1,229 research outputs found
Inverse kinematics of a humanoid robot with non-spherical hip: a hybrid algorithm approach
This paper describes an approach to solve the
inverse kinematics problem of humanoid robots whose
construction shows a small but non negligible offset at
the hip which prevents any purely analytical solution to
be developed. Knowing that a purely numerical solution
is not feasible due to variable efficiency problems, the
proposed one first neglects the offset presence in order to obtain an approximate âsolutionâ by means of an
analytical algorithm based on screw theory, and then uses
it as the initial condition of a numerical refining
procedure based on the LevenbergâMarquardt algorithm.
In this way, few iterations are needed for any specified
attitude, making it possible to implement the algorithm
for realâtime applications. As a way to show the
algorithmâs implementation, one case of study is
considered throughout the paper, represented by the
SILO2 humanoid robot
Asymmetric Dual-Arm Task Execution using an Extended Relative Jacobian
Coordinated dual-arm manipulation tasks can be broadly characterized as
possessing absolute and relative motion components. Relative motion tasks, in
particular, are inherently redundant in the way they can be distributed between
end-effectors. In this work, we analyse cooperative manipulation in terms of
the asymmetric resolution of relative motion tasks. We discuss how existing
approaches enable the asymmetric execution of a relative motion task, and show
how an asymmetric relative motion space can be defined. We leverage this result
to propose an extended relative Jacobian to model the cooperative system, which
allows a user to set a concrete degree of asymmetry in the task execution. This
is achieved without the need for prescribing an absolute motion target.
Instead, the absolute motion remains available as a functional redundancy to
the system. We illustrate the properties of our proposed Jacobian through
numerical simulations of a novel differential Inverse Kinematics algorithm.Comment: Accepted for presentation at ISRR19. 16 Page
An Overview of Kinematic and Calibration Models Using Internal/External Sensors or Constraints to Improve the Behavior of Spatial Parallel Mechanisms
This paper presents an overview of the literature on kinematic and calibration models of parallel mechanisms, the influence of sensors in the mechanism accuracy and parallel mechanisms used as sensors. The most relevant classifications to obtain and solve kinematic models and to identify geometric and non-geometric parameters in the calibration of parallel robots are discussed, examining the advantages and disadvantages of each method, presenting new trends and identifying unsolved problems. This overview tries to answer and show the solutions developed by the most up-to-date research to some of the most frequent questions that appear in the modelling of a parallel mechanism, such as how to measure, the number of sensors and necessary configurations, the type and influence of errors or the number of necessary parameters
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