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.

Intelligent Operation Control for the Fused Magnesia Production

2011 ◽  
Vol 391-392 ◽  
pp. 1450-1454
Author(s):  
Yong Jian Wu ◽  
Ping Zhou ◽  
Pin Shang ◽  
Tian You Chai
Keyword(s):  
Control System ◽  
Intelligent Control ◽  
Control Strategy ◽  
Control Method ◽  
Level Control ◽  
Loop Control ◽  
Intelligent Control System ◽  
Technical Requirements ◽  
Operation Control ◽  
Lower Loop

An electro-fused magnesia furnace (EFMF) is used to produce electro-fused magnesia. Due to the complex dynamic characteristics of the EFMF production process, it is difficult to achieve the satisfactory control performances only by the independent conventional control method. As a result, the lower loop control with manual operations is still widely used in practice. However, the manual operation cannot ensure that the actual production qualities and the energy consumption of unit production meet the technical requirements all the time. In this paper, an intelligent operation control strategy is developed for the EFMF to automatically adjust the setpoints of the lower level control system. Based on the proposed intelligent control strategy, an intelligent control system for the EFMF is built and implemented on site. Industrial application has demonstrated that the intelligent control system can achieve reliable, accurate and timely control performances.

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.

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 Motion Control of Four-Wheel Independently Actuated Electric Ground Vehicles considering Tire Force Saturations

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Rongrong Wang ◽  
Hamid Reza Karimi ◽  
Nan Chen ◽  
Guodong Yin ◽  
Jinxiang Wang
Keyword(s):  
Control Method ◽  
Stability Control ◽  
Ground Vehicles ◽  
Level Control ◽  
Control Approach ◽  
Tire Force ◽  
Vehicle Stability Control ◽  
Tire Forces ◽  
High Level ◽  
Allocation Algorithms

A vehicle stability control approach for four-wheel independently actuated (FWIA) electric vehicles is presented. The proposed control method consists of a higher-level controller and a lower-level controller. An adaptive control-based higher-level controller is designed to yield the vehicle virtual control efforts to track the desired vehicle motions due to the possible modeling inaccuracies and parametric uncertainties. The lower-level controller considering tire force saturation is given to allocate the required control efforts to the four in-wheel motors for providing the desired tire forces. An analytic method is given to distribute the high-level control efforts, without using the numerical-optimization-based control allocation algorithms. Simulations based on a high-fidelity, CarSim, and full-vehicle model show the effectiveness of the control approach.

Human-like control strategy of a bipedal walking model

Robotica ◽  
2008 ◽  
Vol 26 (3) ◽  
pp. 295-306 ◽  
Author(s):  
Andrej Olenšek ◽  
Zlatko Matjačić
Keyword(s):  
Control Strategy ◽  
Control Level ◽  
Bipedal Walking ◽  
Gait Velocity ◽  
Level Control ◽  
Power Absorption ◽  
Gait Parameters ◽  
Walking Mechanism ◽  
Map Analysis ◽  
Step Control

SUMMARYThis paper presents a two-level control strategy for bipedal walking mechanism that accounts for implicit control of push-off on the between-step control level and tracking of imposed holonomic constraints on kinematic variables via feedback control on within-step control level. The proposed control strategy was tested in a biologically inspired model with minimal set of segments that allows evolution of human-like push-off and power absorption. We investigated controller's stability characteristics by using Poincaré return map analysis in eight simulation cases and further evaluated the performance of the biped walking model in terms of how variations in torso position and gait velocity relate to push-off and power absorption. The results show that the proposed control strategy, with the same set of controller's gains, enables stable walking in a variety of chosen gait parameters and can accommodate to various trunk inclinations and gait velocities in a similar way as seen in humans.

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.

Single-Phase Independent Droop Control Strategy in Low-Voltage Microgrid

2015 ◽  
Vol 733 ◽  
pp. 684-690 ◽  
Author(s):  
Zhong Lin Zhang ◽  
Tao Wang
Keyword(s):  
Control Strategy ◽  
Single Phase ◽  
Control Method ◽  
Low Voltage ◽  
Frequency Stability ◽  
Droop Control ◽  
Level Control ◽  
Independent Control ◽  
Three Phase ◽  
Micro Grid

In the three-phase four-wire low-voltage micro grid, three-phase imbalance usually happens because of a large number of single-phase loads. In this situation, the traditional control method cannot effectively control the voltage and frequency stability when the low-voltage micro grid operates in the island mode. According to the characteristics of the three-phase four-wire low-voltage micro grid, this paper designs a single-phase independent control based on the droop control. This paper firstly uses the improved droop control considering that the impedance characteristic of the low voltage micro gird is mainly resistance, and also designs single-phase independent control to ensure the control system have the ability to run under the unbalanced loads. Then this paper designs a two-level control strategy to control the voltage and frequency in the micro grid during the island operation. Finally, a simulation analysis based on the proposed method is used to prove the effectiveness. A micro grid is set up on PSCAD, and verifies the effectiveness of the single-phase control strategy based on the improved droop control. The proposed method can also realize the requirement of the voltage and frequency stability during the island operation. At the same time, the control method proposed in this paper can achieve the control objective under the condition of unbalanced three-phase.

scholarly journals Research on Coordinated Robotic Motion Control Based on Fuzzy Decoupling Method in Fluidic Environments

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Wei Zhang ◽  
Haitian Chen ◽  
Tao Chen ◽  
Zheping Yan ◽  
Hongliang Ren
Keyword(s):  
Motion Control ◽  
Control Method ◽  
Fuzzy Theory ◽  
Autonomous Underwater Vehicles ◽  
Strong Nonlinearity ◽  
Water Tank ◽  
Level Control ◽  
Decoupling Method ◽  
Heading Control ◽  
High Level

The underwater recovery of autonomous underwater vehicles (AUV) is a process of 6-DOF motion control, which is related to characteristics with strong nonlinearity and coupling. In the recovery mission, the vehicle requires high level control accuracy. Considering an AUV called BSAV, this paper established a kinetic model to describe the motion of AUV in the horizontal plane, which consisted of nonlinear equations. On the basis of this model, the main coupling variables were analyzed during recovery. Aiming at the strong coupling problem between the heading control and sway motion, we designed a decoupling compensator based on the fuzzy theory and the decoupling theory. We analyzed to the rules of fuzzy compensation, the input and output membership functions of fuzzy compensator, through compose operation and clear operation of fuzzy reasoning, and obtained decoupling compensation quantity. Simulation results show that the fuzzy decoupling controller effectively reduces the overshoot of the system, and improves the control precision. Through the water tank experiments and analysis of experimental data, the effectiveness and feasibility of AUV recovery movement coordinated control based on fuzzy decoupling method are validated successful, and show that the fuzzy decoupling control method has a high practical value in the recovery mission.

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