Switching Control Method for Stable Landing by Legged Robot Based on Zero Moment Point

2013 ◽  
Vol 25 (5) ◽  
pp. 831-839 ◽  
Author(s):  
Naoki Motoi ◽  
◽  
Kenta Sasahara ◽  
Atsuo Kawamura
Keyword(s):  
Control Method ◽  
Biped Robot ◽  
Switching Control ◽  
Contact Condition ◽  
Smooth Transition ◽  
Switching Function ◽  
Legged Robot ◽  
Position Controller ◽  
Zero Moment ◽  
The Moment

This paper proposes a switching control method to achieve a smooth transition from an edge landing to a sole landing for a legged robot. When a biped robot walks, an undesirable condition at the moment of landing, such as hunting between the ground and the foot, may occur for several reasons. To avoid this condition, this paper focuses on a method that uses simple controllers to ensure a smooth transition from an edge landing to a sole landing. In the event of an edge landing, a force controller should be implemented for a smooth transition to a sole landing. This is because the force controller enables the foot to contact the ground softly. After the landing state is shifted to the sole landing, the control method should be changed to the position controller. Therefore, it is necessary to switch the control method according to the contact condition between the foot and the ground. To avoid the chattering of the controller switching, several hysteresis values are used for the zeromoment point (ZMP) position and ZMP velocity in the switching function. Simulations and experimental results confirmed the validity of the proposed method.

Near-Optimal Trajectory Generation of a Two-Legged Robot with Soft Sole on Staircase using PSO and ABC

2015 ◽  
Vol 3 (2) ◽  
pp. 1-19
Author(s):  
Naga Sudha Rani B ◽  
Vundavilli Pandu Ranga
Keyword(s):  
Dynamic Balance ◽  
Reaction Force ◽  
Biped Robot ◽  
Legged Robot ◽  
Walking Machine ◽  
Bee Colony ◽  
Zero Moment ◽  
Lumped Masses ◽  
Least Energy ◽  
Generation Problem

During biped locomotion the foot ground interaction plays an important role, as it takes the reaction force acting on the foot and allows stable walking of the biped robot. Generally, the foot is considered to be hard to solve the gait generation problem and dynamic balance aspects of the two-legged robot. However, a layer of rubber is placed on the sole of the robot to act as a shock absorber for all practical purposes. It is important to note that the soft sole gets deformed during walking of the robot and allows the limbs of the robot to bend that influences the dynamic balance of the walking machine. The aim of this study is to use two different non-traditional optimization algorithms, such as particle swarm optimization (PSO) and artificial bee colony (ABC) algorithms to obtain the optimal hip trajectory, damping coefficient and position of the lumped masses for a 7-DOF biped robot ascending the staircase. The dynamic balance of the gaits generated with soft sole is verified using the concept of zero moment point (ZMP). Further, the energy consumed in ascending the staircase with and without soft sole has been computed. The results of this study proved that, least energy is consumed with soft sole having correction for the deformation.

scholarly journals Collaborative robot zero moment control for direct teaching based on self-measured gravity and friction

2018 ◽  
Vol 15 (6) ◽  
pp. 172988141880871 ◽  
Author(s):  
Saixuan Chen ◽  
Minzhou Luo ◽  
Guanwu Jiang ◽  
Omar Abdelaziz
Keyword(s):  
Position Control ◽  
Control Method ◽  
Viscous Friction ◽  
Theoretical Method ◽  
Friction Torque ◽  
Viscous Friction Force ◽  
Moment Control ◽  
Zero Moment ◽  
The Moment ◽  
Collaborative Robot

The focus of this study is a moment compensation control algorithm driven by a direct current servo motor. Zero moment robot teaching is achieved with a joint moment compensation algorithm. The moment equilibrium equation is derived based on moment compensation. The current signal detected by a Hall effect sensor is multiplied by a torque constant to estimate the torque value of the robot joint. The compensation current is obtained through parameter identification to overcome gravitational and friction torques. The two variables of speed and position are separately controlled, allowing the compensation current of Coulomb friction and viscous friction force to be separated from the compensation current of friction torque. This study presents the system research, design, and development of a high-precision position control theory of a robot zero moment teaching control method. A collaborative robot is used as the test and verification platform to confirm the feasibility and effectiveness of the proposed theoretical method and implementation technology.

scholarly journals Finite-Time Switching Control of Nonholonomic Mobile Robots for Moving Target Tracking Based on Polar Coordinates

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Hua Chen ◽  
Shen Xu ◽  
Lulu Chu ◽  
Fei Tong ◽  
Lei Chen
Keyword(s):  
Mobile Robots ◽  
Finite Time ◽  
Control Method ◽  
Tracking Error ◽  
Switching Control ◽  
Polar Coordinates ◽  
Control Law ◽  
Moving Target ◽  
Nonholonomic Mobile Robots ◽  
Time Switching

In this paper, finite-time tracking problem of nonholonomic mobile robots for a moving target is considered. First of all, polar coordinates are used to characterize the distance and azimuth between the moving target and the robot. Then, based on the distance and azimuth transported from the sensor installed on the robot, a finite-time tracking control law is designed for the nonholonomic mobile robot by the switching control method. Rigorous proof shows that the tracking error converges to zero in a finite time. Numerical simulation demonstrates the effectiveness of the proposed control method.

scholarly journals A Joint-space Position Control-based Approach to Haptic Rendering of Stiff Objects using Gain Scheduling

2021 ◽  
Vol 103 (3) ◽  
Author(s):  
Yang Wang ◽  
Lei Feng ◽  
Kjell Andersson
Keyword(s):  
Simulation Model ◽  
Position Control ◽  
Gain Scheduling ◽  
Joint Space ◽  
Haptic Rendering ◽  
Smooth Transition ◽  
Position Controller ◽  
Detailed Simulation ◽  
Stability Issues ◽  
Computing Models

AbstractHaptic rendering often deals with interactions between stiff objects. A traditional way of force computing models the interaction using a spring-damper system, which suffers from stability issues when the desired stiffness is high. Instead of computing a force, this paper continues to explore shifting the focus to rendering an interaction with no penetration, which can be accomplished by using a position controller in the joint space using the encoders as feedback directly. In order to make this approach easily adaptable to any device, an alternative way to model the dynamics of the device is also presented, which is to linearize a detailed simulation model. As a family of linearized models is used to approximate the full dynamic model of the system, it is important to have a smooth transition between multiple sets of controller gains generated based on these models. Gain scheduling is introduced to improve the performance in certain areas and a comparison among three controllers is conducted in a simulation setup.

scholarly journals Multi-scale Simulation in Railway Planning and Operation

2012 ◽  
Vol 23 (6) ◽  
pp. 511-517 ◽  
Author(s):  
Yong Cui ◽  
Ullrich Martin
Keyword(s):  
Simulation Model ◽  
Process Simulation ◽  
Level Of Detail ◽  
Smooth Transition ◽  
Simulation Methods ◽  
Multi Scale ◽  
Railway Planning ◽  
The Moment ◽  
Discrete Scaling ◽  
Planning And Operation

Simulation methods are widely used in railway planning and operation. However, at the moment there are no applicable solutions in the process simulation for a smooth transition among different infrastructure levels on the basis of a unified structure with consistent algorithm. In this paper, a multi-scale simulation model is designed with consideration of the level of detail of the investigated infrastructure model and the homogeneity of the processes running in the simulation model. A comprehensive and synthesized view of railway planning and operation is therefore obtained. Within the multi-scale simulation model, railway planning and operation processes can be simulated, evaluated and optimized consistently. KEY WORDS: railway planning, simulation, multi-scale, aggregation, discrete scaling, continuous scaling, homogenous process, inhomogeneous process

scholarly journals HIS-Based Semiactive Suspension Dual-Frequency-Range Switching Control to Improve Ride Comfort and Antiroll Performance

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Xiaojian Wu ◽  
Xiang Qiu ◽  
Bing Zhou ◽  
Juhua Huang ◽  
Tingfang Zhang
Keyword(s):  
Ride Comfort ◽  
Control Method ◽  
Excitation Frequency ◽  
Switching Control ◽  
Parameter Sensitivity ◽  
The Body ◽  
Semiactive Control ◽  
Frequency Bandwidth ◽  
Dual Frequency ◽  
Frequency Range

The parameter sensitivity analysis of a hydraulically interconnected suspension (HIS) system shows that the sensitivity of the vibration responses in the bounce and roll modes to the hydraulic parameters are complementary. A novel HIS-based semiactive control method was thereby proposed to improve ride comfort and antiroll performance. In addition, the classic sky-hook max-min damping switched strategy provides significant benefits around the body resonance, but otherwise performs similarly to, or sometimes even worse than, passive suspension. Therefore, a dual-frequency-range switching strategy, which has optimal max-min damping in both frequency ranges, was developed for improving the ride comfort in a wider frequency bandwidth. In this study, a 9-DOF HIS system dynamics model was established, and the hydraulically interconnected subsystem model was validated experimentally. Subsequently, the elastic and damping characteristics of the hydraulically interconnected subsystem, as well as the parameter sensitivity in bounce mode and roll mode, were analyzed. Next, the sensitive parameters were optimized under sinusoidal excitation at various frequencies, and a frequency-range selector used to determine the excitation frequency range and adjust the shock absorber damping was designed. Finally, simulations in the frequency domain and time domain show that the proposed HIS-based semiactive dual-frequency-range switching control suspension improves the ride comfort in a wider frequency bandwidth and enhances the antiroll performance in the transient and steady steering process.

scholarly journals Universal Walking Control Framework of Biped Robot Based on Dynamic Model and Quadratic Programming

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Xiaokun Leng ◽  
Songhao Piao ◽  
Lin Chang ◽  
Zhicheng He ◽  
Zheng Zhu
Keyword(s):  
Motion Control ◽  
Dynamic Characteristics ◽  
Control Method ◽  
Constraint Equation ◽  
Biped Robot ◽  
Equation System ◽  
Whole Body ◽  
Optimal Controller ◽  
Control Framework ◽  
The Stability

Biped robot research has always been a research focus in the field of robot research. Among them, the motion control system, as the core content of the biped robot research, directly determines the stability of the robot walking. Traditional biped robot control methods suffer from low model accuracy, poor dynamic characteristics of motion controllers, and poor motion robustness. In order to improve the walking robustness of the biped robot, this paper solves the problem from three aspects: planning method, mathematical model, and control method, forming a robot motion control framework based on the whole-body dynamics model and quadratic planning. The robot uses divergent component of motion for trajectory planning and introduces the friction cone contact model into the control frame to improve the accuracy of the model. A complete constraint equation system can ensure that the solution of the controller meets the dynamic characteristics of the biped robot. An optimal controller is designed based on the control framework, and starting from the Lyapunov function, the convergence of the optimal controller is proved. Finally, the experimental results show that the method is robust and has certain anti-interference ability.

scholarly journals Dynamic Walking of a Legged Robot in Underwater Environments

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3588 ◽  
Author(s):  
Portilla ◽  
Saltarén ◽  
Espinosa ◽  
Barroso ◽  
Cely ◽  
...  
Keyword(s):  
Legged Robot ◽  
Dynamic Walking ◽  
Zero Moment Point ◽  
Hydraulic Actuators ◽  
External Perturbations ◽  
Underwater Environment ◽  
Zero Moment

In this research, the dynamic walking of a legged robot in underwater environments is proposed. For this goal, the underwater zero moment point (Uzmp) is proposed in order to generate the trajectory of the centre of the mass of the robot. Also, the underwater zero moment point auxiliary (Uzmp aux.) is employed to stabilize the balance of the robot before it undergoes any external perturbations. The concept demonstration of a legged robot with hydraulic actuators is developed. Moreover, the control that was used is described and the hydrodynamic variables of the robot are determined. The results demonstrate the validity of the concepts that are proposed in this article, and the dynamic walking of the legged robot in an underwater environment is successfully demonstrated.

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