A Balance Control Method of a Walking Biped Robot under a Continuous External Force

2013 ◽  
pp. 237-245 ◽  
Author(s):  
Yeoun-Jae Kim ◽  
Joon-Yong Lee ◽  
Ju-Jang Lee
Keyword(s):  
External Force ◽  
Control Method ◽  
Balance Control ◽  
Biped Robot

Step-exchange strategy for balance control of a walking biped under a lateral impact

2014 ◽  
Vol 41 (5) ◽  
pp. 456-464
Author(s):  
Yeoun-Jae Kim ◽  
Joon-Yong Lee ◽  
Ju-Jang Lee
Keyword(s):  
External Force ◽  
Balance Control ◽  
Biped Robot ◽  
Conservation Equation ◽  
Hill Climbing ◽  
Lateral Impact ◽  
Content Type ◽  
Double Support ◽  
The Right ◽  
The Impact

Purpose – This paper aims to present a step-exchange strategy for balance control of a walking biped robot when a lateral impact acts suddenly. A step-out strategy has been recently proposed for balance control when an unknown lateral force acts to a biped robot during walking. This step-out strategy causes a robot to absorb the impact kinetic energy and efficiently maintain balance without falling down. Nevertheless, it was found that the previous strategies have drawbacks that the two foots should always be on the ground (double-support mode) after being balanced and the authors think it is difficult to continue walking after being balanced. Unlike the existing balance strategies, the proposed step-exchange strategy is to not only maintain balance but also to lift one leg in the air (single-support mode) after being balanced so that it is easy for a biped robot to keep walking after being balanced. Design/methodology/approach – In the proposed step-exchange strategy, forward Newton–Euler equation, angular momentum and energy conservation equation were derived. Hill-climbing algorithm is utilized for numerically finding a solution. To verify the proposed strategy, a biped robot by Open Dynamics Engine was stimulated, and experiments with a real biped robot (LRH-1) were also conducted. Findings – The proposed step-exchange strategy enables a walking biped robot under a lateral impact to keep balance and to keep a single-support mode after exchanging a leg. It is helpful for a biped robot to continue walking without any stop. It is found that the proposed step-exchange strategy can be applicable for maintaining balance even if a biped robot is moving. Even though this proposal seems immature yet, it is the first attempt to exchange the supporting foot itself. This strategy is very straightforward and intuitive because humans are also likely to exchange their supporting foot onto the opposite side when an unexpected force is acting. Research limitations/implications – The proposed step-exchange strategy described in this paper can be applicable in the situation when the external force is applied in the +Y direction, the left leg is the swing leg and the right leg is the stance leg, or it can also be applicable in the situation when the external force is applied in −Y direction, the right leg is the swing leg and the left leg is the stance leg (Figure 2 for ±Y force direction). If an impact force acts to the side of the swing leg, the other step-exchange strategy is needed. The authors are studying this issue as a future work. Originality/value – The authors have originated the proposed step-exchange strategy for balance control of a walking biped robot under lateral impact. The strategy is genuine and superior in comparison with the state-of-the-art strategy because not only can a biped robot be balanced but it can also easily continue walking by using the step-exchange strategy.

A force-resisting balance control strategy for a walking biped robot under an unknown, continuous force

Robotica ◽  
2014 ◽  
Vol 34 (7) ◽  
pp. 1495-1516
Author(s):  
Yeoun-Jae Kim ◽  
Joon-Yong Lee ◽  
Ju-Jang Lee
Keyword(s):  
External Force ◽  
Control Strategy ◽  
Balance Control ◽  
Biped Robot ◽  
Second Step ◽  
Double Support ◽  
Zero Moment ◽  
External Forces ◽  
Single Support Phase ◽  
Support Phase

SUMMARYIn this paper, we propose and examine a force-resisting balance control strategy for a walking biped robot under the application of a sudden unknown, continuous force. We assume that the external force is acting on the pelvis of a walking biped robot and that the external force in the z-direction is negligible compared to the external forces in the x- and y-directions. The main control strategy involves moving the zero moment point (ZMP) of the walking robot to the center of the robot's sole resisting the externally applied force. This strategy is divided into three steps. The first step is to detect an abnormal situation in which an unknown continuous force is applied by examining the position of the ZMP. The second step is to move the ZMP of the robot to the center of the sole resisting the external force. The third step is to have the biped robot convert from single support phase (SSP) to double support phase (DSP) for an increased force-resisting capability. Computer simulations and experiments of the proposed methods are performed to benchmark the suggested control strategy.

SVR CONTROLLER FOR A BIPED ROBOT IN THE SAGITTAL PLANE WITH HUMAN-BASED ZMP TRAJECTORY REFERENCE AND GAIT

2012 ◽  
Vol 09 (03) ◽  
pp. 1250018 ◽  
Author(s):  
JOÃO P. FERREIRA ◽  
MANUEL CRISÓSTOMO ◽  
A. PAULO COIMBRA
Keyword(s):  
Control Method ◽  
Sagittal Plane ◽  
Balance Control ◽  
Biped Robot ◽  
Control Technique ◽  
Human Gait ◽  
Support Vector ◽  
Shift Parameter ◽  
Intelligent Computing ◽  
Swing Time

This paper introduces two new important issues to be considered in the design of the zero moment point (ZMP) trajectory of a biped robot. It was verified experimentally that in the human gait the ZMP trajectory moves along the foot in a way that it is shifted forward relative to its center. To take this into account a shift parameter is then proposed. It was also verified experimentally that in the human gait the ZMP trajectory amplitude depends on the swing time, reducing to zero for a static gait. It is then proposed a parameter to take into account this variation with the swing time of the gait. Six experiments were carried out for three different X ZMP trajectory references. In order to evaluate and compare the performance of the biped robot using the three X ZMP trajectory references two performance indexes are proposed. For the real-time balance control of this 8 link biped robot it was used an intelligent computing control technique, the Support Vector Regression (SVR). The control method uses the ZMP error and its variation as inputs and the output is the correction of the robot's ankle and torso angles, necessary for the sagittal balance of the biped robot.

scholarly journals Real-Time FPGA-Based Balance Control Method for a Humanoid Robot Pushed by External Forces

2020 ◽  
Vol 10 (8) ◽  
pp. 2699
Author(s):  
Chih-Cheng Liu ◽  
Tsu-Tian Lee ◽  
Sheng-Ru Xiao ◽  
Yi-Chung Lin ◽  
Yi-Yang Lin ◽  
...  
Keyword(s):  
Real Time ◽  
External Force ◽  
Inclination Angle ◽  
Humanoid Robot ◽  
Control Method ◽  
Balance Control ◽  
Central Pattern Generators ◽  
Field Programmable ◽  
Fpga Chip ◽  
External Forces

In this paper, a real-time balance control method is designed and implemented on a field-programmable gate array (FPGA) chip for a small-sized humanoid robot. In the proposed balance control structure, there are four modules: (1) external force detection, (2) push recovery balance control, (3) trajectory planning, and (4) inverse kinematics. The proposed method is implemented on the FPGA chip so that it can quickly respond to keep the small-sized humanoid robot balanced when it is pushed by external forces. A gyroscope and an accelerometer are used to detect the inclination angle of the robot. When the robot is under the action of an external force, an excessively large inclination angle may be produced, causing it to lose its balance. A linear inverted pendulum with a flywheel model is employed to estimate a capture point where the robot should step to maintain its balance. In addition, the central pattern generators (CPGs) with a sinusoidal function are adopted to plan the stepping trajectories. Some experimental results are presented to illustrate that the proposed real-time balance control method can effectively enable the robot to keep its balance to avoid falling down.

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.

A Torso-Moving Balance Control Strategy for a Walking Biped Robot Subject to External Continuous Forces

2015 ◽  
Vol 12 (01) ◽  
pp. 1550003 ◽  
Author(s):  
Yeoun-Jae Kim ◽  
Joon-Yong Lee ◽  
Ju-Jang Lee
Keyword(s):  
External Force ◽  
Control Strategy ◽  
Balance Control ◽  
Pressure Sensors ◽  
Stable State ◽  
Biped Robot ◽  
Zero Moment Point ◽  
Preliminary Step ◽  
Zero Moment ◽  
Support Phase

Moving the torso laterally in a walking biped robot can be mechanically more torque-efficient than not moving the torso according to recent research. Motivated by this observation, a torque-efficient torso-moving balance control strategy of a walking biped robot subject to a persistent continuous external force is suggested and verified in this paper. The torso-moving balance control strategy consists of a preliminary step and two additional steps. The preliminary step (disturbance detection) is to perceive the application of an external force by a safety boundary of zero moment point, detected approximately from cheap pressure sensors. Step 1 utilizes center of gravity (COG) Jacobian, centroidal momentum matrix and linear quadratic problem calculation to shift the zero moment point to the center of the support polygon. Step 2 makes use of H∞ controllers for a more stable state shift from single support phase to double support phase. By comparing the suggested torso moving control strategy to the original control strategy that we suggested previously, a mixed balance control strategy is suggested. The strategy is verified through numerical simulation results.

A Balance Control Strategy for a Walking Biped Robot under Unknown Lateral External Force using a Genetic Algorithm

2015 ◽  
Vol 12 (02) ◽  
pp. 1550021 ◽  
Author(s):  
Yeoun-Jae Kim ◽  
Joon-Yong Lee ◽  
Ju-Jang Lee
Keyword(s):  
Genetic Algorithm ◽  
External Force ◽  
Control Strategy ◽  
Degrees Of Freedom ◽  
Sliding Mode ◽  
Balance Control ◽  
Phase 1 ◽  
Biped Robot ◽  
Double Support ◽  
Support Phase

In this paper, we propose a force-resisting balance control strategy for a walking biped robot subject to an unknown continuous external force. We assume that the biped robot has 12 degrees of freedom (DOFs) with position-controlled joint motors, and that the unknown continuous external force is applied to the pelvis of the biped robot in the single support phase (SSP) walking gait. The suggested balance control strategy has three phases. Phase 1 is to recognize the application of an unknown external force using only zero moment point (ZMP) sensors. Phase 2 is to control the joint motors according to a method that uses a genetic algorithm and the linear interpolation technique. Against an external continuous force, the robot retrieves the pre-calculated solutions and executes the desired torques with interpolation performed in real time. Phase 3 is to make the biped robot move from the SSP to the double support phase (DSP), rejecting external disturbances using the sliding mode controller. The strategy is verified by numerical simulations and experiments.

scholarly journals Realization of a Biped Robot Lower Limb Walking without Double Support Phase on Uneven Terrain

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Hai-yan Wang ◽  
Yi-bin Li
Keyword(s):  
Lower Limb ◽  
Control Method ◽  
Dynamic Equilibrium ◽  
Balance Control ◽  
Biped Robot ◽  
Pattern Generation ◽  
Control Methods ◽  
Double Support ◽  
Walking Control ◽  
Lateral Plane

Zero moment point (ZMP) is widely used in dynamical walking control of the biped robot, but it is hard to obtain the ZMP exactly. The paper describes a simple walking control method without using ZMP information directly. Firstly, the paper introduced a biped robot lower-limb prototype which is driven by linear hydraulic servocylinder. Then the paper simplifies the walking control in the lateral plane with a simple walking pattern generation method named “dynamic equilibrium method,” which is fit for active and underactuated biped robots. In the following section the paper provides the balance control methods without using ZMP information directly. Finally, simulation experiments with MD.DAMS and experiments in physical prototype are given. The experimental results confirm the effectiveness of the proposed control methods.

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