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One popular approach to controlling humanoid robots is through inverse kinematics (IK) with stiff joint position tracking. On the other hand, inverse dynamics (ID) based approaches have gained increasing acceptance by providing compliant motions and robustness to external perturbations. However, the performance of such methods is heavily dependent on high quality dynamic models, which are often very...
To plan dynamic, whole-body motions for robots, one conventionally faces the choice between a complex, full-body dynamic model containing every link and actuator of the robot, or a highly simplified model of the robot as a point mass. In this paper we explore a powerful middle ground between these extremes. We exploit the fact that while the full dynamics of humanoid robots are complicated, their...
The paper presents a novel dynamic model which can be applied for hyper-redundant robots. The proposed model combines multiple pendulum theory and Lagrange method, and was extracted to illustrate the dynamics of HipRob 01 robot, developed in our laboratory.
This paper considers the problem of planning the motion of a humanoid robot that must execute a manipulation task, possibly requiring stepping, in environments cluttered by obstacles. The proposed method explores the submanifold of the configuration space that is admissible with respect to the assigned task and at the same time satisfies other constraints, including humanoid equilibrium. The exploration...
This paper focuses on motion-planning problems for high-dimensional mobile robots with nonlinear dynamics operating in complex environments. It is motivated by a recent framework that combines sampling-based motion planning in the state space with discrete search over a workspace decomposition. Building on this line of work, the premise of this paper is that the computational efficiency can be significantly...
Planning physically realistic and easily controllable motions of flying robots requires considering dynamics. This paper presents a local trajectory planner, based on a simplified dynamic model of quadrotors, which fits the requirements to be integrated into a global motion planning approach. It relies on a closed-form solution to compute curves in the kinodynamic state space that tend to minimize...
The current paper proposes a trajectory optimization approach for navigating a non-holonomic wheeled mobile robot in dynamic environments. The dynamic obstacle's motion is not known and hence is represented by a band of predicted trajectories. The trajectory optimization can account for large number of predicted obstacle trajectories and seeks to avoid each predicted trajectory of every obstacle in...
This paper discusses a new control approach for robotic-assisted tele-echography. A dynamically consistent hierarchical architecture is proposed, where an explicit Cartesian force control arises as the primary task while orientation control is designed in the null space. Cartesian force control, driven by position errors, establishes the interaction dynamics between probe and patient, implemented...
In this paper we address the problem of accurate trajectory tracking while ensuring compliant robotic behaviour for periodic tasks. We propose an approach for on-line learning of task-specific dynamics, i.e. task specific movement trajectories and corresponding force/torque profiles. The proposed control framework is a multi-step process, where in the first step a human tutor shows how to perform...
Collision free navigation in dynamic environments, where motion of moving obstacles is unknown, still presents a significant challenge. Sampling based algorithms are well known for their simplicity and are widely used in many real time motion planning problems. While many sampling based algorithms for dynamic environments exist, assumptions taken by these algorithms such as known trajectories of moving...
This paper focus on dynamic modeling and a kind of controller for the variable structure bicycle robot's (which called VSBR) track-stand motion when its front wheel is fixed at 45 degrees about its front fork. Firstly, making dynamic analysis for the VSBR whose front wheel is fixed at arbitrary degrees about its front fork. The roll angle, yaw angle, the angle front fork rotated and the angle front...
Object closure using a robot team can be used as a suitable transportation method which does not rely on contact force control to perform this task. Previously, the conditions to achieve object closure and dynamic object closure were defined. In this paper it is introduced the estimation of a feasible dynamic caging zone, as the range within an object which allows for a robot to move freely without...
This paper presents a solution to the residual vibration of 3-DOF Delta parallel robots. As the parallel mechanism is highly nonlinear, inverse dynamics analysis in explicit form by using Lagrangian formulation is proposed to linearize the system. To apply the Lagrangian method to the parallel mechanism, the structure is divided to sub-chains by imaginary open tree method. After deriving inverse dynamics...
This paper introduces a new distributed manipulation concept whereby objects operating under the action of a uniform force field are positioned perpendicular to the force field and oriented by selectively applying braking forces at various locations on the object. We assume that the braking locations do not slip, which gives the object dynamics the familiar form of the pendulum equation, but with...
The paper presents iterative learning control of an exoskeleton for human upper limbs to provide forearm movement assistance, which enables a human forearm to track any continuous desired trajectory (or constant setpoint), in the presence of parametric/functional uncertainties, unmodelled dynamics including actuator dynamics, and/or disturbances from the environment. Given desired trajectories of...
Performance of constrained movements in multiple directions of a workspace simultaneously and in presence of uncertainty is a great challenge for robots. Achieving such tasks by employing control policies which are fully determined a priori and do not take into account the system uncertainty can cause undesired stress on the robot end-effector or the environment and result in poor performance. Instead,...
In the past decade, model learning techniques have provided appealing approaches for determining the dynamic model of robots from data. These techniques strongly capture the complicated effects of robot dynamics, which are often neglected in hand-crafted dynamic models. However, unlike robust performance shown in trained tasks, learned models do not exhibit a reliable performance in new tasks as they...
In this paper, we present a method to improve a robot's imitation performance in a drawing scenario by inserting pauses in motion. Human's drawing skills are said to develop through five stages: 1) Scribbling, 2) Fortuitous Realism, 3) Failed Realism, 4) Intellectual Realism, and 5) Visual Realism. We focus on stages 1) and 3) for creating our system, each corresponding to body babbling and imitation...
This paper presents a control framework for arm/hand systems aimed at controlling internal forces exchanged between the fingers and the grasped object, and enforcing a compliant behavior in presence of environmental interactions. A dynamic planner computes the motion references for the fingers by using the feedback of the contact forces, while an impedance control, in which dynamic effects exerted...
On a new demand of safe human-robot interaction for robotic applications, the Compact Compliant Actuator, named CompActTM, is recently developed with physical compliance and active variable damping. In this mechanism, a desired physical damping behavior is realized by generating a friction force which is actively controlled by piezoelectric actuators (PEAs). However, nonlinearities such as hysteresis...
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