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A new generalized method of stable model inversion is presented with the aim of providing solutions for the feedforward control of underactuated robots. The area of application is in SISO and MIMO systems within robotics which contain only scleronomous constraints. This generalized restriction is discussed followed by a justification of its sufficiency. The method uses a boundary value problem framework...
This paper introduces an experimental rescue robot, HUBO T-100 for a development of a Korean rescue robot with a large load carrying capacity and presents its optimal motion control methods. The mission of the rescue robot is to move and lift patients or soldiers with impaired mobility for the rescue and assistance in the battlefields, hospitals, hazardous and disastrous environments. Another mission...
This paper deals with a new CLIE (Closed Loop Input Error) method for dynamic identification of flexible joint robots. This is a straightforward extension of the DIDIM (Direct and Inverse Dynamic Identification Models) method from rigid robots to flexible joint robots. DIDIM is a fast closed loop input error method which minimizes the quadratic error between the actual motor force/torque (the control...
The paper presents the development of a measurement system for dynamic stability analysis. The system is composed of an actuation device, that is a robotic platform with four degrees of freedom, and two measurement systems: a force platform, to measure the position of the centre of pressure (COP), and a vision system, to measure the position of the centre of mass (COM). The purpose of the system is...
This paper presents a compliant locomotion framework for torque-controlled humanoids using model-based whole-body control. In order to stabilize the centroidal dynamics during locomotion, we compute linear momentum rate of change objectives using a novel time-varying controller for the Divergent Component of Motion (DCM). Task-space objectives, including the desired momentum rate of change, are tracked...
Learning motion tasks in a real environment with deformable objects requires not only a Reinforcement Learning (RL) algorithm, but also a good motion characterization, a preferably compliant robot controller, and an agent giving feedback for the rewards/costs in the RL algorithm. In this paper, we unify all these parts in a simple but effective way to properly learn safety-critical robotic tasks such...
A model predictive controller is developed for following the position of a human dancer in robot ballroom dancing. The control design uses a dynamic model of a dancer, based on a variant of the so-called 3D Linear Inverted Pendulum Mode that includes also the swing foot. This model serves as a basis for a Kalman predictor of the human motion during the single-support phase, while a simpler kinematic...
Many motion planning problems in robotics are high dimensional planning problems. While sampling-based motion planning algorithms handle the high dimensionality very well, the solution qualities are often hard to control due to the inherent randomization. In addition, they suffer severely when the configuration space has several ‘narrow passages’. Search-based planners on the other hand typically...
This paper discusses a new control approach for robotic-assisted tele-echography where contact dynamics are driven by a 3D time-of-flight camera and a force sensor. Based on 3D camera and force data, contact stiffness is anticipated, allowing adaptation before contact. This approach enables to slow down robot dynamics before contact which is adequate for tele-echographic tasks. Additionally, free...
We consider the manipulation planning problem of an extensible elastic rod in collision-free or contact space. We assume the rod can be handled by grippers either at both or at only one of its extremities and during the manipulation, the grasped end may change. We show that the use of both quasi-static and dynamic models can be coupled efficiently with sampling-based methods. By sampling directly...
We present a new framework for reactive synthesis that considers the dynamics of the robot when synthesizing correct-by-construction controllers for nonlinear systems. Many high-level synthesis approaches employ discrete abstractions to reason about the dynamics of the continuous system in a simplified manner. Often, these abstractions are expensive to compute. We circumvent the need to have detailed...
Similar to combustion engines comprising multiple cylinders engaged with a crankshaft, multiple piezoelectric stack actuators (PSA) engaged with a common output rod can produce smooth, long stroke motion with desired properties. In particular, when equally spaced multiple units are arranged to push sinusoidal gear teeth on the output rod, the system exhibits unique collective behaviors thanks to “harmonic”...
This paper discusses a dynamic nonprehensile manipulation by using a vibrating plate. The manipulation method, where two DOF (degrees of freedom) motion of an object on the plate surface is controlled by a single active joint, is proposed. For the plate vibration mechanism, we newly introduce an active-passive hybrid joint whose two axes are arranged in nonparallel to each other. This mechanism features...
This paper presents a new approach to high speed visual servoing in the case of a 6 DOF industrial manipulator that takes into account the dynamics of the manipulator in the synthesis of the visual controller. The manipulator with its actuators (DC motors), their current feedback loops and their velocity control loops, is modelled as a "virtual Cartesian motion device". A linearized model...
This paper presents an Iterative Learning Control algorithm for direct-drive robots. The learning algorithm assumes linear dynamics, which is created using a nonlinear model-based compensator. The convergence criterion of the learning controller is derived in the frequency domain. Rules for designing the filters, used in the update law, are explained. The effectiveness of the algorithm is demonstrated...
In this paper, the problem of a class of hyperredundant arms with continuum elements that performs the grasping function by coiling is discussed. This function is often met in the animal world as the elephant's trunk or octopus tentacle. First, the dynamic model in 3D-space is developed. The equations that describe the motion of the arm that carries a load by coiling are inferred. The stability of...
This paper presents a path-planning approach to enable a swarm of robots move to a goal region while avoiding collisions with static and dynamic obstacles. To provide scalability and account for the complexity of the interactions in the swarm, the proposed approach combines probabilistic roadmaps with potential fields. The underlying idea is to provide the swarm with a series of intermediate goals...
Sampling-based methods, such as Probabilistic Roadmap Method(PRM)[l], Rapidly-Exploring Random Tree(RRT)[2], have been proposed as promising solutions for kinodynamic problems. Nevertheless, it's still a challenge for practical application especially for complex systems. In particular, most of the forward propagation is fruitless, which lead to heavy computation and be time-consuming. This paper presents...
When possible, non-prehensile transportation (i.e. transporting objects without grasping them) can be faster and more efficient than prehensile transportation. However, the need to explicitly consider reaction and friction forces yields kino-dynamic constraints that are difficult to take into account by traditional planning algorithms. Based on the recently developed Admissible Velocity Propagation...
This paper proposes a new generic strategy to investigate the dynamic limits of the humanoid robot HRP-2 based on whole body optimal control optimization. In this study we exploit the intuitive access to complex motion characteristics, given by optimal control, to effectively resolve a major technical coupling effect, namely between the ankle elasticity and the stabilizing algorithms. Control efforts...
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