Although backdrivability is recognized as an important property of actuators, this term is often used without clear definition. In order to design mechanisms with advanced controllability, it is important to understan...
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Although backdrivability is recognized as an important property of actuators, this term is often used without clear definition. In order to design mechanisms with advanced controllability, it is important to understand the fundamental mechanism of backdrivability. In this paper, we introduced idea of series elasticity and series dissipation of actuators. Based on this idea, total/output backdrivability and their fundamental properties are stated. EHA was shown to be series dissipative and it was confirmed from the model of the actuator. Utilizing the backdrivability of EHA, position based impedance control was implemented and evaluated. Application of this EHA in a robot hand is also reported.
In this paper, a jumping motion is considered with the goal of achieving high-speed dynamic motion for legged robots. We propose a two-step jumping pattern which makes use of the characteristic of a lightweight and fa...
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In this paper, a jumping motion is considered with the goal of achieving high-speed dynamic motion for legged robots. We propose a two-step jumping pattern which makes use of the characteristic of a lightweight and fast actuator. In addition, jumping strategies based on the dynamics of the robots are presented, and the effect of structural parameter on jumping height is analyzed. Experimental results are shown in which a 1-DOF two-legged robot jumps with three patterns.
Impedance and Admittance control are two distinct implementations of the same control goal. It is well known that their stability and performance properties are complementary. In this paper, we present a hybrid system...
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ISBN:
(纸本)9781424450381;9781424450404
Impedance and Admittance control are two distinct implementations of the same control goal. It is well known that their stability and performance properties are complementary. In this paper, we present a hybrid system approach, which incorporates Impedance and Admittance control as two extreme cases of one family of controllers. This approach allows to continuously switch and interpolate between Impedance and Admittance control. We compare the basic stability and performance properties of the resulting controllers by means of an extensive case study of a one-dimensional system and present an experimental evaluation using the KUKA-DLR-lightweight arm.
This paper addresses the problem of acquiring a hierarchically structured robotic skill in a nonstationary environment. This is achieved through a combination of learning primitive strategies from observation of an ex...
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This paper addresses the problem of acquiring a hierarchically structured robotic skill in a nonstationary environment. This is achieved through a combination of learning primitive strategies from observation of an expert, and autonomously synthesising composite strategies from that basis. Both aspects of this problem are approached from a game theoretic viewpoint, building on prior work in the area of multiplicative weights learning algorithms. The utility of this procedure is demonstrated through simulation experiments motivated by the problem of autonomous driving. We show that this procedure allows the agent to come to terms with two forms of uncertainty in the world - continually varying goals (due to oncoming traffic) and nonstationarity of optimisation criteria (e.g., driven by changing navigability of the road). We argue that this type of factored task specification and learning is a necessary ingredient for robust autonomous behaviour in a “large-world” setting.
In the paper, infinite-dimensional, continuous-time control systems described by nonlinear and semilinear abstract differential equations are considered. Using methods of functional analysis sufficient conditions for ...
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In the paper, infinite-dimensional, continuous-time control systems described by nonlinear and semilinear abstract differential equations are considered. Using methods of functional analysis sufficient conditions for constrained exact local controllability are formulated and proved. It is generally assumed that the values of controls are in a convex and closed cone with vertex at zero. Illustrative application is also given. Moreover, some remarks and comments on controllability problems for nonlinear dynamical systems are presented.
This paper presents a mind model for controlling autonomous robot systems, based on human psychology. A cognitive system and a motivational system (emotions and needs) constitute its main parts. The motivational syste...
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This paper presents a mind model for controlling autonomous robot systems, based on human psychology. A cognitive system and a motivational system (emotions and needs) constitute its main parts. The motivational system controls the reactions of a robot with the use of changeable states of needs. Emotions control the behavior of the robot by modulating certain parameters of needs. The cognitive system controls both the memory of the robot and its data processing.
Humanoid robots should be able to stand and walk in the presence of external disturbances. This paper addresses the robustness of a humanoid robot to unknown disturbances. Applying the maximal CPI set, it becomes poss...
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Humanoid robots should be able to stand and walk in the presence of external disturbances. This paper addresses the robustness of a humanoid robot to unknown disturbances. Applying the maximal CPI set, it becomes possible to consider the physical constraint explicitly in the COG-ZMP inverted pendulum model control. In our previous research, the convergence speed of COG was improved by applying the switching control based on the maximal CPI set to the stabilization control assuming the contact region is constant. This paper presents updating calculation method of the maximal CPI set when the contact region changes, and the authors propose a falling avoidance control as an application of it. Detecting the stepping necessity based on the maximal CPI set enables to unify the upright position stabilization and stepping motion for falling avoidance. The validity of the proposed method is verified with experiments.
Experiments showed that Hierarchical Task Network (HTN) planners are suitable to find solutions for nontrivial tasks in complex scenarios. Mobile service robots are able to execute actions which may constitute the bas...
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Experiments showed that Hierarchical Task Network (HTN) planners are suitable to find solutions for nontrivial tasks in complex scenarios. Mobile service robots are able to execute actions which may constitute the basic building blocks to achieve high-level goals. However, only few experiments demonstrate the application of a general purpose deliberative planner in the domain of mobile service robots. One challenging problem arises from the fact that adaptive AI-based planners presume the closed-world assumption (CWA) and are therefore unable to deal with incomplete information. Unknown objects which are not represented in the planning domain, for example, cannot be integrated into the planning process. Since mobile service robots act in a real dynamic environment and construct or adapt their world model autonomously based on sensory data, they are inevitably confronted with uncertain and incomplete information about the world. This conflict between simplified assumptions for planning on the one hand and the complexity of the real world on the other constitutes a major problem of modern robotics. This paper describes two approaches to dealing with incomplete world knowledge in the context of HTN robot planning. Several experiments demonstrate that the approaches can successfully be applied in a dynamic and unstructured environment.
The use of Autonomous Underwater Vehicles (AUV) as robots for exploration and oceanology science has been a field of interest of several universities and research center's around the world in the last decade. Cuba...
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ISBN:
(纸本)9781424478149
The use of Autonomous Underwater Vehicles (AUV) as robots for exploration and oceanology science has been a field of interest of several universities and research center's around the world in the last decade. Cuba being a country surrounded by the Caribbean Sea, having most of it's resources in it. Researchers from the Central University of Las Villas (UCLV) and the Hydrographic Research Center (HRC) have joined forces in the development of the HRC-AUV project, whit the objective of the implementation of a AUV capable to operate in the Cuban sea for exploration and supervision. The platform is based on low cost sensors and hardware. In the present document the hardware and software architectures of the AUV are presented. Also a set of experimental results are presented to validate the system.
The approach extends control principles of standard building automation. Introducing control commands based on information from 3D head pose estimation and tracking systems, new methods in communication and contactles...
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The approach extends control principles of standard building automation. Introducing control commands based on information from 3D head pose estimation and tracking systems, new methods in communication and contactless controlled systems are made accomplishable. Using a visual user-interface, visually detected movements can be transformed into standard control commands. Using a defined markup language, an application dependent command set is correlated with actual head movements. The mapping itself can be adapted to application dependent demands and the individual needs of the users. The concept of “visual control” is intended to be a further step towards bridging the information gap between (physically challenged) people and their smart environments. The concept is applied to a prototype used in different settings of a building automation, utilising cutting-edge software with standard control devices and sensors.
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