Biomechanics of Step Initiation After Balance Recovery With Implications for Humanoid Robot Locomotion

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Christine Miller Buffinton ◽  
Elise M. Buffinton ◽  
Kathleen A. Bieryla ◽  
Jerry E. Pratt
Keyword(s):  
Humanoid Robot ◽  
Center Of Mass ◽  
Human Motion ◽  
Single Step ◽  
The Body ◽  
Balance Recovery ◽  
Joint Torques ◽  
Double Support ◽  
Step Initiation ◽  
Capture Point

Balance-recovery stepping is often necessary for both a human and humanoid robot to avoid a fall by taking a single step or multiple steps after an external perturbation. The determination of where to step to come to a complete stop has been studied, but little is known about the strategy for initiation of forward motion from the static position following such a step. The goal of this study was to examine the human strategy for stepping by moving the back foot forward from a static, double-support position, comparing parameters from normal step length (SL) to those from increasing SLs to the point of step failure, to provide inspiration for a humanoid control strategy. Healthy young adults instrumented with joint reflective markers executed a prescribed-length step from rest while marker positions and ground reaction forces (GRFs) were measured. The participants were scaled to the Gait2354 model in opensim software to calculate body kinematic and joint kinetic parameters, with further post-processing in matlab. With increasing SL, participants reduced both static and push-off back-foot GRF. Body center of mass (CoM) lowered and moved forward, with additional lowering at the longer steps, and followed a path centered within the initial base of support (BoS). Step execution was successful if participants gained enough forward momentum at toe-off to move the instantaneous capture point (ICP) to within the BoS defined by the final position of both feet on the front force plate. All lower extremity joint torques increased with SL except ankle joint. Front knee work increased dramatically with SL, accompanied by decrease in back-ankle work. As SL increased, the human strategy changed, with participants shifting their CoM forward and downward before toe-off, thus gaining forward momentum, while using less propulsive work from the back ankle and engaging the front knee to straighten the body. The results have significance for human motion, suggesting the upper limit of the SL that can be completed with back-ankle push-off before additional knee flexion and torque is needed. For biped control, the results support stability based on capture-point dynamics and suggest strategy for center-of-mass trajectory and distribution of ground force reactions that can be compared with robot controllers for initiation of gait after recovery steps.

scholarly journals Knee-stretched walking with toe-off and heel-strike for a position-controlled humanoid robot based on model predictive control

2021 ◽  
Vol 18 (4) ◽  
pp. 172988142110362
Author(s):  
Zelin Huang ◽  
Zhangguo Yu ◽  
Xuechao Chen ◽  
Qingqing Li ◽  
Libo Meng ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Energy Efficient ◽  
Humanoid Robot ◽  
Center Of Mass ◽  
Heel Strike ◽  
Gait Generation ◽  
Double Support ◽  
Transition Moments ◽  
Efficient Gait

Knee-stretched walking is considered to be a human-like and energy-efficient gait. The strategy of extending legs to obtain vertical center of mass trajectory is commonly used to avoid the problem of singularities in knee-stretched gait generation. However, knee-stretched gait generation utilizing this strategy with toe-off and heel-strike has kinematics conflicts at transition moments between single support and double support phases. In this article, a knee-stretched walking generation with toe-off and heel-strike for the position-controlled humanoid robot has been proposed. The position constraints of center of mass have been considered in the gait generation to avoid the kinematics conflicts based on model predictive control. The method has been verified in simulation and validated in experiment.

Biomechanics of Single Stair Climb with Implications for Inverted Pendulum Modeling

2021 ◽  
Author(s):  
Christine Buffinton ◽  
Roberta K. Blaho ◽  
Kathleen Bieryla
Keyword(s):  
Lower Limb ◽  
Inverted Pendulum ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Humanoid Robots ◽  
Single Step ◽  
Vertical Projection ◽  
Joint Kinetics ◽  
Target Values ◽  
Capture Point

Abstract Step-by-step (SBS) stair navigation is used by those with movement limitations or lower-limb prosthetics, and by humanoid robots. Knowledge of biomechanical parameters for SBS gait, however, is limited. Inverted pendulum (IP) models used to assess dynamic stability have not been applied to SBS gait. This study examined the ability of the linear inverted pendulum (LIP) model and a closed-form, variable-height inverted pendulum (VHIP) model to predict capture point stability in healthy adults executing a single stair climb. A second goal was to provide baseline kinematic and kinetic data for SBS gait. Twenty young adults executed a single step onto stairs of two heights while attached marker positions and ground reaction forces were recorded. OpenSim software determined body kinematics and joint kinetics. Trials were analyzed with LIP and VHIP models, and the predicted capture point compared to the actual center-of-pressure on the stair. Lower-limb joint moments were larger than those reported for step-over-step stair gait. Leading knee rather than trailing ankle was dominant. Center-of-mass (CoM) velocity peaked at push-off. The VHIP model accounted for only slightly more than half of the forward progression of the vertical projection of the CoM, and was not better than LIP predictions. This suggests that IP models are limited in modeling SBS gait, likely due to large hip and knee moments. The results from this study may also provide target values and strategies to aid design of lower-limb prostheses and powered exoskeletons.

Validating Determinants for an Alternate Foot Placement Selection Algorithm During Human Locomotion in Cluttered Terrain

2007 ◽  
Vol 98 (4) ◽  
pp. 1928-1940 ◽  
Author(s):  
Renato Moraes ◽  
Fran Allard ◽  
Aftab E. Patla
Keyword(s):  
Dynamic Stability ◽  
Center Of Mass ◽  
Frontal Plane ◽  
Human Locomotion ◽  
The Body ◽  
Selection Algorithm ◽  
Foot Placement ◽  
Double Support ◽  
One Step ◽  
Base Of Support

The goal of this study was to validate dynamic stability and forward progression determinants for the alternate foot placement selection algorithm. Participants were asked to walk on level ground and avoid stepping, when present, on a virtual white planar obstacle. They had a one-step duration to select an alternate foot placement, with the task performed under two conditions: free (participants chose the alternate foot placement that was appropriate) and forced (a green arrow projected over the white planar obstacle cued the alternate foot placement). To validate the dynamic stability determinant, the distance between the extrapolated center of mass (COM) position, which incorporates the dynamics of the body, and the limits of the base of support was calculated in both anteroposterior (AP) and mediolateral (ML) directions in the double support phase. To address the second determinant, COM deviation from straight ahead was measured between adaptive and subsequent steps. The results of this study showed that long and lateral choices were dominant in the free condition, and these adjustments did not compromise stability in both adaptive and subsequent steps compared with the short and medial adjustments, which were infrequent and adversely affected stability. Therefore stability is critical when selecting an alternate foot placement in a cluttered terrain. In addition, changes in the plane of progression resulted in small deviations of COM from the endpoint goal. Forward progression of COM was maintained even for foot placement changes in the frontal plane, validating this determinant as part of the selection algorithm.

Measurement and Analysis of Human Lower Limbs Movement Parameters during Walking

2015 ◽  
Vol 220-221 ◽  
pp. 538-543 ◽  
Author(s):  
Sergei Zhigailov ◽  
Artem Kuznetcov ◽  
Victor Musalimov ◽  
Gennady Aryassov
Keyword(s):  
Human Motion ◽  
The Body ◽  
Lower Limbs ◽  
Human Gait ◽  
Inertial Measurement ◽  
Double Support ◽  
Motion Parameters ◽  
Using Data ◽  
Movement Parameters ◽  
Different Parts

It is necessary to analyze human gait for treatment and rehabilitation of human with musculoskeletal disorders of the locomotion apparatus (LA). The main goal of this work is evaluation of locomotion apparatus motion parameters captured by inertial measurement units (IMU) during walking. Motion Capture technology is process of getting practical results and data from IMU installed in different parts of human lower limbs. Synchronously, IMU send information about human movements to PC at the same moment of time. Such method gives an opportunity to follow parameters in some points of human leg in real time. The way of devices mounting and instruction for human under monitoring are based on related medical projects. Walking is selected for estimation of the musculoskeletal system as typical action. Experiment results got from several experiments were considered and analyzed.Basically, walking is described as a set of the system “human” discrete states. In the same time, the IMU sensors transmit motion parameters data continuously. It is proposed to present the man as a system with a control signal in the form of the double support period. The length will be measured using data from IMU. Double support period is chosen because its presence distinguishes walking from running.The most attention is given to getting the same practical results and data that can be obtained by placing the devices in different parts of the body. Moreover, a technique of using inertial measurement devices for measuring human motion to get some numerical results is shown. The use of this technique in practice demonstrated that it can be used to obtain an objective parameter describing the motion of the person. Continuation of this work is directed to create a complete model of the lower limbs motion for usage in practice [1].

scholarly journals Force Shadows: An Online Method to Estimate and Distribute Vertical Ground Reaction Forces from Kinematic Data

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5709
Author(s):  
Alexander Weidmann ◽  
Bertram Taetz ◽  
Matthias Andres ◽  
Felix Laufer ◽  
Gabriele Bleser
Keyword(s):  
Reaction Force ◽  
Human Motion ◽  
The Body ◽  
Contact Phase ◽  
Kinematic Data ◽  
Double Support ◽  
Hip Muscle ◽  
Reaction Forces ◽  
Muscle Activations ◽  
Vertical Ground Reaction Forces

Kinetic models of human motion rely on boundary conditions which are defined by the interaction of the body with its environment. In the simplest case, this interaction is limited to the foot contact with the ground and is given by the so called ground reaction force (GRF). A major challenge in the reconstruction of GRF from kinematic data is the double support phase, referring to the state with multiple ground contacts. In this case, the GRF prediction is not well defined. In this work we present an approach to reconstruct and distribute vertical GRF (vGRF) to each foot separately, using only kinematic data. We propose the biomechanically inspired force shadow method (FSM) to obtain a unique solution for any contact phase, including double support, of an arbitrary motion. We create a kinematic based function, model an anatomical foot shape and mimic the effect of hip muscle activations. We compare our estimations with the measurements of a Zebris pressure plate and obtain correlations of 0.39≤r≤0.94 for double support motions and 0.83≤r≤0.87 for a walking motion. The presented data is based on inertial human motion capture, showing the applicability for scenarios outside the laboratory. The proposed approach has low computational complexity and allows for online vGRF estimation.

scholarly journals Variability in the Center of Mass State During Initiation of Accurate Forward Step Aimed at Targets of Different Sizes

2021 ◽  
Vol 3 ◽  
Author(s):  
Hiroki Yamada ◽  
Masahiro Shinya
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Body Height ◽  
The Body ◽  
Target Condition ◽  
Large Target ◽  
Step Initiation ◽  
Task Requirements ◽  
The Central Nervous System ◽  
Stepping Accuracy

Motor control for forward step initiation begins with anticipatory postural adjustments (APAs). During APAs, the central nervous system controls the center of pressure (CoP) to generate an appropriate center of mass (CoM) position and velocity for various task requirements. In this study, we investigated the effect of required stepping accuracy on the CoM and CoP parameters during APA for a step initiation task. Sixteen healthy young participants stepped forward onto the targets on the ground as soon as and as fast as possible in response to visual stimuli. Two target sizes (small: 2 cm square and large: 10 cm square) and two target distances (short: 20% and long: 40% of the body height) were tested. CoP displacement during the APA and the CoM position, velocity, and extrapolated CoM at the timing of the takeoff of the lead leg were compared among the conditions. In the small condition, comparing with the large condition, the CoM position was set closer to the stance limb side during the APA, which was confirmed by the location of the extrapolated center of mass at the instance of the takeoff of the lead leg [small: 0.09 ± 0.01 m, large: 0.06 ± 0.01 m, mean and standard deviation, F(1, 15) = 96.46, p < 0.001, η2 = 0.87]. The variability in the mediolateral extrapolated center of mass location was smaller in the small target condition than large target condition when the target distance was long [small: 0.010 ± 0.002 m, large: 0.013 ± 0.004 m, t(15) = 3.8, p = 0.002, d = 0.96]. These findings showed that in the step initiation task, the CoM state and its variability were task-relevantly determined during the APA in accordance with the required stepping accuracy.

Humanoid gait generation in complex environments based on template models and optimality principles learned from human beings

2018 ◽  
Vol 37 (10) ◽  
pp. 1184-1204 ◽  
Author(s):  
Debora Clever ◽  
Yue Hu ◽  
Katja Mombaur
Keyword(s):  
Optimal Control ◽  
Motion Capture ◽  
Humanoid Robot ◽  
Center Of Mass ◽  
Humanoid Robots ◽  
Human Motion ◽  
Human Beings ◽  
Inverse Optimal Control ◽  
Gait Generation ◽  
Template Model

In this paper, we present an inverse optimal control-based transfer of motions from human experiments to humanoid robots and apply it to walking in constrained environments. To this end, we introduce a 3D template model, which describes motion on the basis of center-of-mass trajectory, foot trajectories, upper-body orientation, and phase duration. Despite its abstract architecture, with prismatic joints combined with damped series elastic actuators instead of knees, the model (including dynamics and constraints) is suitable for describing both human and humanoid locomotion with appropriate parameters. We present and apply an inverse optimal control approach to identify optimality criteria based on human motion capture experiments. The identified optimal strategy is then transferred to a humanoid robot template model for gait generation by solving an optimal control problem, which takes into account the properties of the robot and differences in the environment. The results of this step are the center-of-mass trajectory, the foot trajectories, the torso orientation, and the single and double support phase durations for a sequence of steps, allowing the humanoid robot to walk within a new environment. In a previous paper, we have already presented one computational cycle (from motion capture data to an optimized robot template motion) for the example of walking over irregular stepping stones with the aim of transferring the motion to two very different humanoid robots (iCub@Heidelberg and HRP-2@LAAS). This study represents an extension, containing an entirely new part on the transfer of the optimized template motion to the iCub robot by means of inverse kinematics in a dynamic simulation environment and also on the real robot.

Effects of COM Vertical Oscillation on Joint Torques During 3D Walking of Humanoid Robots

2016 ◽  
Vol 13 (04) ◽  
pp. 1650019 ◽  
Author(s):  
Sahab Omran ◽  
Sophie Sakka ◽  
Yannick Aoustin
Keyword(s):  
Humanoid Robot ◽  
Inverted Pendulum ◽  
Center Of Mass ◽  
Vertical Motion ◽  
Humanoid Robots ◽  
Dynamics Simulation ◽  
Vertical Oscillation ◽  
Human Beings ◽  
Joint Torques ◽  
Consequent Reduction

This paper proposes an analysis of the effect of vertical motion of the center of mass (COM) during humanoid walking. The linear inverted pendulum (LIP) model is classically used to deal with humanoid balance during walking. The effects on energy consumption of the COM height remaining constant for humanoid robots, or varying like human beings are studied here. Two approaches are introduced for the comparison: the LIP which offers the great advantage of analytical solving (i.e., fast and easy calculations), and a numerical solving of the IP dynamics, which allows varying the height of the center of mass during walking. The results are compared using a sthenic criterion in a 3D dynamics simulation of the humanoid robot Romeo (Aldebaran Robotics Company) and show a consequent reduction of the robot torque solicitation when the COM oscillates vertically.

On the motion of bodies based on changes in the kinetic moment

2019 ◽  
Vol 20 (4) ◽  
pp. 267-275
Author(s):  
Yury N. Razoumny ◽  
Sergei A. Kupreev
Keyword(s):  
Center Of Mass ◽  
Stellar Dynamics ◽  
Elementary Particles ◽  
The Body ◽  
Accelerated Motion ◽  
Indirect Confirmation ◽  
Physical Principles ◽  
Two Bodies ◽  
Central Gravitational Field ◽  
Kinetic Moment

The controlled motion of a body in a central gravitational field without mass flow is considered. The possibility of moving the body in the radial direction from the center of attraction due to changes in the kinetic moment relative to the center of mass of the body is shown. A scheme for moving the body using a system of flywheels located in the same plane in near-circular orbits with different heights is proposed. The use of the spin of elementary particles is considered as flywheels. It is proved that using the spin of elementary particles with a Compton wavelength exceeding the distance to the attracting center is energetically more profitable than using the momentum of these particles to move the body. The calculation of motion using hypothetical particles (gravitons) is presented. A hypothesis has been put forward about the radiation of bodies during accelerated motion, which finds indirect confirmation in stellar dynamics and in an experiment with the fall of two bodies in a vacuum. The results can be used in experiments to search for elementary particles with low energy, explain cosmic phenomena and to develop transport objects on new physical principles.

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