Application of ultrasonic motors to MR-compatible haptic interfaces

Functional Magnetic Resonance Imagery (fMRI) is an imaging technique allowing the observation of brain activity. Haptic interfaces can be used in conjunction with fMRI to stimulate the subject while measuring brain activity. Using robotic stimulation over conventional methods offers repeatability, flexibility and the possibility of logging of different experiment variables. Such system becomes a powerful tool for neuroscience study, diagnostic and rehabilitation. The MR scanner with its high magnetic fields and radio frequency pulses is a harsh environment for a robotic system. Robots that can operate safely and do not induce disturbances in the imaging of the scanner are qualified as MR-compatible. The actuation of these robots is an important issue. Electrical power brought to the actuator represents an important source of interferences with the scanner. Since electrical motors cannot be introduced in the MR room, haptic interfaces are conventionally remotely actuated over a long transmission with the actuators placed outside of the MR room. In particular cases, such as the study of finger motion, small haptic interfaces with limited force ranges are required. Remote actuation methods impose transmission lengths and means that cannot be reduced nor scaled down thus imposing a trade-off between performances and size reduction in these applications. This work investigates an alternative actuator that can achieve high-quality force-interactions with the fingers. The Ultrasonic Motor (USM) is MR-compatible and offers good performances. But it is not well suited for force-feedback and may be hazardous for the users. To address these issues, mechanical solutions are investigated by using an electrical analogy applied to mechanical systems. A novel actuation system using the USM as a power source and a clutch to control the output torque is proposed: the Hybrid USM Clutch Actuator (HUCA). The first prototype validates the different mechanical concepts developed in this work. The second, MR-compatible, integrates a clutch based on electrorheological fluids (ER). MR-compatibility has been validated and performances evaluated. Since the HUCA has the unique property of behaving both like a force source and a velocity source, dedicated control schemes have been developed to implement impedance and admittance force control. These enable the display of stiff walls and the rendering of a wide range of impedances thanks to the overlap of their range of displayable impedances. Compared to the hydrostatic transmission actuation, the HUCA shows higher performances and user safety. Furthermore, the powering through electrical wires allows developments of multi-DOF interfaces

Advanced Mobile Robotics: Volume 3

Mobile robotics is a challenging field with great potential. It covers disciplines including electrical engineering, mechanical engineering, computer science, cognitive science, and social science. It is essential to the design of automated robots, in combination with artificial intelligence, vision, and sensor technologies. Mobile robots are widely used for surveillance, guidance, transportation and entertainment tasks, as well as medical applications. This Special Issue intends to concentrate on recent developments concerning mobile robots and the research surrounding them to enhance studies on the fundamental problems observed in the robots. Various multidisciplinary approaches and integrative contributions including navigation, learning and adaptation, networked system, biologically inspired robots and cognitive methods are welcome contributions to this Special Issue, both from a research and an application perspective

Designing a New Tactile Display Technology and its Disability Interactions

People with visual impairments have a strong desire for a refreshable tactile interface that can provide immediate access to full page of Braille and tactile graphics. Regrettably, existing devices come at a considerable expense and remain out of reach for many. The exorbitant costs associated with current tactile displays stem from their intricate design and the multitude of components needed for their construction. This underscores the pressing need for technological innovation that can enhance tactile displays, making them more accessible and available to individuals with visual impairments. This research thesis delves into the development of a novel tactile display technology known as Tacilia. This technology's necessity and prerequisites are informed by in-depth qualitative engagements with students who have visual impairments, alongside a systematic analysis of the prevailing architectures underpinning existing tactile display technologies. The evolution of Tacilia unfolds through iterative processes encompassing conceptualisation, prototyping, and evaluation. With Tacilia, three distinct products and interactive experiences are explored, empowering individuals to manually draw tactile graphics, generate digitally designed media through printing, and display these creations on a dynamic pin array display. This innovation underscores Tacilia's capability to streamline the creation of refreshable tactile displays, rendering them more fitting, usable, and economically viable for people with visual impairments

Hybrid Ultrasonic Motor and Electrorheological Clutch System for MR-Compatible Haptic Rendering

Using haptic interfaces in combination with functional magnetic resonance imaging (fMRI) could lead to important insights into the brain mechanisms of human motor control and related dysfunctions. However, in addition to the usual requirements for haptic interfaces (e.g. smooth force control, back-drivability, low friction and inertia) these devices must also be MR safe and MR compatible. Previous MR-compatible actuation methods for force-feedback present drawbacks with respect to conventional haptic interfaces. Here, we present a novel MR-compatible actuator designed especially for impedance control and to meet the requirements for haptic interfaces. It consists of an ultrasonic motor controlled in speed combined with an electrorheological fluid brake which modulates the output torque over a differential gear. The entire system is integrated into a compact housing with an encoder at the output

Advanced Sensors for Real-Time Monitoring Applications

It is impossible to imagine the modern world without sensors, or without real-time information about almost everything—from local temperature to material composition and health parameters. We sense, measure, and process data and act accordingly all the time. In fact, real-time monitoring and information is key to a successful business, an assistant in life-saving decisions that healthcare professionals make, and a tool in research that could revolutionize the future. To ensure that sensors address the rapidly developing needs of various areas of our lives and activities, scientists, researchers, manufacturers, and end-users have established an efficient dialogue so that the newest technological achievements in all aspects of real-time sensing can be implemented for the benefit of the wider community. This book documents some of the results of such a dialogue and reports on advances in sensors and sensor systems for existing and emerging real-time monitoring applications