Plamen Petrov

Technical University of Sofia | TU · Faculty of Mechanical Engineering

This paper proposes a nonlinear feedback path controller for a skid-steering mining vehicle. The dynamic model of the vehicle is derived using the Boltzmann-Hamel formalism. The control design utilizes the computed torque type technique combined with an auxiliary continuous static state feedback, which involves error coordinates expressed in a movi...

In this paper, a dynamic model and adaptive motion controller of a two-wheeled self-balancing vehicle is presented. First, we derive a dynamic model of the vehicle with respect to the wheel motor torques as inputs using the Boltzmann-Hamel method in quasi-coordinates for nonholonomic systems. Using estimation-based approach, an adaptive controller...

In this paper, we present a mathematical model and adaptive controller for an autonomous vehicle overtaking maneuver. We consider the problem of an autonomous three-phase overtaking without the use of any roadway marking scheme or intervehicle communication. The developed feedback controller requires information for the current relative intervehicl...

This paper addresses the control of an autonomous leader-follower formation of nonholonomic mobile robots in a specific case, when the following robot is moving ahead of the leading robot. Using a look-ahead approach, first, a kinematic model of the leader-follower formation in error coordinates is developed. A nonlinear feedback control is design...

In this paper, a kinematic model of a mechanically connected platoon of two car-like vehicles for cooperative driving is developed. The kinematic equations of motion are obtained in the form of a nonlinear driftless control system, which is affine in the control inputs and can be employed for the design of different types of low-speed steering cont...

In this paper, we consider the problem of controlling an autonomous mobile robot in a homogeneous longitudinal platoon of mobile robots without inter-robot communication using constant spacing policy. The proposed decentralized control requires only information for the separation distance to the preceding robot and the estimate of its velocity obta...

This paper presents a study on the possibilities offered by the multi-scale wavelet decomposition in the medical image fusion of the brain obtained by MRI and SPECT technology. The influences of various discrete wavelet functions by which the decomposition was obtained and the corresponding level at which it was constructed are analysed. The implem...

This paper addresses the control of an autonomous mobile robot in a specific case, when the robot is following a person in front of him. Using a leader-follower formation approach combined with a look-ahead concept, a human-robot kinematic model in error coordinates with respect to a local Cartesian coordinate system is developed. A nonlinear feedb...

In this paper, a path following controller for nonholonomic unicycle-type mobile robots is presented. First, a kinematic model in error coordinates appropriate for path following applications is developed. Using the classical linear control theory, a feedback path control based on distance-only measurements is proposed. The stability of the closed-...

The quality of medical images is very important in clinical use, such as clinical diagnosis, pathology analysis, etc. This paper presents a brief survey of the advantages and trends of medical image processing techniques based on multidimensional wavelet transforms as well as their combinations with other methods, which model each coefficient set a...

This paper addresses the problem of vision-based line tracking control of unicycle mobile robots. First, a robot-camera model suitable for path following applications is derived. Using a look-ahead approach, a feedback controller is proposed for tracking curved paths on the ground using information from an onboard down-looking camera using distance...

In this paper, we present an adaptive mobile robot controller for autonomous person following, such that the robot keeps a desired distance from the human. Using a platooning-based approach, first, a human-robot kinematic model in error coordinates suitable for tracking applications is proposed. An adaptive control law is designed to tackle the pro...

Most of the known methods of segmentation of the abdominal organs are not automated for the whole series of images or are semi-automatic and require additional intervention by the user. This is typical for cases where the difference in intensity of the grey level between the subject and the background is small. This paper presents a multistage appr...

In this paper, a path tracking controller based on distance-only measurements for nonholonomic mobile robots is presented. First, a kinematic model of the robot appropriate for path tracking applications is derived. Using a look-ahead approach, a time-varying feedback controller is proposed. The stabilities properties of the closed-loop system are...

In this paper a novel hybrid segmentation approach for optimization of the renal cyst diagnosis from CT image sequences is proposed. The approach is based on several segmentation techniques. A locally optimized front propagation algorithm according to the level set paradigm with variable term is in the core of the segmentation of the kidney from CT...

The blind deconvolution algorithms are widely used in microscopy image restoration. However in more of the biological and biomedical experiments due to high level of noise, it is difficult to obtain good results. The blind deconvolution algorithm can be effectively applied when no information about the blurring and noise is given. In addition, a mo...

In this paper, we deal with the problems of geometric collision-free path planning and feedback steering control for automatic perpendicular reverse parking maneuver of front wheel steering vehicles. An important condition to achieve effective collision-free parking is to determine a convenient start position of the vehicle depending on the widths...

As colonoscopy is needed for screening colorectal polyps, and the first step of classification these polyps is recognizing them, it is worth to research, whether the colonoscopy databases could be improved by image processing and contour detection. In the following considerations a reflection filtering and background subtraction with large-sized me...

In this paper, a dynamic model and adaptive motion controller for a two-wheeled inverted pendulum robot are presented. First, a dynamic model of the robot with respect to the wheel motor torques as inputs using the Boltzmann– Hamel method in quasi-coordinatesfor nonholonomic systems is derived. Using estimation-based approach, anadaptive control er...

Prostate segmentation in ultrasound images is a challenging problem due to the inherent speckle and some artifacts like shadows, attenuation and signal dropout. In this paper we propose an approach, which includes pre-processing for image enhancement and uses hybrid method, which combines a priori boundary, shape and region information of the prost...

The new and effective approach for dental X-ray image enhancement is proposed. It can be applied for detection of dental caries by location of the lesion.

In this paper, an effective approach for dental X-ray image enhancement for detection of caries on the base of location of the lesion is presented. It consists of contrast improvement by limited adaptive histogram equalization (CLAHE) and morphological processing. Then homomorphic wavelet filter is used to remove noise components and to eliminate n...

In this paper, we present an effective approach for colorectal polyp segmentation by processing of endoscopy images. In regard to quality limitations of colonoscopy images, a preprocessing stage is proposed. It consists of noise reduction with modified homomorphic filter based on wavelet packet decomposition of the transformed image, additionally...

In this paper, In this paper, we present an adaptive longitudinal controller for an autonomous mobile robot platoon, where the only information that the follower robot can use for feedback control is the distance measurements between the robots obtained from a laser range finder. The control velocity of the following robot is computed using the lea...

This paper considers the perpendicular reverse parking problem of front wheel steering vehicles. Relationships between the widths of the parking aisle and the parking place, as well as the parameters and the starting position of the vehicle for planning a collision-free reverse perpendicular parking in one maneuver are presented. A nonlinear satura...

This paper considers the parallel parking problem of automatic front-wheel steering vehicles. The problem of stabilizing the vehicle at desired position and orientation is seen as an extension of the tracking problem. A saturated control is proposed which achieves quick steering of the system near the desired position of the parking spot with desir...

This paper presents a framework for determining the direction of human gaze with an active multi-camera system. A fixed camera is employed in order to estimate the position of the human face and its features, like the eyes. By means of the Supervised Descent Method (SDM) for minimizing a Non-linear Least Squares (NLS) function we can compute correc...

In this paper, we present a two-layer nonlinear adaptive steering controller for autonomous lane change maneuver with respect to a stopped vehicle. First, we derive a dynamic model of the vehicle using the Boltzmann-Hamel method in quasi-coordinates for nonholonomic systems. The lane change maneuver is investigated as a tracking problem with respec...

In this paper, we present the architecture of an innovative docking station for electric vehicles recharging and a hybrid control scheme for automatic docking of the vehicles. This work is a part of on-going project concerning the development of a smart charging station for electric vehicles equipped with an automated arm, which connect the vehicle...

In this paper, we present a nonlinear adaptive controller for a two-vehicle automated overtaking maneuver. We consider the problem of a three-phase overtaking without the use of information obtained from road infrastructure. The only information available for feedback control is the current relative inter-vehicle position and orientation. Reference...

This paper presents a framework for determining the orientation of human faces with a fixed monocular camera which can be used for the purposes of the gaze tracking afterwards. We use homography relation between two views/frames to handle with the lack of depth information. In order to compensate for the lack of depth information in the relationshi...

This paper describes a control system for vehicle platoon which permits the ego vehicle to track the trajectory of the vehicle ahead with prescribed inter-vehicle distance. We consider autonomous vehicle following without any information obtained from road infrastructure or communication from the lead vehicle. The relative inter-vehicle position an...

This paper considers the problem of face detection and tracking with an active camera. An algorithm using Haar-like face detector and Mean-shift method for face tracking has been presented. We propose an adaptive algorithm that provides automated control of a Pan-Tilt camera (PTC) to follow a person’s face and keep their image centered in the camer...

This paper proposes an adaptive dynamic-based path control for a differential drive mobile robot. The control law involves error coordinates expressed in a coordinate frame which are partially linked to the robot. The construction of the controller is based on a two-layer structure using the principle of decomposition of the control problem. Assumi...

This paper proposes a nonlinear path control for backward driving of a car-like mobile robot pushing trailer with off-axle hitching. The control law is constructed using high-gain design techniques and involves error coordinates expressed which are partially linked to the trailer and invariant properties with respect to the vehicle speed. The stabi...

In this paper, we present a kinematic description and a simulation for leg trajectory planning of a six-legged robot with 3dof legs. First, the kinematic model of the leg is described. A leg trajectory planning procedure for tripod gait of the robot is proposed, and the desired motion of the leg joint angles is obtained from the assigned desired mo...

This paper describes the modeling of a two-vehicle convoy and the design of a vehicle following controller that tracks the trajectory of the vehicle ahead with prescribed inter-vehicle distance. Kinematic equations of the system are formulated applying standard robotic methodology. We consider autonomous vehicle following without any information ob...

This paper presents an approach to face detection and tracking in video sequences. We use a set of Haar-like features to train a cascade of classifiers. Face-tracking is performed using the mean-shift algorithm. We propose a method for adaptation both of the tracking-window and of the color-distribution model in order to increase robustness to illu...

This paper consider the problem of face detection and tracking with an active camera. An algorithm using the mean-shift method for face detection has been presented. We propose an algorithm that provides automated control of a pan-tilt camera (PTC) to follow a personpsilas face and keep his image centered in the camera view. An error vector defined...

In this paper we present a kinematic description of a six-legged laboratory prototype robot and control algorithm for tracking a target from the robot using active camera. The hexapod hardware platform with fluidic muscle is described. We present an algorithm that provides automatic control of a tilt camera to follow a target and keep its image cen...

This paper describes the modeling of a two-vehicle convoy and the design of a vehicle following controller that tracks the trajectory of the vehicle ahead with prescribed inter-vehicle distance. Kinematic equations of the system are formulated applying standard robotic methodology. We consider autonomous vehicle following without any information ob...

This paper proposes an adaptive tracking controller for a two-vehicle convoy. We consider autonomous vehicle following without any information obtained from road infrastructure or communicated from the lead vehicle. We assume that the lead vehicle linear and angular velocities, as well the curvature radius of the path traveled by the lead vehicle,...

This paper proposes a discontinuous time- invariant controller for the parking problem of a four-wheel-steering (4WS) mobile robot. Using non smooth coordinate transformation based on a polar representation of the kinematic model, the control law is constructed via Lyapunov-based techniques yielding exponential stability of the closed-loop system....

This paper presents an adaptive tracking controller for a two-vehicle convoy where the lead vehicle is driven in reverse. We assume that the lead vehicle linear and angular velocities are unknown constant parameters. We discuss autonomous vehicle control without any information obtained from road infrastructure or communicated from the lead vehicle...

This paper presents an adaptive tracking controller for a two-vehicle convoy where the lead vehicle is driven in reverse. We assume that the lead vehicle linear and angular velocities are unknown constant parameters. We consider the problem of autonomous vehicle tracking without the use of road infrastructure or inter-vehicle communication. The onl...

This paper proposes a feedback path controller for an articulated (LHD) mining vehicle. First, we develop a kinematic model of the vehicle in error coordinates expressed in a moving reference frame, which is partially linked to the vehicle. We give a change of coordinates and input combined with a new variable instead of the time- index that transf...

This paper proposes a feedback path controller for an articulated load-haul-dump (LHD) mining vehicle. First, we develop a kinematic model of the vehicle in error coordinates expressed in a moving reference frame, which is partially linked to the vehicle. We give a change of coordinates and input combined with a new variable instead of the time-ind...

This paper addresses the parking problem of a load-haul-dump (LHD) mine vehicle. The proposed controller stabilizes the configuration coordinates of the vehicle to an arbitrary small neighborhood of the origin. A specific feature of the control scheme is that the location of the reference point of the vehicle depends on the direction of motion. The...

A hybrid dynamic controller for stabilization of a car pulling one trailer to an arbitrary small neighborhood of the origin is presented. The design procedure is based on integrator backstepping techniques and relies on transforming the system equations into chained form. The hybrid strategy combines a trajectory tracking nonlinear control law unti...

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Control algorithms for a wheeled mobile robot to achieve trajectory tracking are presented. A complete electromechanical model is obtained by incorporating the dynamic models of the actuators in the dynamic equations of a tricycle vehicle. The control scheme has been divided into two levels, namely, path error control and motor control. A method ba...

In this paper, we present a kinematic description and leg trajectory generation for curvilinear motion of a six-legged robot with 3dof legs. First, the kinematic model of the leg is derived. A leg trajectory generation procedure for tripod gait of the robot is proposed, and the desired motion of the leg joint angles is obtained from the assigned de...

This paper proposes a nonlinear path controller for an articulated LHD (Load-Haul-Dump) mining vehicle based on a kinematic model in error coordinates expressed in a moving reference frame partially linked to the vehicle. Using a change of coordinates and input combined with time-scale transformation, we derive a nonlinear control law via Lyapunov...

This paper considers the problem of face tracking control with an active (pan-tilt) camera. All sensor information from the camera which is needed for feedback camera control is acquired and processed in real time by using RTMaps software. Assuming that the target motion is unknown in advance, we propose a PID controller that provides automated con...

In this paper, a dynamic model and simulation model of a two-wheeled self-balancing vehicle is presented. First, the dynamic model for rectilinear motion is derived using Lagrange method. Simulations of the 3D model using SolidWorks Motion and analysis of the mechanical construction are presented.

A nonlinear feedback path controller for a differential drive mobile robot is presented in this paper. First, a kinematic model in error coordinates expressed in a moving reference frame partially linked to the robot is developed. The control law is designed using backstepping method yielding exponential stability of the closed-loop system. Stabili...