Feedforward control for underactuated bipedal walking on compliant continuous steps with varying height

2020 ◽  
Vol 42 (13) ◽  
pp. 2410-2422
Author(s):  
Daojin Yao ◽  
Yao Wu ◽  
Jie He ◽  
Jiangchen Zhou ◽  
Xiaohui Xiao
Keyword(s):  
Control Strategy ◽  
Feedforward Control ◽  
Ground Deformation ◽  
Center Of Mass ◽  
Slope Angle ◽  
Biped Robot ◽  
Step Length ◽  
Bipedal Walking ◽  
Zero Dynamic ◽  
Motion State

This study develops a feedforward control strategy based on the motion state of center-of-mass (CoM) of a robot for underactuated biped robot stable walking on compliant continuous steps with a known varying height. First, considering ground deformation, a compliant contact model is employed to characterize foot-ground interaction, and a robot–step coupling dynamic model of sagittal and lateral planes are established through decoupling modelling. Second, based on the gait characteristics of human variable-step walking, a feedforward control strategy based on the motion state of CoM is proposed. Varying height step is equivalent to varying slope, an equivalent slope angle and a desired step length can be calculated for each step according to their height. Underactuated bipedal walking control is decoupled into sagittal and lateral master-slave control. The velocity of robot CoM is considered as a system output. It is controlled through the displacement of CoM in a single walking cycle, and thus walking is stabilized. By the proposed method, the walking system is modelled as a polynomial with definite number of degrees and the controlled input is derived through a simple inverse operation on it. Its effectiveness is validated through simulations in an environment with a step varying height of less than 0.032 m. Simulation results show that the proposed method can improve the tracking performance of robot CoM velocity on varying height steps, as compared to a hybrid zero dynamic (HZD)-based controller.

scholarly journals Feedforward control for underactuated bipedal walking on varying compliant slopes

2018 ◽  
Vol 42 (2) ◽  
pp. 90-104 ◽  
Author(s):  
Daojin Yao ◽  
Siyu He ◽  
Yao Wu ◽  
Xiaohui Xiao ◽  
Yang Wang
Keyword(s):  
Control Strategy ◽  
Walking Speed ◽  
Feedforward Control ◽  
Center Of Mass ◽  
Kinematic Chain ◽  
Bipedal Walking ◽  
Natural Environments ◽  
Gait Characteristics ◽  
Motion State ◽  
Definition Of

In this paper, a feedforward control strategy is proposed to enable stable underactuated bipedal walking on varying compliant slopes with a known inclination angle, to handle the variation in natural environments. First, spring–damper units were employed in the horizontal and vertical directions to model the compliant ground, which is described as a rigid kinematic chain coupled with a spring–damper system. Second, a new definition of stable underactuated bipedal walking, based on walking speed, was proposed. Stable walking is achieved by adjusting the velocity of the biped’s center of mass (CoM) within limits that have been proven to allow at least one walking cycle. The proposed feedforward control strategy was based on the motion state of a robot’s CoM, using the new definition of stability and inspired by the gait characteristics of human walking on varying slopes. Speed control is realized by adjusting the displacement of the CoM with the change of slope to achieve stable walking. Finally, simulations were conducted to validate the proposed controller. The simulation results demonstrate that stable walking is achieved on varying compliant slopes by implementing the proposed control strategy.

scholarly journals A Stabilization Method Based on an Adaptive Feedforward Controller for the Underactuated Bipedal Walking with Variable Step-Length on Compliant Discontinuous Ground

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Yang Wang ◽  
Daojin Yao ◽  
Jie He ◽  
Xiaohui Xiao
Keyword(s):  
Control Strategy ◽  
Control Method ◽  
Ground Surface ◽  
Step Length ◽  
Bipedal Walking ◽  
Level Control ◽  
Stabilization Method ◽  
Feedforward Controller ◽  
High Level ◽  
Adaptive Feedforward

Both compliance and discontinuity are the common characteristics of the real ground surface. This paper proposes a stabilization method for the underactuated bipedal locomotion on the discontinuous compliant ground. Unlike a totally new control method, the method is actually a high-level control strategy developed based on an existing low-level controller meant for the continuous compliant ground. As a result, although the ground environment is more complex, the calculation cost for the robot walking control system is not increased. With the high-level control strategy, the robot is able to adjust its step-length and velocity simultaneously to stride over the discontinuous areas on the compliant ground surface. The effectiveness of the developed method is validated with a numerical simulation and a physical experiment.

SLIP-Based Control of Bipedal Walking Based on Two-Level Control Strategy

Robotica ◽  
2019 ◽  
Vol 38 (8) ◽  
pp. 1434-1449
Author(s):  
Behnam Dadashzadeh ◽  
C.J.B. Macnab
Keyword(s):  
Control Strategy ◽  
Inverted Pendulum ◽  
Biped Robot ◽  
Bipedal Walking ◽  
Level Control ◽  
Walking Motion ◽  
Reaction Forces ◽  
Upper Level ◽  
Torso Angle ◽  
Stable Control

SUMMARYIn this research, we propose a two-level control strategy for simultaneous gait generation and stable control of planar walking of the Assume The Robot Is A Sphere (ATRIAS) biped robot with unlocked torso, utilizing active spring-loaded inverted pendulum (ASLIP) as reference models. The upper level consists of an energy-regulating control calculated using the ASLIP model, producing reference ground reaction forces (GRFs) for the desired gait. In the lower level controller, PID force controllers for the motors ensure tracking of the reference GRFs for ATRIAS direct dynamics. Meanwhile, ATRIAS torso angle is controlled stably to make it able to follow a point mass template model. Advantages of the proposed control strategy include simplicity and efficiency. Simulation results using ATRIAS’s complete dynamic model show that the proposed two-level controller can reject initial condition disturbances while generating stable and steady walking motion.

A Position-Domain Adaptive Control Method for Underactuated Bipedal Walking on a Compliant Ground

2019 ◽  
Vol 16 (02) ◽  
pp. 1950010
Author(s):  
Yang Wang ◽  
Jiatao Ding ◽  
Xiaohui Xiao
Keyword(s):  
Adaptive Control ◽  
Vertical Velocity ◽  
Control Strategy ◽  
Initial Velocity ◽  
Feedback Linearization ◽  
Control Method ◽  
Center Of Mass ◽  
Bipedal Walking ◽  
Vertical Position ◽  
Impact Phase

Motivated by the potential use of humanoid-robot in real environment, a position-domain adaptive control strategy is developed to stabilize the underactuated bipedal walking on a compliant ground. First, the robot-ground system is modeled as a rigid kinematical chain coupled with a spring-damper system. Then by observing the simulation result of walking on compliant ground, we find the improvement of walking stability can be realized by controlling the initial velocity of robot’s center-of-mass (COM) of each walking cycle. In consideration of the highly-complicated impact of real road surface on direct velocity control, through the analysis on the relationship between the robot’s COM velocity and its foot vertical velocity, the robot’s state is parameterized by the normalized relative vertical position between both the feet, and the control of robot’s COM initial velocity of current cycle is realized by controlling the relative vertical velocity between the robot’s two feet during the previous impact phase. To realize it, an adaptive feedback linearization control strategy is developed in position-domain. Finally, the availability and adaptability of this method are validated through simulations: Specific to three initial gaits, on four compliant ground with different damping parameters, the underactuated bipedal walking is stabilized and the performance is improved.

scholarly journals Optimized stable gait planning of biped robot using multi-objective evolutionary JAYA algorithm

2020 ◽  
Vol 17 (6) ◽  
pp. 172988142097634
Author(s):  
Huan Tran Thien ◽  
Cao Van Kien ◽  
Ho Pham Huy Anh
Keyword(s):  
Inverse Kinematics ◽  
Biped Robot ◽  
Step Length ◽  
Jaya Algorithm ◽  
Kinetic Chain ◽  
Biped Walking ◽  
Gait Planning ◽  
Multi Objective ◽  
Simulation And Experiment ◽  
Stable Gait

This article proposes a new stable biped walking pattern generator with preset step-length value, optimized by multi-objective JAYA algorithm. The biped robot is modeled as a kinetic chain of 11 links connected by 10 joints. The inverse kinematics of the biped is applied to derive the specified biped hip and feet positions. The two objectives related to the biped walking stability and the biped to follow the preset step-length magnitude have been fully investigated and Pareto optimal front of solutions has been acquired. To demonstrate the effectiveness and superiority of proposed multi-objective JAYA, the results are compared to those of MO-PSO and MO-NSGA-2 optimization approaches. The simulation and experiment results investigated over the real small-scaled biped HUBOT-4 assert that the multi-objective JAYA technique ensures an outperforming effective and stable gait planning and walking for biped with accurate preset step-length value.

scholarly journals A biomechanical study of load carriage by two paired subjects in response to increased load mass

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillaume Fumery ◽  
Nicolas A. Turpin ◽  
Laetitia Claverie ◽  
Vincent Fourcassié ◽  
Pierre Moretto
Keyword(s):  
Recovery Rate ◽  
Energy Recovery ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Step Length ◽  
Biomechanical Study ◽  
Load Carriage ◽  
Joint Torque ◽  
Total Mechanical Energy ◽  
Load Mass

AbstractThe biomechanics of load carriage has been studied extensively with regards to single individuals, yet not so much with regards to collective transport. We investigated the biomechanics of walking in 10 paired individuals carrying a load that represented 20%, 30%, or 40% of the aggregated body-masses. We computed the energy recovery rate at the center of mass of the system consisting of the two individuals plus the carried load in order to test to what extent the pendulum-like behavior and the economy of the gait were affected. Joint torque was also computed to investigate the intra- and inter-subject strategies occurring in response to this. The ability of the subjects to move the whole system like a pendulum appeared rendered obvious through shortened step length and lowered vertical displacements at the center of mass of the system, while energy recovery rate and total mechanical energy remained constant. In parallel, an asymmetry of joint moment vertical amplitude and coupling among individuals in all pairs suggested the emergence of a leader/follower schema. Beyond the 30% threshold of increased load mass, the constraints at the joint level were balanced among individuals leading to a degraded pendulum-like behavior.

A Data-Driven Iterative Decoupling Feedforward Control Strategy With Application to an Ultraprecision Motion Stage

2015 ◽  
Vol 62 (1) ◽  
pp. 620-627 ◽  
Author(s):  
Yi Jiang ◽  
Yu Zhu ◽  
Kaiming Yang ◽  
Chuxiong Hu ◽  
Dongdong Yu
Keyword(s):  
Control Strategy ◽  
Feedforward Control ◽  
Data Driven ◽  
Motion Stage

scholarly journals Analysis of Platform Leveling Systems for Tracked Feller-Buncher Machines

Inventions ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 96
Author(s):  
Andronov Alexandr ◽  
Bacherikov Ivan ◽  
Zverev Igor
Keyword(s):  
Mathematical Model ◽  
Center Of Mass ◽  
Slope Angle ◽  
Hydraulic Cylinder ◽  
Second Stage ◽  
Modeling Methods ◽  
The Third ◽  
Support Reaction ◽  
Third Stage ◽  
The Stability

The study was devoted to the analysis of feller buncher platform leveling systems. The widespread use of these systems in the design of modern feller-buncher machines makes the study relevant to assess operational efficiency. The analysis was conducted in five stages using analytical and stochastic mathematical modeling methods. In the first stage, the existing layouts of alignment systems were analyzed from the position of force on the hydraulic cylinder rods of the platform tilt drive. The three-cylinder layout scheme, where the force on the hydraulic cylinder rod was 50…60% less than that on the two-cylinder layout, appeared to be the most expedient. In the second stage, a mathematical model for determining changes in the position of the center of mass of the feller-buncher depending on the inclination angle of the platform was derived. In the third stage, a mathematical model was derived for determining the limiting angle of slope of the terrain when the feller buncher moved up the slope. For this purpose, two calculation schemes were considered when the machine moved up the slope without and with a tilted platform. Zero support reaction on the front roller was taken as the stability criterion. In the fourth stage, a mathematical model for determining the limiting angle of slope of the terrain during the roll of the feller-buncher machine was obtained. In the fifth stage, the efficiency of the application of leveling systems was evaluated. A graph of the dependence of changes in the terrain slope angle on the platform slope angle was plotted, and a regression dependence for an approximate estimate was obtained. A regression analysis was also carried out, and dependencies were obtained to determine the weight of a feller-buncher with a leveling system and the added pressure on the ground caused by the increase in the weight of the base machine. The analysis of platform leveling systems showed the effectiveness of their application in the designs of feller-buncher machines, as it allows the machines to work on slopes with an inclination of 50…60% more than without them.

Improving Active Output Capacity of Large-Scale Wind Farm by Installation STATCOM

2012 ◽  
Vol 588-589 ◽  
pp. 574-577 ◽  
Author(s):  
Yan Juan Wu ◽  
Lin Chuan Li
Keyword(s):  
Control Strategy ◽  
Large Scale ◽  
Wind Farm ◽  
Transient Stability ◽  
Reactive Power ◽  
Feedforward Control ◽  
Wind Farms ◽  
Active Power ◽  
Utilization Efficiency ◽  
Grid Voltage

Some faults will result wind turbine generators off-grid due to low grid voltage , furthermore, large-scale wind farms tripping can result in severe system oscillation and aggravate system transient instability . In view of this, static compensator (STATCOM) is installed in the grid containing large-scale wind farm. A voltage feedforward control strategy is proposed to adjust the reactive power of STATCOM compensation and ensure that the grid voltage is quickly restored to a safe range. The mathematical model of the doubly-fed induction wind generator (DFIG) is proposed. The control strategy of DFIG uses PI control for rotor angular velocity and active power. 4-machine system simulation results show that the STATCOM reactive power compensation significantly improve output active power of large-scale wind farm satisfying transient stability, reduce the probability of the tripping, and improve the utilization efficiency of wind farms.

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