120 research outputs found
Technical Report: A Contact-aware Feedback CPG System for Learning-based Locomotion Control in a Soft Snake Robot
Integrating contact-awareness into a soft snake robot and efficiently
controlling its locomotion in response to contact information present
significant challenges. This paper aims to solve contact-aware locomotion
problem of a soft snake robot through developing bio-inspired contact-aware
locomotion controllers. To provide effective contact information for the
controllers, we develop a scale covered sensor structure mimicking natural
snakes' \textit{scale sensilla}. In the design of control framework, our core
contribution is the development of a novel sensory feedback mechanism of the
Matsuoka central pattern generator (CPG) network. This mechanism allows the
Matsuoka CPG system to work like a "spine cord" in the whole contact-aware
control scheme, which simultaneously takes the stimuli including tonic input
signals from the "brain" (a goal-tracking locomotion controller) and sensory
feedback signals from the "reflex arc" (the contact reactive controller), and
generate rhythmic signals to effectively actuate the soft snake robot to
slither through densely allocated obstacles. In the design of the "reflex arc",
we develop two types of reactive controllers -- 1) a reinforcement learning
(RL) sensor regulator that learns to manipulate the sensory feedback inputs of
the CPG system, and 2) a local reflexive sensor-CPG network that directly
connects sensor readings and the CPG's feedback inputs in a special topology.
These two reactive controllers respectively facilitate two different
contact-aware locomotion control schemes. The two control schemes are tested
and evaluated in the soft snake robot, showing promising performance in the
contact-aware locomotion tasks. The experimental results also further verify
the benefit of Matsuoka CPG system in bio-inspired robot controller design.Comment: 17 pages, 19 figure
Multiple chaotic central pattern generators with learning for legged locomotion and malfunction compensation
An originally chaotic system can be controlled into various periodic
dynamics. When it is implemented into a legged robot's locomotion control as a
central pattern generator (CPG), sophisticated gait patterns arise so that the
robot can perform various walking behaviors. However, such a single chaotic CPG
controller has difficulties dealing with leg malfunction. Specifically, in the
scenarios presented here, its movement permanently deviates from the desired
trajectory. To address this problem, we extend the single chaotic CPG to
multiple CPGs with learning. The learning mechanism is based on a simulated
annealing algorithm. In a normal situation, the CPGs synchronize and their
dynamics are identical. With leg malfunction or disability, the CPGs lose
synchronization leading to independent dynamics. In this case, the learning
mechanism is applied to automatically adjust the remaining legs' oscillation
frequencies so that the robot adapts its locomotion to deal with the
malfunction. As a consequence, the trajectory produced by the multiple chaotic
CPGs resembles the original trajectory far better than the one produced by only
a single CPG. The performance of the system is evaluated first in a physical
simulation of a quadruped as well as a hexapod robot and finally in a real
six-legged walking machine called AMOSII. The experimental results presented
here reveal that using multiple CPGs with learning is an effective approach for
adaptive locomotion generation where, for instance, different body parts have
to perform independent movements for malfunction compensation.Comment: 48 pages, 16 figures, Information Sciences 201
Adaptive locomotion of snake-like robots
Adaptive locomotion for multi-robot organisms is a huge challenge in modern robotics. The complexity grows fast with the number of degrees of freedom (DOFs) of a robot. A snake like organism structure usually consists of many DOFs and is hence restricted in their motion capabilities. In this theses, an adaptive gait algorithm for avoiding of obstacles should be analyzed by using techniques of coupled oscillators. The simulation in MATLAB as well as tests on a real snake robot will be done in this work.
In the MATLAB simulation we could see the principle of adaptive snake-like locomotion as it should be. As well we could analyse fitting functions for the oszillator in the Central Pattern Generator. On the real snake robot we had to take the theoretical foundations and adapt them to make them work on real-time operating system. It was faszinating to work on all difficulties be communication, configuration, designing or programming. And finally we saw the robot crawl arround obstacles, controlled by the equations we developed. It would be great to see our work live on in projects like SYMBRION and REPLICATOR
Shape-based compliance control for snake robots
I serpenti robot sono una classe di meccanismi iper-ridondanti che appartiene alla robotica modulare. Grazie alla loro forma snella ed allungata e all'alto grado di ridondanza possono muoversi in ambienti complessi con elevata agilità. L'abilità di spostarsi, manipolare e adattarsi efficientemente ad una grande varietà di terreni li rende ideali per diverse applicazioni, come ad esempio attività di ricerca e soccorso, ispezione o ricognizione.
I robot serpenti si muovono nello spazio modificando la propria forma, senza necessità di ulteriori dispositivi quali ruote od arti. Tali deformazioni, che consistono in movimenti ondulatori ciclici che generano uno spostamento dell'intero meccanismo, vengono definiti andature. La maggior parte di esse sono ispirate al mondo naturale, come lo strisciamento, il movimento laterale o il movimento a concertina, mentre altre sono create per applicazioni specifiche, come il rotolamento o l'arrampicamento.
Un serpente robot con molti gradi di libertà deve essere capace di coordinare i propri giunti e reagire ad ostacoli in tempo reale per riuscire a muoversi efficacemente in ambienti complessi o non strutturati. Inoltre, aumentare la semplicità e ridurre il numero di controllori necessari alla locomozione alleggerise una struttura di controllo che potrebbe richiedere complessità per ulteriori attività specifiche. L'obiettivo di questa tesi è ottenere un comportamento autonomo cedevole che si adatti alla conformazione dell'ambiente in cui il robot si sta spostando, accrescendo le capacità di locomozione del serpente robot. Sfruttando la cedevolezza intrinseca del serpente robot utilizzato in questo lavoro, il SEA Snake, e utilizzando un controllo che combina cedevolezza attiva ad una struttura di coordinazione che ammette una decentralizzazione variabile del robot, si dimostra come tre andature possano essere modificate per ottenere una locomozione efficiente in ambienti complessi non noti a priori o non modellabili
Bio-Inspired Robotics
Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensory–motor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field
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