6,091 research outputs found
Passivity based force control of hydraulic robots
This paper gives a new nonlinear force control of hydraulic robots. Unlike the electrical robots, hydraulic robots are governed not only by the energy conservation but also by the mass conservation. First we propose a generalized continuity law and a canonical form of hydraulic robots. Second, we propose a new nonlinear robust force control based on passivity in order to achieve the desired force in the presence of unknown environment consisting of the energy storing elements and dissipative elements. Finally, we confirm the validity of our proposed methods by simulation and experiment
Nonlinear disturbance attenuation control of hydraulic robotics
This paper presents a novel nonlinear disturbance rejection control for
hydraulic robots. This method requires two third-order filters as well as
inverse dynamics in order to estimate the disturbances. All the parameters for
the third-order filters are pre-defined. The proposed method is nonlinear,
which does not require the linearization of the rigid body dynamics. The
estimated disturbances are used by the nonlinear controller in order to achieve
disturbance attenuation. The performance of the proposed approach is compared
with existing approaches. Finally, the tracking performance and robustness of
the proposed approach is validated extensively on real hardware by performing
different tasks under either internal or both internal and external
disturbances. The experimental results demonstrate the robustness and superior
tracking performance of the proposed approach
Review of Quadruped Robots for Dynamic Locomotion
This review introduces quadruped robots: MITCheetah, HyQ, ANYmal, BigDog, and
their mechanical structure, actuation, and control
A Passivity-based Nonlinear Admittance Control with Application to Powered Upper-limb Control under Unknown Environmental Interactions
This paper presents an admittance controller based on the passivity theory
for a powered upper-limb exoskeleton robot which is governed by the nonlinear
equation of motion. Passivity allows us to include a human operator and
environmental interaction in the control loop. The robot interacts with the
human operator via F/T sensor and interacts with the environment mainly via
end-effectors. Although the environmental interaction cannot be detected by any
sensors (hence unknown), passivity allows us to have natural interaction. An
analysis shows that the behavior of the actual system mimics that of a nominal
model as the control gain goes to infinity, which implies that the proposed
approach is an admittance controller. However, because the control gain cannot
grow infinitely in practice, the performance limitation according to the
achievable control gain is also analyzed. The result of this analysis indicates
that the performance in the sense of infinite norm increases linearly with the
control gain. In the experiments, the proposed properties were verified using 1
degree-of-freedom testbench, and an actual powered upper-limb exoskeleton was
used to lift and maneuver the unknown payload.Comment: Accepted in IEEE/ASME Transactions on Mechatronics (T-MECH
Using humanoid robots to study human behavior
Our understanding of human behavior advances as our humanoid robotics work progresses-and vice versa. This team's work focuses on trajectory formation and planning, learning from demonstration, oculomotor control and interactive behaviors. They are programming robotic behavior based on how we humans “program” behavior in-or train-each other
High speed, precision motion strategies for lightweight structures
Research on space telerobotics is summarized. Adaptive control experiments on the Robotic Arm, Large and Flexible (RALF) were preformed and are documented, along with a joint controller design for the Small Articulated Manipulator (SAM), which is mounted on the RALF. A control algorithm is described as a robust decentralized adaptive control based on a bounded uncertainty approach. Dynamic interactions between SAM and RALF are examined. Unstability of the manipulator is studied from the perspective that the inertial forces generated could actually be used to more rapidly damp out the flexible manipulator's vibration. Currently being studied is the modeling of the constrained dynamics of flexible arms
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