This paper presents a novel parallel planar robot design which is low cost and simple in structure. The design addresses some of the problems, such as concentration of excessive load on the links and joints, due to wrong commanding signals being given by the controller. In this application two of the conventional actuators are replaced by magnetorheological (MR) dampers, and only one actuator is used to generate motion. The design paradigm is based on the concept that a moving object 'intuitively' follows the path with minimum resistance to its motion. This implies that virtual adoptable constraints can be used effectively to define motion trajectories. In fact, motion generation and adaptive constraints are two elements essential to implementing this strategy. In this paper, MR dampers are used to provide adjustable constraints and to guide the platform that is moved by the linear motor. The model of the MR dampers is derived using the Bouc-Wen model. This model is then used for manipulator simulation and controller design. Two controllers are developed for this manipulator: (1) a closed loop on/off one and (2) a proportional-derivative controller. Also, three different trajectories are defined and used for both the simulations and experiments. The results indicate a good agreement between the simulations and experiments. The experimental results also demonstrate the capability of the manipulator for following sophisticated trajectories.
This article presents a novel haptic interface for rehabilitation purposes using MR-dampers. In the rehabilitation, patients are required to do certain exercises to train damaged muscles. Specialized devices are required to ensure patients will do the exercise accurately. Typical devices that are used for this application are difficult to program and may cause damage by applying excessive force to human body. The haptic device that is designed in this article will address the issues by employing MR-dampers and a user-friendly programming methodology. The concept of Resistive-Map generation is introduced as main strategy for activating MR-dampers and restricting the motion to the regions determined by the therapist. To simulate the performance of the system, an accurate model of MR-damper is obtained and validated experimentally. To test the performance of the proposed MR-based haptic device, the resistance-maps are first generated. MR-dampers are activated according to the positions of the MR-dampers in the resistance-map. The system is also simulated in MATLAB Õ / SimMechanics. The experimental and simulation results are in good agreement. The promising results of the proposed haptic interface make it a potential candidate for rehabilitation applications. Patients will be able to take the device home and the physiotherapists can online programme the exercises and monitor the performance of patients.
Governments at all levels rely on energy-economy models to design climate policy portfolios. Models vary in their purposes and methodologies, yet there is limited research comparing model characteristics and identifying models suitable for specific policy questions. We conduct a web-based survey of energy-economy model users and developers (n = 14) in Canada’s public, private, and non-profit sectors, to systematically compare seventeen models against the following characteristics: Technology representations, microeconomic and macroeconomic details, policy representations, treatment of uncertainty, high-resolution spatial and temporal representations, and data transparency. We find that for the most part, models represent technology, micro-, and macroeconomic characteristics according to the typology of bottom-up, top-down, and hybrid models. However, several modelling evolutions have emerged. To varying extents, top-down models can explicitly represent technologies and some bottom-up models incorporate microeconomic (non-financial) characteristics. We find that models differ in the types of policies they can simulate, sometimes underrepresenting performance regulations, government procurement, and research and development programs. All models use at least one method to explore uncertainty, rarely incorporate spatial and temporal representations, and most models lack publicly available methodological documentation. We discuss the implications of our comparative model analysis for climate policy projections and future research.
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