio of the minimum decision step size to the full scale input current of the I2D corresponds to that of a conventional 9.6-b linear ADC. The prototype sensor is composed of 14-channels sharing a single time-reference generator, where each narrow single channel occupies 19 μm × 590 μm in a 65-nm CMOS process.

In this paper, a formation control method of quadrotor Unmanned Aerial Vehicles (UAVs) by vision-based positioning is presented. The relative positions and attitudes of two UAVs with respect to a visual marker attached to the third UAV is estimated by a camera calibration method. Based on the estimated positions and attitudes, two UAVs are controlled to the desired positions to form a given formation with respect to the third UAV. A simplified dynamics model of a quadrotor UAV is utilized to design a controller. The proposed formation control method is validated by an experiment with a motion capture system which provides the ground truth of the position data.

This paper presents a narrow-pitch readout circuit for multi-level phase change memory (PCM) employing an architecture of two-step 5 bit logarithmic ADC. A single-slope-architecture based fine ADC yields a 15 $\mu$ m-width compact single channel readout circuit for column parallel readout structure. A current-mode 2 bit flash ADC for coarse conversion and the pipelined architecture between the coarse and fine conversion enhance the readout rate up to 13 Mcells/sec. With the enhanced residue accuracy provided by the replica circuit of residue generator, the ADC achieves excellent linearity of 9.96 b (linear ADC equivalent). The integration-based residue generation effectively reduces circuit noise and yields 8.7 ENOB. The prototype chip was fabricated in a 65 nm CMOS process and the measured power consumption from a single channel readout circuit was 105 $\mu$ W at 13 Mcells/sec conversion rate at 1.2 V supply.

This paper proposes an adaptive bidirectional platoon-control method for an interconnected vehicular system using a coupled sliding mode control (CSMC) to improve the performance and stability of the bidirectional platoon control and to guarantee string stability. The previous work in the field of platoon control is based on two strategies, i.e., the leader-predecessor and bidirectional strategies. In the case of the leader-predecessor strategy, all vehicles should use the information of all the leading and preceding vehicles. On the other hand, the bidirectional strategy uses the information of its neighboring preceding and following vehicles. Due to the drawbacks of the bidirectional strategy, most previous work has preferred to employ the leader-predecessor strategy, which can guarantee stability and improved performance. The bidirectional strategy is, however, advantageous in that its implementation of the actual system becomes much more feasible than that of the leader-predecessor strategy. Thus, to employ the platoon-control law to an actual system, we propose the platoon-control law using a CSMC method for an interconnected vehicular system based on the bidirectional strategy such that the problems arising from communication devices in the previous work can be overcome. In particular, unlike the previous work using the bidirectional strategy, the proposed adaptive platoon-control law can lead to improved control performance of the whole system and can guarantee string stability. The stability analysis and simulation results of the proposed method in the presence of uncertainties and disturbances are included to demonstrate the practical application of the proposed algorithm.

This paper proposes a vector field guided auto-landing control of an airship with a wind disturbance, whose motion is described in a vertical plane. Whereas hovering and vertical landing abilities are advantages of the airship, there is little research on the auto-landing mechanism. Unlike the previous airship control algorithms which compensate the disturbances using linear and nonlinear control laws such as backstepping control methods, the proposed auto-landing control algorithm is simpler than the backstepping controllers and covers the wind disturbances with unknown bound. To this end, the vector field based guidance law achieving the control objectives and adaptive-robust dynamic control law realizing the desired course are proposed. The stability analysis and simulation results of the proposed auto-landing control law are included to demonstrate the practical applicability of the proposed method.

This paper proposes a target tracking control method for wheeled mobile robots with nonholonomic constraints by using a backstepping-like feedback linearization. For the target tracking, we apply a vision system to mobile robots to obtain the relative posture information between the mobile robot and the target. The robots do not use the sensors to obtain the velocity information in this paper and therefore assumed the unknown velocities of both mobile robot and target. Instead, the proposed method uses only the maximum velocity information of the mobile robot and target. First, the pseudo command for the forward linear velocity and the heading direction angle are designed based on the kinematics by using the obtained image information. Then, the actual control inputs are designed to make the actual forward linear velocity and the heading direction angle follow the pseudo commands. Through simulations and experiments for the mobile robot we have confirmed that the proposed control method is able to track target even when the velocity sensors are not used at all.

This paper proposes a bidirectional platoon control law using a coupled distance error based on the backstepping-like feedback linearization control method for an interconnected mobile agent system with a string structure. Unlike the previous results where the single agent was controlled using the only own information without other agents, the proposed control law cannot show the only distance error convergence of each agent, but also the string stability of the whole system. Also, the control performances are improved by the proposed control law in spite of low performance of bidirectional control strategy in the previous results. The proposed bidirectional platoon control algorithm is based on the backstepping-like feedback linearization control method. The position errors between each agent and the preceding and the behind agents are coupled by weighted summation. By the proposed control law, the distance error of each agent can converge to zero while the string stability is guaranteed when the coupled errors can converge to zero. To this end, the back-stepping control method is employed. The pseudo velocity input is determined considering the kinematic relationship between agents and the string stability. Then, the actual dynamic control input is determined to make the actual velocity converge to the pseudo velocity input. The stability analysis and the simulation results of the proposed method are included in order to demonstrate the practical application of the proposed algorithm. Keywords: platoon system, interconnected mobile agent system, back-stepping control, mobile agent, coupled error I. 서론 차량간의 거리 유지 시스템에 대한 연구는 차량의 안전과 운송 효율성 증가를 위한 시스템 (예를 들어, 지능형 운송 시스템(ITS: Intelligent Transportation System), 적응 순항 제어(ACC: Adaptive Cruise Control), 지능형 고속도로 시스템(HIS: Intelligent Highway System) 등) 에 대한 관심이 증가하면서 많은 주목을 받고 있다. 차량 주행 및 운송 시스템들을 안전하고 효율적으로 구성하기 위하여 로봇 제어 및 다개체 시스템 제어 기술이 응용되어 왔다. 또한, 위 시스템들은 상호 연관 다개체 시스템(interconnected multi-agent system)으로 표현될 수 있는 만큼 개별 개체의 제어뿐만 아니라 개체 간 상호 연관성에 의하여 발생할 수 있는 현상들에 대한 고려가 강조 되었다[3-10]. 차량간 거리 유지 시스템과 같이 끈 구조(string structure)를 가지는 상호 연관성을 갖는 시스템에서 개별 개체만을 고려한 제어[1,2]는 slinky type effect에 의하여 개체들간의 오차가 뒤따라 오는 개체들에 전달되고 누적되어 전체 시스템의 안정도를 해치게(sting instability) 된다[3-6]. 1차원적 열 대형을 이루는 상호 연관 시스템에서 끈 안정성(string stability)으로 명명된 시스템의 전체 안정성은 [3,4]에서 잘 정의되어 있으며, 많은 연구들이 이 정의에 따라 상호 연관 시스템의 플레툰 제어를 수행하여 왔다. 먼저, 끈 안정성을 유지하면서 차량간의 간격을 제어하기 위하여 개별 차량의 제어기 설계 시 최 선도 차량의 정보를 사용하는 선도-선행 전략(leader-predecessor strategy)들이 등장하였다[3-5]. 이 방법은 이 후 많은 연구들에 영향을 주었고 [7-10]등의 연구들이 수행되었다. 이 방법은 시스템 내의 모든 차량에 최 선도 차량의 정보를 전달해야 하는 문제를 가진다. 실제 시스템을 고려하였을 때 최 선도 차량의 정보를 뒤 따라 오는 모든 차량에 제 시간에 정보를 전달하는 것은 매우 어려운 일이다. 이러한 문제를 해결하기 위하여 주변 차량들의 지역적 정보만을 이용하는 양방향 제어 전략(bidirectional strategy)이 제안되었다. 이 기법은 앞 뒤의 차량의 정보를 on-board 센서로 측정가능하고 통신을 통한 정보전달의 필요가 없어 적용비용이 적고 실제 시스템에 적용할 수 있는 가능성이 높다. 그러나 [6]에서 언급된 것과 같이 이 기법은 선도-선행 전략에 비해 성능이 떨어질 수 있고 [4]에서 언급한 것과 같이 전체 시스템의 끈 안정성을 보장하는 것이 쉽지 않다. 그럼에도 불구하고, 양방향 제어전략은 선도-선행 전략에 비해 다수 차량의 플레툰 제어를 실제 시스템에 적용할 수 있는 여지가 높아 계속적인 관심의 대상이 되어왔다. 따라서 본 논문에서는 오차결합을 이용한 역보행 제어 형태의 궤환 선형화 기법(Backstepping-like Feedback Linearization) 기반의 양방향 플레툰 제어 법칙을 제안한다. 제안된 제어 법칙은 오차 결합(error coupling)을 이용하여 양방향 제어 전략의 성능을 향상 시키고 동시에 상화 연관 시스템의 끈 안정성을 보인다. 본 논문에서 제안하는 양방향 제어 기법은 앞, 뒤 차량과의 거리 오차들을 가중합하여 결합하고 이를 제어한다. 이를 위하여 역보행 기법 형태의 궤환 선형화 기법 [11]을 사용한다. 이 제어기법은 기존의 역보행 제어

This paper proposes mapping and path planning algorithms for an unknown environment using a communication graph of an unlocalized robotic swarm system. Unlike the previous efforts that used the absolute position information of all the robots, in the proposed algorithms, the unknown environment is described as the communication connectivity graph achieved via a distributed consensus algorithm. Thus, since robots have no positioning sensors, the proposed mapping and path planning algorithms can simplify the procedures and reduce the costs. The numerical simulations are included to demonstrate the performance of the proposed algorithms.

This paper proposes an environment monitoring algorithm using a behavior-based multiple robot system. This paper handles an escort and a boundary-tracking especially. Unlike previous research works, the proposed environment monitoring system which is based on the behavior-based multiple robot control allows the system to employ the reusable code and general algorithm. Also, the proposed method can be applied to cheaper process with low performances. In the proposed method, escort and boundary-tracking missions are constructed by weighted sum of predefined basic behaviors after redefining the basic behaviors in previous works and introducing the novel basic behavior. Simulation results of the proposed method are included to demonstrate the practical application of the proposed algorithm.

This paper introduces a simple variable gain amplifier (VGA) structure that shows an inherently dB-linear gain control property. Requiring no additional components for dB-linear control, the structure is compact and power efficient. The designed two-stage VGA shows a gain control range of 60dB with the gain error in the range of ±0.4 dB. The power consumption including the output buffer is 20.4 mW from 1.2 V supply voltage with bandwidth of 630 MHz. The prototype was fabricated in a 0.13 m CMOS process and the VGA core occupies 0.06 mm 2

This paper proposes a posture stabilization control algorithm for a wheeled mobile robot using hybrid visual servo control method with a position based and an image based visual servoing (PBVS and IBVS). To overcome chattering phenomena which were shown in the previous researches using a simple switching function based on a threshold, the proposed hybrid visual servo control law introduces the fusion function based on a blending function. Then, the chattering problem and rapid motion of the mobile robot can be eliminated. Also, we consider the nonlinearity of the wheeled mobile robot unlike the previous visual servo control laws using linear control methods to improve the performances of the visual servo control law. The proposed posture stabilization control law using hybrid visual servoing is verified by a theoretical analysis and simulation and experimental results.

A docking control algorithm of a non-holonomic mobile agent is proposed, which can be employed in both the stationary and the underway docking stations. To this end, a leader–follower docking formation is proposed, where the size of the formation is reduced until docking surfaces of the agent and the docking stations contact each other. Also, a feedback linearisation control law that can compensate for the input constraint is implemented to maintain the docking formation. Numerical simulations are included to show the performance of the proposed docking control algorithm.

We derive a systematic and iterative calibration algorithm, and position and pose estimation algorithm for the mobile robots in formation system based on the vision system. In addition, we develop a coordinate matching algorithm which calculates matched sequence of order in both extracted image coordinates and object coordinates for non interactive calibration and pose estimation. Based on the results of calibration, we also develop a camera simulator to confirm the results of calibration and compare the results of simulations with those of experiments in position and pose estimation.

This paper presents a localization algorithm of the outdoor wheeled mobile robot using the sensor fusion method based on indirect Kalman filter(IKF). The wheeled mobile robot considered with in this paper is approximated to the two wheeled mobile robot. The mobile robot has the IMU and encoder sensor for inertia positioning system and GPS. Because the IMU and encoder sensor have bias errors, divergence of the estimated position from the measured data can occur when the mobile robot moves for a long time. Because of many natural and artificial conditions (i.e. atmosphere or GPS body itself), GPS has the maximum error about when the mobile robot moves for a short time. Thus, the fusion algorithm of IMU, encoder sensor and GPS is needed. For the sensor fusion algorithm, we use IKF that estimates the errors of the position of the mobile robot. IKF proposed in this paper can be used other autonomous agents (i.e. UAV, UGV) because IKF in this paper use the position errors of the mobile robot. We can show the stability of the proposed sensor fusion method, using the fact that the covariance of error state of the IKF is bounded. To evaluate the performance of proposed algorithm, simulation and experimental results of IKF for the position(x-axis position, y-axis position, and yaw angle) of the outdoor wheeled mobile robot are presented.

This paper proposes a vision-based kinematic control method for mobile robots with camera-on-board. In the previous literature on the control of mobile robots using camera vision information, the forward velocity is set to be a constant, and only the rotational velocity of the robot is controlled. More efficient motion, however, is needed by controlling the forward velocity, depending on the position in the corridor. Thus, both forward and rotational velocities are controlled in the proposed method such that the mobile robots can move faster when the comer of the corridor is far away, and it slows down as it approaches the dead end of the corridor. In this way, the smooth turning motion along the corridor is possible. To this end, visual information using the camera is used to obtain the perspective lines and the distance from the current robot position to the dead end. Then, the vanishing point and the pseudo desired position are obtained, and the forward and rotational velocities are controlled by the LOS(Line Of Sight) guidance law. Both numerical and experimental results are included to demonstrate the validity of the proposed method.

A power-saving readout scheme for CMOS image sensors (CIS) that utilizes the image properties is presented. The proposed delta-readout (Δ-readout) scheme reads the signal difference between two pixels located next to each other. By effectively reducing the dynamic range of the signal, the readout ADC can reduce the number of decision cycles and save power consumption while maintaining the ADC performance at the level of a conventional ADC. The prototype QQVGA CIS with ten 10-bit SAR ADCs in a multi-column-parallel (MCP) configuration was fabricated in a 1P4M 0.18 μm CIS process with metal-insulator-metal (MIM) capacitors. The measurement results show the power-saving effect of 26 % depending on the image patterns.

This paper proposes the consensus algorithm for obstacle avoidance behavior of a robotic swarm system such that the orientations of all the robots are converged to consented value of them. In the previous robotic swarm algorithms based on a behavior based control has contended with obtaining the routes of the robots when accomplishing objectives such as aggregation, dispersion, or homing. In this paper, the robots move with smooth path by the proposed consensus algorithm. This advantage can lead to reduce the moving distance and the moving cost. Finally, simulation results are included to demonstrate the performance of the proposed algorithm for the robotic swarm system based on the behavior-based control with consensus algorithm for obstacle avoidance.

This paper studies the design problem of a controller to achieve a consensus of a group of N identical and high-order linear systems that possibly have non-uniform ranks but do not have finite zeros. The local interactions among the N systems are modeled by a switching graph that ranges over a finite set of connected and undirected graphs and has a non-vanishing dwell time. Under these conditions, we propose a controller for the consensus of the N systems which uses only relative output measurements from the neighboring systems for the purpose of feedback.

The research of multi-robot surveillance has increasingly gained interest in recent years, mainly due to the possibility of security applications. In previous papers, multi-robot patrolling algorithms were focused on the minimization of time required to complete the patrolling of an entire area. However, these approaches of reducing time can overlook an important objective of patrolling such as preserving a certain level of overall security. This paper introduces the patrolling algorithm for multi-robot in the time-varying environment to maintain security at a safe level. The environment is represented in a graph with nodes for valuable places and shows links for paths between nodes. The safe level of nodes is measured by the function of time, the distance between robots and a node, and the existence of an intruder in a node. After the level of nodes is measured and when the node's security level is below “safe”, the patrolling robots move toward that node. As the evaluation of the patrolling algorithm, we considered the safe level distribution curve for each node and the average security level distribution curve.

A reference driver-free pipelined ADC with a low drop-out (LDO) regulator for power supply is proposed for SoC applications. An LDO-based regulated voltage provides not only power supply for digital and analog circuits but also works as a reference voltage for the ADC. Conventional residue function from a 2.5b/stage design can use its max input as much as 93% of the internal supply voltage. A prototype 10-bit 32MS/s ADC has been designed for a 0.18µm CMOS technology. Under a regulated 1.5V internal supply from an external 1.8V, the design shows 65.1dB SFDR with 7.06mA (including LDO) current consumption.

A multi-unmanned aerial vehicle (UAV)-based stereo vision system is proposed to assist global path planning of an unmanned ground vehicle (UGV) even in GPS-denied environments. The proposed system can optimally generate the depth map of ground objects and robustly detect obstacles. The proposed multi-UAV-based system with a movable baseline overcomes the limitations of a single-UAV-based stereo vision system with a fixed baseline. Thus, the performance of the proposed system does not degrade significantly based on the altitude of UAVs. The relative position and altitude estimation, multi-agent formation control and image processing techniques are considered to implement a prototype system. The experimental results demonstrate the performance of the implemented system for various baseline conditions between UAVs.

This paper proposes a localization algorithm for mobile agents in sensor networks using the data fusion method based on indirect Kalman filter. The fusion method of an inertial navigation sensor and sensor nodes data is used to acquire the correct position information. Since indirect Kalman filter is used for estimation of the mobile agent position, the position of the mobile agent can be estimated even when the sensor node cannot work or data acquired from the network are not reliable. Because measurement errors are used for estimation, its implementation is easy. Finally, a sequence of simulations is carried out to confirm the performance of the proposed localization algorithm.

This paper proposes a novel vector field control method based on nonlinear control algorithm for wheeled-mobile robots. A new vector field control method is proposed for wheeled-mobile robots. In the proposed method, the controller is designed to asymptotically stabilize the tracking errors in both position and orientation angle. By the proposed controller, trajectory tracking can be achieved for arbitrary reference trajectory even with large initial tracking errors and bounded disturbances. The performance analysis is performed and also simulations are included to confirm the effectiveness of the proposed scheme.

This paper proposes the polynomial fuzzy modeling and tracking control methods for wheeled mobile robots by using sum of squares (SOS) approach, which is developed as SOSTOOL under the Matlab environment. Due to the polynomial fuzzy modeling, we can obtain the linearized tracking error dynamics such that both LMI (Linear Matrix Inequality) and SOS approaches can be applied. Since SOS approach handles more nonlinear system characteristics than LMI, we can obtain the better tracking performance, which is demonstrated in the numerical simulations. The proposed method has advantages in that the control structure can be simplified and it can be further extended to accommodate the input saturation, disturbance compensation, etc., which is well developed for LMI control methods.

This paper presents the method for the compensation of sinusoidal disturbance with time-varying frequency in an uncertain nonlinear system. Unlike the previous works on the disturbance accommodation method which handles the sinusoidal disturbances with time-invariant frequency in nominal linear systems, the proposed method deals with the sinusoidal disturbance with time-varying frequency in uncertain nonlinear systems by modifying the previous disturbance accommodation technique. In particular, the nonlinear systems with uncertainties are considered such that the proposed disturbance compensation method can be more practically employed. The stability analysis and numerical simulations are performed to verify the proposed approach.

This paper proposes a vision-based simple fuzzy angular velocity control method for mobile robots with vision system in a corridor. To this end, visual information from the camera is obtained as vanishing point and middle point. They are employed for collision free navigation in the corridor. To control the mobile robot in the corridor using vision system, we generate the kinematic model of the system from the image directly, and design the simple fuzzy controller using vanishing point and middle point. The simulation results are included to demonstrate the validity of the proposed method.

This paper proposes a data-mining algorithm for mobile robots in an object detection. It is important that is used to localization and map building. The proposed method uses three algorithms to divide sections. To this end, the laser scanner is used to recognized objects for mobile robots. To control the mobile robots in the researches of collision avoidance, we can recognize approximation of objects. By using data-mining algorithm, the processing speed is faster and more correct. Simulation results are included to demonstrate the validity of the proposed algorithm.

We propose a corridor lines extraction algorithm. The algorithm is based on a vision-system. It uses the patterns of slopes between two points, K-means, and least-square method. The proposed algorithm offers intersection lines between the wall and the floor. The proposed method consists of image preprocessing, noise filtering, and line extraction algorithm stage. The method has been tested on a large number of real corridor images. The experimental results are included to demonstrate the validity of the proposed algorithm.

This paper proposes a local path planning algorithm for a mobile robot with a vision system. Based on projective geometry and the wavefornt-based skeleton method, the proposed algorithm performs obstacle extraction, 2D-3D transformation, and local path planning. The effectiveness of the proposed method is illustrated by experiments where a vision-equipped mobile robot navigates a maze using the proposed path planning algorithm.

In this paper, we discuss about the experimental results of camera calibration and pose estimation for the application to vehicle's wheel alignment system using single camera. At first, we define a camera model for the camera system considered. For this model which consists of a linear part (ideal pinhole camera model) and a nonlinear part (lens distortion model), we drive a systematic and iterative calibration algorithm and pose estimation algorithm. In addition, we develop a coordinate matching algorithm which calculates matched sequence of order in both extracted image coordinate and object coordinate for non-interactive calibration and pose estimation. Based on the results of calibration, we also develop a camera simulator to confirm the results of calibration and compare the results of simulations with those of experiments in pose estimation

There can be collisions among multiple mobile robots when they move in the same workspace. First, we propose a new roadmap construction algorithm to improve the defects of the skeleton map. Secondly, we propose a decoupled collision avoidance algorithm for multiple mobile robots moving along their paths with independent start and goal configurations in a same workspace. Finally, simulation results are performed to show the effectiveness of the proposed roadmap generation algorithm and collision avoidance algorithm for multiple mobile robots.

This paper studies the design problem of a controller to achieve an asymptotic consensus for a class of non-uniform rank linear systems. The interconnection topology for the N non-uniform rank systems is assumed to be modeled by a time-varying graph that switches in a finite set of connected and undirected graphs and has a non-vanishing dwell time. Under these conditions, we propose a controller for the asymptotic consensus of the N systems and provide a closed formula for an agreed trajectory that in fact indicates the attainment of average consensus. The controller is implemented through the backstepping and high-gain observer techniques, and uses only relative output measurements from the neighboring systems for the purpose of feedback. The idea behind this implementation is that the output feedback controller implemented in this way can make the norm of the state of the closed-loop system arbitrary small within any given dwell time, even for non-uniform rank systems.