Triggermuscle: Exploring Weight Perception for Virtual Reality Through Adaptive Trigger Resistance in a Haptic VR Controller

It is challenging to provide users with a haptic weight sensation of virtual objects in VR since current consumer VR controllers and software-based approaches such as pseudo-haptics cannot render appropriate haptic stimuli. To overcome these limitations, we developed a haptic VR controller named Triggermuscle that adjusts its trigger resistance according to the weight of a virtual object. Therefore, users need to adapt their index finger force to grab objects of different virtual weights. Dynamic and continuous adjustment is enabled by a spring mechanism inside the casing of an HTC Vive controller. In two user studies, we explored the effect on weight perception and found large differences between participants for sensing change in trigger resistance and thus for discriminating virtual weights. The variations were easily distinguished and associated with weight by some participants while others did not notice them at all. We discuss possible limitations, confounding factors, how to overcome them in future research and the pros and cons of this novel technology.

Development of a Control System and Interface Design Based on an Electric Wheelchair

Recently, personal mobility has been researched and developed to make short-distance travel within the community more comfortable and convenient. However, from the viewpoint of personal mobility, there are problems such as difficulty in picking up items while shopping when operating the joystick for shopping and the inability to use hands freely. Accordingly, because the speed of personal mobility can be controlled by foot stepping like an accelerator pedal, we developed an electric wheelchair system that can control the speed by pedal operation. Furthermore, we developed a control system that considers the ride quality using an electric wheelchair with pedal control. In this study, the proposed method is detailed in three parts. Firstly, to develop the pedal mechanism, a potentiometer was used to detect the angle of the pedal mechanism, and a spring mechanism was designed for return to its original position after the pedal was pushed. Next, we propose a feedback control system that considers the ride quality of the operator. In addition, we integrated the system with a smart device-based robot system to realize the mobility as a service (MaaS). Finally, we present several examples of the system and discuss the applicability of the proposed system.

Evaluation of the Negative Stiffness Mechanism on the Performance of a Hinged Wave Energy Converter

This paper presents the numerical and experimental study of a new spring mechanism adapted to a cone-shaped point absorber wave energy converter (WEC). The WEC is intended to be hinged to a floating wind platform with a long arm to create a combined wind and wave harvesting concept. The main objective of the spring mechanism is to improve the platform restoring moments against the wind thrust forces, generated by the wind turbine while contributing to wave energy harvesting. However, the study is presented for the case where the WEC dynamics is investigated outside the platform and attached to a fixed frame, to validate the mathematical model of the WEC concept. Moreover, the impact on the power harvesting performance is investigated with and without negative springs in this scenario.

Development of dielectric elastomeric actuators for morphing wings

In the last decades, wing morphing structures have aroused great interest due to their capability to improve the aerodynamic efficiency of modern aircraft. DE actuators, also known as “artificial muscles” due to their ability to exhibit large actuation strains at high voltages, are suitable candidates for morphing applications. This paper focuses on the research and development of miniature dielectric elastomeric actuators for variable-thickness morphing wings. A conical elastomeric actuation configuration has been proposed, consisting of a VHB4910 dielectric membrane preloaded with a spring mechanism and constrained to a rigid circular ring. The mini-actuators are developed to be fixed in an actuation array, mounted to the wing skin. This new electromechanical actuation system is designed to be integrated on thin airfoil wings, where conventional morphing structures cannot be used, because of restricted mass and space requirements. By controlling the thickness distribution using the proposed actuators, we may be able to maintain and delay the location of the laminar-turbulent transit towards the trailing edge, promoting laminar flow over the wing surface. Experimental models and prototypes will be developed in the next phase of the research project for further investigations.

Passive Air Leakage Detection Mechanism for a Vacuum Suction Actuator

Recently, research on vacuum actuators for holding and transporting objects has been actively conducted. In particular, many vacuum actuators are used to hold and transport several objects at once. However, there is a possibility that a problem of reducing vacuum efficiency may occur when several vacuum actuators are used simultaneously in the process of transporting multiple objects. The first factor is that, due to the diversity of the object’s shape, the vacuum pad of some actuators may not touch the object, so that gripping may not occur. Second, some actuators’ vacuum pad touches the object, but the pad is not completely blocked, resulting in air leakage. This paper used a spring mechanism to solve this problem and developed a vacuum gripping actuator that can block airflow into the actuator that is not used for vacuum efficiency when driving the system before the system is driven. Due to the spring inside the actuator that can play the role of passive compliance, the length can be adjusted, so even if the distance to the object is not constant, it can hold and transport several objects. Furthermore, the pretension of the spring makes it possible to block air inflow initially. We have also developed a brake system using pneumatic and tendon to hold the actuators to maintain each actuator’s length when holding and moving objects. We unified the driving method for operating both systems for simplicity by receiving pneumatic pressure from a pneumatic compressor.

Acid-Sensing Ion Channels and Mechanosensation

Acid-sensing ion channels (ASICs) are mainly proton-gated cation channels that are activated by pH drops and nonproton ligands. They are part of the degenerin/epithelial sodium channel superfamily due to their sodium permeability. Predominantly expressed in the central nervous system, ASICs are involved in synaptic plasticity, learning/memory, and fear conditioning. These channels have also been implicated in multiple disease conditions, including ischemic brain injury, multiple sclerosis, Alzheimer’s disease, and drug addiction. Recent research has illustrated the involvement of ASICs in mechanosensation. Mechanosensation is a form of signal transduction in which mechanical forces are converted into neuronal signals. Specific mechanosensitive functions have been elucidated in functional ASIC1a, ASIC1b, ASIC2a, and ASIC3. The implications of mechanosensation in ASICs indicate their subsequent involvement in functions such as maintaining blood pressure, modulating the gastrointestinal function, and bladder micturition, and contributing to nociception. The underlying mechanism of ASIC mechanosensation is the tether-gate model, which uses a gating-spring mechanism to activate ASIC responses. Further understanding of the mechanism of ASICs will help in treatments for ASIC-related pathologies. Along with the well-known chemosensitive functions of ASICs, emerging evidence has revealed that mechanosensitive functions of ASICs are important for maintaining homeostasis and contribute to various disease conditions.