Yaw Joint Research Articles

Design and Analysis of a Bionic Gliding Robotic Dolphin

In this paper, we focus on the design and analysis of a bionic gliding robotic dolphin. Inspired by natural dolphins, a novel bionic gliding robotic dolphin is developed. Different from the existing ones, the gliding robotic dolphin developed in this work is specially introduced with a yaw joint to connect its three oscillating joints to improve maneuverability in both dolphin-like swimming and gliding motion. Consequently, the gliding robotic dolphin can realize several flexible motion patterns under the coordination of its flippers, yaw joint, oscillating joints, and buoyancy-driven modular. Thereafter, relying on the Newton-Euler method, a hybrid-driven dynamic model is constructed to further analyze the propulsive performance in both dolphin-like swimming and gliding motions. Finally, various simulations and experiments, including forward swimming, gliding, and turning in both dolphin-like swimming and gliding modes, are carried out to validate the effectiveness of the developed gliding robotic dolphin.

Development of a Motion Control for a highly dynamic, self-propelled driving simulator

The new concept of the self-propelled driving simulator comprises a hexapod, a yaw joint and a wheel-based motion platform with four individually steerable wheels. This concept provides a theoretically unlimited motion range, which especially enables highly dynamic drive maneuvers. To ensure an omnidirectional motion, the motion platform has to accelerate instantly in any direction. This requirement leads to the main challenges in the control system of the simulator: taking into account the nonlinear and transient tire characteristics and generating the target accelerations as expected by the driver. According to these requirements, the Motion Control is only for controlling the horizontal dynamics of the motion platform. The Motion Control presented in this paper includes various model definitions, especially regarding the essential tire characteristics considered within an extended HSRI (Highway Safety Research Institute) tire model. The Motion Control as Two-Degrees-of-Freedom control contains a Feedforward for generating target body forces, a Control Allocation for an optimal force distribution to the wheels, a Single Wheel Control as a specific control of the tire forces, and a Compensation Control on acceleration level. Investigation of this control by simulation, using a simplified reference model, already revealed a high controller performance regarding accuracy and quality. The optimal force distribution leads to an equal adhesion utilization and the Compensation Control compensates the remaining Single Wheel Control deviations. Difficulties only occur for the steering angle in the case of low velocity up to a standstill. Due to the exact input–output linearization, the Single Wheel Control leads to a singularity and instability. Therefore, the steering angle requires exceptional control in this case.

Optimization of Pelvic Rotation Walking Pattern Considering Future States Using Model Predictive Control to Increase the Step Length

Pelvic rotation, which is observed in human gait, is used to increase a robot’s step length in the humanoid robot walking. Existing methods empirically or experimentally generate the pelvic-rotation angle offline using predetermined pelvis and foot trajectories. Therefore, these methods are difficult to be used with the method to generate the center of mass (CoM) trajectory in real time using techniques such as preview control or model predictive model control. In this study, we propose a method that generates a pelvic-rotation trajectory that can be used with a real-time CoM generation method while reflecting the future state of the robot. The step length increased due to pelvic rotation was kinematically analyzed and compared with the step length increased by the proposed method. Upper body motion to compensate for yaw angular momentum generated by lower body movement during walking using pelvic rotation was optimized using centroial dynamics. The waist yaw joint for pelvic rotation, leg joint for the walking, and upper body joint for arm swing were optimized using separate optimal controllers. Energy efficiency, increase in step length, and decrease in the possibility of singularity occurrence of pelvic rotation walking were analyzed and compared in simulations. The proposed method was experimentally verified using humanoid robot Dyros-Jet.

Tension Control Method Utilizing Antagonistic Tension to Enlarge the Workspace of Coupled Tendon-Driven Articulated Manipulator

The exploration and inspection of narrow spaces in industrial plants require the use of long-reach redundant manipulators with large three-dimensional (3D) workspaces. To this end, in a previous work, a coupled tendon-driven articulated manipulator with a total length of 10 m and yaw joints for 3D motion was developed. This study focuses on employing the antagonistic tension in a yaw joint to support a tendon that drives a pitch joint with high gravitational loading. Herein, a tension control method that employs the antagonistic tension to reduces the amount of tension required to support the weight of an arm is proposed. The effectiveness of the proposed method is evaluated based on the workspace volume of the previously developed Super Dragon, and the results demonstrate that the proposed method expands the workspace by up to 45%.

Equivalent kinematics and pose-configuration planning of segmented hyper-redundant space manipulators

With multiple segments and associated universal joints, a segmented hyper-redundant manipulator can perform on-orbital servicing tasks in confined space due to its superior flexibility and dexterity. However, its inverse kinematics resolving and trajectory planning are challenging because of special structure and strict environment constraints. In this paper, we propose an equivalent kinematics modelling and pose-configuration simultaneous planning method to perform given missions with high efficiency. First, a kinematic equivalence arm (KEA) with revolution joints is constructed by rearranging the associated universal joints of each segment. The motion of n associated universal joints in each segment is simplified as that of a serial arm composed of 1 Roll and n coplanar Yaw joints. The endpoint pose (position and orientation) of the KEA is the same as that of each segment; its shape is also easily described as the Roll angle and the normal vector of the configuration plane. Correspondingly, the kinematics of the whole manipulator composed of N segments is modeled as the combined kinematics of N KEAs. Here KEAs is denoted as the kinematic equivalence model of the proposed manipulator. Then, its configuration represented by KEAs' shape parameters and end-effector's pose are planned simultaneously according to the environment constraints. Finally, trajectory tracking and narrow space detection task are simulated and experimented respectively. The results of trajectory tracking show that the computation time of the proposed method is greatly reduced. The simulation and experiment results of narrow space detection verify the proposed method.

Reconstruction of Backbone Curves for Snake Robots

Snake robots composed of alternating single-axis pitch and yaw joints have many internal degrees of freedom, which make them capable of versatile three-dimensional locomotion. In motion planning process, snake robot motions are often designed kinematically by a chronological sequence of continuous backbone curves that capture desired macroscopic shapes of the robot. However, as the geometric arrangement of single-axis rotary joints creates constraints on the rotations in the robot, it is challenging for the robot to reconstruct an arbitrary 3D curve. When the robot configuration does not accurately achieve the desired shapes defined by these backbone curves, the robot can have unexpected contacts with the environment, such that the robot does not achieve the desired motion. In this work, we propose a method for snake robots to reconstruct desired backbone curves by posing an optimization problem that exploits the robot's geometric structure. We verified that our method enables fast and accurate curve-configuration conversions through its applications to commonly used 3D gaits. We also demonstrated via robot experiments that 1) our method results in smooth locomotion on the robot; 2) our method allows the robot to approach the numerically predicted locomotive performance of a sequence of continuous backbone curve.

Improvement of Winding Gait for Snake Robot

In order to solve the problem that the image information is difficult to handle due to the swing of the snake robot’s head during its serpentine locomotion, this paper improves the control function of the general winding gait for the orthogonal joint-connected snake-like robot, and the useful image information is obtained by reducing the swing of the camera-mounted snake’s head based on the improved function. Combining the Sigmoid function with the general function to control the rotation of the yaw joints and applying the Gaussian function to the pitch joints to lift the snake head off the ground, this new control function presented in this paper not only enables the joints to rotate smoothly, but also decreases the swing range of the snake head. Additionally, it can also fasten the robot’s movement. Experiments based on MATLAB and GAZEBO platform demonstrate the superiority and effectiveness of the improved winding gait.

A highly intuitive and ergonomic redundant joint master device for four-degrees of freedom flexible endoscopic surgery robot.

Studies have been conducted on slave-specific master devices with a similar kinematic structure to the slave to enhance intuitiveness. However, for the four-degrees of freedom (DOFs) slave of a flexible endoscopic surgery robot, only four DOFs in the master device causes low ergonomic performance. To enhance ergonomic performance, a second yaw joint was added as a redundant joint after considering the range of wrist motion and the workspace shape. Three experiments were performed to compare the intuitiveness and ergonomic performance of the proposed device with four-DOFs slave-specific and six-DOFs general-purpose master devices. Significant differences were observed in terms of intuitiveness performance between the slave-specific and the general-purposed master device. On the other hand, there was no significant difference in ergonomic performance between the master devices with redundant joint. Compared with a general-purpose master device, the proposed one exhibited noticeably improved intuitiveness performance and comparable ergonomic performance.

Control of an articulated wheeled mobile robot in pipes

We propose a control method in which an articulated wheeled mobile robot moves inside straight, curved and branched pipes. This control method allows the articulated wheeled mobile robot to inspect a larger area. The articulated wheeled mobile robot comprises pitch and yaw joints is and propelled by active wheels attached to the robot. Via the proposed control method, the robot takes on two different shapes; one prevents the robot from slipping inside straight pipes and the other allows movement in a pipe that curves in any direction. The robot is controlled by a simplified model for the robot's joint angles. The joint angles of the robot are obtained by fitting to a continuous curve along the pipe path. In addition, the angular velocity of the robot's active wheels is determined by a simplified model. The effectiveness of the proposed the control method was demonstrated with a physical implementation of the robot, and the robot was able to move inside straight, curved and branched pipes.

Suppression of Roll Oscillation in Turning of Quadruped Robot by Asymmetric Amplification of Central Pattern Generator Output Waveform

Quadruped robots experience excessive vibrations in the roll direction when turning by controlling their hip yaw joint. In the case of image-based teleoperation of the robot, the operator cannot aware the situation of the robot, due to excessive vibrations of the viewpoint of the image from the camera mounted on the robot. Especially, it is known that vibration in the roll direction is most likely to cause motion sickness. To overcome this problem, we proposed the asymmetric amplification of the output waveforms of central pattern generators. We implemented the proposed method on a robot in a dynamic simulator and verified the effectiveness of the proposed method, during the turning operation. As a result, we confirmed that the proposal method can suppress 43.7% vibration of the robot body in the roll direction and 7.4% vibration in the pitch direction compared with the conventional method.

Conceptual design of EAST multi-purpose maintenance deployer system

EAST multi-purpose maintenance deployer (EMMD) system, being collaboratively developed by ASIPP and CEA-IRFM, is built as upgrades for EAMA. Updated kinematics parameters such as DOF distribution and joint angle for EMMD robot are performed and verified in a simulation platform. A new modular joint has been developed to optimize the yaw joint actuator for easy assembly and flexibility reduction. A 3-DOF gripper with cameras and torque sensor has been designed to provide inspection and dexterous handling of small fragments inside the EAST chamber. A conceptual upgrade for EAMA-CASK has been developed for the purpose of protecting the end-effector's sensors which do not have temperature-resistant qualification. The high temperature and vacuum compatible solutions and validation experiments have been presented in this paper.

Advantage of straight walk instability in turning maneuver of multilegged locomotion: a robotics approach.

Multilegged locomotion improves the mobility of terrestrial animals and artifacts. Using many legs has advantages, such as the ability to avoid falling and to tolerate leg malfunction. However, many intrinsic degrees of freedom make the motion planning and control difficult, and many contact legs can impede the maneuverability during locomotion. The underlying mechanism for generating agile locomotion using many legs remains unclear from biological and engineering viewpoints. The present study used a centipede-like multilegged robot composed of six body segments and twelve legs. The body segments are passively connected through yaw joints with torsional springs. The dynamic stability of the robot walking in a straight line changes through a supercritical Hopf bifurcation due to the body axis flexibility. We focused on a quick turning task of the robot and quantitatively investigated the relationship between stability and maneuverability in multilegged locomotion by using a simple control strategy. Our experimental results show that the straight walk instability does help the turning maneuver. We discuss the importance and relevance of our findings for biological systems and propose a design principle for a simple control scheme to create maneuverable locomotion of multilegged robots.

手先位置頻度マップを用いた作業傾向の分析と操作技能の推定

This paper proposes a framework for analyzing comprehensive work tendency and operational skills using a frequency plot map of the end-point of a manipulator as a fundamental study of work analysis using long-term data for human-operated work machines. The proposed framework creates a two-dimensional end-point plot map with its origin fixed at the yaw joint of the manipulator to deal with arbitrary usage conditions. It then extracts arbitrary characteristics by using hierarchical feature extraction filters defined by feature values such as movement, and load. Finally, it quantifies the filtered map by gridding and normalization to visually grasp its frequency distribution.

Influence of rotation of humanoid hip joint axes on joint power during locomotion

Most of the fully actuated legs of existing humanoids have a straight kinematics, i.e. roll, pitch and yaw joint rotary axes are aligned, respectively, along longitudinal, lateral and vertical axes of the robot’s body. This work explores different orientations of the hip joint axes where the yaw joint and the pitch joint axes are rotated about the longitudinal axis, keeping the serial order – yaw, roll and pitch – from the pelvis. Two walking movements are simulated dynamically: forward walk and turn-in-place. The measurements of joint mechanical power (JMP) consumption are used to compare the different kinematics configurations. The results obtained from simulation show that the inward and outward rotations of hip yaw and pitch joint axes about the longitudinal axis bring a significant reduction of pitch JMP, and lead to a better JMP distribution among the hip joint actuators compared with the classical straight configuration. In addition, the outward configuration presents a significant reduction of JMP consumption of the hip pitch joint of the supporting leg during acceleration and regular steps, compared with the inward configuration.

2P1-G06 ヨー軸能動関節を有する蠕動運動型ロボットの旋回動作

2P1-G06 ヨー軸能動関節を有する蠕動運動型ロボットの旋回動作

1P2-R07 狭所・段差の清掃が可能な多連結掃除ロボットの開発と制御

In this paper, we develop an articulated mobile robot for cleaning on steps and narrow paths. The robot consists of links which has a cleaning unit, wheels for propulsion, a pitch joint for three-dimensional motion, and sensors for collision detection, and the links are serially connected by a yaw joint. A control method which the robot effectively cleans a plane floor is proposed, and simulations and experiments were carried out to demonstrate the effectiveness of it. Furthermore, experiments were performed to test feasibility of climbing a step.

A Fast Turning Method for Biped Robots With Foot Slip During Single-Support Phase

For a biped robot to have the capability to change the direction of locomotion fast without tripping itself is important in enhancing its mobility. This paper proposes a new method to realize a quick and natural turn, or to make an abrupt change in the walking direction of a biped robot by taking advantage of a foot slip, which is created intentionally between the sole of the foot and the ground. By using the slip at the supporting foot, the robot can turn its body, in a single step, beyond the kinetic limit of its yaw joint. Thus, the proposed method makes it possible for the robot to make a single turning motion during the single-support phase in order to achieve a change in the locomotion that would not be possible unless the robot takes multiple steps. This reduces the time and the amount of space needed for a biped robot to make a turn. The mathematical conditions for a foot slip to occur are derived based on a simplified 3-D dynamic model of a biped robot consisting of three parts: a swing leg, a supporting leg, and the rest of the body. Under these conditions, the desired translational and rotational trajectories for the swing foot and the main body are generated based on the expected floor surface condition. Computer simulations and experiments were carried out to prove the effectiveness of the proposed method for a quick and natural turn.

Towards development of a slider-crank centered self-propelled dolphin robot

This paper is devoted to the mechatronic design and implementation of a dolphin-like robot capable of fast swimming. In the context of multiple coordinated control surfaces, a set of serially connected flapping modules is responsible for dorsoventral oscillations, an internal moving slider for pitch control and a yaw joint for lateral turns. To improve the swimming speed, an updated modular slider-crank-based flapping mechanism that fully capitalizes on the continuous high-speed rotation of the DC motor is proposed and constructed. With the proposed mechanisms, the resulting dolphin robot achieved a high level of propulsive speed, largely illustrating the validity of the present design scheme.

Control of Yaw and Pitch Maneuvers of a Multilink Dolphin Robot

This paper is devoted to the active turn control of a free-swimming multilink dolphin-like robot, with emphasis on yaw and pitch controls. With full consideration of both mechanical configuration and propulsive principle of the robot consisting of a yaw joint and multiple pitch joints, a viable approach to perform yaw maneuvers via laterally directed biases is formed, providing an advantage in qualitative and quantitative assessment. Meanwhile, based on the feedback of the pitch angle measured by an onboard gyroscope, a closed-loop control strategy in dorsoventral motions is proposed to achieve agile and swift pitch maneuvers. More remarkably, two hybrid acrobatic stunts, i.e., frontflip and backflip, are first implemented on the physical robot. The latest results obtained demonstrate the effectiveness of the proposed methods. It is also confirmed that the dolphin robot achieves better performance for pitch maneuvers than it does for yaw maneuvers, agreeing well with the biological observations.

Structural health monitoring of wind turbines: method and application to a HAWT

AbstractStructural health monitoring in the context of a Micon 65/13 horizontal axis wind turbine was described in this paper as a process in statistical pattern recognition. Simulation data from a calibrated model with less than 8% error in the first 14 natural frequencies of vibration was used to study the operational response under various wind states as well as the effects of three types of damage in the blade, low speed shaft and yaw joint. It was shown that vertical wind shear and turbulent winds lead to different modal contributions in the operational response of the turbine suggesting that the sensitivity of operational data to damage depends on the wind loads. It is also shown that there is less than a 4% change in the wind turbine natural frequencies given a 25% reduction in the stiffness at the root of one blade. The modal assurance criterion was used to analyse the corresponding changes in modal deflections, and this criterion exhibited nearly orthogonal changes because of the three damage scenarios suggesting that the modal deflection determines which damage is observable at a given frequency for a given wind state. The' modal contribution is calculated as a damage feature, which changes as much as 100% for 50% reductions in blade root stiffness, but only the blade damage is detected using this feature. Operational data was used to study variations in the forced blade response to determine the likelihood that small levels of damage can be detected amidst variations in wind speed across the rotor plane. The standard deviation in measured data was shown to be smallest for the span and edge‐wise measurements at 1P due to gravity, which provides the dominant forcing function at this frequency. A 3% change in the response in the span and edge‐wise directions because of damage is required to detect a change of three standard deviations in contrast to the 90% change in flap direction response that is required to detect a similar change because of damage. The dynamic displacement in the span direction is then used to extract a damage feature from the simulation data that provides the ability to both locate and quantify the reduction in stiffness in the blade root. Copyright © 2011 John Wiley & Sons, Ltd.