Robust Bipedal Locomotion Based on a Hierarchical Control Structure

Robotica ◽  
2019 ◽  
Vol 37 (10) ◽  
pp. 1750-1767 ◽  
Author(s):  
Jianwen Luo ◽  
Yao Su ◽  
Lecheng Ruan ◽  
Ye Zhao ◽  
Donghyun Kim ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Hierarchical Control ◽  
Middle Level ◽  
Smooth Transition ◽  
Whole Body ◽  
Joint Torques ◽  
Low Level ◽  
Hybrid Controller ◽  
High Level

SummaryTo improve biped locomotion’s robustness to internal and external disturbances, this study proposes a hierarchical structure with three control levels. At the high level, a foothold sequence is generated so that the Center of Mass (CoM) trajectory tracks a planned path. The planning procedure is simplified by selecting the midpoint between two consecutive Center of Pressure (CoP) points as the feature point. At the middle level, a novel robust hybrid controller is devised to drive perturbed system states back to the nominal trajectory within finite cycles without chattering. The novelty lies in that the hybrid controller is not subject to linear CoM dynamic constraints. The hybrid controller consists of two sub-controllers: an oscillation controller and a smoothing controller. For the oscillation controller, the desired CoM height is specified as a sine-shaped function, avoiding a new attractive limit cycle. However, this controller results in the inevitable chattering because of discontinuities. A smoothing controller provides continuous properties and thus can inhibit the chattering problem, but has a smaller region of attraction compared with the oscillation controller. A hybrid controller merges the two controllers for a smooth transition. At the low level, the desired CoM motion is defined as tasks and embedded in a whole body operational space (WBOS) controller to compute the joint torques analytically. The novelty of the low-level controller lies in that within the WBOS framework, CoM motion is not subject to fixed CoM dynamics and thus can be generalized.

Whole-Body Balancing Walk Controller for Position Controlled Humanoid Robots

2016 ◽  
Vol 13 (01) ◽  
pp. 1650011 ◽  
Author(s):  
Seung-Joon Yi ◽  
Byoung-Tak Zhang ◽  
Dennis Hong ◽  
Daniel D. Lee
Keyword(s):  
Hierarchical Control ◽  
Humanoid Robots ◽  
Whole Body ◽  
Appropriate Behavior ◽  
Low Level ◽  
Push Recovery ◽  
Hierarchical Control Architecture ◽  
High Level ◽  
Experimental Trials ◽  
Decision Boundaries

Bipedal humanoid robots are intrinsically unstable against unforeseen perturbations. Conventional zero moment point (ZMP)-based locomotion algorithms can reject perturbations by incorporating sensory feedback, but they are less effective than the dynamic full body behaviors humans exhibit when pushed. Recently, a number of biomechanically motivated push recovery behaviors have been proposed that can handle larger perturbations. However, these methods are based upon simplified and transparent dynamics of the robot, which makes it suboptimal to implement on common humanoid robots with local position-based controllers. To address this issue, we propose a hierarchical control architecture. Three low-level push recovery controllers are implemented for position controlled humanoid robots that replicate human recovery behaviors. These low-level controllers are integrated with a ZMP-based walk controller that is capable of generating reactive step motions. The high-level controller constructs empirical decision boundaries to choose the appropriate behavior based upon trajectory information gathered during experimental trials. Our approach is evaluated in physically realistic simulations and on a commercially available small humanoid robot.

scholarly journals Transfer and generalization of learned manipulation between unimanual and bimanual tasks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Trevor Lee-Miller ◽  
Marco Santello ◽  
Andrew M. Gordon
Keyword(s):  
Learning Transfer ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Pressure Point ◽  
Torque Generation ◽  
Before And After ◽  
Object Center ◽  
High Level ◽  
Bimanual Grasping ◽  
Partial Learning

AbstractSuccessful object manipulation, such as preventing object roll, relies on the modulation of forces and centers of pressure (point of application of digits on each grasp surface) prior to lift onset to generate a compensatory torque. Whether or not generalization of learned manipulation can occur after adding or removing effectors is not known. We examined this by recruiting participants to perform lifts in unimanual and bimanual grasps and analyzed results before and after transfer. Our results show partial generalization of learned manipulation occurred when switching from a (1) unimanual to bimanual grasp regardless of object center of mass, and (2) bimanual to unimanual grasp when the center of mass was on the thumb side. Partial generalization was driven by the modulation of effectors’ center of pressure, in the appropriate direction but of insufficient magnitude, while load forces did not contribute to torque generation after transfer. In addition, we show that the combination of effector forces and centers of pressure in the generation of compensatory torque differ between unimanual and bimanual grasping. These findings highlight that (1) high-level representations of learned manipulation enable only partial learning transfer when adding or removing effectors, and (2) such partial generalization is mainly driven by modulation of effectors’ center of pressure.

Real-Time Planning and Nonlinear Control for Quadrupedal Locomotion With Articulated Tails

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Randall T. Fawcett ◽  
Abhishek Pandala ◽  
Jeeseop Kim ◽  
Kaveh Akbari Hamed
Keyword(s):  
Real Time ◽  
Degrees Of Freedom ◽  
Center Of Mass ◽  
Hierarchical Control ◽  
Nonlinear Feedback ◽  
Nonlinear Controller ◽  
External Disturbances ◽  
Quadrupedal Locomotion ◽  
Control Scheme ◽  
High Level

Abstract The primary goal of this paper is to develop a formal foundation to design nonlinear feedback control algorithms that intrinsically couple legged robots with bio-inspired tails for robust locomotion in the presence of external disturbances. We present a hierarchical control scheme in which a high-level and real-time path planner, based on an event-based model predictive control (MPC), computes the optimal motion of the center of mass (COM) and tail trajectories. The MPC framework is developed for an innovative reduced-order linear inverted pendulum (LIP) model that is augmented with the tail dynamics. At the lower level of the control scheme, a nonlinear controller is implemented through the use of quadratic programming (QP) and virtual constraints to force the full-order dynamical model to track the prescribed optimal trajectories of the COM and tail while maintaining feasible ground reaction forces at the leg ends. The potential of the analytical results is numerically verified on a full-order simulation model of a quadrupedal robot augmented with a tail with a total of 20 degrees-of-freedom. The numerical studies demonstrate that the proposed control scheme coupled with the tail dynamics can significantly reduce the effect of external disturbances during quadrupedal locomotion.

scholarly journals Human kinematic, kinetic and EMG data during different walking and stair ascending and descending tasks

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Tiziana Lencioni ◽  
Ilaria Carpinella ◽  
Marco Rabuffetti ◽  
Alberto Marzegan ◽  
Maurizio Ferrarin
Keyword(s):  
Lower Limb ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Simulation Models ◽  
Human Locomotion ◽  
Surface Emg ◽  
Whole Body ◽  
Bipedal Robots ◽  
Lower Limb Muscles ◽  
Reaction Forces

AbstractThis paper reports the kinematic, kinetic and electromyographic (EMG) dataset of human locomotion during level walking at different velocities, toe- and heel-walking, stairs ascending and descending. A sample of 50 healthy subjects, with an age between 6 and 72 years, is included. For each task, both raw data and computed variables are reported including: the 3D coordinates of external markers, the joint angles of lower limb in the sagittal, transversal and horizontal anatomical planes, the ground reaction forces and torques, the center of pressure, the lower limb joint mechanical moments and power, the displacement of the whole body center of mass, and the surface EMG signals of the main lower limb muscles. The data reported in the present study, acquired from subjects with different ages, represents a valuable dataset useful for future studies on locomotor function in humans, particularly as normative reference to analyze pathological gait, to test the performance of simulation models of bipedal locomotion, and to develop control algorithms for bipedal robots or active lower limb exoskeletons for rehabilitation.

scholarly journals STRUKTUR BAHASA PEMROGRAMAN PASCAL ATAU BAHASA C

2019 ◽  
Author(s):  
Ronal Watrianthos
Keyword(s):  
Functional Programming ◽  
Object Oriented ◽  
Middle Level ◽  
Object Oriented Programming ◽  
Low Level ◽  
High Level

Bahasa pemrograman procedural merupakan bahasa pemerograman yang melibatkan fungsi-fungsi atau prosedur-prosedur sebagai sub program untuk membentuk solusi dari suatu permasalahan. Ada yang mengelompokanya menjadi 3 level bahasa yaitu: high level (Seperti pascaldan basic), middle Level (Seperti Bahasa C), dan low level (Seperti Bahasa Assembly). Ada juga yang mengelompokannya menjadi procedural/ functional programming, Object oriented programming, dansebagainya.Berbeda halnya dengan bahasa pemerograman yang berorientasi obyek, yang menggunakanpendekatan obyek dalam menyelesaikan suatu persoalan. Dengan memahami element-elementbahasa, kita dapat dengan cepat dan muda untuk memepelajari berbagai macam bahasapemrograman

scholarly journals Humanoid standing control: learning from human demonstration

2002 ◽  
Vol 12 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Andreas Hofmann ◽  
Marko Popovic ◽  
Hugh Herr
Keyword(s):  
Ground Reaction Force ◽  
Center Of Pressure ◽  
Human Subjects ◽  
Reaction Force ◽  
Morphological Data ◽  
Human Model ◽  
Joint Torques ◽  
Double Support ◽  
High Level ◽  
Force Data

A three-dimensional numerical model of human standing is presented that reproduces the dynamics of simple swaying motions while in double-support. The human model is structurally realistic, having both trunk and two legs with segment lengths and mass distributions defined using human morphological data from the literature. In this investigation, model stability in standing is achieved through the application of a high-level reduced-order control system where stabilizing forces are applied to the model's trunk by virtual spring- damper elements. To achieve biologically realistic model dynamics, torso position and ground reaction force data measured on human subjects are used as demonstration data in a supervised learning strategy. Using Powell's method, the error between simulation data and measured human data is minimized by varying the virtual high-level force field. Once optimized, the model is shown to track torso position and ground reaction force data from human demonstrations. With only these limited demonstration data, the humanoid model sways in a biologically realistic manner. The model also reproduces the center-of-pressure trajectory beneath the foot, even though no error term for this is included in the optimization algorithm. This indicates that the error terms used (the ones for torso position and ground reaction force) are sufficient to compute the correct joint torques such that independent metrics, like center-of-pressure trajectory, are correct.

Classification of coastal vegetation of the Rybachiy and Sredniy peninsulas (Barents Sea coast)

2017 ◽  
pp. 77-92 ◽  
Author(s):  
K. B. Popova ◽  
O. V. Cherednichenko ◽  
A. V. Razumovskaya
Keyword(s):  
Salt Marsh ◽  
Plant Communities ◽  
Salt Marshes ◽  
Barents Sea ◽  
Middle Level ◽  
Coastal Vegetation ◽  
Vegetation Types ◽  
Low Level ◽  
Murmansk Region ◽  
High Level

The Rybachiy and Sredniy peninsulas are situated at the 69th latitude and bounded by the Barents Sea. Their territories belong to the subarctic tundra. Coastal vegetation is the case of the azonal one, which is regularly disturbed by sea. The aim of the study is to find out the coastal plant communities diversity and investigate ecological and floristic features of the vegetation types. The classification, based on 99 original relevés using TWINSPAN algorithm and following analytical revision, was carried out with Braun-Blanquet approach. The plant communities were classified into 5 associations and one community type. These syntaxa belong to 4 alliances, 4 orders, and 3 classes (Cakiletea maritimae R. Tüxen et Preising in R. Tüxen 1950, Honckenyo peploidis–Leymetea arenarii R. Tüxen 1966, Juncetea maritimi Br.-Bl. in Br.-Bl., Roussine et Negre 1952). There is a special change in coastal vegetation while moving away from sea. Therefore, it is a case of local zonality. The halo-nitrophilous communities of ass. Atriplicetum lapponicae on sandy and shingle wash margins with seaweed debris are common for the low-level beaches. Further from sea they are changing by communities of all. Mertensio maritimae–Honcke­nyion diffusae. The sea influence gradually decrea­ses, but amount of seaweed debris is still high on the coastal sand dunes that is a common place for ass. Honckenyo diffusae–Leymetum arenarii. The communities of Ligusticum scoticum–Festuca rubra com. type cover the higher-level beaches. The nitrophilous species are common for low-level beaches but they are almost absent in high-level phytocoenoses which are considered being an intermediate stage between monodominant seashore grasslands of ass. Honckenyo diffusae–Leymetum arenarii and multispecies high-level seashore meadows (Koroleva et al., 2011). The Rybachiy and Sredniy peninsulas coastal ve­getation seems to be common with another arctic/subarctic areas but having more similarities with western coasts. Communities of ass. Atriplicetum lapponicae have not been marked for Murmansk region, and probab­ly do not occur to the east of the peninsulas (Koroleva, 2006; Koroleva et al., 2011; Matveyeva, Lavrinenko, 2011). However, they are common in western areas (Northern Norway and apparently Iceland) (Tüxen, 1970; Thannheiser, 1974). Silty and sandy low-level salt marshes belong to ass. Puccinellietum phryganodis. Ass. Puccinellietum coarctatae (syn. Puccinellietum retroflexae Nordh. 1954) communities are found on the shingle low and middle level salt mar­shes. The further decreasing of salt seawater influence results in ass. Junco gerardii–Caricetum glareosae community formation. They occupy middle and high level of salt marshes. Communities of associations Puccinellietum phryganodis and Puccinellietum coarctatae on low and middle salt marsh levels are widespread in arctic and subarctic zones (Thannheiser, 1974; Koroleva et al., 2011; Matveyeva, Lavrinenko, 2011). There is an interesting notice that communities of widespread ass. Caricetum subspathaceae were not found on the studied area. The diagnostic species of this association – Carex subspathacea – vegetated only in Junco gerardii–Caricetum glareosae communities. The reason of such phenomenon could be a small area occupied by salt marsh communities on the Rybachiy and Sredniy peninsulas, which turns out that all vegetation types cannot completely evolve.

Hierarchical safety supervisory control strategy for robot-assisted rehabilitation exercise

Robotica ◽  
2013 ◽  
Vol 31 (5) ◽  
pp. 757-766 ◽  
Author(s):  
Lizheng Pan ◽  
Aiguo Song ◽  
Guozheng Xu ◽  
Huijun Li ◽  
Baoguo Xu ◽  
...  
Keyword(s):  
Control Strategy ◽  
Therapeutic Process ◽  
Hierarchical Control ◽  
Hierarchical Architecture ◽  
Robot Assisted ◽  
Low Level ◽  
Emergency Situations ◽  
Impaired Limb ◽  
High Level ◽  
Rehabilitation Exercise

SUMMARYClinical outcomes have shown that robot-assisted rehabilitation is potential of enhancing quantification of therapeutic process for patients with stroke. During robotic rehabilitation exercise, the assistive robot must guarantee subject's safety in emergency situations, e.g., sudden spasm or twitch, abruptly severe tremor, etc. This paper presents a hierarchical control strategy, which is proposed to improve the safety and robustness of the rehabilitation system. The proposed hierarchical architecture is composed of two main components: a high-level safety supervisory controller (SSC) and low-level position-based impedance controller (PBIC). The high-level SSC is used to automatically regulate the desired force for a reasonable disturbance or timely put the emergency mode into service according to the evaluated physical state of training impaired limb (PSTIL) to achieve safety and robustness. The low-level PBIC is implemented to achieve compliance between the robotic end-effector and the impaired limb during the robot-assisted rehabilitation training. The results of preliminary experiments demonstrate the effectiveness and potentiality of the proposed method for achieving safety and robustness of the rehabilitation robot.

POSTURE CONTROL AND BALANCE DURING TAI CHI CHUAN PUSH HANDS MOVEMENTS IN A FIXED STANCE

2012 ◽  
Vol 12 (05) ◽  
pp. 1250030 ◽  
Author(s):  
LIN-HWA WANG ◽  
KUO-CHENG LO ◽  
FONG-CHIN SU
Keyword(s):  
Tai Chi ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Whole Body ◽  
Expert Group ◽  
Tai Chi Chuan ◽  
Kinematic Data ◽  
Analysis System ◽  
Force Data

The present study investigated the adequacy of the interaction between the center of mass (COM) and the center of pressure (COP) for maintaining dynamic stability during Tai Chi Chuan (TCC) Push Hands movements in a fixed stance. The COM of the whole body and COP were calculated. Four TCC experts, with 10.3 ± 1.7 years' experience in the Push Hands technique, and 4 TCC beginners, with 2.5 ± 1.3 years' Push Hands experience, were recruited. An Expert Vision Eagle motion analysis system collected kinematic data and 4 Kistler force plates collected the ground reaction force data. The expert group of TCC practitioners showed a significantly more vertical (P = 0.001) direction in the neutralizing circle, and significantly larger values for anterior–posterior (A–P) (P = 0.006) and vertical (P = 0.0004) displacement in the enticing circle, than the beginner group. Compared with the beginner group, the expert group demonstrated significantly greater velocity A–P (P = 0.001) and vertical (P = 0.001) COM displacements in the enticing circle. A significant extent main effect (P = 0.0028) was observed for the COPA–P excursion between the expert and beginner groups during Push Hands movements. The greater A–P force generated by both groups during the initiation of the Push Hands cycle probably reflects the more rapid and forward-oriented nature of this movement. The TCC beginners might have difficulties with movement transfers because of disruptions in the temporal sequencing of the forces. Overall, results indicated that the initial experience-related differences in COM transfers are reflected in the Push Hands movement cycle.

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