Design of an Unobtrusive Reaction Force Measurement and Its Application on Treadmills

2012 ◽  
Vol 61 (7) ◽  
pp. 1955-1965 ◽  
Author(s):  
Kuan-Hung Chen ◽  
Jiunn Fang ◽  
Shih-Wei Yeh
Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2641 ◽  
Author(s):  
Junghoon Park ◽  
Sangjoon Kim ◽  
Youngjin Na ◽  
Yeongjin Kim ◽  
Jung Kim

Wearable ground reaction force (GRF) measurement systems make it possible to measure the GRF in any environment, unlike a commercial force plate. When performing kinetic analysis with the GRF, measurement of multiaxial GRF is important for evaluating forward and lateral motion during natural gait. In this paper, we propose a bendable GRF measurement system that can measure biaxial (vertical and anterior-posterior) GRF without interrupting the natural gait. Eight custom small biaxial force sensors based on an optical sensing mechanism were installed in the proposed system. The interference between two axes on the custom sensor was minimized by the independent application of a cantilever structure for the two axes, and the hysteresis and repeatability of the custom sensor were investigated. After developing the system by the installation of force sensors, we found that the degree of flexibility of the developed system was comparable to that of regular shoes by investigating the forefoot bending stiffness. Finally, we compared vertical GRF (vGRF) and anterior-posterior GRF (apGRF) measured from the developed system and force plate at the same time when the six subjects walked, ran, and jumped on the force plate to evaluate the performance of the GRF measurement system.


2016 ◽  
Vol 2016 (0) ◽  
pp. J2320102
Author(s):  
Takahito SUZUKI ◽  
Kiyoshi HIROSE ◽  
Haruka CHIBA ◽  
Akiko KONDO ◽  
Hitoshi DOKI

Author(s):  
Hiroki Manabe ◽  
Shota Yabui ◽  
Hideyuki Inoue ◽  
Tsuyoshi Inoue

In turbomachinery, seals are used to prevent fluid leakage. At seal part, rotordynamic fluid force (RD fluid force), which causes whirling motion of rotor, is generated. Under certain conditions, the RD fluid force may contribute to instability of the machine. There are several cases that the whirling is accompanied by eccentricity due to the influence of gravity, or the whirling orbit becomes elliptical due to the influence of the bearing support anisotropy. In these cases, mathematical modeling of the RD fluid forces becomes increasingly complex. As a result, the RD fluid force measurement is more preferable. To improve the measurement and evaluation technology of the RD fluid force, a method to arbitrarily control whirling of the orbit is required. In this paper, RD fluid force measurement by controlling the shape of the orbit using an active magnetic bearing (AMB) is proposed. A contact type mechanical seal is used as a test specimen. When the rotating shaft is whirling, the RD fluid force due to hydrodynamics lubrication and the frictional force due to contact occur on the sliding surface. The resultant force of these forces is taken as the reaction force of mechanical seal and the measurement is performed. The measured reaction force of the mechanical seal is compared with simulation results and the validity of the proposed measurement method is confirmed.


Electronics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1147
Author(s):  
Tomasz Mańkowski ◽  
Jakub Tomczyński ◽  
Krzysztof Walas ◽  
Dominik Belter

In this article, the design of a five-fingered anthropomorphic gripper is presented specifically designed for the manipulation of elastic objects. The manipulator features a hybrid design, being equipped with three fully actuated fingers for precise manipulation, and two underactuated, tendon-driven digits for secure power grasping. For ease of reproducibility, the design uses as many off-the-shelf and 3D-printed components as possible. The on-board controller circuit and firmware are also presented. The design includes resistive position and angle sensors in each joint, resulting in full joint observability. The controller has a position-based controller integrated, along with USB communication protocol, enabling gripper state reporting and direct motor control from a PC. A high-level driver operating as a Robot Operating System node is also provided. All drives and circuitry of the PUT-Hand are integrated within the hand itself. The sensory system of the hand includes tri-axial optical force sensors placed on fully actuated fingers’ fingertips for reaction force measurement. A set of experiments is provided to present the motion and perception capabilities of the gripper. All design files and source codes are available online under CC BY-NC 4.0 and MIT licenses.


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