scholarly journals The compliant effect of controlled spine on interaction with the ground in quadruped trotting

2019 ◽  
Vol 234 (1) ◽  
pp. 27-45 ◽  
Author(s):  
Zhang Li ◽  
Yuegang Tan ◽  
Ping Wu ◽  
Shun Zeng
Keyword(s):  
High Speed ◽  
Lumbar Vertebra ◽  
Quadruped Robot ◽  
Ground Reaction Forces ◽  
Gait Simulation ◽  
Compliant Control ◽  
Reaction Forces ◽  
Motion Performance ◽  
The Stability ◽  
Flat Ground

The spine plays important roles in the quadruped locomotion. These effects not only stand out in high-speed gait but also function in low-speed gait, especially the transition gait – trotting gait. In order to investigate the effects of the spine on the motion performance of the quadruped trotting, the spine with two joints is applied into the structure of the quadruped robot. This structure is inspired from the analyses for the canine, which imitates the configuration of thoracic vertebra, front lumbar vertebra and hind lumbar vertebra. Different from the quadruped robot with the passive spine or the active spine by inputting position, a compliant control is applied to the spinal joints. The feature of force control not only possesses the soft feature of the passive spine but also has the advantage of enlarging the motion ability. In the simulation process, a large amount of analyses are carried out including the influence of the control parameters of the controlled spine, the comparison with the quadruped robot with rigid torso and the gait simulation when the robot moves on the flat ground and across an obstacle. The results reveal that the controlled spine has an excellent compliant effect on the interaction with the ground. It contributes to reducing the ground reaction forces; meanwhile, the compliant effect is beneficial for improving the stability. By establishing the prototype robot and performing the motion experiment, the compliant effect of the spine is proven effective.

Twisting and Bending: The Functional Role of Salamander Lateral Hypaxial Musculature During Locomotion

2001 ◽  
Vol 204 (11) ◽  
pp. 1979-1989 ◽  
Author(s):  
Wallace O. Bennett ◽  
Rachel S. Simons ◽  
Elizabeth L. Brainerd
Keyword(s):  
High Intensity ◽  
High Speed ◽  
The Body ◽  
Transversus Abdominis ◽  
Fine Motor ◽  
Emg Activity ◽  
Ground Reaction Forces ◽  
Terrestrial Locomotion ◽  
Reaction Forces ◽  
Hypaxial Muscle

SUMMARY The function of the lateral hypaxial muscles during locomotion in tetrapods is controversial. Currently, there are two hypotheses of lateral hypaxial muscle function. The first, supported by electromyographic (EMG) data from a lizard (Iguana iguana) and a salamander (Dicamptodon ensatus), suggests that hypaxial muscles function to bend the body during swimming and to resist long-axis torsion during walking. The second, supported by EMG data from lizards during relatively high-speed locomotion, suggests that these muscles function primarily to bend the body during locomotion, not to resist torsional forces. To determine whether the results from D. ensatus hold for another salamander, we recorded lateral hypaxial muscle EMGs synchronized with body and limb kinematics in the tiger salamander Ambystoma tigrinum. In agreement with results from aquatic locomotion in D. ensatus, all four layers of lateral hypaxial musculature were found to show synchronous EMG activity during swimming in A. tigrinum. Our findings for terrestrial locomotion also agree with previous results from D. ensatus and support the torsion resistance hypothesis for terrestrial locomotion. We observed asynchronous EMG bursts of relatively high intensity in the lateral and medial pairs of hypaxial muscles during walking in tiger salamanders (we call these ‘α-bursts’). We infer from this pattern that the more lateral two layers of oblique hypaxial musculature, Mm. obliquus externus superficialis (OES) and obliquus externus profundus (OEP), are active on the side towards which the trunk is bending, while the more medial two layers, Mm. obliquus internus (OI) and transversus abdominis (TA), are active on the opposite side. This result is consistent with the hypothesis proposed for D. ensatus that the OES and OEP generate torsional moments to counteract ground reaction forces generated by forelimb support, while the OI and TA generate torsional moments to counteract ground reaction forces from hindlimb support. However, unlike the EMG pattern reported for D. ensatus, a second, lower-intensity burst of EMG activity (‘β-burst’) was sometimes recorded from the lateral hypaxial muscles in A. tigrinum. As seen in other muscle systems, these β-bursts of hypaxial muscle coactivation may function to provide fine motor control during locomotion. The presence of asynchronous, relatively high-intensity α-bursts indicates that the lateral hypaxial muscles generate torsional moments during terrestrial locomotion, but it is possible that the balance of forces from both α- and β-bursts may allow the lateral hypaxial muscles to contribute to lateral bending of the body as well.

A Dynamic Analysis Based on MBD ADAMS Program for a Variant of Quadruped Robot

2016 ◽  
Vol 823 ◽  
pp. 429-434 ◽  
Author(s):  
Florina Pop ◽  
Erwin Christian Lovasz ◽  
Valer Dolga ◽  
Marco Ceccarelli ◽  
Dan Mărgineanu ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
3D Model ◽  
Quadruped Robot ◽  
Moment Of Inertia ◽  
Ground Reaction Forces ◽  
Generalized Coordinates ◽  
Mass Moment ◽  
Adams Software ◽  
Mass Moment Of Inertia ◽  
Reaction Forces

For stability and impact reaction forces assessment of a quadruped robot during walking, a dynamic analysis is considered. For this purpose, a variant of a quadruped robot based on Jansen mechanism is presented. For interpreting the influence of the reaction forces from the ground during walking, the analysis was conducted with help of ADAMS software using a 3D model of the robot. Material specifications, forces and moments acting in the robot structure were considered. Graphical results obtained regarding the ground reaction forces are displayed. Also a reduced mass moment of inertia at the crankshaft is taken into consideration based on Lagrange motion equation and generalized coordinates.

A Nonlinear Leg Damping Model for the Prediction of Running Forces and Stability

2015 ◽  
Vol 10 (5) ◽  
Author(s):  
Ian Abraham ◽  
ZhuoHua Shen ◽  
Justin Seipel
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Energetic Cost ◽  
Ground Reaction Forces ◽  
Slip Model ◽  
Damping Force ◽  
Reaction Forces ◽  
Linear Damping ◽  
The Stability ◽  
Damping Model

Despite the neuromechanical complexity underlying animal locomotion, the steady-state center-of-mass motions and ground reaction forces of animal running can be predicted by simple spring-mass models such as the canonical spring-loaded inverted pendulum (SLIP) model. Such SLIP models have been useful for the fields of biomechanics and robotics in part because ground reaction forces are commonly measured and readily available for comparing with model predictions. To better predict the stability of running, beyond the canonical conservative SLIP model, more recent extensions have been proposed and investigated with hip actuation and linear leg damping (e.g., hip-actuated SLIP). So far, these attempts have gained improved prediction of the stability of locomotion but have led to a loss of the ability to accurately predict ground reaction forces. Unfortunately, the linear damping utilized in current models leads to an unrealistic prediction of damping force and ground reaction force with a large nonzero magnitude at touchdown (TD). Here, we develop a leg damping model that is bilinear in leg length and velocity in order to yield improved damping force and ground reaction force prediction. We compare the running ground reaction forces, small and large perturbation stability, parameter sensitivity, and energetic cost resulting from both the linear and bilinear damping models. We found that bilinear damping helps to produce more realistic, smooth vertical ground reaction forces, thus fixing the current problem with the linear damping model. Despite large changes in the damping force and power loss profile during the stance phase, the overall dynamics and energetics on a stride-to-stride basis of the two models are largely the same, implying that the integrated effect of damping over a stride is what matters most to the stability and energetics of running. Overall, this new model, an actuated SLIP model with bilinear damping, can provide significantly improved prediction of ground reaction forces as well as stability and energetics of locomotion.

Obesity: Effects on Gait in an Osteoarthritic Population

1996 ◽  
Vol 12 (2) ◽  
pp. 161-172 ◽  
Author(s):  
Stephen P. Messier ◽  
Walter H. Ettinger ◽  
Thomas E. Doyle ◽  
Timothy Morgan ◽  
Margaret K. James ◽  
...  
Keyword(s):  
Older Adults ◽  
High Speed ◽  
Ground Reaction Forces ◽  
Vertical Force ◽  
Kinematic Data ◽  
Knee Oa ◽  
Significant Relationships ◽  
Gait Mechanics ◽  
Reaction Forces ◽  
Walking Velocity

The purpose of our study was to examine the association between obesity and gait mechanics in older adults with knee osteoarthritis (OA). Subjects were 101 older adults (25 males and 76 females) with knee OA. High-speed video analysis and a force platform were used to record sagittal view lower extremity kinematic data and ground reaction forces. Increased body mass index (BMI) was significantly related to both decreases in walking velocity and knee maximum extension. There were no significant relationships between BMI and any of the hip or ankle kinematic variables. BMI was directly related to vertical force minimum and maximum values, vertical impulse, and loading rate. Increases in braking and propulsive forces were significantly correlated with increased BMI. Maximum medially and laterally directed ground reaction forces were positively correlated with BMI. Our results suggests that, in subjects with knee OA, obesity is associated with an alteration in gait.

Effects of head and tail as swinging appendages on the dynamic walking performance of a quadruped robot

Robotica ◽  
2016 ◽  
Vol 34 (12) ◽  
pp. 2878-2891 ◽  
Author(s):  
Xiuli Zhang ◽  
Jiaqing Gong ◽  
Yanan Yao
Keyword(s):  
Stride Length ◽  
Pattern Generator ◽  
Flight Time ◽  
Quadruped Robot ◽  
Ground Reaction Forces ◽  
Reaction Forces ◽  
Fixed Phase ◽  
Walking Performance ◽  
Hopf Oscillator ◽  
Phase Differences

SUMMARYWe designed a quadruped robot with a one-degree-of-freedom (1-DOF)-pitch head, a 1-DOF-roll tail, and 14 active DOFs in total, which are controlled via a central pattern generator (CPG) based on a Hopf oscillator. Head and tail movements are coupled to the leg movements with fixed phase differences. Experiments show that tail swinging in roll can equilibrate feet–ground reaction forces (GRF), reducing yaw errors and enabling the robot to maintain its direction when trotting. Head swing in pitch has the potential to increase flight time and stride length of the swinging legs and increase the robot's forward velocity when running in bounds.

scholarly journals Race Walking Ground Reaction Forces at Increasing Speeds: A Comparison with Walking and Running

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 873
Author(s):  
Gaspare Pavei ◽  
Dario Cazzola ◽  
Antonio La Torre ◽  
Alberto E. Minetti
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
The Body ◽  
Ground Reaction Forces ◽  
Centre Of Mass ◽  
Walking Gait ◽  
Wide Range ◽  
Reaction Forces ◽  
Race Walking ◽  
Walking Speeds

Race walking has been theoretically described as a walking gait in which no flight time is allowed and high travelling speed, comparable to running (3.6–4.2 m s−1), is achieved. The aim of this study was to mechanically understand such a “hybrid gait” by analysing the ground reaction forces (GRFs) generated in a wide range of race walking speeds, while comparing them to running and walking. Fifteen athletes race-walked on an instrumented walkway (4 m) and three-dimensional GRFs were recorded at 1000 Hz. Subjects were asked to performed three self-selected speeds corresponding to a low, medium and high speed. Peak forces increased with speeds and medio-lateral and braking peaks were higher than in walking and running, whereas the vertical peaks were higher than walking but lower than running. Vertical GRF traces showed two characteristic patterns: one resembling the “M-shape” of walking and the second characterised by a first peak and a subsequent plateau. These different patterns were not related to the athletes’ performance level. The analysis of the body centre of mass trajectory, which reaches its vertical minimum at mid-stance, showed that race walking should be considered a bouncing gait regardless of the presence or absence of a flight phase.

scholarly journals Gravity Compensation and Feedback of Ground Reaction Forces for Biped Balance Control

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Satoshi Ito ◽  
Shingo Nishio ◽  
Yuuki Fukumoto ◽  
Kojiro Matsushita ◽  
Minoru Sasaki
Keyword(s):  
Control Method ◽  
Balance Control ◽  
Biped Robot ◽  
Effective Control ◽  
Ground Reaction Forces ◽  
Gravity Compensation ◽  
Reaction Forces ◽  
Error Accumulation ◽  
Integral Feedback ◽  
The Stability

This paper considers the balance control of a biped robot under a constant external force or on a sloped ground. We have proposed a control method with feedback of the ground reaction forces and have realized adaptive posture changes that ensure the stability of the robot. However, fast responses have not been obtained because effective control is achieved by an integral feedback that accompanies a time delay necessary for error accumulation. To improve this response, here, we introduce gravity compensation in a feedforward manner. The stationary state and its stability are analyzed based on dynamic equations, and the robustness as well as the response is evaluated using computer simulations. Finally, the adaptive behaviors of the robot are confirmed by standing experiments on the slope.

scholarly journals Effect of Additional Weight on Human Squat Exercise Stability: Ground Reaction Forces and Centers of Pressure

2020 ◽  
Author(s):  
Jose Galarza ◽  
Dumitru I. Caruntu
Keyword(s):  
Time Series ◽  
Center Of Pressure ◽  
Normal Component ◽  
Ground Reaction Forces ◽  
Additional Weight ◽  
Squat Exercise ◽  
Weight One ◽  
Reaction Forces ◽  
Analysis System ◽  
The Stability

Abstract The main focus of this work is to investigate the effect of weight on the stability of human squat exercise. The squat exercise is a common daily activity. Experiments are conducted using one human subject. A VICON motion analysis system integrated with Force Plates is utilized for these experiments. An experimental protocol is developed and followed. This work analyzes the time series of the normal component of the ground reaction forces and each coordinate of the center of pressure. These time series are used to estimate the Lyapunov Exponents using Rosenstein method. MATLAB software package is used for this investigation. The results of this work are compared with results from literature. Present work gives more information relating the safety of the squat exercise when adding additional weight. One can see that the effect of additional weight on stability depends on its value. In the cases of small and moderate additional weight the stability is the same or increases, while for the largest additional weight the investigated stability decreases.

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