Whole-Body Control for Multi-Contact Balancing of Humanoid Robots

Whole-Body Control for Multi-Contact Balancing of Humanoid Robots
Author: Bernd Henze
Publisher: Springer Nature
Total Pages: 209
Release: 2021-11-03
Genre: Technology & Engineering
ISBN: 3030872122

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This book aims at providing algorithms for balance control of legged, torque-controlled humanoid robots. A humanoid robot normally uses the feet for locomotion. This paradigm is extended by addressing the challenge of multi-contact balancing, which allows a humanoid robot to exploit an arbitrary number of contacts for support. Using multiple contacts increases the size of the support polygon, which in turn leads to an increased robustness of the stance and to an increased kinematic workspace of the robot. Both are important features for facilitating a transition of humanoid robots from research laboratories to real-world applications, where they are confronted with multiple challenging scenarios, such as climbing stairs and ladders, traversing debris, handling heavy loads, or working in confined spaces. The distribution of forces and torques among the multiple contacts is a challenging aspect of the problem, which arises from the closed kinematic chain given by the robot and its environment.

Whole-Body Impedance Control of Wheeled Humanoid Robots

Whole-Body Impedance Control of Wheeled Humanoid Robots
Author: Alexander Dietrich
Publisher: Springer
Total Pages: 196
Release: 2016-07-02
Genre: Technology & Engineering
ISBN: 3319405578

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Introducing mobile humanoid robots into human environments requires the systems to physically interact and execute multiple concurrent tasks. The monograph at hand presents a whole-body torque controller for dexterous and safe robotic manipulation. This control approach enables a mobile humanoid robot to simultaneously meet several control objectives with different pre-defined levels of priority, while providing the skills for compliant physical contacts with humans and the environment. After a general introduction into the topic of whole-body control, several essential reactive tasks are developed to extend the repertoire of robotic control objectives. Additionally, the classical Cartesian impedance is extended to the case of mobile robots. All of these tasks are then combined and integrated into an overall, priority-based control law. Besides the experimental validation of the approach, the formal proof of asymptotic stability for this hierarchical controller is presented. By interconnecting the whole-body controller with an artificial intelligence, the immense potential of the integrated approach for complex real-world applications is shown. Several typical household chores, such as autonomously wiping a window or sweeping the floor with a broom, are successfully performed on the mobile humanoid robot Rollin’ Justin of the German Aerospace Center (DLR). The results suggest the presented controller for a large variety of fields of application such as service robotics, human-robot cooperation in industry, telepresence in medical applications, space robotics scenarios, and the operation of mobile robots in dangerous and hazardous environments.

Compliant Whole-body Control of Humanoid Robots

Compliant Whole-body Control of Humanoid Robots
Author: Taizo Yoshikawa
Publisher:
Total Pages:
Release: 2019
Genre:
ISBN:

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A major obstacle that prevents humanoid robots from accomplishing real world tasks is their inability to physically interact with, and effectively manipulate, the most common objects generally found in human environments. Even tasks that seem simple for a human remain a significant challenge for most robots. Robots generally employ precision to perform a manipulation task. Humans, in contrast, employ compliance through tactile and force feedback to overcome their imprecision, allowing them to resolve uncertainties associated with the task. The lack of compliance and force control has been indeed a major limiting factor in the ability of robots to interact and manipulate in human environments. One of the major objectives of this research is to endow humanoid robots with whole-body compliant motion abilities. With compliance, a robot overcomes position uncertainties by moving in directions that reduce contact forces, which in turn directs it towards its goal. Whole-body framework was designed to allow the robot to compliantly interact with its environment at multiple contact points. The synthesis of compliant tasks is greatly simplified by being independent of postures and constraints, which are automatically integrated in the control hierarchy. This research focuses on the development of (I) sensor-based whole-body compliant motion primitives, (II) contact sensing and contact force control, (III) whole-body multi-contact for extended support, kneeling, crawling, leaning table, and locomotion strategy to improve support in unstructured terrains, (IV) dynamic collision-free motion planning and (V) dynamic collision-free walking path planning.

Human-Inspired Balancing and Recovery Stepping for Humanoid Robots

Human-Inspired Balancing and Recovery Stepping for Humanoid Robots
Author: Kaul, Lukas Sebastian
Publisher: KIT Scientific Publishing
Total Pages: 258
Release: 2019-05-15
Genre: Computers
ISBN: 3731509032

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Robustly maintaining balance on two legs is an important challenge for humanoid robots. The work presented in this book represents a contribution to this area. It investigates efficient methods for the decision-making from internal sensors about whether and where to step, several improvements to efficient whole-body postural balancing methods, and proposes and evaluates a novel method for efficient recovery step generation, leveraging human examples and simulation-based reinforcement learning.

Humanoid Robotics: A Reference

Humanoid Robotics: A Reference
Author: Prahlad Vadakkepat
Publisher: Springer
Total Pages: 0
Release: 2017-02-14
Genre: Technology & Engineering
ISBN: 9789400760455

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Humanoid Robotics provides a comprehensive compilation of developments in the conceptualization, design and development of humanoid robots and related technologies. Human beings have built the environment they occupy (living spaces, instruments and vehicles) to suit two-legged systems. Building systems, especially in robotics, that are compatible with the well-established, human-based surroundings and which could naturally interact with humans is an ultimate goal for all researches and engineers. Humanoid Robots are systems (i.e. robots) which mimic human behavior. Humanoids provide a platform to study the construction of systems that behave and interact like humans. A broad range of applications ranging from daily housework to complex medical surgery, deep ocean exploration, and other potentially dangerous tasks are possible using humanoids. In addition, the study of humanoid robotics provides a platform to understand the mechanisms and offers a physical visual of how humans interact, think, and react with the surroundings and how such behaviors could be reassembled and reconstructed. Currently, the most challenging issue with bipedal humanoids is to make them balance on two legs, The purportedly simple act of finding the best balance that enables easy walking, jumping and running requires some of the most sophisticated development of robotic systems- those that will ultimately mimic fully the diversity and dexterity of human beings. Other typical human-like interactions such as complex thought and conversations on the other hand, also pose barriers for the development of humanoids because we are yet to understand fully the way in which we humans interact with our environment and consequently to replicate this in humanoids.

Balance Preservation and Task Prioritization in Whole Body Motion Control of Humanoid Robots

Balance Preservation and Task Prioritization in Whole Body Motion Control of Humanoid Robots
Author: Alexander Sherikov
Publisher:
Total Pages: 0
Release: 2016
Genre:
ISBN:

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One of the greatest challenges in robot control is closing the gap between themotion capabilities of humans and humanoid robots. The difficulty lies in thecomplexity of the dynamical systems representing the said robots: theirnonlinearity, underactuation, discrete behavior due to collisions and friction,high number of degrees of freedom. Moreover, humanoid robots are supposed tooperate in non-deterministic environments, which require advanced real timecontrol. The currently prevailing approach to coping with these difficulties isto impose various limitations on the motions and employ approximate models ofthe robots. In this thesis, we follow the same line of research and propose anew approach to the design of balance preserving whole body motion controllers.The key idea is to leverage the advantages of whole body and approximate modelsby mixing them within a single predictive control problem with strictlyprioritized objectives.Balance preservation is one of the primary concerns in the control of humanoidrobots. Previous research has already established that anticipation of motionsis crucial for this purpose. We advocate that anticipation is helpful in thissense as a way to maintain capturability of the motion, i.e., the ability tostop. We stress that capturability of anticipated motions can be enforced withappropriate constraints. In practice, it is common to anticipate motions usingapproximate models in order to reduce computational effort, hence, a separatewhole body motion controller is needed for tracking. Instead, we propose tointroduce anticipation with an approximate model into the whole body motioncontroller. As a result, the generated whole body motions respect thecapturability constraints and the anticipated motions of an approximate modeltake into account whole body constraints and tasks. We pose our whole bodymotion controllers as optimization problems with strictly prioritizedobjectives. Though such prioritization is common in the literature, we believethat it is often not properly exploited. We, therefore, propose severalexamples of controllers, where prioritization is useful and necessary toachieve desired behaviors. We evaluate our controllers in two simulatedscenarios, where a whole body task influences walking motions of the robot andthe robot optionally exploits a hand contact to maintain balance whilestanding.

Introduction to Humanoid Robotics

Introduction to Humanoid Robotics
Author: Shuuji Kajita
Publisher: Springer
Total Pages: 232
Release: 2014-07-15
Genre: Technology & Engineering
ISBN: 364254536X

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This book is for researchers, engineers, and students who are willing to understand how humanoid robots move and be controlled. The book starts with an overview of the humanoid robotics research history and state of the art. Then it explains the required mathematics and physics such as kinematics of multi-body system, Zero-Moment Point (ZMP) and its relationship with body motion. Biped walking control is discussed in depth, since it is one of the main interests of humanoid robotics. Various topics of the whole body motion generation are also discussed. Finally multi-body dynamics is presented to simulate the complete dynamic behavior of a humanoid robot. Throughout the book, Matlab codes are shown to test the algorithms and to help the reader ́s understanding.

Humanoid Robotics and Neuroscience

Humanoid Robotics and Neuroscience
Author: Gordon Cheng
Publisher: CRC Press
Total Pages: 288
Release: 2014-12-19
Genre: Medical
ISBN: 1420093673

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Humanoid robots are highly sophisticated machines equipped with human-like sensory and motor capabilities. Today we are on the verge of a new era of rapid transformations in both science and engineering-one that brings together technological advancements in a way that will accelerate both neuroscience and robotics. Humanoid Robotics and Neuroscienc

Whole-body Trajectory Generation and Control Strategies for Multi-contact Robots

Whole-body Trajectory Generation and Control Strategies for Multi-contact Robots
Author: Jaemin Lee (Ph. D.)
Publisher:
Total Pages: 0
Release: 2022
Genre:
ISBN:

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The fundamental objective of robotics is to enhance the productivity of humans while interacting in potentially unstructured environments. In this sense, Human-centered robots must be fast, stable, and robust when performing varied and complicated tasks during mission execution. Although industrial robots have seen some advancements regarding motion planning and control, they are largely limited to simple pre-defined tasks in structured environments. However, to achieve highly dynamic motions for dexterous manipulation or agile locomotion in complex robots, we need to consider the use of nonlinear dynamics, complex constraints, multiple contacts, disturbances, and uncertainties. These are fundamental requirements needed to advance the use of general purpose robots dynamically interacting in a wider variety of environments. Therefore, this thesis addresses challenges that arise from the employment of optimization techniques and sophisticated realtime algorithms for the control and deployment of realistic and practical robots in human environments. Considering the above challenges, we propose efficient trajectory generation and trajectory tracking methods as the next paradigms for whole-body control (WBC). First, we formulate a class of motion planning problems to directly obtain dynamically feasible state trajectories in multi-contact robots and the corresponding control inputs. Typically, it takes a tremendous amount of time to solve the end-to-end trajectory generation problem using large-scale standard Nonlinear Programming (NLP). We propose a new sampling-based method together with a Partially Observable Markov Decision Process to break down the trajectory generation problem into tractable parts. In doing so, the number of decision variables is drastically reduced. As a result, we solve the optimization problem much faster than using existing NLP techniques. In addition, we incorporate reachability analysis tools for determining whether the planned trajectories are reachable and discard unfeasible trajectories during optimization. Because simplified models are frequently utilized in locomotion studies to generate walking patterns, planned contact locations may not be feasible due to model mismatch and robot constraints. In contrast, our method enables the generation of dynamically feasible trajectories to reach planned contact location considering full-body dynamics and realistic constraints. The proposed methods are applied to contact constrained manipulation and bipedal locomotion problems to enhance capabilities of robots maneuvering in complex environments without slip or loss of balance. Second, we explore the fundamentals of WBC and use this insight to push forward the capabilities of WBC approaches. One of the problems we explore is the verification of stability of legged robots under unknown external perturbations. In such cases, the closed-loop control system controlled by WBC approaches may become unstable if external perturbations are not properly analyzed with stability verification. To verify stability, we leverage the so-called Centroidal Dynamics of legged robots and a type of WBC dubbed Whole-Body Locomotion Control (WBLC). Using a feedback-linearized state-space model, we obtain appropriate feedback gains for WBC to make our robot stable and robust under perturbations. Another challenge of WBC stems from the reliance on classical feedback control theory. Classical PD control is unsuitable for a noisy system, therefore WBC cannot be directly applied to stochastic systems. Classical WBC approaches do not consider the covariance of the terminal states as constraints which is a more efficient way to control robots with precision. We propose a new control approach, called Hierarchical Covariance Control (HCC) to enforce covariance constraints. Our proposed HCC is a stochastic version of WBC to decrease task errors when uncertainty is substantial. The last improvement I explore regarding WBC is the employment of Model Predictive Control (MPC) instead of solving an instantaneous optimization problem, which cannot guarantee global optimality. As such, we consider longer receding time horizons for MPC, thus improving the tracking performance by reducing the accumulated error norm while executing hierarchical tasks. Overall, our research focuses on the end-to-end process spanning trajectory planning to feedback control enabling the generating of multi-contact and constrained dynamic motions of complex robots operating in realistic setups. The various contributions of this thesis are in the areas of computational efficiency for whole-body trajectory generation, robustness of WBC control algorithms, and significant improvements in trajectory tracking using WBC algorithms. We verify the proposed approaches both in simulations and real experiments using various robotic systems