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.

scholarly journals Characterizing the Validity of the Inverted Pendulum Model for Quiet Standing

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Jia-Li Sung ◽  
Chih-Yuan Hong ◽  
Chin-Hsuan Liu ◽  
Posen Lee ◽  
Lan-Yuen Guo ◽  
...  
Keyword(s):  
Human Body ◽  
Inverted Pendulum ◽  
Sagittal Plane ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Age Groups ◽  
Quiet Standing ◽  
Aging Effects ◽  
Vertical Projection

By assuming that the human body rotates primarily around the ankle joint in the sagittal plane, the human body has been modelled as a single inverted pendulum (IP) to simulate the human quiet stance. Despite its popularity, the validity of the IP model has been challenged in many studies. Rather than testing the validity of the IP model as a true or false question, this work proposes a feature to quantify the degree of validity of the IP model. The development of the proposed feature is based on the fact that the IP model predicts that the horizontal acceleration of COM is proportional to the COP error which is defined as the difference between the center of pressure (COP) and the vertical projection of the center of mass (COM). Since the horizontal components of the acceleration of COM and the ground reaction force (GRF) are always proportional, the proposed feature is the correlation coefficient between the anterior-posterior (AP) components of GRF and the COP error. The efficacy of the proposed feature is demonstrated by comparing its differences for individuals in two age groups (18–24 and 65–73 years) in quiet standing. The experimental results show that the IP model is more suited for predicting the motion of the older group than the younger group. Our results also show that the proposed feature is more sensitive to aging effects than one of the most reliable and accurate COP-based postural stability features.

scholarly journals Turning Gait Planning Method for Humanoid Robots

2018 ◽  
Vol 8 (8) ◽  
pp. 1257 ◽  
Author(s):  
Tianqi Yang ◽  
Weimin Zhang ◽  
Xuechao Chen ◽  
Zhangguo Yu ◽  
Libo Meng ◽  
...  
Keyword(s):  
Inverted Pendulum ◽  
Center Of Mass ◽  
Translational Motion ◽  
Humanoid Robots ◽  
Inverted Pendulum Model ◽  
Straight Line ◽  
Pendulum Model ◽  
The Stability ◽  
And Control ◽  
Present Simulation

The most important feature of this paper is to transform the complex motion of robot turning into a simple translational motion, thus simplifying the dynamic model. Compared with the method that generates a center of mass (COM) trajectory directly by the inverted pendulum model, this method is more precise. The non-inertial reference is introduced in the turning walk. This method can translate the turning walk into a straight-line walk when the inertial forces act on the robot. The dynamics of the robot model, called linear inverted pendulum (LIP), are changed and improved dynamics are derived to make them apply to the turning walk model. Then, we expend the new LIP model and control the zero moment point (ZMP) to guarantee the stability of the unstable parts of this model in order to generate a stable COM trajectory. We present simulation results for the improved LIP dynamics and verify the stability of the robot turning.

Stabilized Walking of Humanoid NAO using Enhanced Spring-Loaded Inverted Pendulum Model on Uneven Terrain

2022 ◽  
Vol 13 (1) ◽  
pp. 0-0
Keyword(s):  
Path Length ◽  
Inverted Pendulum ◽  
Center Of Mass ◽  
Humanoid Robots ◽  
Slip Model ◽  
Turning Angle ◽  
Uneven Terrain ◽  
Inverted Pendulum Model ◽  
Pendulum Model ◽  
Spring Loaded Inverted Pendulum

In the coming decades, humanoid robots will play a rising role in society. The present article discusses their walking control and obstacle avoidance on uneven terrain using enhanced spring-loaded inverted pendulum model (ESLIP). The SLIP model is enhanced by tuning it with an adaptive particle swarm optimization (APSO) approach. It helps the humanoid robot to reach closer to the obstacles in order to optimize the turning angle to optimize the path length. The desired trajectory, along with the sensory data, is provided to the SLIP model, which creates compatible COM (center of mass) dynamics for stable walking. This output is fed to APSO as input, which adjusts the placement of the foot during interaction with uneven surfaces and obstacles. It provides an optimum turning angle for shunning the obstacles and ensures the shortest path length. Simulation has been carried out in a 3D simulator based on the proposed controller and SLIP controller in uneven terrain.

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 Biomechanical Control of Paretic Lower Limb During Imposed Weight Transfer in Individuals Post-Stroke

2020 ◽  
Author(s):  
Hao-Yuan Hsiao ◽  
Vicki L Gray ◽  
James Borrelli ◽  
Mark W Rogers
Keyword(s):  
Lower Limb ◽  
Center Of Pressure ◽  
Weight Bearing ◽  
Center Of Mass ◽  
Step Test ◽  
Control Group ◽  
Post Stroke ◽  
Paretic Limb ◽  
Four Square ◽  
Weight Transfer

Abstract Background: stroke is a leading cause of disability with associated hemiparesis resulting in difficulty bearing and transferring weight on to the paretic limb. Difficulties in weight bearing and weight transfer may result in impaired mobility and balance, increased fall risk, and decreased community engagement. Despite considerable efforts aimed at improving weight transfer after stroke, impairments in its neuromotor and biomechanical control remain poorly understood. In the present study, a novel experimental paradigm was used to characterize differences in weight transfer biomechanics in individuals with chronic stroke versus able-bodied controls. Methods: fifteen participants with stroke and fifteen age-matched able-bodied controls participated in the study. Participants stood with one foot on each of two custom built platforms. One of the platforms dropped 4.3 cm vertically to induce lateral weight transfer and weight bearing. Paretic lower extremity joint kinematics, vertical ground reaction forces, and center of pressure velocity were measured. All participants completed the clinical Step Test and Four-Square Step Test. Results: reduced paretic ankle, knee, and hip joint angular displacement and velocity, delayed ankle and knee inter-joint timing, and altered center of pressure (COP) and center of mass control were exhibited in the stroke group compared to the control group. In addition, paretic COP velocity stabilization time during induced weight transfer predicted Four-Square Step Test scores in individuals post-stroke. Conclusions: the induced weight transfer approach identified stroke-related abnormalities in the control of weight transfer towards the paretic limb side compared to controls. Decreased joint flexion of the paretic ankle and knee, altered inter-joint timing, and altered COP and center of mass control appear to limit rapid lower limb loading ability. Future work will investigate the potential of improving functional weight transfer through induced weight transfer training exercise.

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 Dynamic walking control of humanoid robots combining linear inverted pendulum mode with parameter optimization

2018 ◽  
Vol 15 (1) ◽  
pp. 172988141774967 ◽  
Author(s):  
Chengju Liu ◽  
Jing Ning ◽  
Qijun Chen
Keyword(s):  
Inverted Pendulum ◽  
Fitness Function ◽  
Center Of Mass ◽  
Humanoid Robots ◽  
Optimization Method ◽  
The Body ◽  
Parameters Optimization ◽  
Model Parameters ◽  
Optimization Strategy ◽  
Gradient Learning

To improve the robustness of biped walking, a model parameters optimization method based on policy gradient decent learning is presented. For the linear inverted pendulum mode-based model parameters optimization, firstly, select the input parameters of the inverted pendulum model and the torso attitude parameters of the robot as the correction variables and establish the correction equation. Then, using the tracking errors of center of mass (CoM) of the robot and the errors of the robot posture relative to the upright state of the body to establish the fitness function. According to the fitness function, the gain coefficients in the model parameters correction equation are optimized by using the strategy gradient learning method, and the modified gain parameters are substituted into the model parameters correction equation to obtain the correction amount. By applying the model parameters optimization strategy, the robot can quickly and in real time adjust the body posture and walking patterns under unknown disturbances, hence, the walking robustness can be enhanced. Simulation and experiments on a full-body humanoid robot NAO validate the effectiveness of the proposed method. The experiments show that the optimized model yields a more controlled, robust walk on NAO robot and on various surfaces without additional manual parameters tuning.

Dynamic balance optimization in biped robots: Physical modeling, implementation and tests using an innovative formula

Robotica ◽  
2014 ◽  
Vol 33 (10) ◽  
pp. 2083-2099 ◽  
Author(s):  
G. G. Muscolo ◽  
C. T. Recchiuto ◽  
R. Molfino
Keyword(s):  
Dynamic Balance ◽  
Center Of Mass ◽  
Analytical Formula ◽  
Humanoid Robots ◽  
Biped Robots ◽  
Target Values ◽  
Zero Moment ◽  
Torque Values ◽  
Mass Position

SUMMARYIn this paper, an analytical formula for the determination of the center of mass position in humanoid platforms is proposed and tested in a real humanoid robot. The formula uses the force-torque values obtained by the two force-torque sensors applied on the feet of the robot and the measured currents required from the motors to maintain balance as inputs. The proposed formula outputs the real center of mass position that minimizes the errors between real humanoid robots and virtual models. Data related to the Zero Moment Point positions and to the joint movements are compared with the target values, showing how the application of the proposed formula enables achieving better repeatability and predictability of the static and dynamic robot behaviour.

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.

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.

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