Screw theory provides geometrical insight into the mechanics of rigid bodies. Screw axis is defined as the line coinciding with the joint axis. Line transformations in the form of a screw operator are used to determine the joint axes of a seven degree of freedom manipulator, representing the human upper limb. Multiplication of a unit screw axis with the joint angular velocity provides the joint twist. Instantaneous motion of a joint is the summation of the twists of the preceding joints and the joint twist itself. Inverse kinematics, velocities and accelerations are calculated using the screw Jacobian for a non-redundant six degree of freedom manipulator. Netwon and Euler dynamic equations are then utilized to solve for the forward and inverse dynamic problems. Dynamics of the upper limb and the upper limb combined with an exoskeleton are only different due to the additional mass and inertia of the exoskeleton. Dynamic equations are crucial for controlling the exoskeleton in position and force.
Multimodal Control of Manipulators: Coupling Kinematics and Vision for Self-Driving Laboratory Operations
1 Department of Electronics Systems, Aalborg University, Denmark；3 Extreme Robotics Laboratory, School of Metallurgy \& Materials, University of Birmingham, Birmingham, United Kingdom
Learning Neural Observer-Predictor Models for Limb-level Sampling-based Locomotion Planning
Department of Mechanical Engineering, University of Delaware（德克萨斯大学机械工程系）；School of Mechanical Engineering, National Technical University of Athens（希腊国家技术大学机械工程学院）
Southern University of Science and Technology（南方科技大学）；The University of Hong Kong（香港大学）；School of Design（设计学院）；ZJU-University of Illinois Urbana-Champaign Institute（浙江大学-伊利诺伊大学厄巴纳-香槟分校联合研究所）；Zhejiang University（浙江大学）；System Design and Intelligent Manufacturing（系统设计与智能制造学院）；Design & Learning Research Group（设计与学习研究组）
Hybrid systems, such as bipedal walkers, are challenging to control because of discontinuities in their nonlinear dynamics. Little can be predicted about the systems' evolution without modeling the guard conditions that govern transitions between hybrid modes, so even systems with reliable state sensing can be difficult to control. We propose an algorithm that allows for determining the hybrid mode of a system in real-time using data-driven analysis. The algorithm is used with data-driven dynamics identification to enable model predictive control based entirely on data. Two examples---a simula…
Lower extremity exoskeleton has been developed as a motion assistive technology in recent years. Walking pattern generation is a fundamental topic in the design of these robots. The usual approach with most exoskeletons is to use a pre-recorded pattern as a look-up table. There are some deficiencies with this method, including data storage limitation and poor regulation relating to the walking parameters. Therefore modeling human walking patterns to use in exoskeletons is required. The few existing models provide piece by piece walking patterns, only generating at the beginning of each stride …
Kinematic structure of an exoskeleton is the most fundamental block of its design and is determinant of many functional capabilities of it. Although numerous upper limb rehabilitation devices have been designed in the recent years, there is not a framework that can systematically guide the kinematic design procedure. Additionally, diversity of currently available devices and the many minute details incorporated to address certain design requirements hinders pinpointing the core kinematics of the available devices to compare them against each other. This makes the review of literature for ident…
Personal Autonomous Robotics Lab (PeARL), The University of Texas at Austin（德克萨斯大学奥斯汀分校个人自主机器人实验室）
Sudden changes in the dynamics of robotic tasks, such as contact with an object or the latching of a door, are often viewed as inconvenient discontinuities that make manipulation difficult. However, when these transitions are well-understood, they can be leveraged to reduce uncertainty or aid manipulation---for example, wiggling a screw to determine if it is fully inserted or not. Current model-free reinforcement learning approaches require large amounts of data to learn to leverage such dynamics, scale poorly as problem complexity grows, and do not transfer well to significantly different pro…
University of Michigan（密歇根大学）；University of Texas at Dallas（得克萨斯大学达拉斯分校）；Shirley Ryan AbilityLab（雪莉瑞安能力实验室）；University of Texas at Austin（得克萨斯大学奥斯汀分校）；Northwestern University（西北大学）
Human locomotion involves continuously variable activities including walking, running, and stair climbing over a range of speeds and inclinations as well as sit-stand, walk-run, and walk-stairs transitions. Understanding the kinematics and kinetics of the lower limbs during continuously varying locomotion is fundamental to developing robotic prostheses and exoskeletons that assist in community ambulation. However, available datasets on human locomotion neglect transitions between activities and/or continuous variations in speed and inclination during these activities. This data paper reports a…
In this paper, a new numerical method to solve the forward kinematics (FK) of a parallel manipulator with three-limb spherical-prismatic-revolute (3SPR) structure is presented. Unlike the existing numerical approaches that rely on computation of the manipulator's Jacobian matrix and its inverse at each iteration, the proposed algorithm requires much less computations to estimate the FK parameters. A cost function is introduced that measures the difference of the estimates from the actual FK values. At each iteration, the problem is decomposed into two steps. First, the estimates of the platfor…
Ground Perturbation Detection via Lower-Limb Kinematic States During Locomotion
Department of Mechanical Engineering, Carnegie Mellon University（机械工程系，卡内基梅隆大学）；Department of Kinesiology and Health Education, The University of Texas at Austin（运动科学与健康教育系，德克萨斯大学奥斯汀分校）
Exploiting Intrinsic Kinematic Null Space for Supernumerary Robotic Limbs Control
Department of Information Engineering and Mathematics, University of Siena（信息工程与数学系，锡耶纳大学）；department of Humanoids and Human Centered Mechatronics (HHCM), Istituto Italiano di Tecnologia（人形与以人为中心的机电一体化系（HHCM），意大利理工学院）；Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina（生物医学与牙科学及形态功能成像系，梅斯纳大学）；Center for Information and Neural Networks, Advanced ICT Research Institute, National Institute of Information and Communications Technology（信息与神经网络中心，先进ICT研究机构，日本信息与通信技术研究院）；Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia（神经运动生理实验室，IRCCS圣拉齐娅基金会）
Functional kinematic and kinetic requirements of the upper limb during activities of daily living: a recommendation on necessary joint capabilities for prosthetic arms
Chair of Robotics and Systems Intelligence, MIRMI - Munich Institute of Robotics and Machine Intelligence, Technical University of Munich (TUM)（慕尼黑工业大学机器人与系统智能主席席位、慕尼黑机器人与机器智能研究所（MIRMI））
University of Birmingham（伯明翰大学）；Technology Innovation Institute（技术创新研究院）；Imperial College London（伦敦帝国理工学院）
Adapting upper-limb impedance (i.e., stiffness, damping, inertia) is essential for humans interacting with dynamic environments for executing grasping or manipulation tasks. On the other hand, control methods designed for state-of-the-art upper-limb prostheses infer motor intent from surface electromyography (sEMG) signals in terms of joint kinematics, but they fail to infer and use the underlying impedance properties of the limb. We present a framework that allows a human user to simultaneously control the kinematics, stiffness, and damping of a simulated robot through wrist's flexion-extensi…
Ankle push-off largely contributes to limb energy generation in human walking, leading to smoother and more efficient locomotion. Providing this net positive work to an amputee requires an active prosthesis, but has the potential to enable more natural assisted locomotion. To this end, this paper uses multi-contact models of locomotion together with force-based nonlinear optimization-based controllers to achieve human-like kinematic behavior, including ankle push-off, on a powered transfemoral prosthesis for 2 subjects. In particular, we leverage model-based control approaches for dynamic bipe…
Deep-Learning Estimation of Weight Distribution Using Joint Kinematics for Lower-Limb Exoskeleton Control
Legs and Walking Lab, Shirley Ryan AbilityLab（腿部与行走实验室，Shirley Ryan AbilityLab）；Center for Robotics and Biosystems, Department of Mechanical Engineering, Northwestern University（机器人与生物系统中心，机械工程系，西北大学）；Shirley Ryan AbilityLab；Biorobotics Institute, Scuola Superiore Sant’Anna（生物机器人研究所，Scuola Superiore Sant’Anna）；Department of Excellence in Robotics & AI, Scuola Superiore Sant’Anna（机器人与人工智能卓越部门，Scuola Superiore Sant’Anna）；Shirley Ryan AbilityLab, Center for Robotics and Biosystems, Department of Mechanical Engineering, Department of Biomedical Engineering, and Department of Physical Medicine and Rehabilitation, Northwestern University（Shirley Ryan AbilityLab，机器人与生物系统中心，机械工程系，生物医学工程系，物理医学与康复系，西北大学）
A Novel Transformer-Based Method for Full Lower-Limb Joint Angles and Moments Prediction in Gait Using sEMG and IMU data
Faculty of Engineering and IT, the University of Melbourne（墨尔本大学工程与信息技术学院）；Faculty of Caspian College of Engineering, University of Tehran（德黑兰大学波斯湾工程学院）
DexTwist: Dexterous Hand Retargeting for Twist Motion via Mixed Reality-based Teleoperation
Autonomous Systems Lab, Institute of Computer Technology, TU Wien（自主系统实验室，计算机技术学院，维也纳技术大学）；Institute of Robotics and Mechatronics (DLR), German Aerospace Center（机器人与机电系统研究所（DLR），德国航空航天中心）
UNSW Sydney（悉尼新南威尔士大学）；University College Dublin（都柏林大学）
This paper presents an algorithm that makes novel use of a Lie group representation of position and orientation alongside a constrained extended Kalman filter (CEKF) to accurately estimate pelvis, thigh, and shank kinematics during walking using only three wearable inertial sensors. The algorithm iterates through the prediction update (kinematic equation), measurement update (pelvis height, zero velocity update, flat-floor assumption, and covariance limiter), and constraint update (formulation of hinged knee joints and ball-and-socket hip joints). The paper also describes a novel Lie group for…
Texas A&M University（德州农工大学）；Texas A&M University at Qatar（德州农工大学卡塔尔分校）
This paper proposes a computational approach for generation of reference path for upper-limb exoskeletons considering the scapulohumeral rhythms of the shoulder. The proposed method can be used in upper-limb exoskeletons with 3 Degrees of Freedom (DoF) in shoulder and 1 DoF in elbow, which are capable of supporting shoulder girdle. The developed computational method is based on Central Nervous System (CNS) governing rules. Existing computational reference generation methods are based on the assumption of fixed shoulder center during motions. This assumption can be considered valid for reaching…
University Hospital of Freiburg（弗莱堡大学医院）；Scuola Superiore Sant’Anna（圣安娜高等研究院）
Lower limbs exoskeletons provide assistance during standing, squatting, and walking. Gait dynamics, in particular, implies a change in the configuration of the device in terms of contact points, actuation, and system dynamics in general. In order to provide a comfortable experience and maximize performance, the exoskeleton should be controlled smoothly and in a transparent way, which means respectively, minimizing the interaction forces with the user and jerky behavior due to transitions between different configurations. A previous study showed that a smooth control of the exoskeleton can be a…
Synergies have been adopted in prosthetic limb applications to reduce complexity of design, but typically involve a single synergy setting for a population and ignore individual preference or adaptation capacity. However, personalization of the synergy setting is necessary for the effective operation of the prosthetic device. Two major challenges hinder the personalization of synergies in human-prosthesis interfaces. The first is related to the process of human motor adaptation and the second to the variation in motor learning dynamics of individuals. In this paper, a systematic personalizatio…
Goal: This paper presents an algorithm for accurately estimating pelvis, thigh, and shank kinematics during walking using only three wearable inertial sensors. Methods: The algorithm makes novel use of a constrained Kalman filter (CKF). The algorithm iterates through the prediction (kinematic equation), measurement (pelvis position pseudo-measurements, zero velocity update, flat-floor assumption, and covariance limiter), and constraint update (formulation of hinged knee joints and ball-and-socket hip joints). Results: Evaluation of the algorithm using an optical motion capture-based sensor-to-…
University of Texas at Dallas（得克萨斯大学达拉斯分校）；The University of Texas at Austin（得克萨斯大学奥斯汀分校）
Natural control of limb motion is continuous and progressively adaptive to individual intent. While intuitive interfaces have the potential to rely on the neuromuscular input by the user for continuous adaptation, continuous volitional control of assistive devices that can generalize across various tasks has not been addressed. In this study, we propose a method to use spatiotemporal ultrasound features of the rectus femoris and vastus intermedius muscles of able-bodied individuals for task-invariant learning of continuous knee kinematics during steady-state and transient ambulation. The task-…
Synergistic prostheses enable the coordinated movement of the human-prosthetic arm, as required by activities of daily living. This is achieved by coupling the motion of the prosthesis to the human command, such as the residual limb movement in motion-based interfaces. Previous studies demonstrated that developing human-prosthetic synergies in joint-space must consider individual motor behaviour and the intended task to be performed, requiring personalisation and task calibration. In this work, an alternative synergy-based strategy, utilising a synergistic relationship expressed in task-space,…
Methods from algebra and algebraic geometry have been used in various ways to study linkages in kinematics. These methods have failed so far for the study of linkages with helical joints (joints with screw motion), because of the presence of some non-algebraic relations. In this article, we explore a delicate reduction of some analytic equations in kinematics to algebraic questions via a theorem of Ax. As an application, we give a classification of mobile closed 5-linkages with revolute, prismatic, and helical joints.
École Polytechnique de Montréal（蒙特利尔理工学院）；Technopole in pediatric rehabilitation of Ste-Justine UHC（圣贾斯汀大学医院中心儿童康复科技园）
The potential of wearable robotics technology is undeniable. However, quantifying its value is difficult. Various types of exoskeleton robots have already been developed and tested for upper limb rehabilitation but, evaluations are not standardized, particularly in pediatric rehabilitation. This paper proposes a methodology for the quantitative evaluation of upper limb exoskeletons that, like a test bench, would serve for replicable testing. We determined the range of motion (ROM) and joint torques using both kinematic modeling and experimental measurements (using sensors integrated into Dynam…
Reducing Robotic Upper-Limb Assessment Time While Maintaining Precision: A Time Series Foundation Model Approach
School of Computing（计算学院）；Queen’s University（皇后大学）；Hotchkiss Brain Institute（霍克奇斯脑研究所）；University of Calgary（卡尔加里大学）；Centre for Neuroscience Studies（神经科学研究中心）；Providence Care Hospital（普罗维登斯护理医院）
Imperial College of Science, Technology and Medicine（帝国理工学院）；Queen Mary University of London（伦敦玛丽女王大学）；University of Waterloo（滑铁卢大学）；Toronto Rehabilitation Institute-University Health Network（多伦多康复研究所-大学健康网络）；École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）
This paper presents a versatile cable-driven robotic interface to investigate the single-joint joint neuromechanics of the hip, knee and ankle. This endpoint-based interface offers highly dynamic interaction and accurate position control, as is typically required for neuromechanics identification. It can be used with the subject upright, corresponding to natural posture during walking or standing, and does not impose kinematic constraints on a joint, in contrast to existing interfaces. Mechanical evaluations demonstrated that the interface yields a rigidity above 500N/m with low viscosity. Tes…
Continual Learning from Simulated Interactions via Multitask Prospective Rehearsal for Bionic Limb Behavior Modeling
ETH Zurich（苏黎世联邦理工学院）；University of Goettingen（戈丁根大学）；Bielefeld University（比勒菲尔德大学）；European Neuroscience Institute, Goettingen (ENI-G)（戈丁根欧洲神经科学研究所）；Qatar Computing Institute（卡塔尔计算研究所）；University Medical Center, Goettingen (UMG)（戈丁根大学医学中心）
K2MUSE: A human lower-limb multimodal walking dataset spanning task and acquisition variability for rehabilitation robotics
State Key Laboratory of Robotics and Intelligent Systems, Shenyang Institute of Automation, Chinese Academy of Sciences（机器人与智能系统国家重点实验室，沈阳自动化研究所，中国科学院）；University of Chinese Academy of Sciences（中国科学院大学）；College of Artificial Intelligence, Tianjin Key Laboratory of Intelligent Robotics, Nankai University（人工智能学院，天津智能机器人重点实验室，南开大学）；School of Artificial Intelligence and Automation, Huazhong University of Science and Technology（人工智能与自动化学院，华中科技大学）
LEGO: Latent-space Exploration for Geometry-aware Optimization of Humanoid Kinematic Design
Department of Artificial Intelligence, Korea University（高丽大学人工智能系）；Contoro Robotics；Department of Mechanical Engineering, Massachusetts Institute of Technology（麻省理工学院机械工程系）；Department of Statistics, Korea University（高丽大学统计系）
Robots will become ubiquitously useful only when they can use few attempts to teach themselves to perform different tasks, even with complex bodies and in dynamical environments. Vertebrates, in fact, successfully use trial-and-error to learn multiple tasks in spite of their intricate tendon-driven anatomies. Roboticists find such tendon-driven systems particularly hard to control because they are simultaneously nonlinear, under-determined (many tendon tensions combine to produce few net joint torques), and over-determined (few joint rotations define how many tendons need to be reeled-in/payed…
