A class of 5 degree-of-freedom (DoF) hybrid robots consisting of one translational and two rotational (1T2R) parallel module and 2T serial module is presented for assembling in the aircraft cabin. The 1T2R parallel modules are with three limb topologies (PRS, RRS and internal closed-loop) and two layouts (symmetrical and “T” shape). Herein, P, R and S denote prismatic, rotational and spherical joints. This paper presents the multi-objective optimization of the hybrid robot regarding different limb topology, limb layout and corresponding dimensions as design variables. Considering demands from the in-cabin assembling, kinematic, linear stiffness along z-axis and total mass of the robot are the objectives. The Pareto fronts and cooperative equilibrium point (CEP) indicate that the robot with 3-PRS and 3-RRS parallel module have better performances than the one with internal closed-loop. The overall performances of robot with symmetrical layout are superior than the one with “T” shape layout. In addition, two optimization methods are compared. One is to separately optimize six robots with specific topology and layout. The other is to optimize all design variables in a model. It is found that six robots have their own performance zones. Therefore, final optimums of two methods are close to each other. But optimization in one model is able to eliminate unfeasible topologies in the early stage of searching and thus is more efficient. Optimal module is 3-PRS with symmetrical layout. Experiments on the physical prototype validates performances of the optimal robot.
{"title":"Optimal design of assembling robot considering different limb topologies and layouts","authors":"Binbin Lian, Jinhua Guo, Zhiyuan He, Yimin Song","doi":"10.1115/1.4065999","DOIUrl":"https://doi.org/10.1115/1.4065999","url":null,"abstract":"\u0000 A class of 5 degree-of-freedom (DoF) hybrid robots consisting of one translational and two rotational (1T2R) parallel module and 2T serial module is presented for assembling in the aircraft cabin. The 1T2R parallel modules are with three limb topologies (PRS, RRS and internal closed-loop) and two layouts (symmetrical and “T” shape). Herein, P, R and S denote prismatic, rotational and spherical joints. This paper presents the multi-objective optimization of the hybrid robot regarding different limb topology, limb layout and corresponding dimensions as design variables. Considering demands from the in-cabin assembling, kinematic, linear stiffness along z-axis and total mass of the robot are the objectives. The Pareto fronts and cooperative equilibrium point (CEP) indicate that the robot with 3-PRS and 3-RRS parallel module have better performances than the one with internal closed-loop. The overall performances of robot with symmetrical layout are superior than the one with “T” shape layout. In addition, two optimization methods are compared. One is to separately optimize six robots with specific topology and layout. The other is to optimize all design variables in a model. It is found that six robots have their own performance zones. Therefore, final optimums of two methods are close to each other. But optimization in one model is able to eliminate unfeasible topologies in the early stage of searching and thus is more efficient. Optimal module is 3-PRS with symmetrical layout. Experiments on the physical prototype validates performances of the optimal robot.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"7 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141642782","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}
This paper presents the design and optimization of a cable-driven parallel polishing robot (CDPPR) with kinematic error modeling and introduces an improved non-dominated sorting genetic algorithm II (NSGA-II) for multi-objective optimization. First, the mechanical design and kinematic and static modeling of the CDPPR are conducted. Subsequently, a kinematic error transfer model is established based on the evidence theory by considering the change of exit points of cables, and an error index is derived to measure the accuracy of the robot. Besides, another two performance indices including the workspace and static stiffness are also proposed. Thus, a multi-objective optimization model is established to optimize the workspace, static stiffness, and error index, and an improved NSGA-II is developed. Finally, an experimental scaled prototype of the CDPPR is constructed, and numerical examples and experimental results demonstrate the effectiveness of the improved NSGA-II and the stability of the optimal configuration.
{"title":"Design and Optimization of a Cable-driven Parallel Polishing Robot with Kinematic Error Modeling","authors":"Bin Zhou, Shuainan Wu, Bin Zi, Weidong Zhu","doi":"10.1115/1.4065915","DOIUrl":"https://doi.org/10.1115/1.4065915","url":null,"abstract":"\u0000 This paper presents the design and optimization of a cable-driven parallel polishing robot (CDPPR) with kinematic error modeling and introduces an improved non-dominated sorting genetic algorithm II (NSGA-II) for multi-objective optimization. First, the mechanical design and kinematic and static modeling of the CDPPR are conducted. Subsequently, a kinematic error transfer model is established based on the evidence theory by considering the change of exit points of cables, and an error index is derived to measure the accuracy of the robot. Besides, another two performance indices including the workspace and static stiffness are also proposed. Thus, a multi-objective optimization model is established to optimize the workspace, static stiffness, and error index, and an improved NSGA-II is developed. Finally, an experimental scaled prototype of the CDPPR is constructed, and numerical examples and experimental results demonstrate the effectiveness of the improved NSGA-II and the stability of the optimal configuration.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"70 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141655354","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}
Mostaan Lotfalian Saremi, Isabella Ziv, Onur Asan, A. E. Bayrak
Intelligent systems have been rapidly evolving and play a pivotal role in assisting individuals across diverse domains, from healthcare to transportation. Understanding the dynamics of human-Artificial Intelligence (AI) partnering, particularly how humans trust and collaborate with intelligent systems, is becoming increasingly critical to design effective systems. This paper presents an experimental analysis to assess the impact of AI design attributes on users' trust, workload and performance when solving classification problems supported by an AI assistant. Specifically, we study the effect of transparency, fairness, and robustness in the design of an AI assistant and analyze the role of participants' gender and education background on the outcomes. The experiment is conducted with 47 students in undergraduate, master's and Ph.D. programs using a drawing game application where the users are asked to recognize incomplete sketches revealed progressively while receiving recommendations from multiple versions of an AI assistant. The results show that when collaborating with the AI, participants achieve a higher performance than their individual performance or the performance of the AI. The results also show that gender does not have an impact on users' trust and performance when collaborating with different versions of the AI system, whereas education level has a significant impact on the participants' performance but not on trust. Finally, the impact of design attributes on participants' trust and performance highly depends on the accuracy of the AI recommendations, and improvements in participants' performance and trust in some cases come at the expense of increased workload.
{"title":"Trust, Workload and Performance in Human-AI Partnering: The Role of AI Attributes in Solving Classification Problems","authors":"Mostaan Lotfalian Saremi, Isabella Ziv, Onur Asan, A. E. Bayrak","doi":"10.1115/1.4065916","DOIUrl":"https://doi.org/10.1115/1.4065916","url":null,"abstract":"\u0000 Intelligent systems have been rapidly evolving and play a pivotal role in assisting individuals across diverse domains, from healthcare to transportation. Understanding the dynamics of human-Artificial Intelligence (AI) partnering, particularly how humans trust and collaborate with intelligent systems, is becoming increasingly critical to design effective systems. This paper presents an experimental analysis to assess the impact of AI design attributes on users' trust, workload and performance when solving classification problems supported by an AI assistant. Specifically, we study the effect of transparency, fairness, and robustness in the design of an AI assistant and analyze the role of participants' gender and education background on the outcomes. The experiment is conducted with 47 students in undergraduate, master's and Ph.D. programs using a drawing game application where the users are asked to recognize incomplete sketches revealed progressively while receiving recommendations from multiple versions of an AI assistant. The results show that when collaborating with the AI, participants achieve a higher performance than their individual performance or the performance of the AI. The results also show that gender does not have an impact on users' trust and performance when collaborating with different versions of the AI system, whereas education level has a significant impact on the participants' performance but not on trust. Finally, the impact of design attributes on participants' trust and performance highly depends on the accuracy of the AI recommendations, and improvements in participants' performance and trust in some cases come at the expense of increased workload.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"11 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661133","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}
Effective coordination of design teams must account for the influence of costs incurred while searching for the best design solutions. This paper introduces a cost-aware multi-agent system (MAS), a theoretical model to 1) explain how individuals in a team should search, assuming that they are all rational utility-maximizing decision-makers, and 2) study the impact of cost on the search performance of both individual agents and the system. First, we develop a new multi-agent Bayesian Optimization framework accounting for information exchange among agents to support their decisions on where to sample in search. Second, we employ a reinforcement learning approach based on the multi-agent deep deterministic policy gradient for training MAS to identify where agents cannot sample due to design constraints. Third, we propose a new cost-aware stopping criterion for each agent to determine when costs outweigh potential gains in search as a criterion to stop. Our results indicate that cost has a more significant impact on MAS communication in complex design problems than in simple ones. For example, when searching in complex design spaces, some agents could initially have low-performance gains, thus stopping prematurely due to negative payoffs, even if those agents could perform better in the later stage of the search. Therefore, global-local communication becomes more critical in such situations for the entire system to converge. The proposed model can serve as a benchmark for empirical studies to quantitatively gauge how humans would rationally make design decisions in a team.
设计团队的有效协调必须考虑到在寻找最佳设计方案时产生的成本影响。本文介绍了成本感知多代理系统（MAS），这是一个理论模型，用于：1）解释团队中的个体应如何搜索，假设他们都是理性的效用最大化决策者；2）研究成本对个体代理和系统搜索性能的影响。首先，我们开发了一种新的多代理贝叶斯优化框架，该框架考虑到了代理之间的信息交流，以支持他们在搜索中决定在哪里采样。其次，我们采用了一种基于多代理深度确定性策略梯度的强化学习方法来训练 MAS，以确定代理因设计限制而无法采样的位置。第三，我们为每个代理提出了一个新的成本感知停止标准，以确定何时成本超过搜索中的潜在收益，并以此作为停止标准。我们的研究结果表明，在复杂的设计问题中，成本对 MAS 通信的影响比在简单问题中更为显著。例如，在复杂的设计空间中进行搜索时，一些代理可能会在最初阶段获得较低的性能收益，从而由于负回报而过早停止搜索，即使这些代理在搜索的后期阶段会有更好的表现。因此，在这种情况下，全局-本地通信对于整个系统的收敛变得更加重要。所提出的模型可以作为实证研究的基准，定量衡量人类在团队中如何理性地做出设计决策。
{"title":"A Cost-Aware Multi-Agent System for Black-Box Design Space Exploration","authors":"Siyu Chen, A. E. Bayrak, Zhenghui Sha","doi":"10.1115/1.4065914","DOIUrl":"https://doi.org/10.1115/1.4065914","url":null,"abstract":"\u0000 Effective coordination of design teams must account for the influence of costs incurred while searching for the best design solutions. This paper introduces a cost-aware multi-agent system (MAS), a theoretical model to 1) explain how individuals in a team should search, assuming that they are all rational utility-maximizing decision-makers, and 2) study the impact of cost on the search performance of both individual agents and the system. First, we develop a new multi-agent Bayesian Optimization framework accounting for information exchange among agents to support their decisions on where to sample in search. Second, we employ a reinforcement learning approach based on the multi-agent deep deterministic policy gradient for training MAS to identify where agents cannot sample due to design constraints. Third, we propose a new cost-aware stopping criterion for each agent to determine when costs outweigh potential gains in search as a criterion to stop. Our results indicate that cost has a more significant impact on MAS communication in complex design problems than in simple ones. For example, when searching in complex design spaces, some agents could initially have low-performance gains, thus stopping prematurely due to negative payoffs, even if those agents could perform better in the later stage of the search. Therefore, global-local communication becomes more critical in such situations for the entire system to converge. The proposed model can serve as a benchmark for empirical studies to quantitatively gauge how humans would rationally make design decisions in a team.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"16 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661476","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}
Four-bar linkages are critical fundamental elements of many mechanical systems, and their design synthesis is often mathematically complicated with iterative numerical solutions. Analytical methods based on Fourier coefficients can circumvent these difficulties but have difficulties with sampling points adjustment and solutions of the design equations in previous studies. In this paper, an improved Fourier-based analytical synthesis method is presented, which transforms the function generation synthesis of planar four-bar linkages into a problem of solving design equations. Calculation of the Fourier coefficients is discussed, including the discretization of the prescribed function and an improved sampling points adjustment method. It is shown that the Fourier coefficients can be computed efficiently and accurately by discretizing the prescribed function with a small number of sampling points. The proposed sampling adjustment method overcomes the difficulty of easily resulting in non-Grashof solutions by considering the complete period of the prescribed function. An improved Sylvester's dialytic elimination method is presented to solve design equations. The method reduces the computation time and avoids cumbersome procedures without generating additional invalid solutions. Several examples are presented to demonstrate the advantages of the proposed synthesis method, which is easy-understanding and efficient and yields more accurate solutions than available synthesis methods.
{"title":"Fourier-Based Function Generation of Four-Bar Linkages with an Improved Sampling Points Adjustment and Sylvester's Dialytic Elimination Method","authors":"Yahui Qian, Hong Zhong, Chin-An Tan, Liangmo Wang","doi":"10.1115/1.4065913","DOIUrl":"https://doi.org/10.1115/1.4065913","url":null,"abstract":"\u0000 Four-bar linkages are critical fundamental elements of many mechanical systems, and their design synthesis is often mathematically complicated with iterative numerical solutions. Analytical methods based on Fourier coefficients can circumvent these difficulties but have difficulties with sampling points adjustment and solutions of the design equations in previous studies. In this paper, an improved Fourier-based analytical synthesis method is presented, which transforms the function generation synthesis of planar four-bar linkages into a problem of solving design equations. Calculation of the Fourier coefficients is discussed, including the discretization of the prescribed function and an improved sampling points adjustment method. It is shown that the Fourier coefficients can be computed efficiently and accurately by discretizing the prescribed function with a small number of sampling points. The proposed sampling adjustment method overcomes the difficulty of easily resulting in non-Grashof solutions by considering the complete period of the prescribed function. An improved Sylvester's dialytic elimination method is presented to solve design equations. The method reduces the computation time and avoids cumbersome procedures without generating additional invalid solutions. Several examples are presented to demonstrate the advantages of the proposed synthesis method, which is easy-understanding and efficient and yields more accurate solutions than available synthesis methods.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"7 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141658748","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}
Nikoleta Dimitra Charisi, J.J. Hopman, Austin Kana
Early-stage design of complex systems is considered by many to be one of the most critical design phases because that is where many of the major decisions are made. The design process typically starts with low-fidelity tools, such as simplified models and reference data, but these prove insufficient for novel designs, necessitating the introduction of high-fidelity tools. This challenge can be tackled through the incorporation of multi-fidelity models. The application of MF models in the context of design optimization problems represents a developing area of research. This study proposes incorporating compositional kernels into the autoregressive scheme (AR1) of Multi-Fidelity Gaussian Processes, aiming to enhance the predictive accuracy and reduce uncertainty in design space estimation. The effectiveness of this method is assessed by applying it to 5 benchmark problems and a simplified design scenario of a cantilever beam. The results demonstrate significant improvement in the prediction accuracy and a reduction in the prediction uncertainty. Additionally, the paper offers a critical reflection on scaling up the method and its applicability in early-stage design of complex engineering systems, providing valuable insights into its practical implementation and potential benefits.
{"title":"Multi-fidelity design framework integrating compositional kernels to facilitate early-stage design exploration of complex systems","authors":"Nikoleta Dimitra Charisi, J.J. Hopman, Austin Kana","doi":"10.1115/1.4065890","DOIUrl":"https://doi.org/10.1115/1.4065890","url":null,"abstract":"\u0000 Early-stage design of complex systems is considered by many to be one of the most critical design phases because that is where many of the major decisions are made. The design process typically starts with low-fidelity tools, such as simplified models and reference data, but these prove insufficient for novel designs, necessitating the introduction of high-fidelity tools. This challenge can be tackled through the incorporation of multi-fidelity models. The application of MF models in the context of design optimization problems represents a developing area of research. This study proposes incorporating compositional kernels into the autoregressive scheme (AR1) of Multi-Fidelity Gaussian Processes, aiming to enhance the predictive accuracy and reduce uncertainty in design space estimation. The effectiveness of this method is assessed by applying it to 5 benchmark problems and a simplified design scenario of a cantilever beam. The results demonstrate significant improvement in the prediction accuracy and a reduction in the prediction uncertainty. Additionally, the paper offers a critical reflection on scaling up the method and its applicability in early-stage design of complex engineering systems, providing valuable insights into its practical implementation and potential benefits.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"182 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141681775","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}
Rohan Prabhu, Jenna Herzog, Rebekah Fodale, Mohammad Alsager Alzayed, Elizabeth Starkey
Research suggests novice designers find it challenging to integrate social context into engineering design. This challenge could be pronounced in sustainable design because the effects of climate change are perceived to be psychologically distant, which inhibits active engagement in sustainable behavior. However, prior work assesses psychological distance as an aggregate of its various subcomponents (e.g., temporal, social, spatial, and hypothetical). Limited research has explored how these components vary based on the socio-spatial context of the problem. Additionally, empathy development could be an effective mechanism to bridge psychological distance. However, little is known about the impact of empathy-focused problem formulation on student perceptions. We studied students' perceptions of problem formulations in a 2×2 factorial between-subjects experiment. The problems varied in (1) their socio-spatial context and (2) their empathy-focus. We measured the students' perceptions of the problem formulations using: (1) perceived psychological distance and (2) perceived empathic response. We find that participants reported the problem contextualized in India to be a more immediate threat compared to the one in the USA. Moreover, we find no significant differences in the other components of psychological distance or empathic response between the problem variants. This finding suggests that participants perceive environmental issues as currently affecting people in other parts of the world, and not themselves, but only from a temporal lens. These findings call for educators to carefully consider temporal framing when using socio-spatially far sustainable design problems as a lack of consideration could create faulty perceptions.
{"title":"Feeling The Distance: Exploring Novice Student Designers' Perceptions of the Psychological Distance and Empathic Response Towards Variations of a Sustainable Design Problem","authors":"Rohan Prabhu, Jenna Herzog, Rebekah Fodale, Mohammad Alsager Alzayed, Elizabeth Starkey","doi":"10.1115/1.4065850","DOIUrl":"https://doi.org/10.1115/1.4065850","url":null,"abstract":"\u0000 Research suggests novice designers find it challenging to integrate social context into engineering design. This challenge could be pronounced in sustainable design because the effects of climate change are perceived to be psychologically distant, which inhibits active engagement in sustainable behavior. However, prior work assesses psychological distance as an aggregate of its various subcomponents (e.g., temporal, social, spatial, and hypothetical). Limited research has explored how these components vary based on the socio-spatial context of the problem. Additionally, empathy development could be an effective mechanism to bridge psychological distance. However, little is known about the impact of empathy-focused problem formulation on student perceptions. We studied students' perceptions of problem formulations in a 2×2 factorial between-subjects experiment. The problems varied in (1) their socio-spatial context and (2) their empathy-focus. We measured the students' perceptions of the problem formulations using: (1) perceived psychological distance and (2) perceived empathic response. We find that participants reported the problem contextualized in India to be a more immediate threat compared to the one in the USA. Moreover, we find no significant differences in the other components of psychological distance or empathic response between the problem variants. This finding suggests that participants perceive environmental issues as currently affecting people in other parts of the world, and not themselves, but only from a temporal lens. These findings call for educators to carefully consider temporal framing when using socio-spatially far sustainable design problems as a lack of consideration could create faulty perceptions.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"142 1‐2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141687356","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}
This paper focuses on the design procedures of Alizade's direct and Gezgin's inverse structural synthesis methodologies for platform type manipulators. These task based synthesis procedures includes versatile methodologies for any designer to generate various platform type manipulators with respect to given constraints via simple universal mobility formulation. However they rely on manual generation of mobility independent coarse topological structures, where it is nearly impossible to generate all possible results. In light of this, current study introduces a unique connection based adjacency matrix (CAM) for topology representation, in which legs connected to the fixed ground and platform connections (hinges and branches) are treated separately. The main objective of CAM is to ensure an efficient transition from manual topology generation to automated methods by providing compatibility with software algorithms to describe topologies. Throughout the paper CAM based automated topology generation algorithm that reveals all possible unique coarse topologies with respect to given design constraints is also presented along with examples. Introduced algorithm both allows investigation of isomorphism and eliminates necessity of inversion.
{"title":"Structural Synthesis of Platform Type Manipulators via Connection Based Adjacency Matrix: Topology Generation","authors":"M. Yazıcı, M. Koçak, Tuğrul Uslu, E. Gezgin","doi":"10.1115/1.4065849","DOIUrl":"https://doi.org/10.1115/1.4065849","url":null,"abstract":"\u0000 This paper focuses on the design procedures of Alizade's direct and Gezgin's inverse structural synthesis methodologies for platform type manipulators. These task based synthesis procedures includes versatile methodologies for any designer to generate various platform type manipulators with respect to given constraints via simple universal mobility formulation. However they rely on manual generation of mobility independent coarse topological structures, where it is nearly impossible to generate all possible results. In light of this, current study introduces a unique connection based adjacency matrix (CAM) for topology representation, in which legs connected to the fixed ground and platform connections (hinges and branches) are treated separately. The main objective of CAM is to ensure an efficient transition from manual topology generation to automated methods by providing compatibility with software algorithms to describe topologies. Throughout the paper CAM based automated topology generation algorithm that reveals all possible unique coarse topologies with respect to given design constraints is also presented along with examples. Introduced algorithm both allows investigation of isomorphism and eliminates necessity of inversion.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"64 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141711254","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}
Bing Chen, Chenpu Shi, Bin Zi, Ling Qin, Qingsong Xu
This paper presents the development of a robotic ankle exoskeleton for human walking assistance. First, the biomechanical properties of a human ankle joint during walking are presented. Next, design of the robotic ankle exoskeleton is introduced. The exoskeleton is actuated by a novel parallel nonlinear elastic actuator. The cam-spring mechanism in the actuator can function as a parallel nonlinear spring with an adjustable stiffness, and the design of the cam profile curve is described. Additionally, an adaptive controller is proposed for the exoskeleton to generate a desired assistive torque according to the wearer's total weight. Finally, experiments are conducted to validate the effectiveness of the developed robotic ankle exoskeleton. The experimental results demonstrate that during a gait cycle, reductions of 42.7% and 40.1% of the peak and average currents of the driving motor in the actuator are observed, respectively, with the designed cam-spring mechanism. A peak assistive torque of 23.9 Nm can be provided for the wearers by the exoskeleton during walking. With the assistance provided by the exoskeleton, the average and peak soleus activities of the wearers during a gait cycle are decreased by 25.42% and 31.94%, respectively.
{"title":"Development and Validation of Robotic Ankle Exoskeleton With Parallel Nonlinear Elastic Actuator","authors":"Bing Chen, Chenpu Shi, Bin Zi, Ling Qin, Qingsong Xu","doi":"10.1115/1.4065561","DOIUrl":"https://doi.org/10.1115/1.4065561","url":null,"abstract":"\u0000 This paper presents the development of a robotic ankle exoskeleton for human walking assistance. First, the biomechanical properties of a human ankle joint during walking are presented. Next, design of the robotic ankle exoskeleton is introduced. The exoskeleton is actuated by a novel parallel nonlinear elastic actuator. The cam-spring mechanism in the actuator can function as a parallel nonlinear spring with an adjustable stiffness, and the design of the cam profile curve is described. Additionally, an adaptive controller is proposed for the exoskeleton to generate a desired assistive torque according to the wearer's total weight. Finally, experiments are conducted to validate the effectiveness of the developed robotic ankle exoskeleton. The experimental results demonstrate that during a gait cycle, reductions of 42.7% and 40.1% of the peak and average currents of the driving motor in the actuator are observed, respectively, with the designed cam-spring mechanism. A peak assistive torque of 23.9 Nm can be provided for the wearers by the exoskeleton during walking. With the assistance provided by the exoskeleton, the average and peak soleus activities of the wearers during a gait cycle are decreased by 25.42% and 31.94%, respectively.","PeriodicalId":506672,"journal":{"name":"Journal of Mechanical Design","volume":"14 25","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141271215","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}
Liuqing Chen, H. Zuo, Zebin Cai, Y. Yin, Yuan Zhang, Lingyun Sun, Peter R.N. Childs, Boheng Wang
Recent research in the field of design engineering is primarily focusing on using AI technologies such as Large Language Models (LLMs) to assist early-stage design. The engineer or designer can use LLMs to explore, validate and compare thousands of generated conceptual stimuli and make final choices. This was seen as a significant stride in advancing the status of the generative approach in computer-aided design. However, it is often difficult to instruct LLMs to obtain novel conceptual solutions and requirement-compliant in real design tasks, due to the lack of transparency and insufficient controllability of LLMs. This study presents an approach to leverage LLMs to infer Function-Behavior-Structure (FBS) ontology for high-quality design concepts. Prompting design based on the FBS model decomposes the design task into three sub-tasks including functional, behavioral, and structural reasoning. In each sub-task, prompting templates and specification signifiers are specified to guide the LLMs to generate concepts. User can determine the selected concepts by judging and evaluating the generated function-structure pairs. A comparative experiment has been conducted to evaluate the concept generation approach. According to the concept evaluation results, our approach achieves the highest scores in concept evaluation, and the generated concepts are more novel, useful, functional, and low-cost compared to the baseline.
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