Design and control of an MRI compatible series elastic actuator

Bidirectional compatibility requirements with Magnetic Resonance Imaging (MRI) have limited the adaptation of rehabilitation robots for use in MRI machines. In this paper, we present the design and control of a Bowden cable-actuated, MRI-compatible series elastic actuator (SEA) that aims to fulfil the bidirectional compatibility requirements to the maximum extend. The proposed device is built using nonconductive diamagnetic MRI compatible materials, fiber optic sensing units and a Bowden cable based actuation, such that imaging artifacts created under strong magnetic field required for neuro-imaging are minimized. In particular, utilization of Bowden-cable transmission enables the placement of the conventional non-MRI compatible control/signal processing units and electric actuators outside the MRI room. This approach not only helps avoid the MR interference caused by these parts and eliminates safety hazards within the MRI room, but also ensures that the performance of the device is not affected by the strong magnetic field, resulting in ideal bidirectional MRI compatibility. Use of a custom-built fiber optic encoder together with nonconductive leaf spring based elastic element enables torque outputs of the device to be measured and used for closed-loop torque control, rendering the system into a series elastic actuator. The proposed MRI compatible SEA is easily customizable and can be used as the building block of higher degrees of freedom MRI compatible robotic devices. Current prototype is validated to administer continuous torques up to 2 Nm with a torque control bandwidth of 1 Hz and a torque sensing resolution of 0.05 Nm

MRI-VisAct: a Bowden cable-driven MRI compatible series viscoelastic actuator

Presence of the strong magnetic fields in the Magnetic Resonance Imaging (MRI) environment limits the integration of robotic rehabilitation systems to the MRI process. The tendency to improve imaging quality by the amplification of magnetic field strength further tightens the bidirectional compatibility constraints on MRI compatible rehabilitation devices. We present the design, control, and characterization of MRI-VisAct—a low-cost, Bowden cable-actuated rotary series viscoelastic actuator that fulfills the bidirectional compatibility requirements to the maximum extend. Components of MRI-VisAct that are placed in the magnet room are built using nonconductive, diamagnetic MRI compatible materials, while ferromagnetic/paramagnetic components are placed in the control room, located outside the MRI room. Power and data transmission are achieved through Bowden-cables and fiber optics, respectively. This arrangement ensures that neuroimaging artifacts are minimized, while safety hazards are eliminated, and the device performance is not affected by the magnetic field. MRIVisAct works under closed-loop torque control enabled through series viscoelastic actuation. MRI-VisAct is fully customizable; it can serve as the building block of higher degrees of freedom MRI compatible robotic devices

Design and control of a Bowden-cable driven magnetic resonance imaging compatible series-elastic actuator

Presence of the strong magnetic fields in the Magnetic Resonance Imaging (MRI) environment limits the integration of robotic rehabilitation systems to the MRI process. The tendency to improve imaging quality by the amplification of magnetic field strength further tightens the bidirectional compatibility constraints on MRI compatible rehabilitation devices. In this thesis, the design, control, and characterization of MRI-VisAct—a low-cost, Bowden cable-actuated rotary series viscoelastic actuator that fulfills the bidirectional compatibility requirements to the maximum extend, are presented. Components of MRI-VisAct that are placed in the magnet room are built using nonconductive, diamagnetic MRI compatible materials, while ferromagnetic/ paramagnetic components are placed in the control room, located outside the MRI room. Power and data transmission are achieved through Bowden-cables and fiber optics, respectively. This arrangement ensures that neuro-imaging artifacts are minimized, while safety hazards are eliminated, and the device performance is not affected by the magnetic field. MRI-VisAct works under closed-loop torque control enabled through series viscoelastic actuation. MRI-VisAct is fully customizable; it can serve as the building block of higher degrees of freedom MRI compatible robotic devices

Kentsel Mekânda Soğutma Yayılımının Araştırılması, İzmir Örneği

Kentsel mekânda, doğal ve doğal olmayan yeşil- mavi altyapı elemanları bitki örtüsüz alanların ısınma etkisine karşı yerel sıcaklıkları düzenlenme konusunda önemli rol oynamaktadır. Kentsel mekânda sıcaklığın mekânsal dağılımını biçimlendiren bu alanlar, kentsel soğuk ada olarak adlandırılmaktadır. Bu çalışma İzmir kentsel alanı yüzey sıcaklığı (YS) mekânsal dağılımını etkileyen unsurların araştırılmasında bir yöntem geliştirmeyi amaçlamaktadır. Kentsel soğuk adaların sınırlarının tespiti için uzaktan algılama ve mekânsal istatistik yöntemlerinden yararlanılarak bir yöntem önerilmiştir. Kentsel mekânda soğutma kapasitesinin incelenmesinde soğutma yayılım alanı ölçüt olarak belirlenmiştir. Çalışma kapsamında, kentsel soğuk ada büyüklüğü ve soğutma şiddetinin yayılım alanıyla ilişkisi ölçülmüştür. Elde edilen bulgular, soğutma etkisi yayılım alanını açıklamada kentsel soğuk ada büyüklüğünün soğutma şiddetine göre çok daha etkili olduğunu ortaya koymuştur. Sonuç olarak, çalışmanın geliştirdiği araştırma yaklaşımı ve elde ettiği sonuçların sürdürülebilir kentsel planlama ve yönetim bağlamında iklim değişikliğine uyum sürecinde kent bütününde sıcaklığın desenini belirleyen unsurları araştıran kısıtlı sayıdaki çalışmalara katkı sunacaktır.In urban space, green-blue infrastructure plays an important role in regulating local temperatures against the heating effect of areas without vegetation. These areas, which shape the spatial distribution of temperature in urban space, are called urban cold islands. This study aims to develop a method for investigating the factors affecting the spatial distribution of land surface temperature (LST). A method has been proposed for extracting the boundary of urban cold islands by using remote sensing and spatial statistics methods. Cooling extend was determined as a measure in analyzing cooling capacity of urban environment. According to scope of the study, the relationship between both of size of urban cool island and cooling intensity, and cooling extend was measured, then, discussed the impact on local climate conditions. The findings showed that size of urban cool island was more effective than the intensity in explaining cooling extend. As a result, the research approach and the findings will insight for mitigation of urban heat island effect in the context of sustainable urban planning and management