3 research outputs found
Design, modeling and implementation of a biphasic media variable stiffness actuator
Nowadays, an increasing number of industrial processes are expected
to have robots interacting safely with humans and the environment.
Compliance control of robotic systems strongly addresses these scenarios.
This thesis develops a variable stiffness actuator (VSA) whose
position and stiffness can be controlled independently. Actuator\u2019s stiffness
is controlled by changing pressure of control fluid into distribution
lines. The used control fluid is biphasic, composed of separated gas
and liquid fractions with predefined ratio. Firstly, an approach for the
mathematical model is introduced and a model-based control method
is implemented to track the desired position and stiffness. Results
from force loaded and unloaded simulations proved the feasibility of
these methods. Based on the previous outcome, a compliant revolute
joint mechanism was modeled and implemented in order to use it as a
test bench for the VSA. The mechanism is able to track position and
stiffness accurately; however, better mechanical design and manufacturing
methods are suggested in order to avoid excessive friction. Later
on, a momentum-based collision detection and reaction algorithm is
proposed, simulated and tested on the mechanism. Experimental results
confirm that this method can be used to attain a higher level
of safety in the system. Finally, a compliant cable-driven revolute
joint using biphasic media variable stiffness actuators is modeled and
simulated. This cable-driven mechanism is characterized by a wide
range of stiffness and high-power output
Design Analysis of a 3-DOF Cable-driven Variable-stiffness Joint Module
Variable-stiffness manipulators can produce intrinsically-safe motions, which are essential for next generation service robots. In this paper, the design analysis of a 3-DOF cable-driven joint module with variable stiffness is proposed. To achieve significant change of the stiffness, a flexure-based variable-stiffness device is serially connected to each of the cables. Due to the existence of redundant actuation, the stiffness of the joint module is controlled by regulating the cable tensions. To this end, the relationship between the stiffness matrix of the joint module and the cable tensions has been formulated and analyzed. Simulation examples are provided to illustrate the effectiveness of the proposed stiffness evaluation algorithm
Design, modeling and implementation of a biphasic media variable stiffness actuator
Nowadays, an increasing number of industrial processes are expected
to have robots interacting safely with humans and the environment.
Compliance control of robotic systems strongly addresses these scenarios.
This thesis develops a variable stiffness actuator (VSA) whose
position and stiffness can be controlled independently. Actuator’s stiffness
is controlled by changing pressure of control fluid into distribution
lines. The used control fluid is biphasic, composed of separated gas
and liquid fractions with predefined ratio. Firstly, an approach for the
mathematical model is introduced and a model-based control method
is implemented to track the desired position and stiffness. Results
from force loaded and unloaded simulations proved the feasibility of
these methods. Based on the previous outcome, a compliant revolute
joint mechanism was modeled and implemented in order to use it as a
test bench for the VSA. The mechanism is able to track position and
stiffness accurately; however, better mechanical design and manufacturing
methods are suggested in order to avoid excessive friction. Later
on, a momentum-based collision detection and reaction algorithm is
proposed, simulated and tested on the mechanism. Experimental results
confirm that this method can be used to attain a higher level
of safety in the system. Finally, a compliant cable-driven revolute
joint using biphasic media variable stiffness actuators is modeled and
simulated. This cable-driven mechanism is characterized by a wide
range of stiffness and high-power output