209 research outputs found
Dört bacaklı robotlar için önizlemeli kontrol ile sıfır moment noktası tabanlı yürüme yörüngesi sentezi
Bacakları üzerinde hareket eden robotların engel aşma konusunda önemli avantajları söz konusudur. Özellikle dört bacaklı robotların değişken arazi yapıları üzerinde birçok uygulamaları düşünülmektedir. Bu çalışmada, dört bacaklı bir robotun düz zemin üzerinde hızlı yol almasına yönelik tırıs türü ilerleme üzerinde durulmaktadır. Sıfır Moment Noktası (SMN) karalılık kriterine ve Doğrusal Ters Sarkaç Modeli’ne (DTSM) dayalı bir yürüme referansı sentez yöntemi sunulmaktadır. Tırıs ilerleme için bir SMN referans yörüngesi önerilmiş, bu yörüngeden, önizlemeli kontrol yaklaşımı ile Robot Ağırlık Merkezi (RAM) için bir referans yörünge elde edilmiştir. Oluşturulan ağırlık merkezi yörüngesi ters kinematik yöntemi ile bacak eklemlerinin konum referanslarının hesaplanmasında kullanılmıştır. Önerilen referans sentezi yöntemi, 16 serbestlik dereceli bir robot modeli ile üç boyutlu ve tam dinamikli bir simülasyon ortamında denenmiştir. Simülasyon sonuçları sunulan yaklaşımın başarılı olduğunu göstermektedir
Quadrupedal Robots with Stiff and Compliant Actuation
In the broader context of quadrupedal locomotion, this overview article introduces and compares two platforms that are similar in structure, size, and morphology, yet differ greatly in their concept of actuation. The first, ALoF, is a classically stiff actuated robot that is controlled kinematically, while the second, StarlETH, uses a soft actuation scheme based on Changedhighly compliant series elastic actuators. We show how this conceptual difference influences design and control of the robots, compare the hardware of the two systems, and show exemplary their advantages in different application
Inverse Dynamics Trajectory Optimization for Contact-Implicit Model Predictive Control
Robots must make and break contact to interact with the world and perform
useful tasks. However, planning and control through contact remains a
formidable challenge. In this work, we achieve real-time contact-implicit model
predictive control with a surprisingly simple method: inverse dynamics
trajectory optimization. While trajectory optimization with inverse dynamics is
not new, we introduce a series of incremental innovations that collectively
enable fast model predictive control on a variety of challenging manipulation
and locomotion tasks. We implement these innovations in an open-source solver,
and present a variety of simulation examples to support the effectiveness of
the proposed approach. Additionally, we demonstrate contact-implicit model
predictive control on hardware at over 100 Hz for a 20 degree-of-freedom
bi-manual manipulation task
On the Biomimetic Design of Agile-Robot Legs
The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for the agile and powerful locomotion of these animals is presented. The proposed biomimetic leg model defines the effective leg length, leg kinematics, limb mass distribution, actuator power, and elastic energy recovery as determinants of agile locomotion, and values for these five key elements are given. The transfer of the extracted principles to technological instantiations is analyzed in detail, considering the availability of current materials, structures and actuators. A real leg prototype has been developed following the biomimetic leg concept proposed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural motion. From the experimental evaluation of this prototype, conclusions on the current technological barriers to achieve real functional legged robots to walk dynamically in agile locomotion are presented
Multi-expert learning of adaptive legged locomotion
Achieving versatile robot locomotion requires motor skills which can adapt to
previously unseen situations. We propose a Multi-Expert Learning Architecture
(MELA) that learns to generate adaptive skills from a group of representative
expert skills. During training, MELA is first initialised by a distinct set of
pre-trained experts, each in a separate deep neural network (DNN). Then by
learning the combination of these DNNs using a Gating Neural Network (GNN),
MELA can acquire more specialised experts and transitional skills across
various locomotion modes. During runtime, MELA constantly blends multiple DNNs
and dynamically synthesises a new DNN to produce adaptive behaviours in
response to changing situations. This approach leverages the advantages of
trained expert skills and the fast online synthesis of adaptive policies to
generate responsive motor skills during the changing tasks. Using a unified
MELA framework, we demonstrated successful multi-skill locomotion on a real
quadruped robot that performed coherent trotting, steering, and fall recovery
autonomously, and showed the merit of multi-expert learning generating
behaviours which can adapt to unseen scenarios
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