scholarly journals Contact-Dependent Balance Stability of Biped Robots

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
Carlotta Mummolo ◽  
William Z. Peng ◽  
Carlos Gonzalez ◽  
Joo H. Kim
Keyword(s):  
Stability Boundary ◽  
Theoretical Models ◽  
Biped Robot ◽  
Walking Robots ◽  
Stability Boundaries ◽  
Biped Robots ◽  
Double Support ◽  
Contact Configuration ◽  
Multiple Contacts ◽  
Balance Stability

A theoretical–algorithmic framework for the construction of balance stability boundaries of biped robots with multiple contacts with the environment is proposed and implemented on a robotic platform. Comprehensive and univocal definitions of the states of balance of a generic legged system are introduced with respect to the system's contact configuration. Theoretical models of joint-space and center of mass (COM)-space dynamics under multiple contacts, distribution of contact wrenches, and robotic system parameters are established for their integration into a nonlinear programing (NLP) problem. In the proposed approach, the balance stability capabilities of a biped robot are quantified by a partition of the state space of COM position and velocity. The boundary of such a partition provides a threshold between balanced and falling states of the biped robot with respect to a specified contact configuration. For a COM state to be outside of the stability boundary represents the sufficient condition for falling, from which a change in the system's contact is inevitable. Through the calculated stability boundaries, the effects of different contact configurations (single support (SS) and double support (DS) with different step lengths) on the robot's balance stability capabilities can be quantitatively evaluated. In addition, the balance characteristics of the experimental walking trajectories of the robot at various speeds are analyzed in relation to their respective stability boundaries. The proposed framework provides a contact-dependent balance stability criterion for a given system, which can be used to improve the design and control of walking robots.

Contact-Dependent Balance Stability of Walking Robots

2017 ◽  
Author(s):  
Carlotta Mummolo ◽  
William Z. Peng ◽  
Carlos Gonzalez ◽  
Joo H. Kim
Keyword(s):  
Stability Region ◽  
Balance Control ◽  
Center Of Mass ◽  
Biped Robot ◽  
Walking Robots ◽  
Ground Contact ◽  
Robotic Platform ◽  
Contact Configuration ◽  
The Stability ◽  
Balance Stability

A novel theoretical framework for the identification of the balance stability regions of biped systems is implemented on a real robotic platform. With the proposed method, the balance stability capabilities of a biped robot are quantified by a balance stability region in the state space of center of mass (COM) position and velocity. The boundary of such a stability region provides a threshold between balanced and falling states for the robot by including all possible COM states that are balanced with respect to a specified feet/ground contact configuration. A COM state outside of the stability region boundary is the sufficient condition for a falling state, from which a change in the specified contact configuration is inevitable. By specifying various positions of the robot’s feet on the ground, the effects of different contact configurations on the robot’s balance stability capabilities are investigated. Experimental walking trajectories of the robot are analyzed in relationship with their respective stability boundaries, to study the robot balance control during various gait phases.

scholarly journals Effects of Torso Pitch Motion on Energy Efficiency of Biped Robot Walking

2021 ◽  
Vol 11 (5) ◽  
pp. 2342
Author(s):  
Long Li ◽  
Zhongqu Xie ◽  
Xiang Luo ◽  
Juanjuan Li
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Biped Robot ◽  
Gait Pattern ◽  
Pattern Generation ◽  
Biped Robots ◽  
Pitch Motion ◽  
Double Support ◽  
Gait Parameters ◽  
Support Phase

Gait pattern generation has an important influence on the walking quality of biped robots. In most gait pattern generation methods, it is usually assumed that the torso keeps vertical during walking. It is very intuitive and simple. However, it may not be the most efficient. In this paper, we propose a gait pattern with torso pitch motion (TPM) during walking. We also present a gait pattern with torso keeping vertical (TKV) to study the effects of TPM on energy efficiency of biped robots. We define the cyclic gait of a five-link biped robot with several gait parameters. The gait parameters are determined by optimization. The optimization criterion is chosen to minimize the energy consumption per unit distance of the biped robot. Under this criterion, the optimal gait performances of TPM and TKV are compared over different step lengths and different gait periods. It is observed that (1) TPM saves more than 12% energy on average compared with TKV, and the main factor of energy-saving in TPM is the reduction of energy consumption of the swing knee in the double support phase and (2) the overall trend of torso motion is leaning forward in double support phase and leaning backward in single support phase, and the amplitude of the torso pitch motion increases as gait period or step length increases.

Biped Landing Pattern Modification Method and Walking Experiments in Outdoor Environment

2008 ◽  
Vol 20 (5) ◽  
pp. 775-784 ◽  
Author(s):  
Kenji Hashimoto ◽  
◽  
Yusuke Sugahara ◽  
Hun-Ok Lim ◽  
Atsuo Takanishi ◽  
...  
Keyword(s):  
Biped Robot ◽  
Stability Control ◽  
Outdoor Environment ◽  
Walking Robots ◽  
Control Algorithms ◽  
Biped Robots ◽  
Uneven Terrain ◽  
Walking Pattern ◽  
Actual Compliance ◽  
Modification Method

Many researchers have studied walking stability control for biped robots, most of which involve highly precise acceleration controls based on robot model mechanics. Modeling error, however, makes the control algorithms used difficult to apply to biped walking robots intended to transport human users. The “landing pattern modification method” we propose is based on nonlinear admittance control. Theoretical compliance displacement calculated from walking patterns is compared to actual compliance displacement, when a robot's foot contacts slightly uneven terrain. Terrain height is detected and the preset walking pattern is modified accordingly. The new biped foot we also propose forms larger support polygons on uneven terrain than conventional biped foot systems do. Combining our new modification method and foot, a human-carrying biped robot can traverse uneven terrain, as confirmed in walking experiments.

scholarly journals Constrained Quadratic Programming and Neurodynamics-Based Solver for Energy Optimization of Biped Walking Robots

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Liyang Wang ◽  
Ming Chen ◽  
Xiangkui Jiang ◽  
Wei Wang
Keyword(s):  
Energy Consumption ◽  
Quadratic Programming ◽  
Energy Optimization ◽  
Biped Robot ◽  
High Energy ◽  
Walking Robots ◽  
Biped Robots ◽  
Biped Walking ◽  
Joint Torques ◽  
Force Moment

The application of biped robots is always trapped by their high energy consumption. This paper makes a contribution by optimizing the joint torques to decrease the energy consumption without changing the biped gaits. In this work, a constrained quadratic programming (QP) problem for energy optimization is formulated. A neurodynamics-based solver is presented to solve the QP problem. Differing from the existing literatures, the proposed neurodynamics-based energy optimization (NEO) strategy minimizes the energy consumption and guarantees the following three important constraints simultaneously: (i) the force-moment equilibrium equation of biped robots, (ii) frictions applied by each leg on the ground to hold the biped robot without slippage and tipping over, and (iii) physical limits of the motors. Simulations demonstrate that the proposed strategy is effective for energy-efficient biped walking.

Optimization-based gait planning and control for biped robots utilizing the optimal allowable ZMP variation region

2018 ◽  
Vol 45 (4) ◽  
pp. 469-480 ◽  
Author(s):  
Hongbo Zhu ◽  
Minzhou Luo ◽  
Jingzhao Li
Keyword(s):  
Energy Efficiency ◽  
Stability Margin ◽  
Biped Robot ◽  
Step Length ◽  
Geometric Constraints ◽  
Average Height ◽  
Biped Robots ◽  
Gait Planning ◽  
Content Type ◽  
Double Support

Purpose The purpose of this study is to present an optimization-based gait planning method for biped robots according to the conditions of terrain, which takes fully the relationship between walking stability margin and energy efficiency into account. Design/methodology/approach First, the authors newly designed a practical gait motion synthesis algorithm by using the optimal allowable zero moment point (ZMP) variation region (OAZR), which can generate different gait motions corresponding to different terrains based on the modifiability of ZMP in lateral (y-axis) direction. Second, an effective gait parameter optimization algorithm is performed to find the optimal set of key gait parameters (step length, duration time of gait cycle, average height of center of mass (CoM), amplitude of the vertical CoM motion and double support ratio), which maximizes either the walking stability margin or the energy efficiency with certain walking stability margin under practical constraints (mechanical constraints of all joint motors, geometric constraints, friction force limit and yawing moment limit) according to the conditions of terrain. Third, the necessary controllers for biped robots have been introduced briefly. Findings The experiment data and results are described and analyzed, showing that the proposed method was verified through simulations and implemented on a DRC-XT biped robot. Originality/value The main contribution is that the OAZR has been defined based on AZR, which could be used to plan and generate the various feasible gait motions to help a biped robot to adapt effectively to various terrains.

High-Efficient Biped Walking Based on Flat-Footed Passive Dynamic Walking with Mechanical Impedance at Ankles

2012 ◽  
Vol 24 (3) ◽  
pp. 498-506 ◽  
Author(s):  
Yuta Hanazawa ◽  
◽  
Masaki Yamakita
Keyword(s):  
Energy Efficient ◽  
Mechanical Impedance ◽  
Biped Robot ◽  
Dynamic Walking ◽  
Passive Dynamic Walking ◽  
Biped Robots ◽  
Biped Walking ◽  
Double Support ◽  
High Efficient ◽  
Support Phase

In this paper, we present novel biped walking based on flat-footed Passive Dynamic Walking (PDW) with mechanical impedance at the ankles. To realize biped robot achieving high-efficient walking, PDW has attracted attention. Recently, flat-footed passive dynamic walkers with mechanical impedance at the ankles have been proposed. We show that this passive walker achieves fast, energy-efficient walking using ankle springs and inerters. For this reason, we propose novel biped walking control that mimics PDW to realize biped robots achieving fast, energy-efficient walking on level ground. First, we design a flat-footed biped robot that achieves fast, energy-efficient PDW. To achieve walking based on PDW, the biped robot then takes advantage of a virtual gravitational field that is generated by actuators. The biped robot also pushes off with the foot in the double-support phase to restore energy. By walking simulation, we show that a flat-footed biped robot achieves fast, energy-efficient walking on level ground by the proposed method.

Bibot-U6: A Novel 6-DoF Biped Active Walking Robot - Modeling, Planning and Control

2014 ◽  
Vol 11 (02) ◽  
pp. 1450014 ◽  
Author(s):  
Xuefeng Zhou ◽  
Yisheng Guan ◽  
Haifei Zhu ◽  
Wenqiang Wu ◽  
Xin Chen ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Biped Robot ◽  
High Energy ◽  
Walking Robots ◽  
Walking Robot ◽  
Biped Robots ◽  
Planning And Control ◽  
Biped Walking Robot ◽  
And Control ◽  
High Energy Consumption

Most of current biped robots are active walking platforms. Though they have strong locomotion ability and good adaptability to environments, they have a lot of degrees of freedom (DoFs) and hence result in complex control and high energy consumption. On the other hand, passive or semi-passive walking robots require less DoFs and energy, but their walking capability and robustness are poor. To overcome these shortcomings, we have developed a novel active biped walking robot with only six DoFs. The robot is built with six 1-DoF joint modules and two wheels as the feet. It achieves locomotion in special gaits different from those of traditional biped robots. In this paper, this novel biped robot is introduced, four walking gaits are proposed, the criterion of stable walking is addressed and analyzed, and walking patterns and motion planning are presented. Experiments are carried out to verify the locomotion function, the effectiveness of the presented gaits and to illustrate the features of this novel biped robot. It has been shown that biped active walking may be achieved with only a few DoFs and simple kinematic configuration.

Stability Region-Based Analysis of Walking and Push Recovery Control

2020 ◽  
Author(s):  
William Z. Peng ◽  
Hyunjong Song ◽  
Joo H. Kim
Keyword(s):  
Biped Robot ◽  
Step Length ◽  
Stability Control ◽  
Human Gait ◽  
Biped Robots ◽  
Reduced Order ◽  
Double Support ◽  
Push Recovery ◽  
The Stability ◽  
Time Required

Abstract Push recovery is a vital aspect of balance stability control in biped robots. In this work, the response of a biped system to unexpected external perturbations is analyzed for different tasks and controllers using stability criteria based on balanced and steppable regions. The steppable region for a given step length and the balanced regions for single and double support contacts are constructed for a biped robot using optimization with its system dynamics, kinematic limits, actuation limits, and contact interactions with the environment. The regions are compared with those of a human subject to demonstrate that human gait exhibits unbalanced (but steppable) phases largely absent in robotic gait. These regions are also applied to a comparative analysis against capturability, where the computed steppable region is significantly larger than the capture region of an equivalent reduced-order model. The stability regions are also used to compare the performance of controllers during a double support balancing task. The implemented hip, knee, and ankle strategy-based controller led to improved stabilization — i.e., decreased foot tipping and time required to balance — relative to an existing hip and ankle controller and a gyro feedback controller. The proposed approaches are applicable to the analysis of any bipedal task and stability controller in general.

The Effect of the Toe on the Biped Robot

2013 ◽  
Vol 325-326 ◽  
pp. 1076-1082
Author(s):  
Seyed Mehdi Torklarki ◽  
Mohammad Danesh
Keyword(s):  
Reaction Force ◽  
Stability Margin ◽  
Biped Robot ◽  
Body Motion ◽  
Upper Body ◽  
Biped Robots ◽  
Double Support ◽  
The Stability ◽  
Single Support Phase ◽  
Support Phase

Evaluation of 9-DOF biped robots based on designated smooth and stable trajectories with two added toes is a challenging problem that is the focus of this paper. Simultaneously rotation of feet and toes is considered, which allows the robot to walk more efficiently and like a human being. A desired trajectory for the lower body is designed to increase the stability margin. This obtained by fitting proper polynomials at appropriate break points. Then, the upper body motion is planned based on the Zero Moment Point (ZMP) criterion to provide a stable motion for the biped robot. Next, dynamics equations are obtained for both single support phase (SSP) and double support phase (DSP). On the other hand, two biped robots, which one accompanied by toes, are also compared. Simulation results reveal that the biped robots with toes have better stability margin, less power consumption and more vertical reaction force.

Energy expenditure of a biped walking robot: instantaneous and degree-of-freedom-based instrumentation with human gait implications

Robotica ◽  
2016 ◽  
Vol 35 (5) ◽  
pp. 1054-1071 ◽  
Author(s):  
Dustyn Roberts ◽  
Joseph Quacinella ◽  
Joo H. Kim
Keyword(s):  
Energy Expenditure ◽  
Dynamic Balance ◽  
Biped Robot ◽  
Human Gait ◽  
Walking Robots ◽  
Time Duration ◽  
Cost Of Transport ◽  
Biped Walking ◽  
Double Support ◽  
Robotic Gait

SUMMARYEnergy expenditure (EE) is an important criterion for design and control of biped walking robots. However, the cause-effect analyses enabled by total EE, which is lumped over a time duration and all system degrees-of-freedom (DOFs), are limited. In this study, robotic gait energetics is evaluated through a DOF-based instrumentation system designed for instantaneous evaluation of bidirectional current and applied voltage at each joint actuator. The instrumentation system includes a dual-module arrangement of buffers and attenuators, and accommodates and synchronizes the voltage and current measurements from multiple actuators. For illustrative purposes, this system is implemented at each DC servomotor in a biped robot, DARwIn-OP, to analyze the electrical EE rates for walking at various speeds. In addition, a DOF-based model of instantaneous human EE rate is employed to enable quantitative characterization of robotic walking EE relative to that of humans. The robot's instantaneous lower-body EE rates are consistent with its periodic walking cycle, and their relative trends between single and double support phases are analogous to those of humans. The robotic cost of transport (COT) curve as a function of normalized speed is also consistent with the human COT in terms of its convexity. Conversely, the contrasting distributions of EE throughout the robot and human DOFs and the robotic COT curve's considerably larger magnitudes, smaller speed ranges, and higher sensitivity to speed illustrate the energetic consequences of stable but inefficient static walking in the biped robot relative to the more efficient dynamic walking of humans. These energetic characteristics enable the identification of the joints and gait cycle phases associated with inefficiency in biped robotic gait, and reflect the noticeable differences in the system parameters (rigid and flat versus segmented feet) and gait control strategies (bent versus straight knees, instants of peak ankle actuator torques, static versus dynamic balance stability). The proposed general instrumentation provides a quantitative approach to benchmarking human gait as well as general guidelines for the development of energy-efficient walking robots.

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