Safe Supervisory Control of Soft Robot Actuators

Although soft robots show safer interactions with their environment than traditional robots, soft mechanisms and actuators still have significant potential for damage or degradation particularly during unmodeled contact. This article introduces a feedback strategy for safe soft actuator operation during control of a soft robot. To do so, a supervisory controller monitors actuator state and dynamically saturates control inputs to avoid conditions that could lead to physical damage. We prove that, under certain conditions, the supervisory controller is stable and verifiably safe. We then demonstrate completely onboard operation of the supervisory controller using a soft thermally-actuated robot limb with embedded shape memory alloy (SMA) actuators and sensing. Tests performed with the supervisor verify its theoretical properties and show stabilization of the robot limb's pose in free space. Finally, experiments show that our approach prevents overheating during contact (including environmental constraints and human contact) or when infeasible motions are commanded. This supervisory controller, and its ability to be executed with completely onboard sensing, has the potential to make soft robot actuators reliable enough for practical use

Methodological guide to deploy Functional Analysis into CODAC Systems for the Tritium Processing in ITER

The present document is focused on the a nalysis of the ITER - TBM‘s Proto - CODAC system. ITER is considered to be the first nuclear fusion reactor to be energetically feasible for a sustained period of time with a rated fusion power of 500 MW. ITER Project involves 35 countries with a total est imated budget of some 15.000 M€; being the first of its kind from the point of view of international collaboration, engineering and supply sources; where every country participate with the best of its possibilities. The hearth of the fusion reactor is a giant Tokamak (6.2 m plasma major radius) with a se ries of ancillary buildings and facilities that might complete the whole p roject. The operation of ITER is scheduled to operate along the next 50 years , after completion of the facilities construction and commissioning of the plant, considering first to b e operated in D - D and further in a D - T modes. In this sense, the activity that supports the development of the present work was stated to be necessary to consider a tritium balance for the self - sufficient reaction and operation of the whole. Tritium is a v ery scarce element being its global sto cks to the present date of 2016 of some 20 kg, being produced mainly collected from the operation of Candu reactors in Canada [Raeder, 1986] . Also the operation of the ITER reactor might produce Tritium at a rate that might b e able to support the fusion reaction indefinitely on a time basis. Because of the tritium balance it is difficult to state due to its highly permeation throughout confinement of first walls and joint materials . Not to mention its high ly dangerous potential to human health, according to radiologic al properties . This is why it is necessary to establish predictive tools that might indicate the concentration and inventory across the facility, including emissions to the environment. In this sense, ITER Instrumentation and Control systems for Control and Data Acquisition (DACS) mainly constitute the layers between the users (Control Room) and the field Instrumentation (sensors and actuators). This is nam ed as ITER CODAC, which is the primary global system analyzed in the present document. The control philosophy it is stated to be predictive and from the author‘s point of view must include the comparison between field measurement and advanced modeling, including machine learning utility system that might be deployed in computational base

Feasibility of remotely manipulated welding in space. A step in the development of novel joining technologies

In order to establish permanent human presence in space technologies of constructing and repairing space stations and other space structures must be developed. Most construction jobs are performed on earth and the fabricated modules will then be delivered to space by the Space Shuttle. Only limited final assembly jobs, which are primarily mechanical fastening, will be performed on site in space. Such fabrication plans, however, limit the designs of these structures, because each module must fit inside the transport vehicle and must withstand launching stresses which are considerably high. Large-scale utilization of space necessitates more extensive construction work on site. Furthermore, continuous operations of space stations and other structures require maintenance and repairs of structural components as well as of tools and equipment on these space structures. Metal joining technologies, and especially high-quality welding, in space need developing

Supervisory controller synthesis for product lines using CIF 3

Using the CIF 3 toolset, we illustrate the general idea of controller synthesis for product line engineering for a prototypical example of a family of coffee machines. The challenge is to integrate a number of given components into a family of products such that the resulting behaviour is guaranteed to respect an attributed feature model as well as additional behavioural requirements. The proposed correctness-by-construction approach incrementally restricts the composed behaviour by subsequently incorporating feature constraints, attribute constraints and temporal constraints. The procedure as presented focusses on synthesis, but leaves ample opportunity to handle e.g. uncontrollable behaviour, dynamic reconfiguration, and product- and family-based analysis

Doctor of Philosophy

dissertationThis dissertation can be divided into three parts: (1) the study of delithiation process of Li-Mg alloy as anode for Li-ion batteries by both experiments and theoretical modeling, (2) the investigation of the feasibility to study Li spatial distribution

Doctor of Philosophy

dissertationRefractive errors of vision are very common in all human beings, namely myopia, hyperopia, presbyopia, and astigmatism. Worldwide, over 1 billion people were estimated to suffer from presbyopia with around 410 million of them suffering from near vision loss. The result of refractive errors is blurred vision, affecting our ability to focus on near or far objects. The utilization of conventional fixed, uniform, or graded power eyeglasses is generally unsatisfactory as fixed power eyepieces cannot provide any accommodation restoration. In this dissertation, we demonstrate compact tunable-focus liquid lenses suitable for ophthalmic adaptive eyeglasses. These lightweight, low footprint tunable-focus lenses augment the accommodation range of vision, thus restoring normal vision function. First, a tunable-focus large aperture liquid lens is constructed using shape memory alloy (SMA) springs as actuators. The lens mainly consists of a shallow liquid-filled cylindrical cavity bound by a thin compressible annular rim and encapsulated by a flexible circular membrane on the top of the rim and a rigid circular plate at the rim bottom. The lens optical power is adjusted by a controlled compression of the annular rim in vertical direction via actuation of the three shape memory alloy (SMA) springs. Second, we report a compact tunable-focus liquid lens with large aperture actuated by piezo-electric bimorph actuators. The lens consists of a rigid annular sealing rim encapsulated by two membranes forming a sealed chamber with a fixed volume of high index optical fluid filled in it. When a normal force is applied to the bottom piston via piezo-electric bimorph actuators, the shape of the top membrane is changed, causing the change of focal length. We did the simulation using Python to improve the lens optical quality, and lens parameters were determined from the simulation. While simulation and fabrication of the tunable-focus liquid lens using piezo-electric bimorph actuators, we noticed the effect of tension over lens membrane to determine lens optical power and optical quality. This gave us the idea of implementing tunable-focus liquid lens by changing the tension of the membrane. The theory, simulation, fabrication, and experimentation for these three different lenses are discussed in this dissertation