29 accepted papers
This paper presents a coordinated compliant control strategy for space manipulator systems to enable safe and robust target capture during on-orbit servicing and assembly missions. The proposed controller operates in two distinct phases: free-space motion and contact interaction. In the free-space p…
This paper introduces a virtual gravity controller for underactuated biped robots. A bio-inspired model of passive bipedal walking is used as the basis for the controller's design. An analytical expression of the controller is obtained, allowing on-line implementations of the developed control schem
Present electromagnetic soft actuators rely on external magnetic fields or power supplies, while the very few that operate autonomously produce weak actuating forces, limiting their practicality. This work introduces a novel current-controlled electromagnetic actuator that employs copper coils and p
To accurately accomplish on-orbit tasks using Space Manipulator Systems (SMS), advanced model-based controllers, dependent on the knowledge of SMS parameters, can be employed. However, these parameters may change on orbit for several reasons. Also, during an SMS task, excitation of flexible appendag…
Space manipulator system (SMS) maneuvers can excite flexible appendages, while fuel sloshing effects impact its dynamics and performance. To predict this behavior and control such systems, sloshing and flexible appendages are modeled. A novel system identification scheme is developed, which identifi…
Efficient and thorough vineyard inspection is crucial for optimizing yield and preventing disease from spreading. Manual approaches are labor-intensive and prone to human error, motivating the development of automated solutions. Precision viticulture benefits greatly from access to photo-realistic 3…
Analytical expressions are derived for actuator demands in quadrupedal locomotion of constant speed and height by using a reduction from a trot/ pace 6-bar model to a single-legged model and employing two widely used two-segmented leg architectures, the serial and the parallel. A method is developed…
During maneuvers of a space manipulator system (SMS), thruster fuel in its spacecraft (S/C) results in sloshing effects which impact its dynamics and performance. In this work, sloshing effects are modeled by a 3D mass-spring-damper. A novel system identification scheme is developed, which identifie
This paper studies the effects of replacing pin-joint knees in passive dynamic bipedal walkers with biomimetic four-bar knees. The kinetic model of the four-bar knees is presented in detail, and an analytical model of the passive walking dynamics is derived. The resulting four-bar kneed biped is com…
This paper studies a passive biped walker with knees and biomimetic feet and its behavior, as a function of key parameters. The model includes a continuous dynamic representation of the knee joint's interaction with a viscoelastic kneecap, as well as a complete kinematic description of feet that are…
In this paper, we study the effect of alternative leg designs on energy consumption in legged locomotion. Focusing on gaits with constant horizontal velocity and constant height we introduce models of two simplified parallel and serial designs with realistic mechanical and actuation parameters. The…
A methodology for implementing arbitrary foot shapes in the passive walking dynamics of biped robots is developed. The dynamic model of a walking robot is defined in a way that allows shape-dependent foot kinetics to contribute to the robot's dynamics, for all convex foot shapes regardless of the ex…
To control a free-floating robotic system with uncertain parameters in OOS tasks with high accuracy, a fast parameter identification method, previously developed by the authors, is enhanced further and used concurrently with a controller. The method provides accurate parameter estimates, without any…
Space manipulator systems in orbit are subject to link flexibilities since they are designed to be lightweight and long reaching. Often, their joints are driven by harmonic gear-motor units, which introduce joint flexibility. Both of these types of flexibility may cause structural vibrations. To imp…
A novel identification method is developed which identifies the accumulated angular momentum (AAM) of spinning reaction wheels (RWs) of an uncooperative satellite captured by a robotic servicer. In contrast to other methods that treat captured satellite's RWs as non-spinning, the developed method pr…
This paper presents the mathematical derivation and experimental validation of a computational model, which accurately predicts static, large-strain deformations of tendon driven non-slender soft-arm manipulators subjected to gravity. The large strain behaviors are captured by employing the Green-La…
The parameter estimation of space manipulator systems on orbit is studied, whose manipulators are subject to joint flexibilities. To improve path planning and tracking capabilities, advanced control strategies that benefit from the knowledge of system parameters are required. These parameters includ…
This paper studies the effects of varying rollover curvature on the passive dynamic gait of a biped walker. The dynamic model of a compliant biped robot is extended with the implementation of semielliptical feet, to mimic human rollingradius progression during a step. The process of modeling the sem…
An optimal leg sequence selection method is developed, which maximizes hexapod robot stability, considering feasible gaits, motion modes, and terrain slope. A novel and fast search method is employed to find the most stable leg sequence for a given gait; if no such sequence exists, the next fastest…
Quadrupedal trotting gaits of constant forward velocity and body height are studied. A method is developed, which is structured upon analytical expressions derived from the dynamics of a reduced single-legged model comprised of a point mass, and two actuated rotational joints. The inputs of the meth…
This paper introduces alternative behaviors described by the SLIP model when it is subject to a range of initial conditions. A non-dimensional SLIP model and a numerical return map search scheme are used to determine fixed points as a function of non-dimensional leg stiffness and vertical displaceme…
This paper presents an efficient method of stabilizing the gait of an underactuated biped with compliant legs and semicircular feet. First, the model is defined, incorporating elements that are often present in experimental biped robots. The biped's passive behavior is studied through numerical simu…
This paper introduces a leg design method aiming at speed maximization for quadruped robots with two-segment compliant legs, in trotting and bounding. The proposed method is an effort to address the leg design challenge in a holistic way, exploiting the coupling between gait parameters, leg design p…
To accomplish tasks with high accuracy, advanced control strategies that benefit from the knowledge of system parameters are required. However, during operation some of them may change, or be unknown. In this paper, a novel parameter estimation method is proposed, which is based on the conservation…
This paper studies the effect of a flexible linear torso on the dynamics of passive quadruped bounding. A reduced-order passive and conservative model with translational spinal joint and springy legs is introduced. Numerical return map studies reveal the existence of a confined area of fixed points…
While legged locomotion is a rapidly advancing area in robotics, several issues regarding the performance of such robots on deformable ground are still open. In this paper, we generate a pronking gait on a quadruped robot using a controller, which takes into account the effects of ground deformation
We propose a biomechatronics-based master/slave topology which is going to provide an Extended Physiological Proprioception (EPP)-equivalent control but without the use of a harness, cineplasty, or Bowden cable. The proposed control uses an implanted micro servo actuator. The original Bowden-cable E…
We present the design of a backstepping controller for a triangular over-actuated marine platform, controlled by three rotating jets. Our goal is the stabilization of the position and the orientation of the platform, under realistic environmental disturbances, such as wind forces, wave forces and hy…
The modeling and control of a vectoring tricopter UAV are developed in this article. The UAV is actuated by three thrust motors, each guided by suitable actuators, thus forming a platform able to independently track any desired attitude and trajectory. The derivation of the equations of motion is fo…