Gait Control Algorithm Research Articles

Sequential sensor fusion-based W-DDPG gait controller of bipedal robots for adaptive slope walking

Walking is a critical topic to the research and development of humanoid robots. However, humanoid robots in action often encounter diverse terrain, which impedes their ability to walk. A slope is a major challenge for humanoid robots. To address this challenge, a gait control algorithm based on wavelet transform and Deep Deterministic Policy Gradient was proposed in this study to enable robots to correct gait parameters in real time through continuous self-learning. In the algorithm, the signals of the three-axis accelerometer and three-axis gyroscope measured by an inertial measurement unit are decomposed and analyzed through wavelet transform to improve the learning outcomes. Robots were trained to walk on slopes with various angles to verify the proposed algorithm, which was also used to optimize the gait parameters of the central pattern generator. The experimental results revealed that the proposed algorithm is superior and more stable than other advanced algorithms. The feasibility and practicality of this algorithm were also verified in the experiments.

Snake Robots for Surgical Applications: A Review

Although substantial advancements have been achieved in robot-assisted surgery, the blueprint to existing snake robotics predominantly focuses on the preliminary structural design, control, and human–robot interfaces, with features which have not been particularly explored in the literature. This paper aims to conduct a review of planning and operation concepts of hyper-redundant serpentine robots for surgical use, as well as any future challenges and solutions for better manipulation. Current researchers in the field of the manufacture and navigation of snake robots have faced issues, such as a low dexterity of the end-effectors around delicate organs, state estimation and the lack of depth perception on two-dimensional screens. A wide range of robots have been analysed, such as the i2Snake robot, inspiring the use of force and position feedback, visual servoing and augmented reality (AR). We present the types of actuation methods, robot kinematics, dynamics, sensing, and prospects of AR integration in snake robots, whilst addressing their shortcomings to facilitate the surgeon’s task. For a smoother gait control, validation and optimization algorithms such as deep learning databases are examined to mitigate redundancy in module linkage backlash and accidental self-collision. In essence, we aim to provide an outlook on robot configurations during motion by enhancing their material compositions within anatomical biocompatibility standards.

Straight Gait Research of a Small Electric Hexapod Robot

Gait is an important research content of hexapod robots. To better improve the motion performance of hexapod robots, many researchers have adopted some high-cost sensors or complex gait control algorithms. This paper studies the straight gait of a small electric hexapod robot with a low cost, which can be used in daily life. The strategy of “increasing duty factor” is put forward in the gait planning, which aims to reduce foot sliding and attitude fluctuation in robot motion. The straight gaits of the robot include tripod gait, quadrangular gait, and pentagonal gait, which can be described conveniently by discretization and a time sequence diagram. In order to facilitate the user to control the robot to achieve all kinds of motion, an online gait transformation algorithm based on the adjustment of foot positions is proposed. In addition, according to the feedback of the actual attitude information, a yaw angle correction algorithm based on kinematics analysis and PD controller is designed to reduce the motion error of the robot. The experiments show that the designed gait planning scheme and control algorithm are effective, and the robot can achieve the expected motion. The RMSE of the row, pitch, and yaw angle was reduced by 35%, 25%, and 12%, respectively, using the “increasing duty factor” strategy, and the yaw angle was limited in the range −3°~3° using the yaw angle correction algorithm. Finally, the comparison with related works and the limitations are discussed.

A Comparison of Six Legged ODE (Open Dynamics Engine) Based Gait control Algorithm and Standard Walking Gaits

In legged robots, there are changes in the sequence of legs and the foothold positions depending on the speed. The walking sequence, known as gait, is important for the robot's ability to move in a stable and less energy-consuming way. In this study, the previously developed ODE-based gait control algorithms for a six-legged mobile robot and the standard walking gaits were compared in terms of stability and repeatability. In the ODE-based gait control algorithm, dynamic effects are not neglected, as in standard gait patterns. Owing to this, the ODE-based gait controller has the ability to constantly balance itself against external disturbances. In order to test this feature of the control algorithm, the same comparison operations were repeated for a fixed motion scenario on a rotatable inclined floor. In this study firstly layered control architecture has explained which developed for ODE-based controllers. Thereafter, servo motor controllers, ODE based stability and ODE based gait controllers used in robot are introduced respectively. After in order to make the performance of these controllers comparable to the methods in the literature, standard gait patterns have been introduced. Following this section, the performance criteria to be used in the comparison procedures and the reasons for their selection are given. Later on, the rotatable inclined floor, which was builded in order to demonstrate the performance of the robot and controller used in the test system better, has explained. Afterwards, an experimental scenario in which the slopes are changed periodically over time was determined, with the aim of using this scenario in comparison experiments in which performed on the rotatable inclined floor. In the comparison results section, the experimental performance results shown by ODE-based gait controller and standard walking arrangements are given in detail through this test system and comparison criteria. As a result of the study, a 65 percent improvement was observed in stability of robot, both flat and inclined floor according to standard walking gaits.

Research on Gait control algorithm of Bionic Hexapod Robot System based on Adams and Matlab

The control algorithm of bionic hexapod robot based on biological control algorithm has been designed and realized. Through the establishment of virtual prototype physical model by Adams, Adams and Matlab simulation software is realized to carry out joint simulation of the robot to verify the feasibility of the algorithm. At the same time, the algorithm was improved according to the emerging problems. Firstly, the gait control model of hexapod bionic robot is established in Matlab/Simulink, and pure theoretical simulation is carried out for it as the control system part of the joint simulation system. Secondly, a three-dimensional solid model of hexapod bionic robot is established in SolidWorks, which is then imported into the mechanical simulation software for kinematic analysis to verify the constraint relationship of the virtual prototype model, and the corresponding Simulink file is exported through the Adams/Controls interface module as the mechanical system part of the joint simulation system. Finally, Adams and Matlab are used for joint simulation of the robot to verify the feasibility of this algorithm and lay a foundation for the construction of entity prototype.

Design of the three-bus control system utilising periodic relay for a centipede-like robot

SUMMARYA centipede-like robot, which has high degrees of freedom (DOFs) and similar body segments, requires new real-time control to achieve diverse gaits. Therefore, we have studied the movement characteristics of multi-legged creatures and determined the features for a gait periodic relay. An instruction-relay control scheme, the three-bus control system and the required software were then designed. In our experiments with the designed control system, different gaits for the robot could be achieved, and the phase difference between body segments could be changed by altering the delay time. As a whole, this control system could accomplish the required control task and reasonably simplify the gait control algorithms and procedures.

Energy-Efficiency-Based Gait Control System Architecture and Algorithm for Biped Robots

A novel systematic architecture and algorithm of gait control based on energy-efficiency optimization is represented, aiming at the fatal problem of high energy consumption for biped robots walking in unstructured environments. By designing an optimal controller to minimize the energy criterion, the proposed method provides a remarkable descend rate of energy consumption in the trunk-rotation walking mechanism. The proposed algorithm is able to optimize the trunk trajectory by minimizing the energy-related cost function while guaranteeing zero-moment point (ZMP) criterion. Simulations and experimental results show the validity of the method.

Reliable gait planning and control for miniaturized quadruped robot pet

This paper proposes a gait planning and control algorithm for the quadruped robot pet commercialized by Dasarobot, Korea. Reliable motion and online characteristics are the key requisites for the motion planning algorithm of a commercialized robot. At joint control level of the proposed gait control, sample-based interpolation makes joint trajectory tractable for small motor and controller of the miniaturized robot. Centroid body sway ensures walking stability to achieve reliability of the proposed gaits at the motion planning level. By using ground coordinates representation, it is possible to integrate several online gaits and realize a compact and efficient gait planning algorithm. Experimental results are presented to verify the proposed gait planning and control algorithm.

Modeling and Control of Legged Locomotion via Switching Max-Plus Systems

We present a class of gait generation and control algorithms based on the Switching Max-Plus modeling framework that allow for the synchronization of multiple legs of walking robots. Transitions between stance and swing phases of each leg are modeled as discrete events in a system described by max-plus-linear state equations. Different gaits can be systematically generated and interleaved during motion by switching between different system matrices. We show that such gait switching can be done in an optimal way, minimizing the tip leg velocity variation for all legs simultaneously touching the ground.

Development of a Quadruped Walking Robot TITAN XI for Steep Slope Operation - Step Over Gait to Avoid Concrete Frames on Steep Slopes -

We detail a step over gait for a quadruped walking robot that maintains a continuous walking with sufficient stability margin for avoiding ferroconcrete reinforcement frames covering steep slopes. For this gait, the robot must adapt itself to terrain and step over these frames. We propose a terrain-adaptive gait based on an intermittent crawl gait using map information. After introducing the gait control algorithm, we show results of graphical simulation to verify the proposed algorithm. Then, these discussions are established by walking experiments using the developed quadruped walking robot named TITAN XI.

The design and control of a jointed-leg type of a quadrupedal robot for locomotion on irregular ground

In this paper, a study of a quadrupedal walking robot capable of walking on the irregular ground is presented. The robot has specially-designed feet with toes making soft and safe landings on uneven surfaces. Using the toe angle and landing force sensors integrated within the feet, its gait control algorithm can adapt the foot trajectory to the ground profile, while the body weight is evenly distributed on the supporting legs. After the landing of a foot, the roll and pitch angles of the body are measured and controlled to keep the body attitude parallel to the plane of support. The contents of this study are the design concept and working principle of the foot, including the gait control algorithm for walk on the irregular ground. Experimental results are reported.

Adaptive gait control for a walking robot

AbstractWalking vehicles have the potential to emulate the superior off‐road mobility of biological systems. However, it is important to make the walking machine terrain adaptive and versatile, and to minimize man's role as an operator in order to realize this potential. Terrain adaptive locomotion involves intelligent foothold selection and the control of gait to produce the desired motion. This requires a departure from the idealized, structured stepping patterns for statically stable gaits which have been the object of considerable research. A modified wave gait is used to demonstrate that it is possible for the vehicle velocity to be varied continuously in accordance with higher level commands even with irregular, asymmetric, and changing support patterns, A varying duty factor is employed to enable optimal leg cycling frequencies. Implementation of gait control algorithms and results from a computer simulation are also presented.