Elie Shammas

• Professor (Associate) at American University of Beirut

The superimposition of sequential radiographs of the head is commonly used to determine the amount and direction of orthodontic tooth movement. A harmless method includes the timely unlimited superimposition on the relatively stable palatal rugae, but the method is performed manually and, if automated, relies on the best fit of surfaces, not only r...

Purpose The purpose of this paper is to detail the design and prototyping of a smart automation solution for de-strapping plastic bonding straps on shipping pallets, which are loaded with multiple containers secured by a top-cover as they move on a conveyor belt. Design/methodology/approach The adopted design methodology to have the system perform...

In this paper, the motion planning problem for planar snake-like robots with more than three links that is subjected to nonholonomic constraints is solved explicitly. In other words, for a given desired planar trajectory and a set of initial conditions of the snake, a unique feasible gait is generated to ensure that the origin of the snake robot’s...

One of the challenges facing humanoid robots is the design of a more human-like gait. In this paper, we propose a new paradigm for gait design for humanoids that is founded in the field of Kinesiology and is based on energy-exchange between potential and kinetic energies. Additionally, we propose an energy-based controller, which not only maintains...

In this paper, optimal control theory is used to generate energy-optimal tree-to-tree routes by taking into account the map of the forest environment and the quadrotor’s dynamics. After computing the energy consumption between all pairs of trees, a Travelling Salesman Problem is formulated and solved using Integer Linear Programming along with Sub-...

In this paper, we study the value of using synthetically produced videos as training data for neural networks used for action categorization. Motivated by the fact that texture and background of a video play little to no significant roles in optical flow, we generated simplified texture-less and background-less videos and utilized the synthetic dat...

In this paper, we study the value of using synthetically produced videos as training data for neural networks used for action categorization. Motivated by the fact that texture and background of a video play little to no significant roles in optical flow, we generated simplified texture-less and background-less videos and utilized the synthetic dat...

Motivated by the seriousness of local forests infestation by Pine Processionary Moths, in this paper we devise a method to completely yet optimally scan a forest. More precisely, given a forest map, an optimal path-planning algorithm that is adequate for a drone to visit all of the trees, in an energy optimal manner, is developed. The pre-map of th...

In this work, a six degrees-of-freedom (DOF) nonlinear kinematic and dynamic model of a Hybrid Autonomous Underwater Vehicle (H-AUV) is derived for the two modes of locomotion, propelled and gliding modes. A comprehensive linearization algorithm is developed to include both modes of locomotion. Starting with a three-dimensional time-parameterized c...

This paper introduces a new kinematic model to describe the planar motion of an autonomous underwater vehicle moving in constant current flows. The vehicle is modeled as a rigid body moving at maximum attainable forward velocity with symmetric bounds on the control input for the steering rate. The model approximates the effect a flow will induce on...

The ability to reliably estimate free space is an essential requirement for efficient and safe robot navigation. This paper presents a novel system, built upon a stochastic framework, which estimates free space quickly from stereo data, using self-supervised learning. The system relies on geometric data in the close range of the robot to train a se...

In this paper, we propose a novel approach for ground segmentation and free space estimation of outdoor environments. The system is completely self-supervised and relies on two modules: the first module is built around a Fully Convolutional Network (FCN), and is used for ground segmentation after the system is initiated. The second module relies on...

In this paper, a new calibration method for open-chain robotic arms is developed. By incorporating both prior parameter information and artifact measurement data, and by taking recourse to Bayesian inference methods, not only are the robot kinematic parameters updated but also confidence bounds are computed for all measurement data. In other words,...

This paper presents a tool for analyzing the motion of two-link nonholonomic swimmers. We refer to these systems as Land-sharks, which are a generalization of the well known Roller Racers. By exploiting the symmetry of the system, we are able to reduce the equations of motion and construct the scaled momentum evolution equation. This unveils a very...

Extensive research in the field of monocular SLAM for the past fifteen years has yielded workable systems that found their way into various applications in robotics and augmented reality. Although filter-based monocular SLAM systems were common at some time, the more efficient keyframe-based solutions are becoming the de facto methodology for build...

An efficient approach for the development of a compact integrated wood charcoal retort was designed. The key fundamental requirements to guarantee efficiency and productivity are initially investigated via CFD simulations to identify the temperature and velocity profiles inside the unit. The final compact design is comprised of a double vessel arra...

The design of spread footings on granular soils is generally governed by serviceability requirements. Recent studies have utilized databases of load tests to investigate the use of hyperbolic and power normalized load-settlement curves to model the behavior of footings on sands. The main objective of this paper is to utilize recently-developed norm...

This paper presents a new approach to tackle the problem of infinite chattering, observed at bang-singular junctions of the minimum-time trajectories of car-like robots with bounded angular acceleration control. To eliminate chattering from time-optimal control solutions, we propose to relax the ideal nonholonomic constraint of no-skidding. A proof...

In this paper we propose a novel system that uses sensory input from both vision and inertial sensors for an improved perception of the robot current status of equilibrium. We use MonoSLAM vision odometry as a basis for the visual perception and a gyro for angular velocity measurements; and we devise a reweighting method within a Kalman filter fram...

This paper presents a novel method for generating three-dimensional optimal trajectories for a vehicle or body that moves forward at a constant speed and steers in both horizontal and vertical directions. The vehicle's dynamics limit the body-frame pitch and yaw rates; additionally, the climb and decent angles of the vehicle are also bounded. Given...

Extensive research in the field of Visual SLAM for the past fifteen years has yielded workable systems that found their way into various applications, such as robotics and augmented reality. Although filter-based (e.g., Kalman Filter, Particle Filter) Visual SLAM systems were common at some time, non-filter based (i.e., akin to SfM solutions), whic...

This paper introduces a new approach for designing a simplified control law, which controls an autonomous underwater vehicle (AUV) to track a given 3D trajectory. To get a Linear Time Variant (LTV) state space model, the 6 degrees of freedom (6DOF) dynamics and kinematics model of the AUV is linearized about the given desired 3D trajectory it needs...

In this paper, a three dimensional model for a variable-diameter wheeled mobile base is introduced which is tailored for modeling locomotion on rough terrain. The motion planning of the introduced model is novel, since the forward motion of the robot is governed by a central rolling disk, while its steering is governed by the lateral shifting of th...

This paper proposes a novel technique to extract training data from free space in a scene using a stereo camera. The proposed technique exploits the projection of planes in the v-disparity image paired with Bayesian linear regression to reliably identify training image pixels belonging to free space in a scene. Unlike other methods in the literatur...

This paper introduces a new kinematic model to describe the planar motion of an Autonomous Underwater Vehicle (AUV) moving in constant current flows. The AUV is modeled as a rigid body moving at maximum attainable forward velocity with symmetric bounds on the control input for the turning rate. The model incorporates the effect a flow will induce o...

This paper proposes a novel technique for segmenting the ground plane and at the same time estimating the occupancy probability of each point in a scene. Using a stereo camera rig, our system first calculates a disparity map and transforms it to a v-disparity map, which is then filtered and processed to generate a corresponding probability field. T...

Abstract: This paper presents a method for generating three-dimensional paths for a vehicle with a bounded maximum curvature in both yaw and pitch rotations. We build upon the two-dimensional time-optimal path generation for constant speed vehicles with bounded steering that produces the socalled Dubins curves. We formulate a similar problem in thr...

In this paper, we solve the motion planning problem for a class of underactuated multibodied planar mechanical systems. These systems interact with the environment via viscous frictional forces. The motion planning problem is solved by specifying the location of friction pads on the robot as well as by specifying the input of the actuated degrees o...

An automated solar reactor system was designed and built to carry out catalytic pyrolysis of scrap rubber tires at 550 °C. To maximize solar energy concentration, a two degrees-of-freedom automated sun tracking system was developed and implemented. Both the azimuth and zenith angles were controlled via feedback from six photo-resistors positioned o...

In this paper, we develop an elaborate three-dimensional dynamical model for a novel single-actuator variable-diameter differentially-driven robot by taking recourse to Lagrangian formulation. Utilizing this model, we were able to analyze the various parameters and develop design tools that could be used in realizing such a robot with certain motio...

This paper proposes a new intuitive technique for the haptic teleoperation of unmanned aerial vehicles (UAVs). The UAV is controlled using joystick's velocity commands, and the haptic feedback is a repelling force proportional to the UAV's velocity. Our proposed method that entails sensing the UAV velocity and commanding it using velocity based ges...

In this paper we propose a new method to tackle the problem of discontinuous curvature observed in the time-optimal Dubins trajectories of car-like robots. The discontinuous curvature profile renders the paths untraceable by a real robot due to the existence of infinite accelerations at the transition points. To make way for a continuous curvature...

This paper presents a method for generating three-dimensional paths for a vehicle with a bounded maximum curvature in both yaw and pitch rotations. We build upon the two-dimensional time-optimal path generation for constant speed vehicles with bounded steering that produces the socalled Dubins curves. We formulate a similar problem in three-dimensi...

In this paper, we present a mechanical design of a conceptual hybrid autonomous underwater vehicle (H-AUV) which combines the features of both a propelled underwater vehicle and those of an underwater glider. We develop its dynamic model and perform several simulations to showcase its locomotive capabilities. The main contribution of the paper is i...

In this paper, we present a mechanical design of a conceptual hybrid autonomous underwater vehicle (H-AUV). We develop its dynamic model and perform several simulations to showcase its locomotive capabilities. The main contribution of the paper is in the proposed motion planning technique to solve for trajectories from a start to a goal configurati...

In this paper, we propose a novel localization method for indoor-wheeled robots. The system consists of fusing scene and range data to make more robust the 3Dto- 3D egomotion estimation, which is typically done via ICP. To validate our approach and assess its performance, a system comprised of a laser range finder paired with a monocular camera is...

Humanoid fall avoidance is the ability of a robot to avoid falling when pushed. The decision surface is a region on the phase diagram delimiting the states beyond which the robot cannot recover from a disturbance. The disadvantage of the decision surface is that it is limited to perturbations in the sagittal and coronal planes. This paper deals wit...

In this paper, we introduce a concept design for a single-actuator differentially driven robot. The design is based on connecting two variable-diameter wheels to the same drive shaft. The wheels are designed to have engineered stiffness so that the diameters of the wheels are varied by shifting the weight of the drive mechanism from side to side. W...

In this paper, we introduce a novel mobile robotic platform that is capable of navigating rough terrains. The proposed design utilizes an active angular swivel steering mechanism to perform wide-range steering as well as obstacle climbing. We extend the previously conducted kinematic analysis and develop dynamic models of the proposed platform to s...

In this paper, the effect of wheel skidding on the steering motion of a simple vertical rolling disk is investigated. By modifying the nonholonomic constraints, two novel dynamic models are proposed. The first model rotates the constraints and enforces them along a plane correlated to the skid angle. It then relates the skidding in a wheel to the L...

The design of spread footings on granular soils is generally governed by serviceability requirements. Recent studies have utilized databases of load tests to investigate the use of normalized load-settlement curves to model the behavior of footings on sands. A major limitation of available databases is that they are based primarily on data from pla...

This paper presents a visual odometry system for ground vehicles using a single downward-facing camera. Our method calculates the motion from a monocular camera without using any probabilistic (non-deterministic) or iterative routines neither for motion estimation nor for outliers rejection. Accordingly, the proposed method improves the accuracy, t...

In this paper the motion of a simple vertical rolling disk in the presence of significant skidding effects is investigated. The nonholonomic constraints are adjusted to account for the skidding and two novel friction models are proposed that relate skidding in a wheel to the Lagrange multipliers associated with the kinematic constraints of that whe...

Ankle, momentum, and/or take-a-step strategies constitute different schemes that a humanoid robot may take to avoid falling, where each strategy has a different energy overhead associated to it. To minimize energy consumption it is important to know when each of these strategies can be applied and yet be effective at preventing a fall. This paper i...

In this paper, we analyze the kinematics of a novel active steering mechanism which we shall label as the angular swivel steering mechanism. Inspired by a remotely-controller toy car, we propose using angular swivel steering to construct a robotic mobile base. The kinematic analysis of the proposed angular swivel steering exhibits interesting base...

In teleoperation of collaborative mobile robots different tasks or events require different bandwidth allocation. Thus, different rates of communication on each channel are needed for reliable and efficient task completion. For example, during navigation if obstacles are distant then the rate of video feedback can be reduced versus when the vehicle...

This paper is concerned with gait generation for the simplest underactuated multi-link robot. This robot is realized by a two-link planar system that locomotes in a viscous environment due to the existence of friction pads along its body. The proposed solution of the motion planning problem yields both a control gait for the inter-link angle as wel...

Papers from a flagship conference reflect the latest developments in the field, including work in such rapidly advancing areas as human-robot interaction and formal methods. Robotics: Science and Systems VII spans a wide spectrum of robotics, bringing together researchers working on the algorithmic or mathematical foundations of robotics, robotics...

This paper provides an analytical solution to the motion-planning problem for the Snakeboard. Given a desired planar trajectory in the fiber space, an explicit solution is computed for the controllable inputs in the base space that locomote the Snakeboard along a given trajectory. The motion-planning problem or gait generation problem is solved for...

In real time network based teleoperation, different tasks or events requires different feedback resolutions and thus different rates of feedback are needed for reliable and efficient task completion. For example, in navigation if obstacles are distant then rate of video feedback can be reduced versus when the vehicle is approaching an obstacle. In...

In this paper, we take a rather new approach to solving the motion planning problem for principally kinematic systems, that is, systems whose dynamics is completely specified by the right number of nonholonomic constraints. Given a planar curve in the Special Euclidean group, we analytically solve for the base variables that locomote the principall...

Small robots have the potential to access confined spaces where humans cannot go. However, the mobility of wheeled and tracked systems is severely limited in cluttered environments. Snake robots using biologically inspired gaits for locomotion can provide better access in many situations, but are slow and can easily snag. This paper introduces an a...

We present a refined, second-generation design, construction and integration, of a compact hyper-redundant snakelike robot, called "Woodstock." This robot has substantial advantages over our previous design iteration, "Snoopy," in terms of cost and performance. The robot is composed of six actuated universal joints which are serially chained to con...

In this paper we generate gaits for two types of underactuated mechanical systems: principally kinematic and purely mechanical systems. Our goal is to specify inputs in the form of gaits, that is, a sequence of controlled shape changes of a multi-bodied mechanical system that when executed would produce a desired change in the unactuated position o...

In this paper, we generalize our prior results in motion analysis to design gaits for a more general family of underactuated mechanical systems. In particular, we analyze and generate gaits for mixed mechanical systems which are systems whose motion is simultaneously governed by both a set of non-holonomic velocity constraints and a notion of a gen...

In this paper, we generate gaits for mixed systems, that is, dynamic systems that are subject to a set of non-holonomic constraints. What is unique about mixed systems is that when we express their dynamics in body coordinates, the motion of these system can be attributed to two decoupled terms: the geometric and dynamic phase shifts. In our prior...

We present a new mechanical design for a compact three degrees-of-freedom joint mechanism. This joint design is ideal for use in robotic devices, especially hyper-redundant or snake-like robots. This joint exhibits an unprecedented range of motion: the origin of a coordinate frame attached to the output link of the joint can move on a spherical con...

In this paper we generate gaits for dynamics systems that are subject to non-holonomic velocity constraints. These systems are referred to as mixed non-holonomic systems. The motion of such systems is governed by both the non-holonomic constraints acting on the system and a system of differential equations constraining the evolution of generalized...

In this paper we present a novel gait analysis technique which can directly be used to synthesize gaits for a broad class of mechanical systems. We build upon prior work in locomotion mechanics, however we take a different approach to generate gaits that yield absolute motion of the mechanical system. We present a systematic analysis to control all...

This paper investigates how to generate cyclic gaits for multi-bodied isolated mechanical systems whose configuration space is represented by a trivial fiber bundle. We describe how to generate gaits in the base space of the fiber bundle, or the shape space of the robot on which we assume full control. Such gaits are guaranteed to generate a non-ze...

This paper presents a novel compact design for a two degrees of freedom (DOF) joint mechanism. The joint is optimized for compactness, strength and range of motion which makes it ideal for constructing spatial or three-dimensional hyper redundant robots. We also identify and classify various prior joint designs that led to the development of this n...

In this work we introduce a new concept of a search and rescue robotic system that is composed of an elephant trunk-like robot mounted on a mobile base. This system is capable not only of inspecting areas reachable by the mobile base but also to inspect unreachable areas such as small cracks, and pipes, using the camera mounted on its elephant trun...

Serpentine robots offer advantages over traditional mobile robots and robot arms because they have enhanced flexibility and reachability; especially in convoluted environments. These mechanisms are especially well suited for search and rescue operations where making contact with surviving victims trapped in a collapsed building is essential. The sa...

Serpentine robots offer advances over traditional mobile robots and robot arms because they have enhanced flexibility and reachability, especially in convoluted environments. These mechanisms are especially well suited for search and rescue operations where making contact with surviving victims trapped in a collapsed building is essential. The same...

Serpentine robots offer advances over traditional mobile robots and robot arms because they have enhanced flexibility and reachability, especially in convoluted environments. These mechanisms are especially well suited for search and rescue operations where making contact with surviving victims trapped in a collapsed building is essential. The same...

Seventy-two private practice patients with moderate or severe anxiety-depressive neurosis received mean daily oral doses of 23.8 mg bromazepam, 94 mg amitriptyline, or 4.6 capsules of placebo in a double-blind four-week study. The patient's condition was assessed initially and at weekly intervals by using the Brief Psychiatric Rating Scale and the...

In this paper, we address a particular flavor of the motion planning problem, that is, the gait generation problem for underactuated variable inertia mechanical systems. Additionally, we analyze a rather general type of mechanical systems which we refer to as mixed systems. What is unique about this type of mechanical system is that both non-holono...