A user-programmable computational/control platform was developed at the University of Toronto that offers real-time hybrid simulation （RTHS） capabilities. The platform was verified previously using several linear ph...A user-programmable computational/control platform was developed at the University of Toronto that offers real-time hybrid simulation （RTHS） capabilities. The platform was verified previously using several linear physical substructures. The study presented in this paper is focused on further validating the RTHS platform using a nonlinear viscoelastic-plastic damper that has displacement, frequency and temperature-dependent properties. The validation study includes damper component characterization tests, as well as RTHS of a series of single-degree-of-freedom （SDOF） systems equipped with viscoelastic-plastic dampers that represent different structural designs. From the component characterization tests, it was found that for a wide range of excitation frequencies and friction slip loads, the tracking errors are comparable to the errors in RTHS of linear spring systems. The hybrid SDOF results are compared to an independently validated thermal- mechanical viscoelastic model to further validate the ability for the platform to test nonlinear systems. After the validation, as an application study, nonlinear SDOF hybrid tests were used to develop performance spectra to predict the response of structures equipped with damping systems that are more challenging to model analytically. The use of the experimental performance spectra is illustrated by comparing the predicted response to the hybrid test response of 2DOF systems equipped with viscoelastic-plastic dampers.展开更多
Despite small workspace, parallel manipulators have some advantages over their serial counterparts in terms of higher speed, acceleration, rigidity, accuracy, manufacturing cost and payload. Accordingly, this type of ...Despite small workspace, parallel manipulators have some advantages over their serial counterparts in terms of higher speed, acceleration, rigidity, accuracy, manufacturing cost and payload. Accordingly, this type of manipulators can be used in many applications such as in high-speed machine tools, tuning machine for feeding, sensitive cutting, assembly and packaging. This paper presents a special type of planar parallel manipulator with three degrees of freedom. It is constructed as a variable geometry truss generally known planar Stewart platform. The reachable and orientation workspaces are obtained for this manipulator. The inverse kinematic analysis is solved for the trajectory tracking according to the redundancy and joint limit avoidance. Then, the dynamics model of the manipulator is established by using Virtual Work method. The simulations are performed to follow the given planar trajectories by using the dynamic equations of the variable geometry truss manipulator and computed force control method. In computed force control method, the feedback gain matrices for PD control are tuned with fixed matrices by trail end error and variable ones by means of optimization with genetic algorithm.展开更多
Two limitations of current integrity measurement architectures are pointed out:(1)a reference value is required for every measured entity to verify the system states,as is impractical however;(2)malicious user can for...Two limitations of current integrity measurement architectures are pointed out:(1)a reference value is required for every measured entity to verify the system states,as is impractical however;(2)malicious user can forge proof of inexistent system states.This paper proposes a trustworthy integrity measurement architecture,BBACIMA,through enforcing behavior-based access control for trusted platform module(TPM).BBACIMA introduces a TPM reference monitor(TPMRM)to ensure the trustworthiness of integrity measurement.TPMRM enforces behavior-based access control for the TPM and is isolated from other entities which may be malicious.TPMRM is the only entity manipulating TPM directly and all PCR(platform configuration register)operation requests must pass through the security check of it so that only trusted processes can do measurement and produce the proof of system states.Through these mechanisms malicious user can not enforce attack which is feasible in current measurement architectures.展开更多
为解决脑卒中疾病(cerebrovascular accident,CVA)导致的上肢偏瘫患者在康复过程中不规范以及康复医师不足的问题,提出一种5自由度(degree of freedom,DOF)上肢肘腕关节康复机器人及控制系统,旨在更好地满足患者灵活康复的需求。康复机...为解决脑卒中疾病(cerebrovascular accident,CVA)导致的上肢偏瘫患者在康复过程中不规范以及康复医师不足的问题,提出一种5自由度(degree of freedom,DOF)上肢肘腕关节康复机器人及控制系统,旨在更好地满足患者灵活康复的需求。康复机器人平台为3-RRR(3-转动副-转动副-转动副)串联机构,能够实现独立肘关节屈伸康复、独立腕关节屈伸和内外旋康复、肘腕关节协同屈伸康复、肘关节屈伸腕关节内外旋协同康复功能,同时考虑到患者左右偏瘫部位不同的情况,康复机器人设置镜像功能。触摸屏和控制器(planar lightwave circuit,PLC)进行通信,可以实现人机交互。使用Matlab软件运用蒙特卡洛法(Monte-Carlo,M-C)绘制机器人工作空间云图,从而进行更有效的任务规划和操作控制。结果表明:所设计研制的样机能够满足上肢肘腕关节多种模式下的运动康复,可以对屈肌群和伸肌群进行训练。展开更多
基金NSERC Discovery under Grant 371627-2009 and NSERC RTI under Grant 374707-2009 EQPEQ programs
文摘A user-programmable computational/control platform was developed at the University of Toronto that offers real-time hybrid simulation （RTHS） capabilities. The platform was verified previously using several linear physical substructures. The study presented in this paper is focused on further validating the RTHS platform using a nonlinear viscoelastic-plastic damper that has displacement, frequency and temperature-dependent properties. The validation study includes damper component characterization tests, as well as RTHS of a series of single-degree-of-freedom （SDOF） systems equipped with viscoelastic-plastic dampers that represent different structural designs. From the component characterization tests, it was found that for a wide range of excitation frequencies and friction slip loads, the tracking errors are comparable to the errors in RTHS of linear spring systems. The hybrid SDOF results are compared to an independently validated thermal- mechanical viscoelastic model to further validate the ability for the platform to test nonlinear systems. After the validation, as an application study, nonlinear SDOF hybrid tests were used to develop performance spectra to predict the response of structures equipped with damping systems that are more challenging to model analytically. The use of the experimental performance spectra is illustrated by comparing the predicted response to the hybrid test response of 2DOF systems equipped with viscoelastic-plastic dampers.
文摘Despite small workspace, parallel manipulators have some advantages over their serial counterparts in terms of higher speed, acceleration, rigidity, accuracy, manufacturing cost and payload. Accordingly, this type of manipulators can be used in many applications such as in high-speed machine tools, tuning machine for feeding, sensitive cutting, assembly and packaging. This paper presents a special type of planar parallel manipulator with three degrees of freedom. It is constructed as a variable geometry truss generally known planar Stewart platform. The reachable and orientation workspaces are obtained for this manipulator. The inverse kinematic analysis is solved for the trajectory tracking according to the redundancy and joint limit avoidance. Then, the dynamics model of the manipulator is established by using Virtual Work method. The simulations are performed to follow the given planar trajectories by using the dynamic equations of the variable geometry truss manipulator and computed force control method. In computed force control method, the feedback gain matrices for PD control are tuned with fixed matrices by trail end error and variable ones by means of optimization with genetic algorithm.
基金the National High Technology Research and Development Plan of China(2007AA01Z412)the National Key Technology R&D Program of China(2006BAH02A02)the National Natural Science Foundation of China(60603017)
文摘Two limitations of current integrity measurement architectures are pointed out:(1)a reference value is required for every measured entity to verify the system states,as is impractical however;(2)malicious user can forge proof of inexistent system states.This paper proposes a trustworthy integrity measurement architecture,BBACIMA,through enforcing behavior-based access control for trusted platform module(TPM).BBACIMA introduces a TPM reference monitor(TPMRM)to ensure the trustworthiness of integrity measurement.TPMRM enforces behavior-based access control for the TPM and is isolated from other entities which may be malicious.TPMRM is the only entity manipulating TPM directly and all PCR(platform configuration register)operation requests must pass through the security check of it so that only trusted processes can do measurement and produce the proof of system states.Through these mechanisms malicious user can not enforce attack which is feasible in current measurement architectures.
