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The underwater vehicle-manipulator system (UVMS) is basically a redundant system. Hence, this redundant system can have various combinations of joint velocities that do not affect the given velocity profile of an end-effector and this may induce a self-motion of a vehicle. In the current paper, the performance index based on the concept of Zero Moment Point(ZMP) is proposed to enhance the stability...
Two legged robots have better mobility when compared with wheeled robots, but they tend to tip over easily. This will become a serious problem when the degrees of freedom (DOF) of the two legged walking machine increases. To overcome this problem the gaits of the biped robot need to be planned properly. In the present paper, a closed form solution for whole body motion of a 18-DOF biped robot, based...
Kinesthetic teaching is an established method of teaching robots new skills without requiring robotics or programming knowledge. However, the inertia and uncoordinated motions of individual joints decrease the intuitiveness and naturalness of interaction and impair the quality of the learned skill. This paper proposes a method to ease kinesthetic teaching by combining the idea of incremental learning...
We present an adaptive data-driven algorithm for interactive crowd simulation. Our approach combines realistic trajectory behaviors extracted from videos with synthetic multi-agent algorithms to generate plausible simulations. We use statistical techniques to compute the movement patterns and motion dynamics from noisy 2D trajectories extracted from crowd videos. These learned pedestrian dynamic characteristics...
Predicting the trajectory of a wide receiver in the game of American football requires prior knowledge about the game (e.g., route trees, defensive formations) and an accurate model of how the environment will change over time (e.g., opponent reaction strategies, motion attributes of players). Our aim is to build a computational model of the wide receiver, which takes into account prior knowledge...
Autonomous underwater vehicles (AUVs) is a field of growing interest due to its potential applications in ocean exploration, surveillance, inspection of undersea equipment, defence, and finding sunken ships, aircraft and other lost artifacts. This paper addresses the challenges involved in designing the controller for an open-frame AUV that is described by the complex nonlinear kinematic and dynamic...
Recent advances in road safety have lead to a constant decline of injured traffic participants in Europe per year. Still, the number of injured pedestrians remains nearly constant. As a countermeasure, active pedestrian safety is the focus of current research, for which accurate pedestrian prediction is a prerequisite. In this scope, we propose a method for dynamics-and environment-based pedestrian...
Multi-contact motion generation is an important problem in humanoid robotics because it generalizes bipedal locomotion and thus expands the functional range of humanoid robots. In this paper, we propose a complete solution to compute a fully-dynamic multi-contact motion of a humanoid robot. We decompose the motion generation by computing first a dynamically-consistent trajectory of the center of mass...
This paper proposes a robotic system capable of learning and reproducing robot gestures based on the Learning by Demonstration (LbD) approach. We focused on those gestures that are used for communicative purposes in human-human interaction. These gestures appear in various motions and this variation causes a delicate difference in the meaning and feeling that is delivered. While some (psychology and...
This paper provides an overview of the bipedal walking controller implemented on ESCHER, a new torque-controlled humanoid designed by Virginia Tech to compete in the DARPA Robotics Challenge (DRC). The robot's compliant control approach relies on an optimization-based inverse dynamics solver proposed in a previous publication. This work presents two unique features to improve stability on soft and...
The classical Capture Point (CP) technique allows biped robots to take protective footsteps in case of a push or other disturbance, but only applies to flat terrain and a horizontally-moving Center of Mass (CoM). This paper generalizes the Capture Point technique to arbitrary terrains and CoM paths. Removing the CoM path constraint leads to an infinite number of Capture Points, each corresponding...
Simplified models of the dynamics such as the linear inverted pendulum model (LIPM) have proven to perform well for biped walking on flat ground. However, for more complex tasks the assumptions of these models can become limiting. For example, the LIPM does not allow for the control of contact forces independently, is limited to co-planar contacts and assumes that the angular momentum is zero. In...
In order to be effective, learning of robotic motion by demonstration should not remain limited to direct repetition of movements, but should enable modifications with respect to the state of the external environment, and generation of actions for previously unencountered situations. In this paper we propose an approach that combines these two features, and applies them in the framework of dynamic...
The majority of methods developed for generating locomotion plans for bipedal robots are based upon the linear inverted pendulum model. While this simplified model has proven useful, it possesses certain theoretical limitations such as the inability to account for changes in the height of the center of mass or the effects of angular momentum, the latter of which can be useful for recovering from disturbances...
Highly dynamic tasks that require large accelerations and precise tracking usually rely on precise models and/or high gain feedback. While movement primitives allow for efficient representation of such tasks from demonstrations, the optimization of the required motor commands for systems with inaccurate dynamic models remains an open problem. To achieve accurate tracking for such tasks, we investigate...
This work addresses the problem of whole-body motion planning for a humanoid robot that must execute a certain task in an environment containing obstacles. A randomized planner is proposed that builds a solution by concatenating whole-body motions. Each whole-body motion is generated so as to realize a center of mass (CoM) movement selected from a set of primitives and simultaneously accomplish a...
This paper demonstrates a method for simultaneous transfer of positional and force requirements for in-contact tasks from a human instructor to a robotic arm through kinesthetic teaching. This is achieved by a specific use of the sensory configuration, where a force/torque sensor is mounted between the tool and the flange of a robotic arm endowed with integrated torque sensors at each joint. The human...
In this paper, a new balancing approach is presented for planar cable robot. In fact, an optimal trajectory planning problem is defined in which states, controls and the values of counterweights calculated simultaneously in order to minimize the performance objective in a point to point motion. The necessary conditions for optimality are achieved by calculus of variations which leads to the optimality...
This paper proposes a scenario-based approach for control of multi-object dynamic system motion for the cases when the relative position of the objects relative each to other plays the primary role.
This article is devoted to intense beam dynamics optimization in resonance systems, where particles movement is effected by radio-frequency (RF) fields generated by the beam itself. Klystron or klystron-type buncher are the examples of such devices. Mathematical model of beam longitudinal dynamics is presented by the finite sequence of equations. At every iteration dynamic process is described by...
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