scholarly journals Understanding the stability of deep control policies for biped locomotion

2022 ◽  
Author(s):  
Hwangpil Park ◽  
Ri Yu ◽  
Yoonsang Lee ◽  
Kyungho Lee ◽  
Jehee Lee
Keyword(s):  
Biped Locomotion ◽  
Control Policies ◽  
The Stability

Control of a Dynamical Biped Locomotion System for Steady Walking

1986 ◽  
Vol 108 (2) ◽  
pp. 111-118 ◽  
Author(s):  
J. Furusho ◽  
M. Masubuchi
Keyword(s):  
High Speed ◽  
Hierarchical Control ◽  
Reference Signal ◽  
Biped Locomotion ◽  
Order Model ◽  
Reduced Order ◽  
Locomotion System ◽  
Local Controller ◽  
Local Feedback ◽  
The Stability

A dynamic biped locomotion robot which realizes high speed movement is presented. Its walking cycle is about 0.45 s, its speed is about 0.8m/s, and its appearance resembles a human walking. A hierarchical control structure is adopted at the lower level at which the local feedback is implemented. The reference signal to each local controller is supplied from its higher level. The stability of steady walking is examined by using the reduced order model which has been derived by the authors and it is assured by experiments.

On the Stability of Biped Locomotion

1970 ◽  
Vol BME-17 (1) ◽  
pp. 25-36 ◽  
Author(s):  
M. Vukobratovic ◽  
A. A. Frank ◽  
D. Juricic
Keyword(s):  
Biped Locomotion ◽  
The Stability

scholarly journals Distributed allocation of mobile sensing swarms in gyre flows

2013 ◽  
Vol 20 (5) ◽  
pp. 657-668 ◽  
Author(s):  
K. Mallory ◽  
M. A. Hsieh ◽  
E. Forgoston ◽  
I. B. Schwartz
Keyword(s):  
Distributed Control ◽  
Control Strategy ◽  
Hybrid Control ◽  
Mobile Sensing ◽  
Mobile Sensors ◽  
Control Policies ◽  
Actual Flow ◽  
The Stability ◽  
Geophysical Flow ◽  
Surrounding Fluid

Abstract. We address the synthesis of distributed control policies to enable a swarm of homogeneous mobile sensors to maintain a desired spatial distribution in a geophysical flow environment, or workspace. In this article, we assume the mobile sensors (or robots) have a "map" of the environment denoting the locations of the Lagrangian coherent structures or LCS boundaries. Using this information, we design agent-level hybrid control policies that leverage the surrounding fluid dynamics and inherent environmental noise to enable the team to maintain a desired distribution in the workspace. We discuss the stability properties of the ensemble dynamics of the distributed control policies. Since realistic quasi-geostrophic ocean models predict double-gyre flow solutions, we use a wind-driven multi-gyre flow model to verify the feasibility of the proposed distributed control strategy and compare the proposed control strategy with a baseline deterministic allocation strategy. Lastly, we validate the control strategy using actual flow data obtained by our coherent structure experimental testbed.

Applications of Borovkov's Renovation Theory to Non-Stationary Stochastic Recursive Sequences and Their Control

1997 ◽  
Vol 29 (02) ◽  
pp. 388-413 ◽  
Author(s):  
Eitan Altman ◽  
Arie Hordijk
Keyword(s):  
Stochastic Processes ◽  
Finite Time ◽  
Probability Space ◽  
Initial State ◽  
Control Policies ◽  
Recursive Sequences ◽  
Stationary Stochastic Processes ◽  
Initial States ◽  
Natural Criterion ◽  
The Stability

We investigate in this paper the stability of non-stationary stochastic processes, arising typically in applications of control. The setting is known as stochastic recursive sequences, which allows us to construct on one probability space stochastic processes that correspond to different initial states and even different control policies. It does not require any Markovian assumptions. A natural criterion for stability for such processes is that the influence of the initial state disappears after some finite time; in other words, starting from different initial states, the process will couple after some finite time to the same limiting (not necessarily stationary nor ergodic) stochastic process. We investigate this as well as other types of coupling, and present conditions for them to occur uniformly in some class of control policies. We then use the coupling results to establish new theoretical aspects in the theory of non-Markovian control.

Stability of biped robotic walking with frictional constraints

Robotica ◽  
2012 ◽  
Vol 31 (4) ◽  
pp. 573-588 ◽  
Author(s):  
Xuefeng Zhou ◽  
Yisheng Guan ◽  
Li Jiang ◽  
Haifei Zhu ◽  
Chuanwu Cai ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Closed Form ◽  
Contact Area ◽  
Frictional Force ◽  
Biped Robot ◽  
Biped Locomotion ◽  
Stability Criteria ◽  
Closed Form Solutions ◽  
Zero Moment ◽  
The Stability

SUMMARYTipping-over and slipping, which are related to zero moment point (ZMP) and frictional constraint respectively, are the two most common instability forms of biped robotic walking. Conventional criterion of stability is not sufficient in some cases, since it neglects frictional constraint or considers translational friction only. The goal of this paper is to fully address frictional constraints in biped walking and develop corresponding stability criteria. Frictional constraints for biped locomotion are first analyzed and then the method to obtain the closed-form solutions of the frictional force and moment for a biped robot with rectangular and circular feet is presented. The maximum frictional force and moment are calculated in the case of ZMP at the center of contact area. Experiments with a 6-degree of freedom active walking biped robot are conducted to verify the effectiveness of the stability analysis.

Applications of Borovkov's Renovation Theory to Non-Stationary Stochastic Recursive Sequences and Their Control

1997 ◽  
Vol 29 (2) ◽  
pp. 388-413 ◽  
Author(s):  
Eitan Altman ◽  
Arie Hordijk
Keyword(s):  
Stochastic Processes ◽  
Finite Time ◽  
Probability Space ◽  
Initial State ◽  
Control Policies ◽  
Recursive Sequences ◽  
Stationary Stochastic Processes ◽  
Initial States ◽  
Natural Criterion ◽  
The Stability

We investigate in this paper the stability of non-stationary stochastic processes, arising typically in applications of control. The setting is known as stochastic recursive sequences, which allows us to construct on one probability space stochastic processes that correspond to different initial states and even different control policies. It does not require any Markovian assumptions. A natural criterion for stability for such processes is that the influence of the initial state disappears after some finite time; in other words, starting from different initial states, the process will couple after some finite time to the same limiting (not necessarily stationary nor ergodic) stochastic process. We investigate this as well as other types of coupling, and present conditions for them to occur uniformly in some class of control policies. We then use the coupling results to establish new theoretical aspects in the theory of non-Markovian control.

Synthesis and analysis of distributed ensemble control strategies for allocation to multiple tasks

Robotica ◽  
2013 ◽  
Vol 32 (2) ◽  
pp. 177-192 ◽  
Author(s):  
T. William Mather ◽  
M. Ani Hsieh
Keyword(s):  
Control Strategies ◽  
Feedback Strategy ◽  
Control Policies ◽  
Ensemble Control ◽  
Communication Links ◽  
Individual Task ◽  
Distributed Implementation ◽  
The Stability ◽  
Actuation Failures ◽  
Navigation Errors

SUMMARYWe present the synthesis and analysis of distributed ensemble control policies to enable a team of robots to control their distribution across a collection of tasks. We assume that individual robot controllers are modeled as a sequential composition of individual task controllers. A macroscopic description of the team dynamics is then used to synthesize ensemble feedback control strategies that maintain the desired distribution of robots across the tasks. We present a distributed implementation of the ensemble feedback strategy that can be implemented with minimal communication requirements. Different from existing strategies, the approach results in individual robot control policies that maintain the desired mean and the variance of the robot populations at each task. We present the stability properties of the ensemble feedback strategy, verify the feasibility of the distributed ensemble controller through high-fidelity simulations, and examine the robustness of the strategy to sensing and/or actuation failures. Specifically, we consider the case when robots are subject to estimation and navigation errors resulting from lossy inter-agent wireless communication links and localization errors.

Measurement of robustness for biped locomotion using a linearized Poincaré map

Robotica ◽  
1996 ◽  
Vol 14 (3) ◽  
pp. 253-259 ◽  
Author(s):  
M. -Y. Cheng ◽  
C. -S. Lin
Keyword(s):  
Periodic Motion ◽  
Poincaré Map ◽  
Computational Method ◽  
Biped Locomotion ◽  
Poincare Map ◽  
The Past ◽  
Highly Nonlinear ◽  
The Stability ◽  
Linearized Model ◽  
Continuous Time System

SUMMARYMany studies on control of dynamic biped walking have been done in the past two decades. While the biped dynamics is highly nonlinear, the stability analysis, if done, is usually based on a linearized model. The validity of the linearized model may become questionable if the walking involves states that are too far away from the operating point. In this paper, an approach for evaluating the robustness based on the linearized Poincare map is suggested and examined. The Poincare map is a useful tool to investigate the periodic motion of a dynamic system. Using the Poincare“ map, one can study an associated discrete time map instead of studying the continuous time system directly. Investigation of stability of a periodic motion can be reduced to the study of the stability of a fixed point of the Poincaré map. The computational method that results in a measurement for evaluating the robustness of biped locomotion is developed. Our simulation study has verified that the suggested measurement is a good indicator.

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