Pub Date : 2021-08-01DOI: 10.1142/s0219843621500134
E. Ehsaeyan, A. Zolghadrasli
Multilevel image thresholding is an essential step in the image segmentation process. Expectation Maximization (EM) is a powerful technique to find thresholds but is sensitive to the initial points. Differential Evolution (DE) is a robust metaheuristic algorithm that can find thresholds rapidly. However, it may be trapped in the local optimums and premature convergence occurs. In this paper, we incorporate EM algorithm to DE and introduce a novel algorithm called EM+DE which overcomes these shortages and can segment images better than EM and DE algorithms. In the proposed method, EM estimates Gaussian Mixture Model (GMM) coefficients of the histogram and DE tries to provide good volunteer solutions to EM algorithm when EM converges in local areas. Finally, DE fits GMM parameters based on Root Mean Square Error (RMSE) to reach the fittest curve. Ten standard test images and six famous metaheuristic algorithms are considered and result on global fitness. PSNR, SSIM, FSIM criteria and the computational time are given. The experimental results prove that the proposed algorithm outperforms the EM and DE as well as EM+ other natural-inspired algorithms in terms of segmentation criteria.
多层图像阈值分割是图像分割过程中必不可少的步骤。期望最大化(EM)是一种寻找阈值的强大技术，但对初始点很敏感。差分进化算法是一种鲁棒的能快速找到阈值的元启发式算法。但是，它可能会陷入局部最优，出现过早收敛。本文将EM算法与DE相结合，提出了一种新的算法EM+DE，克服了EM和DE算法的不足，可以更好地分割图像。在该方法中，EM估计直方图的高斯混合模型(GMM)系数，DE试图在EM局部收敛时为EM算法提供良好的志愿解决方案。最后，基于均方根误差(Root Mean Square Error, RMSE)对GMM参数进行拟合，得到拟合曲线。考虑了10个标准测试图像和6种著名的元启发式算法，并得出了全局适应度的结果。给出了PSNR、SSIM、FSIM准则和计算时间。实验结果表明，该算法在分割标准上优于EM和DE以及EM+其他自然算法。
{"title":"Multilevel Image Thresholding Based on Improved Expectation Maximization (EM) and Differential Evolution Algorithm","authors":"E. Ehsaeyan, A. Zolghadrasli","doi":"10.1142/s0219843621500134","DOIUrl":"https://doi.org/10.1142/s0219843621500134","url":null,"abstract":"Multilevel image thresholding is an essential step in the image segmentation process. Expectation Maximization (EM) is a powerful technique to find thresholds but is sensitive to the initial points. Differential Evolution (DE) is a robust metaheuristic algorithm that can find thresholds rapidly. However, it may be trapped in the local optimums and premature convergence occurs. In this paper, we incorporate EM algorithm to DE and introduce a novel algorithm called EM+DE which overcomes these shortages and can segment images better than EM and DE algorithms. In the proposed method, EM estimates Gaussian Mixture Model (GMM) coefficients of the histogram and DE tries to provide good volunteer solutions to EM algorithm when EM converges in local areas. Finally, DE fits GMM parameters based on Root Mean Square Error (RMSE) to reach the fittest curve. Ten standard test images and six famous metaheuristic algorithms are considered and result on global fitness. PSNR, SSIM, FSIM criteria and the computational time are given. The experimental results prove that the proposed algorithm outperforms the EM and DE as well as EM+ other natural-inspired algorithms in terms of segmentation criteria.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126978455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-01DOI: 10.1142/s0219843621500146
B. Beigzadeh, S. Razavi
Owing to their nonlinear structures and dynamics, bipedal walking robots are commonly used as appropriate case studies for nonlinear modeling and control. In this study, the dynamics of a point-feet 4-link biped robot having asymmetric structure is studied. This asymmetry appears on the robot’s legs such that one leg of the robot does have an active knee while the other is knee-less. In this way, the style and analysis of each step depends on which leg is the stance leg. Although the stable steady state behavior of the system is purely periodic, the gait cycle does consist of two sequential steps. Since each step includes a continuous phase followed by an impact phase, hence, we need to model the system as a multiphase (4-phase) hybrid system. The main purpose of this research is to find stable gating pattern and employ appropriate controller to make sure that the gating is accomplished in an asymptotically stable manner. A combination of feedback linearization and finite-time controllers is used to control the walking posture, and the stability of the whole behavior is investigated by analysis of a one-dimensional Poincaré map. Simulation results successfully support the modeling and control approach.
{"title":"Dynamic Walking Analysis of an Underactuated Biped Robot with Asymmetric Structure","authors":"B. Beigzadeh, S. Razavi","doi":"10.1142/s0219843621500146","DOIUrl":"https://doi.org/10.1142/s0219843621500146","url":null,"abstract":"Owing to their nonlinear structures and dynamics, bipedal walking robots are commonly used as appropriate case studies for nonlinear modeling and control. In this study, the dynamics of a point-feet 4-link biped robot having asymmetric structure is studied. This asymmetry appears on the robot’s legs such that one leg of the robot does have an active knee while the other is knee-less. In this way, the style and analysis of each step depends on which leg is the stance leg. Although the stable steady state behavior of the system is purely periodic, the gait cycle does consist of two sequential steps. Since each step includes a continuous phase followed by an impact phase, hence, we need to model the system as a multiphase (4-phase) hybrid system. The main purpose of this research is to find stable gating pattern and employ appropriate controller to make sure that the gating is accomplished in an asymptotically stable manner. A combination of feedback linearization and finite-time controllers is used to control the walking posture, and the stability of the whole behavior is investigated by analysis of a one-dimensional Poincaré map. Simulation results successfully support the modeling and control approach.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124463143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-14DOI: 10.1142/S0219843621500079
Jong-woo An, Youdong Zhao, Jangmyung Lee
A cooperative control of a manipulator and a human operator has been proposed for an efficient direct teaching operation in this research. The main goal is making the operator be convenient and relaxed when he is operating the manipulator for a direct teaching. The proposed control strategy has two layers: In the first layer, human motion estimator (HME) has been designed to estimate a human intention. The recursive least square method has been utilized for the HME to simultaneously estimate the interaction force and the human arm admittance model. In the second layer, human motion reactor has been designed to keep the human motion intention precisely by a proportional derivative and gravity compensation in real time. Real experiments with a 3-degree of freedom robotic manipulator guided by the human operator have been conducted to draw a diamond shape on a panel. The experimental results demonstrate the effectiveness of the proposed cooperative control strategy.
{"title":"Cooperative Control of Manipulator and Human Operator for Direct Teaching","authors":"Jong-woo An, Youdong Zhao, Jangmyung Lee","doi":"10.1142/S0219843621500079","DOIUrl":"https://doi.org/10.1142/S0219843621500079","url":null,"abstract":"A cooperative control of a manipulator and a human operator has been proposed for an efficient direct teaching operation in this research. The main goal is making the operator be convenient and relaxed when he is operating the manipulator for a direct teaching. The proposed control strategy has two layers: In the first layer, human motion estimator (HME) has been designed to estimate a human intention. The recursive least square method has been utilized for the HME to simultaneously estimate the interaction force and the human arm admittance model. In the second layer, human motion reactor has been designed to keep the human motion intention precisely by a proportional derivative and gravity compensation in real time. Real experiments with a 3-degree of freedom robotic manipulator guided by the human operator have been conducted to draw a diamond shape on a panel. The experimental results demonstrate the effectiveness of the proposed cooperative control strategy.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130738140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-09DOI: 10.1142/S0219843621500109
Jose C. Rojas-Rodriguez, A. Aguilar-Bustos, E. Bugarin
In this paper, we introduce an [Formula: see text] algorithm for the computation of the centroidal momentum matrix (CMM) and its time derivative using spatial algebra and expressed with Lie algebra operators. The proposed algorithm is applied to the postural balance of a humanoid robot using whole body control with quadratic programming. The employed tasks only require the CMM and its time derivative without the need of the joint space inertia matrix and the Coriolis terms reducing this way the computational cost of the controller. Finally, four simulation scenarios programmed in Julia are considered where several perturbations for the balance of the robot have been taken into account and according to the tracking graphs of the center of mass, centroidal momentum and the trajectories of the center of pressure it is concluded that the performance of the proposed algorithm is satisfactory.
{"title":"An O(N) Algorithm for the Computation of the Centroidal Dynamics with Application in the Postural Balance of a Humanoid Robot Using Whole Body Control","authors":"Jose C. Rojas-Rodriguez, A. Aguilar-Bustos, E. Bugarin","doi":"10.1142/S0219843621500109","DOIUrl":"https://doi.org/10.1142/S0219843621500109","url":null,"abstract":"In this paper, we introduce an [Formula: see text] algorithm for the computation of the centroidal momentum matrix (CMM) and its time derivative using spatial algebra and expressed with Lie algebra operators. The proposed algorithm is applied to the postural balance of a humanoid robot using whole body control with quadratic programming. The employed tasks only require the CMM and its time derivative without the need of the joint space inertia matrix and the Coriolis terms reducing this way the computational cost of the controller. Finally, four simulation scenarios programmed in Julia are considered where several perturbations for the balance of the robot have been taken into account and according to the tracking graphs of the center of mass, centroidal momentum and the trajectories of the center of pressure it is concluded that the performance of the proposed algorithm is satisfactory.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129714904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-09DOI: 10.1142/S0219843621500092
Mingchao Wang, Yuan Yuan, Huanhuan Yuan
In this paper, the sensorless force/position control problem is investigated for a general class of dynamic contact systems with both motion sensor noise and unknown kinetic friction by designing a force observer-based controller. Firstly, in order to suppress the effect of motion sensor noise, a dead-zone extended state observer (ESO) is introduced, and the contact force is estimated. Then, based on the force estimate, a controller is designed to realize force/position tracking control, where the parameters of the observer and controller are obtained by a linear matrix inequality (LMI) method. The sufficient conditions are provided to ensure the stability of the closed-loop system in terms of LMIs. Finally, a numerical simulation is carried out to illustrate the applicability and effectiveness of the proposed method.
{"title":"Dead-Zone ESO Based Sensorless Force/Position Control for Dynamic Contact Systems","authors":"Mingchao Wang, Yuan Yuan, Huanhuan Yuan","doi":"10.1142/S0219843621500092","DOIUrl":"https://doi.org/10.1142/S0219843621500092","url":null,"abstract":"In this paper, the sensorless force/position control problem is investigated for a general class of dynamic contact systems with both motion sensor noise and unknown kinetic friction by designing a force observer-based controller. Firstly, in order to suppress the effect of motion sensor noise, a dead-zone extended state observer (ESO) is introduced, and the contact force is estimated. Then, based on the force estimate, a controller is designed to realize force/position tracking control, where the parameters of the observer and controller are obtained by a linear matrix inequality (LMI) method. The sufficient conditions are provided to ensure the stability of the closed-loop system in terms of LMIs. Finally, a numerical simulation is carried out to illustrate the applicability and effectiveness of the proposed method.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"104 3-4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131490152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-09DOI: 10.1142/S0219843621500080
E. Hoffman, N. Tsagarakis
This paper proposes a Domain Specific Language to describe in a synthetic and comprehensive way, complex control problems for robotic systems. The proposed language, named Math of Tasks, abstracts from the mathematical description of the problem, which heavily depends on the particular algorithm chosen to solve it, relying on a set of operators and entities which instead, composed together, describes the behavior of the control problem. The Math of Tasks can describe any type of instantaneous controller regardless of the particular controlled variable (e.g., joint velocity, joint acceleration, contact forces). This paper shows the convenience of the proposed formalism using examples from classical control problems for different types of robotic platforms such as manipulators, humanoid bipeds, and quadrupeds.
本文提出了一种领域特定语言，以综合和全面的方式描述机器人系统的复杂控制问题。这种被称为任务数学(Math of Tasks)的语言是从问题的数学描述中抽象出来的，而问题的数学描述在很大程度上依赖于所选择的解决问题的特定算法，它依赖于一组运算符和实体，而这些运算符和实体组合在一起，描述了控制问题的行为。任务数学可以描述任何类型的瞬时控制器，而不考虑特定的控制变量(例如，关节速度，关节加速度，接触力)。本文用不同类型的机器人平台(如机械手、人形两足动物和四足动物)的经典控制问题的例子说明了所提出的形式主义的便利性。
{"title":"The Math of Tasks: A Domain Specific Language for Constraint-Based Task Specification","authors":"E. Hoffman, N. Tsagarakis","doi":"10.1142/S0219843621500080","DOIUrl":"https://doi.org/10.1142/S0219843621500080","url":null,"abstract":"This paper proposes a Domain Specific Language to describe in a synthetic and comprehensive way, complex control problems for robotic systems. The proposed language, named Math of Tasks, abstracts from the mathematical description of the problem, which heavily depends on the particular algorithm chosen to solve it, relying on a set of operators and entities which instead, composed together, describes the behavior of the control problem. The Math of Tasks can describe any type of instantaneous controller regardless of the particular controlled variable (e.g., joint velocity, joint acceleration, contact forces). This paper shows the convenience of the proposed formalism using examples from classical control problems for different types of robotic platforms such as manipulators, humanoid bipeds, and quadrupeds.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"168 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121319400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-04DOI: 10.1142/S0219843621500018
Xu Li, Songyuan Zhang, Haitao Zhou, Haibo Feng, Yili Fu
Compared with the traditional hydraulic humanoid robots, the WLR-II, a novel hydraulic wheel-legged robot developed by using hose-less design, can significantly increase the reliability and maneuverability. The WLR-II combines the rough-terrain capability of legs with the efficiency of wheels. In this paper, a novel framework called rough-terrain adaption framework (RTAF) is presented which allows WLR-II to move on both flat terrains and terrains with unmodeled contact dynamics. RTAF is a hierarchical framework, which has a high-level balance controller and a low-level impedance controller that a high-performance nested torque controller with feed-forward velocity compensation is used. The low-level impedance controller for the hydraulic-driven unit can cancel out the load dynamics influence such as unexpected terrain disturbances and increase the force-tracking performance. With the high-level balance controller, the robot is able to handle unexpected terrain disturbances through wheel-ground force estimation, pitch/roll balance control and impedance parameter regulator. The proposed approach is suitable for a wheel-legged humanoid robot to manage balance through torque control at joints and regulate force-based interaction on rough terrains. The performance of the proposed RTAF is evaluated on variable gradient slopes and grassland which are the typical rough-terrain scenarios for real-world applications. The experimental results reveal that the maximum speed of grassland movement can reach 3 km/h.
{"title":"Locomotion Adaption for Hydraulic Humanoid Wheel-Legged Robots Over Rough Terrains","authors":"Xu Li, Songyuan Zhang, Haitao Zhou, Haibo Feng, Yili Fu","doi":"10.1142/S0219843621500018","DOIUrl":"https://doi.org/10.1142/S0219843621500018","url":null,"abstract":"Compared with the traditional hydraulic humanoid robots, the WLR-II, a novel hydraulic wheel-legged robot developed by using hose-less design, can significantly increase the reliability and maneuverability. The WLR-II combines the rough-terrain capability of legs with the efficiency of wheels. In this paper, a novel framework called rough-terrain adaption framework (RTAF) is presented which allows WLR-II to move on both flat terrains and terrains with unmodeled contact dynamics. RTAF is a hierarchical framework, which has a high-level balance controller and a low-level impedance controller that a high-performance nested torque controller with feed-forward velocity compensation is used. The low-level impedance controller for the hydraulic-driven unit can cancel out the load dynamics influence such as unexpected terrain disturbances and increase the force-tracking performance. With the high-level balance controller, the robot is able to handle unexpected terrain disturbances through wheel-ground force estimation, pitch/roll balance control and impedance parameter regulator. The proposed approach is suitable for a wheel-legged humanoid robot to manage balance through torque control at joints and regulate force-based interaction on rough terrains. The performance of the proposed RTAF is evaluated on variable gradient slopes and grassland which are the typical rough-terrain scenarios for real-world applications. The experimental results reveal that the maximum speed of grassland movement can reach 3 km/h.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122826449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-19DOI: 10.1142/S0219843621500067
Chuqing Cao, Hanwei Liu
For robots in an unstructured work environment, grasping unknown objects that have neither model data nor RGB data is very important. The key to robotic autonomous grasping is not only in the judgment of object type but also in the shape of the object. We present a new grasping approach based on the basic compositions of objects. The simplification of complex objects is conducive to the description of object shape and provides effective ideas for the selection of grasping strategies. First, the depth camera is used to obtain partial 3D data of the target object. Then the 3D data are segmented and the segmented parts are simplified to a cylinder, a sphere, an ellipsoid, and a parallelepiped according to the geometric and semantic shape characteristics. The grasp pose is constrained according to the simplified shape feature and the core part of the object is used for grasping training using deep learning. The grasping model was evaluated in a simulation experiment and robot experiment, and the experiment result shows that learned grasp score using simplified constraints is more robust to gripper pose uncertainty than without simplified constraint.
{"title":"Grasp Pose Detection Based on Shape Simplification","authors":"Chuqing Cao, Hanwei Liu","doi":"10.1142/S0219843621500067","DOIUrl":"https://doi.org/10.1142/S0219843621500067","url":null,"abstract":"For robots in an unstructured work environment, grasping unknown objects that have neither model data nor RGB data is very important. The key to robotic autonomous grasping is not only in the judgment of object type but also in the shape of the object. We present a new grasping approach based on the basic compositions of objects. The simplification of complex objects is conducive to the description of object shape and provides effective ideas for the selection of grasping strategies. First, the depth camera is used to obtain partial 3D data of the target object. Then the 3D data are segmented and the segmented parts are simplified to a cylinder, a sphere, an ellipsoid, and a parallelepiped according to the geometric and semantic shape characteristics. The grasp pose is constrained according to the simplified shape feature and the core part of the object is used for grasping training using deep learning. The grasping model was evaluated in a simulation experiment and robot experiment, and the experiment result shows that learned grasp score using simplified constraints is more robust to gripper pose uncertainty than without simplified constraint.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115343604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-09DOI: 10.1142/S0219843621500031
G. G. Muscolo
This paper presents a novel biped-wheeled-wearable machine, named HANDSHAKE, and obtained by an evolution of two robots presented in other works: one flexible-wheeled leg and one biped-flexible-wheeled robot. A critical design analysis of these two robots helped the author to propose a novel machine able to revolutionize the lower body exoskeletons’ world. Conceptual and functional design, mechanical behavior (kinematics and dynamics), and multibody simulation of the biped-wheeled exoskeleton are presented in this paper, and a first reduced scale prototype is used to show the feasibility of the proposed solution. The simple control architecture used in this work underlines the enormous advantages to use the HANDSHAKE system for people with a complete absence of mobility, which are completely supported by this machine. This is possible thanks to the wheeled feet of the HANDSHAKE system which allow to support more weights respect to the classical exoskeletons, available on market and literature. The proposed machine increases stability, dynamic balance, autonomy, reducing power supply and complexity in comparison with classical exoskeleton systems because the wheeled feet are always in contact with the ground. These advantages, recognized in humanoid robots, may be used also in exoskeletons.
{"title":"HANDSHAKE: HANDling System for Human Autonomous KEeping","authors":"G. G. Muscolo","doi":"10.1142/S0219843621500031","DOIUrl":"https://doi.org/10.1142/S0219843621500031","url":null,"abstract":"This paper presents a novel biped-wheeled-wearable machine, named HANDSHAKE, and obtained by an evolution of two robots presented in other works: one flexible-wheeled leg and one biped-flexible-wheeled robot. A critical design analysis of these two robots helped the author to propose a novel machine able to revolutionize the lower body exoskeletons’ world. Conceptual and functional design, mechanical behavior (kinematics and dynamics), and multibody simulation of the biped-wheeled exoskeleton are presented in this paper, and a first reduced scale prototype is used to show the feasibility of the proposed solution. The simple control architecture used in this work underlines the enormous advantages to use the HANDSHAKE system for people with a complete absence of mobility, which are completely supported by this machine. This is possible thanks to the wheeled feet of the HANDSHAKE system which allow to support more weights respect to the classical exoskeletons, available on market and literature. The proposed machine increases stability, dynamic balance, autonomy, reducing power supply and complexity in comparison with classical exoskeleton systems because the wheeled feet are always in contact with the ground. These advantages, recognized in humanoid robots, may be used also in exoskeletons.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128042401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-02DOI: 10.1142/S021984362150002X
Tianyi Ko, Kazuya Murotani, Ko Yamamoto, Yoshihiko Nakamura
Joints’ backdrivability is desired for robots that perform tasks contacting the environment, in addition to the high torque and fast response property. The electro-hydrostatic actuator (EHA) is an approach to realize force-sensitive robots. To experimentally confirm the performance of a biped robot driven by EHAs, we developed the fully electro-hydrostatically driven humanoid robot Hydra. In this paper, we evaluate the whole-body control performance realized by integrating encoders, pressure sensors, and IMU through a high-speed communication bus to the distributed whole-body control system. We report the first example of bipedal locomotion by an EHA-driven robot in both position-controlled and torque-controlled approaches. The robot could keep the balance even when the ground condition was changing impulsively and utilize its high joint backdrivability to absorb a disturbance by the null space compliance. We also report practical challenges in implementing compliant control in real hardware with limitations in parameter accuracy, torque, and response. We experimentally confirmed that the resolved viscoelasticity control (RVC), which has indirect feedback of operational space tasks by projecting the operational space feedback gain to the joint space one, was effective to tune a proper gain to stabilize the center-of-mass motion while avoiding joint-level oscillation invoked by the control bandwidth limitation. The attached multimedia file includes the video of all experiments presented in the paper.
{"title":"Whole-Body Compliant Motion by Sensor Integration of an EHA-Driven Humanoid Hydra","authors":"Tianyi Ko, Kazuya Murotani, Ko Yamamoto, Yoshihiko Nakamura","doi":"10.1142/S021984362150002X","DOIUrl":"https://doi.org/10.1142/S021984362150002X","url":null,"abstract":"Joints’ backdrivability is desired for robots that perform tasks contacting the environment, in addition to the high torque and fast response property. The electro-hydrostatic actuator (EHA) is an approach to realize force-sensitive robots. To experimentally confirm the performance of a biped robot driven by EHAs, we developed the fully electro-hydrostatically driven humanoid robot Hydra. In this paper, we evaluate the whole-body control performance realized by integrating encoders, pressure sensors, and IMU through a high-speed communication bus to the distributed whole-body control system. We report the first example of bipedal locomotion by an EHA-driven robot in both position-controlled and torque-controlled approaches. The robot could keep the balance even when the ground condition was changing impulsively and utilize its high joint backdrivability to absorb a disturbance by the null space compliance. We also report practical challenges in implementing compliant control in real hardware with limitations in parameter accuracy, torque, and response. We experimentally confirmed that the resolved viscoelasticity control (RVC), which has indirect feedback of operational space tasks by projecting the operational space feedback gain to the joint space one, was effective to tune a proper gain to stabilize the center-of-mass motion while avoiding joint-level oscillation invoked by the control bandwidth limitation. The attached multimedia file includes the video of all experiments presented in the paper.","PeriodicalId":312776,"journal":{"name":"Int. J. Humanoid Robotics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130918906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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