A compliant constant-force mechanism (CCFM) is a specific type of compliant mechanism that serves as a passive force regulation device. When subjected to a load, it undergoes deformation, resulting in an almost consistent output force regardless of changes in input displacement. Traditional methods used to design CCFMs typically rely on either stiffness combination or geometric optimization based on existing design configurations. To enable the direct synthesis of CCFMs according to desired boundary conditions, this study proposes a systematic topology optimization method to accomplish this objective. Using this approach, a CCFM suitable for end effector applications is designed and manufactured through 3D printing. Four of these CCFMs are then utilized to create an innovative compliant constant-force end effector for robotic operations on uneven surfaces. The experimental results demonstrate that the presented design achieves output force modulation through elastic deformation, eliminating the need for additional sensors and controllers to regulate the output force. The presented design can be mounted on a robotic arm to provide overload protection and maintain a consistent force output during operation when encountering irregular and uneven surfaces.
{"title":"Topology Optimization of a Compliant Constant-Force End Effector for Robotic Operations over Uneven Surfaces","authors":"Chih-Hsing Liu, Yuan-Ping Ho, Jui-Chih Chi","doi":"10.1115/1.4065119","DOIUrl":"https://doi.org/10.1115/1.4065119","url":null,"abstract":"\u0000 A compliant constant-force mechanism (CCFM) is a specific type of compliant mechanism that serves as a passive force regulation device. When subjected to a load, it undergoes deformation, resulting in an almost consistent output force regardless of changes in input displacement. Traditional methods used to design CCFMs typically rely on either stiffness combination or geometric optimization based on existing design configurations. To enable the direct synthesis of CCFMs according to desired boundary conditions, this study proposes a systematic topology optimization method to accomplish this objective. Using this approach, a CCFM suitable for end effector applications is designed and manufactured through 3D printing. Four of these CCFMs are then utilized to create an innovative compliant constant-force end effector for robotic operations on uneven surfaces. The experimental results demonstrate that the presented design achieves output force modulation through elastic deformation, eliminating the need for additional sensors and controllers to regulate the output force. The presented design can be mounted on a robotic arm to provide overload protection and maintain a consistent force output during operation when encountering irregular and uneven surfaces.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"112 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140233814","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}
Angelica Ginnante, Stéphane Caro, Enrico Simetti, François Leborne
Determining the workspace of a robotic manipulator is highly significant for knowing its abilities and planning the robot application. Several techniques exist for robot workspace determination. However, these methods are usually affected by computational redundancy, like in the Monte Carlo based method case, and their implementation can be complex. The workspace analysis of kinematic redundant manipulators is even more complex. This paper proposes a kinematically optimized ray-based workspace determination algorithm based on a simple idea and not affected by computational redundancy. The proposed method can be applied to any serial robot but is tested only on spatial kinematic redundant robots. The results show how the approach can correctly determine the robot workspace boundaries in a short time. Then, the correctness and computational time of the proposed optimized ray-based method are compared to pseudo-inverse Jacobian ray-based and Monte Carlo methods. The comparison demonstrates that the proposed method has better results in a shorter time. Finally, some limitations of the proposed algorithm are discussed.
{"title":"Optimized Ray-Based Method for Workspace Determination of Kinematic Redundant Manipulators","authors":"Angelica Ginnante, Stéphane Caro, Enrico Simetti, François Leborne","doi":"10.1115/1.4065071","DOIUrl":"https://doi.org/10.1115/1.4065071","url":null,"abstract":"\u0000 Determining the workspace of a robotic manipulator is highly significant for knowing its abilities and planning the robot application. Several techniques exist for robot workspace determination. However, these methods are usually affected by computational redundancy, like in the Monte Carlo based method case, and their implementation can be complex. The workspace analysis of kinematic redundant manipulators is even more complex. This paper proposes a kinematically optimized ray-based workspace determination algorithm based on a simple idea and not affected by computational redundancy. The proposed method can be applied to any serial robot but is tested only on spatial kinematic redundant robots. The results show how the approach can correctly determine the robot workspace boundaries in a short time. Then, the correctness and computational time of the proposed optimized ray-based method are compared to pseudo-inverse Jacobian ray-based and Monte Carlo methods. The comparison demonstrates that the proposed method has better results in a shorter time. Finally, some limitations of the proposed algorithm are discussed.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"41 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140242763","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}
Ming-Chang Hsu, Hsuan-Yu Chen, Christina Soong, Ting-Jen Yeh
This paper proposes a novel wearable device to monitor and record the posture and alignment of spine. The proposed device adopts an underactuated mechanism design which allows it to adapt to the multiple-degrees-of-freedom spinal posture with minimum weight and complexity. To ensure the validity of measurement and comfort of wearing, the mechanism parameters are determined firstly by considering a special posture then are fine-tuned using an optimization algorithm so that uniform contact forces for several selected spinal postures can be achieved. Experiments demonstrate that the device can automatically maintain contact with the wearer's back and offer real-time spinal posture and alignment data for medical diagnosis and treatment.
{"title":"Design and Optimization of a Wearable Under-actuated Mechanism for Spinal Posture Measurement","authors":"Ming-Chang Hsu, Hsuan-Yu Chen, Christina Soong, Ting-Jen Yeh","doi":"10.1115/1.4065075","DOIUrl":"https://doi.org/10.1115/1.4065075","url":null,"abstract":"\u0000 This paper proposes a novel wearable device to monitor and record the posture and alignment of spine. The proposed device adopts an underactuated mechanism design which allows it to adapt to the multiple-degrees-of-freedom spinal posture with minimum weight and complexity. To ensure the validity of measurement and comfort of wearing, the mechanism parameters are determined firstly by considering a special posture then are fine-tuned using an optimization algorithm so that uniform contact forces for several selected spinal postures can be achieved. Experiments demonstrate that the device can automatically maintain contact with the wearer's back and offer real-time spinal posture and alignment data for medical diagnosis and treatment.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"24 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140243105","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}
The spatial Cable-driven parallel robots (CDPRs) with low DOF (degree of freedom n<6) are like the physiological structure of bone and muscles, which are suitable to design humanoid joints. Therefore, the type synthesis of the CDPR is of great interest for the design of new humanoid wrist joints. In this paper, we present a type synthesis of the coupled-input CDPRs to design a 3-DOF wrist. Coupled-input means that one actuator controls more than one cable. First, the Yamanouchi symbols of the coupled-input CDPRs are listed using the permutation group. In addition, two winding methods for the cable and the actuator are defined in the coupled-input CDPRs. Finally, a topology configuration of the coupled-input CDPR suitable for the 3-DOF wrist model is determined based on a comparative analysis of the workspaces of a class of coupled-input CDPRs. It is shown that type synthesis of the coupled-input CDPRs is an effective way to innovate low DOF CDPRs.
{"title":"Type synthesis of a 3-DOF wrist applying the coupled-input cable-driven parallel robot","authors":"Shibo Liu, Jiangping Mei, Panfeng Wang, Fang Guo, Jiaxing Li, Shuai Wang, Ruizhi Wang","doi":"10.1115/1.4065083","DOIUrl":"https://doi.org/10.1115/1.4065083","url":null,"abstract":"\u0000 The spatial Cable-driven parallel robots (CDPRs) with low DOF (degree of freedom n<6) are like the physiological structure of bone and muscles, which are suitable to design humanoid joints. Therefore, the type synthesis of the CDPR is of great interest for the design of new humanoid wrist joints. In this paper, we present a type synthesis of the coupled-input CDPRs to design a 3-DOF wrist. Coupled-input means that one actuator controls more than one cable. First, the Yamanouchi symbols of the coupled-input CDPRs are listed using the permutation group. In addition, two winding methods for the cable and the actuator are defined in the coupled-input CDPRs. Finally, a topology configuration of the coupled-input CDPR suitable for the 3-DOF wrist model is determined based on a comparative analysis of the workspaces of a class of coupled-input CDPRs. It is shown that type synthesis of the coupled-input CDPRs is an effective way to innovate low DOF CDPRs.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"68 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140242393","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}
Continuum robots have continuous structures and inherent compliance, which can be used for accessing unstructured and confined space in many fields, such as minimally invasive surgery and aero-engine in-situ inspection. A novel continuum robot connected by unique offset cross shaft joints is proposed in this paper, which has excellent bending capacity and appropriate torsional stiffness. Meanwhile, a cable-driven system is designed to actuate it. Furthermore, the kinematic modeling and analysis are carried out. The mappings among robot's actuator space, joint space and task space are established step by step. Particularly, an improved inverse kinematics algorithm is proposed by combining the constant curvature method with the numerical iterative method. This combined inverse kinematics algorithm can effectively reduce the error of approximate solution derived by the traditional constant curvature method. Numerical simulations are conducted to verify the proposed algorithm and analyze workspace of the continuum robot. Finally, experimental prototype of the robot is built to verify its excellent bending capacity and the correctness of the proposed kinematic model.
{"title":"Design and kinematics of a novel continuum robot connected by unique offset cross revolute joints","authors":"Xuhao Wang, Chengfa Wang, Mengli Wu, Mingyu Li, Yilong Xu, Guanhao Li, Zhiyong Guo, Yiran Cao","doi":"10.1115/1.4065084","DOIUrl":"https://doi.org/10.1115/1.4065084","url":null,"abstract":"\u0000 Continuum robots have continuous structures and inherent compliance, which can be used for accessing unstructured and confined space in many fields, such as minimally invasive surgery and aero-engine in-situ inspection. A novel continuum robot connected by unique offset cross shaft joints is proposed in this paper, which has excellent bending capacity and appropriate torsional stiffness. Meanwhile, a cable-driven system is designed to actuate it. Furthermore, the kinematic modeling and analysis are carried out. The mappings among robot's actuator space, joint space and task space are established step by step. Particularly, an improved inverse kinematics algorithm is proposed by combining the constant curvature method with the numerical iterative method. This combined inverse kinematics algorithm can effectively reduce the error of approximate solution derived by the traditional constant curvature method. Numerical simulations are conducted to verify the proposed algorithm and analyze workspace of the continuum robot. Finally, experimental prototype of the robot is built to verify its excellent bending capacity and the correctness of the proposed kinematic model.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"32 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140242786","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}
Loïc Tissot-Daguette, Florent Cosandier, E. Thalmann, S. Henein
Flexure pivots, which are widely used for precision mechanisms, generally have the drawback of presenting parasitic shifts accompanying their rotation. The known solutions for canceling these undesirable parasitic translations usually induce a loss in radial stiffness, a reduction of the angular stroke, and nonlinear moment-angle characteristics. This article introduces a novel family of kinematic structures based on coupled n-RRR planar parallel mechanisms which presents exact zero parasitic shifts, while alleviating the drawbacks of some known pivoting structures. Based on this invention, three symmetrical architectures have been designed and implemented as flexure-based pivots. The performance of the newly introduced pivots has been compared with two known planar flexure pivots having theoretically zero parasitic shift via Finite Element models and experiments performed on plastic mockups. The results show that the newly introduced flexure pivots are an order of magnitude radially stiffer than the considered pivots from the state of the art, while having equivalent angular strokes. To experimentally evaluate the parasitic shift of the novel pivots, one of the architectures was manufactured in titanium alloy using wire-cut electrical discharge machining. This prototype exhibits a parasitic shift under 1.5 µm over a rotation stroke of ±15°, validating the near-zero parasitic shift properties of the presented designs. These advantages are key to applications such as mechanical time bases, surgical robotics, or optomechanical mechanisms.
{"title":"NEAR-ZERO PARASITIC SHIFT FLEXURE PIVOTS BASED ON COUPLED N-RRR PLANAR PARALLEL MECHANISMS","authors":"Loïc Tissot-Daguette, Florent Cosandier, E. Thalmann, S. Henein","doi":"10.1115/1.4065074","DOIUrl":"https://doi.org/10.1115/1.4065074","url":null,"abstract":"\u0000 Flexure pivots, which are widely used for precision mechanisms, generally have the drawback of presenting parasitic shifts accompanying their rotation. The known solutions for canceling these undesirable parasitic translations usually induce a loss in radial stiffness, a reduction of the angular stroke, and nonlinear moment-angle characteristics. This article introduces a novel family of kinematic structures based on coupled n-RRR planar parallel mechanisms which presents exact zero parasitic shifts, while alleviating the drawbacks of some known pivoting structures. Based on this invention, three symmetrical architectures have been designed and implemented as flexure-based pivots. The performance of the newly introduced pivots has been compared with two known planar flexure pivots having theoretically zero parasitic shift via Finite Element models and experiments performed on plastic mockups. The results show that the newly introduced flexure pivots are an order of magnitude radially stiffer than the considered pivots from the state of the art, while having equivalent angular strokes. To experimentally evaluate the parasitic shift of the novel pivots, one of the architectures was manufactured in titanium alloy using wire-cut electrical discharge machining. This prototype exhibits a parasitic shift under 1.5 µm over a rotation stroke of ±15°, validating the near-zero parasitic shift properties of the presented designs. These advantages are key to applications such as mechanical time bases, surgical robotics, or optomechanical mechanisms.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"26 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140241974","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}
A tensegrity-based robot is a locomotive robot that operates on the principle of tensegrity, allowing it to change its shape by adjusting its internal prestress. Tensegrity-based robots can be categorized into different types based on their shape, with the spherical tensegrity-based robot garnering the most attention. However, existing designs for spherical tensegrity-based robots tend to be relatively simple and lack standardized criteria for evaluating their performance. This paper proposes an optimization approach using the force density method to design new spherical regular tensegrity configurations. This is achieved by parameterizing the topology and configuration of the structure, taking into account structural symmetry and the even distribution of internal forces. The proposed approach not only generates classical tensegrities but also novel configurations suitable for locomotive robots. To preliminary evaluate the suitability of classical tensegrities and novel tensegrities to be used as a rolling robot, a set of performance indexes including inner space, compactability, prestress evenness, gait repeatability, tilt stability ratio, stride length, and path efficiency are proposed. The proposed indexes can be quickly determined based on the geometry of the tensegrity and thus are useful in the conceptual selection of the spherical tensegrities for rolling robots. They are used to evaluate a set of six spherical tensegrities. Numerical simulations are carried out to verify the feasibility of geometry-based approximating the gait-dependent indexes. Through the evaluation, a novel spherical tensegrity consisting of 15 struts and 60 tendons is identified as a promising candidate for rolling robots.
{"title":"Form-finding and evaluation of spherical tensegrity towards applying in locomotive robots","authors":"Meijia Wang, Yafeng Wang, Xian Xu","doi":"10.1115/1.4065072","DOIUrl":"https://doi.org/10.1115/1.4065072","url":null,"abstract":"\u0000 A tensegrity-based robot is a locomotive robot that operates on the principle of tensegrity, allowing it to change its shape by adjusting its internal prestress. Tensegrity-based robots can be categorized into different types based on their shape, with the spherical tensegrity-based robot garnering the most attention. However, existing designs for spherical tensegrity-based robots tend to be relatively simple and lack standardized criteria for evaluating their performance. This paper proposes an optimization approach using the force density method to design new spherical regular tensegrity configurations. This is achieved by parameterizing the topology and configuration of the structure, taking into account structural symmetry and the even distribution of internal forces. The proposed approach not only generates classical tensegrities but also novel configurations suitable for locomotive robots. To preliminary evaluate the suitability of classical tensegrities and novel tensegrities to be used as a rolling robot, a set of performance indexes including inner space, compactability, prestress evenness, gait repeatability, tilt stability ratio, stride length, and path efficiency are proposed. The proposed indexes can be quickly determined based on the geometry of the tensegrity and thus are useful in the conceptual selection of the spherical tensegrities for rolling robots. They are used to evaluate a set of six spherical tensegrities. Numerical simulations are carried out to verify the feasibility of geometry-based approximating the gait-dependent indexes. Through the evaluation, a novel spherical tensegrity consisting of 15 struts and 60 tendons is identified as a promising candidate for rolling robots.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"5 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140243480","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}
A 3D printing is a rapidly growing and evolving field filled with a diverse array of printers capable of printing an equally as diverse amount of material. A new type of material extrusion 3D printer was recently developed and features the capabilities of printing infinitely long objects due to design decision of angling the XY plane and incorporating a rotating bed. The innovative design for the infinite 3D printer features a 2-DoF planar parallel manipulator (PPM) that will control the hot-end motion in the XY plane. This innovative design will greatly reduce the mass of moving parts in comparison to other infinite 3D printers. This reduction of weight will reduce inertia and allow for this new printer to achieve higher accelerations. In addition to the development of the new 3D printer, this paper presents a kinematic and dynamic model of the angled PPM, a finite element analysis of the critical components of the PPM, and an optimization approach to determine arm length of the PPM. The dynamic model simulation was developed in MATLAB and the results were compared with field data collected to verify the model. A meta-heuristic optimization was performed to optimize arm length of the connectors while maximizing the dynamic performance of the PPM with consideration of the usable workspace. The results of these examinations yield a validated mechanism that will be suitable for the development of a new type of infinite 3D printer.
{"title":"New Design and Prototype of 2-degree-of-freedom Planar Parallel Manipulator for Use In Creating an Infinite 3D Printer","authors":"Miguel De La Melena, Shanzhong Duan","doi":"10.1115/1.4065082","DOIUrl":"https://doi.org/10.1115/1.4065082","url":null,"abstract":"\u0000 A 3D printing is a rapidly growing and evolving field filled with a diverse array of printers capable of printing an equally as diverse amount of material. A new type of material extrusion 3D printer was recently developed and features the capabilities of printing infinitely long objects due to design decision of angling the XY plane and incorporating a rotating bed. The innovative design for the infinite 3D printer features a 2-DoF planar parallel manipulator (PPM) that will control the hot-end motion in the XY plane. This innovative design will greatly reduce the mass of moving parts in comparison to other infinite 3D printers. This reduction of weight will reduce inertia and allow for this new printer to achieve higher accelerations. In addition to the development of the new 3D printer, this paper presents a kinematic and dynamic model of the angled PPM, a finite element analysis of the critical components of the PPM, and an optimization approach to determine arm length of the PPM. The dynamic model simulation was developed in MATLAB and the results were compared with field data collected to verify the model. A meta-heuristic optimization was performed to optimize arm length of the connectors while maximizing the dynamic performance of the PPM with consideration of the usable workspace. The results of these examinations yield a validated mechanism that will be suitable for the development of a new type of infinite 3D printer.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140241817","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}
Rejecting impact force by adjusting footsteps during walking is crucial for a humanoid robot in an interactive environment. This paper proposes an optimal footstep regulation trigger based on the framework of the singular-linear-quadratic-preview (SLQP) walking controller and our footstep adjustment strategy. The trigger avoids regulating the footstep in every cycle to reduce the computational cost. Moreover, adjusting the footstep at the optimal trigger time achieves lower regulation cost than before and after the optimal trigger time. Before implementing the optimal trigger, we propose a method to identify the impact force occurrence based on the feedback acceleration and zero moment point (ZMP). After that, a determining function about system states is calculated over time. According to our analysis, the regulation cost meets the least extremum when the value of the determining function is null. The moment is taken as the optimal trigger time. Our method is demonstrated by experiments with multiple directions of impact forces.
{"title":"Impact Disturbance Rejection for a Humanoid Robot with Optimal Footstep Regulation Trigger","authors":"Runming Zhang, Xuechao Chen, Yu Zhang, Zhangguo Yu, Qiang Huang","doi":"10.1115/1.4065024","DOIUrl":"https://doi.org/10.1115/1.4065024","url":null,"abstract":"\u0000 Rejecting impact force by adjusting footsteps during walking is crucial for a humanoid robot in an interactive environment. This paper proposes an optimal footstep regulation trigger based on the framework of the singular-linear-quadratic-preview (SLQP) walking controller and our footstep adjustment strategy. The trigger avoids regulating the footstep in every cycle to reduce the computational cost. Moreover, adjusting the footstep at the optimal trigger time achieves lower regulation cost than before and after the optimal trigger time. Before implementing the optimal trigger, we propose a method to identify the impact force occurrence based on the feedback acceleration and zero moment point (ZMP). After that, a determining function about system states is calculated over time. According to our analysis, the regulation cost meets the least extremum when the value of the determining function is null. The moment is taken as the optimal trigger time. Our method is demonstrated by experiments with multiple directions of impact forces.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"40 25","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140076998","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}
Brianne Hargrove, M. Frecker, Angela Nastevska, J. Jovanova
While nonlinear-elastic materials demonstrate potential in enhancing the performance of compliant mechanisms, their behavior still needs to be captured in a generalized mechanical model. To inform new designs and functionality of compliant mechanisms, a better understanding of nonlinear-elastic materials is necessary and, in particular, their mechanical properties that often differ in tension and compression. In the current work, a beam-based analytical model incorporating nonlinear-elastic material behavior is defined for a folding compliant mechanism geometry. Exact equations are derived capturing the nonlinear curvature profile and shift in the neutral axis due to the material asymmetry. The deflection and curvature profile are compared with finite element analysis along with stress-distribution across the beam thickness. The analytical model is shown to be a good approximation of the behavior of nonlinear-elastic materials with tension-compression asymmetry under the assumptions of the von Kármán strain theory. Through a segmentation approach, the geometries of a semicircular arc and folding compliant mechanism design are defined. The deflection of the folding compliant mechanism due to an applied tip load is then evaluated against finite element analysis and experimental results. The generalized methods presented highlight the utility of the model for designing and predicting the behavior of other compliant mechanism geometries and different nonlinear-elastic materials.
虽然非线性弹性材料在提高顺应式机构性能方面表现出潜力，但其行为仍需要在通用机械模型中加以捕捉。要为顺应机构的新设计和功能提供信息，就必须更好地了解非线性弹性材料，特别是它们在拉伸和压缩时通常不同的机械特性。在当前的研究中，针对折叠式顺应机构的几何形状，定义了一个基于梁的分析模型，其中包含非线性弹性材料行为。精确方程的推导捕捉到了非线性曲率曲线和由于材料不对称造成的中轴线偏移。挠度和曲率曲线与有限元分析以及横梁厚度上的应力分布进行了比较。结果表明，在 von Kármán 应变理论的假设条件下，该分析模型可以很好地逼近具有拉伸-压缩不对称的非线性弹性材料的行为。通过分段方法，定义了半圆弧和折叠顺应机构设计的几何形状。然后，根据有限元分析和实验结果，评估了折叠顺应机构在施加顶端载荷时的挠度。所介绍的通用方法强调了该模型在设计和预测其他顺从机构几何形状和不同非线性弹性材料行为方面的实用性。
{"title":"An Analytical Model for Nonlinear-Elastic Compliant Mechanisms with Tension-Compression Asymmetry","authors":"Brianne Hargrove, M. Frecker, Angela Nastevska, J. Jovanova","doi":"10.1115/1.4065025","DOIUrl":"https://doi.org/10.1115/1.4065025","url":null,"abstract":"\u0000 While nonlinear-elastic materials demonstrate potential in enhancing the performance of compliant mechanisms, their behavior still needs to be captured in a generalized mechanical model. To inform new designs and functionality of compliant mechanisms, a better understanding of nonlinear-elastic materials is necessary and, in particular, their mechanical properties that often differ in tension and compression. In the current work, a beam-based analytical model incorporating nonlinear-elastic material behavior is defined for a folding compliant mechanism geometry. Exact equations are derived capturing the nonlinear curvature profile and shift in the neutral axis due to the material asymmetry. The deflection and curvature profile are compared with finite element analysis along with stress-distribution across the beam thickness. The analytical model is shown to be a good approximation of the behavior of nonlinear-elastic materials with tension-compression asymmetry under the assumptions of the von Kármán strain theory. Through a segmentation approach, the geometries of a semicircular arc and folding compliant mechanism design are defined. The deflection of the folding compliant mechanism due to an applied tip load is then evaluated against finite element analysis and experimental results. The generalized methods presented highlight the utility of the model for designing and predicting the behavior of other compliant mechanism geometries and different nonlinear-elastic materials.","PeriodicalId":508172,"journal":{"name":"Journal of Mechanisms and Robotics","volume":"31 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140260537","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：