872 research outputs found
Manipulability analysis of a snake robot without lateral constraint for head position control
Two dynamic manipulability criteria of a snake robot with sideways slipping are proposed with the application to head trajectory tracking control in mind. The singular posture, which is crucial in head tracking control, is characterized by the manipulability and examined for families of typical robot shapes. Differences in the singular postures from those of the robot with lateral constraints, which have not been clear in previous studies, are clarified in the analysis. In addition to the examination of local properties using the concept of manipulability, we discuss the effect of isotropic friction as a global property. It is well known that, at least empirically, a snake robot needs anisotropy in friction to move by serpentine locomotion if there are no objects for it to push around. From the point of view of integrability, we show one of the necessary conditions for uncontrollability is satisfied if the friction is isotropic
In silico case studies of compliant robots: AMARSI deliverable 3.3
In the deliverable 3.2 we presented how the morphological computing ap-
proach can significantly facilitate the control strategy in several scenarios,
e.g. quadruped locomotion, bipedal locomotion and reaching. In particular,
the Kitty experimental platform is an example of the use of morphological
computation to allow quadruped locomotion. In this deliverable we continue
with the simulation studies on the application of the different morphological
computation strategies to control a robotic system
Reinforcement Learning of CPG-regulated Locomotion Controller for a Soft Snake Robot
Intelligent control of soft robots is challenging due to the nonlinear and
difficult-to-model dynamics. One promising model-free approach for soft robot
control is reinforcement learning (RL). However, model-free RL methods tend to
be computationally expensive and data-inefficient and may not yield natural and
smooth locomotion patterns for soft robots. In this work, we develop a
bio-inspired design of a learning-based goal-tracking controller for a soft
snake robot. The controller is composed of two modules: An RL module for
learning goal-tracking behaviors given the unmodeled and stochastic dynamics of
the robot, and a central pattern generator (CPG) with the Matsuoka oscillators
for generating stable and diverse locomotion patterns. We theoretically
investigate the maneuverability of Matsuoka CPG's oscillation bias, frequency,
and amplitude for steering control, velocity control, and sim-to-real
adaptation of the soft snake robot. Based on this analysis, we proposed a
composition of RL and CPG modules such that the RL module regulates the tonic
inputs to the CPG system given state feedback from the robot, and the output of
the CPG module is then transformed into pressure inputs to pneumatic actuators
of the soft snake robot. This design allows the RL agent to naturally learn to
entrain the desired locomotion patterns determined by the CPG maneuverability.
We validated the optimality and robustness of the control design in both
simulation and real experiments, and performed extensive comparisons with
state-of-art RL methods to demonstrate the benefit of our bio-inspired control
design.Comment: 20 pages, 17 figures, 4 tables, in IEEE Transactions on Robotic
Modular Self-Reconfigurable Robot Systems
The field of modular self-reconfigurable robotic systems addresses the design, fabrication, motion planning, and control of autonomous kinematic machines with variable morphology. Modular self-reconfigurable systems have the promise of making significant technological advances to the field of robotics in general. Their promise of high versatility, high value, and high robustness may lead to a radical change in automation. Currently, a number of researchers have been addressing many of the challenges. While some progress has been made, it is clear that many challenges still exist. By illustrating several of the outstanding issues as grand challenges that have been collaboratively written by a large number of researchers in this field, this article has shown several of the key directions for the future of this growing fiel
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