130 research outputs found
Dynamic Balance Control of Multi-arm Free-Floating Space Robots
This paper investigates the problem of the dynamic balance control of
multi-arm free-floating space robot during capturing an active object in close
proximity. The position and orientation of space base will be affected during
the operation of space manipulator because of the dynamics coupling between the
manipulator and space base. This dynamics coupling is unique characteristics of
space robot system. Such a disturbance will produce a serious impact between
the manipulator hand and the object. To ensure reliable and precise operation,
we propose to develop a space robot system consisting of two arms, with one arm
(mission arm) for accomplishing the capture mission, and the other one (balance
arm) compensating for the disturbance of the base. We present the coordinated
control concept for balance of the attitude of the base using the balance arm.
The mission arm can move along the given trajectory to approach and capture the
target with no considering the disturbance from the coupling of the base. We
establish a relationship between the motion of two arm that can realize the
zeros reaction to the base. The simulation studies verified the validity and
efficiency of the proposed control method
Research on a semiautonomous mobile robot for loosely structured environments focused on transporting mail trolleys
In this thesis is presented a novel approach to model, control, and planning the motion of
a nonholonomic wheeled mobile robot that applies stable pushes and pulls to a
nonholonomic cart (York mail trolley) in a loosely structured environment. The method is
based on grasping and ungrasping the nonholonomic cart, as a result, the robot changes its
kinematics properties. In consequence, two robot configurations are produced by the task
of grasping and ungrasping the load, they are: the single-robot configuration and the
robot-trolley configuration. Furthermore, in order to comply with the general planar
motion law of rigid bodies and the kinematic constraints imposed by the robot wheels for
each configuration, the robot has been provided with two motorized steerable wheels in
order to have a flexible platform able to adapt to these restrictions. [Continues.
Optimization of body configuration and joint-driven attitude stabilization for transformable spacecrafts under solar radiation pressure
A solar sail is one of the most promising space exploration system because of
its theoretically infinite specific impulse using solar radiation pressure
(SRP). Recently, some researchers proposed "transformable spacecrafts" that can
actively reconfigure their body configurations with actuatable joints. The
transformable spacecrafts are expected to greatly enhance orbit and attitude
control capability due to its high redundancy in control degree of freedom if
they are used as solar sails. However, its large number of input poses
difficulties in control, and therefore, previous researchers imposed strong
constraints to limit its potential control capabilities. This paper addresses
novel attitude control techniques for the transformable spacecrafts under SRP.
The authors have constructed two proposed methods; one of those is a joint
angle optimization to acquire arbitrary SRP force and torque, and the other is
a momentum damping control driven by joint angle actuation. Our proposed
methods are formulated in general forms and applicable to any transformable
solar sail that consists of flat and thin body components. Validity of the
proposed methods are confirmed by numerical simulations. This paper contributes
to making most of the high control redundancy of transformable solar sails
without consuming any expendable propellants, which is expected to greatly
enhance orbit and attitude control capability.Comment: 16 pages, 11 figures, submitted to Astrodynamics published by
Tsinghua University Press and Springe
Aerospace medicine and biology: A continuing bibliography with indexes (supplement 344)
This bibliography lists 125 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during January, 1989. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance
Collision avoidance and dynamic modeling for wheeled mobile robots and industrial manipulators
Collision Avoidance and Dynamic Modeling are key topics for researchers dealing with mobile and industrial robotics. A wide variety of algorithms, approaches and methodologies have been exploited, designed or adapted to tackle the problems of finding safe trajectories for mobile robots and industrial manipulators, and of calculating reliable dynamics models able to capture expected and possible also unexpected behaviors of robots. The knowledge of these two aspects and their potential is important to ensure the efficient and correct functioning of Industry 4.0 plants such as automated warehouses, autonomous surveillance systems and assembly lines. Collision avoidance is a crucial aspect to improve automation and safety, and to solve the problem of planning collision-free trajectories in systems composed of multiple autonomous agents such as unmanned mobile robots and manipulators with several degrees of freedom. A rigorous and accurate model explaining the dynamics of robots, is necessary to tackle tasks such as simulation, torque estimation, reduction of mechanical vibrations and design of control law
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