scholarly journals Capture Point-Based Controller Using Real-Time Zero Moment Point Manipulation for Stable Bipedal Walking in Human Environment

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3407 ◽  
Author(s):  
Hong
Keyword(s):  
Real Time ◽  
Bipedal Walking ◽  
Reference Trajectory ◽  
Zero Moment Point ◽  
Time Zero ◽  
Tracking Controller ◽  
Zero Moment ◽  
Single Support Phase ◽  
Capture Point ◽  
Support Phase

For collaboration of humans and bipedal robots in human environments, this paper proposes a stability control method for dynamically modifiable bipedal walking using a capture point (CP) tracking controller. A reasonable reference CP trajectory for the CP tracking control is generated using the real-time zero moment point (ZMP) manipulation without information on future footstep commands. This trajectory can be modified at any time during the single support phase according to a given footstep command. Accordingly, this makes it possible for the robot to walk stably with dynamically modifiable walking patterns, including sudden changes in navigational commands during the single support phase. A reference CP trajectory during the double support phase is also generated for continuity. The CP of the robot is controlled to track the reference trajectory using a ZMP-based CP tracking controller. The ZMP while walking is measured by the force-sensing resistor sensors mounted on the sole of each foot. A handling method for infeasible footstep commands is utilized so that the manipulated ZMP satisfies the allowable ZMP region for stability. The validity of the proposed method is verified through simulations and experiments.

scholarly journals A Robust Balance-Control Framework for the Terrain-Blind Bipedal Walking of a Humanoid Robot on Unknown and Uneven Terrain

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4194 ◽  
Author(s):  
Hyun-Min Joe ◽  
Jun-Ho Oh
Keyword(s):  
Humanoid Robot ◽  
Balance Control ◽  
Humanoid Robots ◽  
Bipedal Walking ◽  
Leg Length ◽  
Zero Moment Point ◽  
Uneven Terrain ◽  
Control Framework ◽  
Zero Moment ◽  
Capture Point

Research on a terrain-blind walking control that can walk stably on unknown and uneven terrain is an important research field for humanoid robots to achieve human-level walking abilities, and it is still a field that needs much improvement. This paper describes the design, implementation, and experimental results of a robust balance-control framework for the stable walking of a humanoid robot on unknown and uneven terrain. For robust balance-control against disturbances caused by uneven terrain, we propose a framework that combines a capture-point controller that modifies the control reference, and a balance controller that follows its control references in a cascading structure. The capture-point controller adjusts a zero-moment point reference to stabilize the perturbed capture-point from the disturbance, and the adjusted zero-moment point reference is utilized as a control reference for the balance controller, comprised of zero-moment point, leg length, and foot orientation controllers. By adjusting the zero-moment point reference according to the disturbance, our zero-moment point controller guarantees robust zero-moment point control performance in uneven terrain, unlike previous zero-moment point controllers. In addition, for fast posture stabilization in uneven terrain, we applied a proportional-derivative admittance controller to the leg length and foot orientation controllers to rapidly adapt these parts of the robot to uneven terrain without vibration. Furthermore, to activate position or force control depending on the gait phase of a robot, we applied gain scheduling to the leg length and foot orientation controllers, which simplifies their implementation. The effectiveness of the proposed control framework was verified by stable walking performance on various uneven terrains, such as slopes, stone fields, and lawns.

scholarly journals EXPERIMENTAL AND THEORETICAL OPTIMAL REGULATOR CONTROL OF BALANCE ZERO MOMENT POINT FOR BIPEDAL ROBOT

2020 ◽  
Vol 24 (06) ◽  
pp. 68-82
Author(s):  
Ali Fawzi Abdul Kareem ◽  
◽  
Ahmed Abdul Hussein Ali ◽  
Keyword(s):  
Performance Index ◽  
Settling Time ◽  
Bipedal Walking ◽  
Optimal Feedback Control ◽  
Walking Robot ◽  
Zero Moment Point ◽  
Double Support ◽  
Zero Moment ◽  
Minimum Performance ◽  
Support Phase

In this paper, the optimal control is analyzed to compare the results of the zero moment point of a bipedal walking robot. Seventeen degrees of freedom bipedal walking robot is manufactured of hard Aluminum sheets. The zero moment point is calculated experimentally and theoretically in the single support phase. MATLAB Simulink is used to simulate the results. The experimental results showed that the lower link takes the settling time is (1) sec, the middle link takes settling time (0.9) sec and the upper link takes (1.1) sec to arrive the desired zero moment point for the bipedal walking robot. The minimum performance index in the experimental parts occurs when the optimal feedback control gain is [35.5 30.4 5 -4]. Hence, the minimum performance index in the theoretical part is [35 31 5.2 -4]. The dimensions of the foot area are (12.3cm×6.3cm), 2.3cm thickness, and 32g weight. Also, the approximate balance area in the double support phase equals the area between the feet of the robot

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.

Biped Walking Control Based on Quadratic Programming and Differential Inequalities

2020 ◽  
Author(s):  
Stella Diniz Urban ◽  
Bruno Vilhena Adorno
Keyword(s):  
Quadratic Programming ◽  
Center Of Mass ◽  
Bipedal Walking ◽  
Differential Inequalities ◽  
Double Support ◽  
Cycle Simulation ◽  
Minimum Height ◽  
Joint Limits ◽  
Single Support Phase ◽  
Support Phase

This paper presents a novel method to control a bipedal walking based on quadratic programming and differential inequalities using geometric primitives. We allow the center of mass to move anywhere inside the support polygon during the walking cycle, as opposed to classic methods, which usually rely on tracking a desired trajectory for the zero moment point. The constraints keep the robot balance, the pelvis above a minimum height, and prevent the violation of joint limits during the complete walking cycle. Simulation results using the legs of the Poppy humanoid robot show that the trajectories of the closed-loop system converge to the desired center of mass position during the double support phase and the swing foot's trajectories converge to the desired pose during the single support phase while all constraints are obeyed.

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.

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