Papers by Keyword: Force Measurement

Abstract: Unlike conventional robots, the equipment provided with pneumatic artificial muscles cannot integrate standard systems for force measurement. Applied measurement system involves specific attributes and requirements for pneumatic muscles. Force feedback of rehabilitation device equipped with pneumatic muscles was experimentally verified under the laboratory condition.

Abstract: Incremental Sheet Forming processes have been characterized by their limited forming speed and accompanying lengthy production time. ISF has therefore been considered a process category suitable for small batch sizes or discrete part production only. The potential for greatly increasing the forming speed of incremental forming processes is studied here by means of axisymmetric incremental forming on a lathe. As an aluminium alloy commonly used in automotive applications, AA5182-O, is of interest for incremental forming at increased speed. In this paper the influence of an increasing feed rate on forming forces, temperature and formability is analyzed.

Abstract: Cutting force is one of important parameters for manufacturing processes. The traditional dynamometer is limited by size, machining environments, and so on. This paper introduces a new constantan thin film sensor which embedded on the holder of external turning tool to measure cutting force. The relationship between force and output voltage are deduced from theory. By using the finite element software, the analyses on induction and linearity capability of thin film sensor are simulated, and the influences of the location and thickness of film on the output voltage are analyzed. The results show that the linearity of input and output is good and the deviation between the calculated value and simulation results is identical. As the result, the constantan thin film sensor unit can be used to measure the cutting forces.

Abstract: This paper presents a low cost pressure sensor for SHU dexterous hand and outlines the pressure experiments performed. The sensor is based on the semiconductive material, and multi-layer structure. The operating principle of the sensor is explained. The experimental results demonstrate the sensor has linear properties and can provide available information.

Abstract: In near-field levitation, an object can be levitated vertically upward above vibrating surface of an ultrasonic transducer. In this case, a repulsive force acts on the object. On the other hand, it has been reported that a minute object can be suspended vertically downward under the vibrating surface with a small gap in the air. We call this phenomenon ultrasonic suspension. Under the suspension, an attractive force acts on the object. When an object is suspended, there is restoring force, which pulls the object to the center of the vibrating surface. Our aim is to characterize the actuation forces under the suspension. Simultaneous measurement of vertical and horizontal actuation forces is required. A servo type measuring mechanism was proposed. A 1 DOF mechanism with a cantilever and a voice coil motor (VCM) was fabricated as a prototype. The prototype was calibrated and utilized for measurement of vertical actuation force. The result showed enough accuracy and repeatability. Then, a 2 DOF actuation force measurement mechanism was fabricated. The mechanism was consisted of a base to fix the object and two thin wires to support the base. Position of the base was controlled by three VCMs based on PID control. The ultrasonic suspension actuation forces were characterized successfully.

Abstract: The roll forming process is a very interesting process for the production of profile shaped parts because of its high production rate, low investment and efficient use of the material. However, as in most of the manufacturing processes, the set up of the machine is very important for the quality of the profiles to be manufactured being the traditionally used trial and error method high time and scrap consuming. Within the set up, one of the most important variables to be defined is the right gap or distance between the upper and the lower roll at each station. This gap can lead to, or avoid, the appearance of geometrical errors such as differences in springback effect or longitudinal bow of the final profile. Furthermore, to find the correct gap between the rolls,a traditional tedious and costly work must be made based on a trial and error methodology. Different sensor based methodologies have already been implemented successfully in other forming processes. The present work aims at evaluating if force and torque measurements are a viable solution to decrease the roll forming process set-up time. This way, the effect of the gap for three different materials, a DC01, DP600 and MS1200 steel, has been analyzed. For this purpose, force and torque measurement together with final geometry measurements have been made at different gap configurations. A correlation between the profile quality and the process variables has been carried out in order to identify the influence of the gap at the setting up of the machine.

Abstract: Super high-speed point grinding is a good performance grinding with high surface quality due to its low force. To model point grinding forces including swivel angle formed by tilting wheel to the horizontal workpiece axis seems necessary. In this research, a point grinding force model was present, and the point grinding forces are influenced by factors such as grinding depth, wheel velocity, swivel angle as well as equivalent diameter. And then some experimental tests are carried out. It is found that the experimental data was in good agreement with theoretical model.

Abstract: The article deals with description of design of sensor system for linear actuators. These constitute a part of a parallel kinematic machine based on a structure of a Stewart platform. The machine is intended for testing of bone implants in biomechanical and medical practice. The developed Stewart platform presents a mechatronic system. Hence the design of mechatronic systems known as a V-model was used. The system of sensors has been developed since the middle phase of the Stewart platform development.

Abstract: Distraction Osteogenesis (DO) is a surgical technique used to reconstruct bone defects. In the maxillofacial specialty, it account for one of the best procedures to treat severe traumas as ballistic wounds. The evolution of forces acting during DO is known to be strongly linked with the clinical issue of the treatment. In this context, the aim of this study was to determine the time-dependent forces supported by a distraction device (DEOS, OBL, France), particularly indicated for severe traumas. Bone transport forces were evaluated for two patients undergoing respectively mandibular and malar DO following a gunshot wound. In order to evaluate the distraction forces, some fixing pins of the distraction device were equipped with strain gauges. Strain values were recorded by means of a data acquisition system (SCXI, National Instruments, USA) connected to a PC computer and executing a LabView program (National Instruments, USA). Records started about one minute before the DO activation and ended about one hour later. Eighteen measurements were done for both cases during the early phases of the treatment. An equilibrium analysis was achieved in order to determine the force and moment acting in bone regenerate from strains in the pins. This procedure was coded through a Fortran program, allowing to plot the evolution of DO force and moment. The present work confirmed the time-dependent feature of the bone regenerate mechanical behaviour. Important data have been obtained concerning forces and their evolution for both mandibular and malar DO.

Abstract: The conversion of chemical energy into mechanical forces that powers cell movements is a ubiquitous theme across biology. Besides molecular motors such as kinesin-microtubule and actin-myosin complexes, biological springs and ratchets can also store and release energy to rectify motion. The acrosome reaction of horseshoe crab sperm is a simple example of a biological spring where a 60!μm-long crystalline bundle of actin filaments, tightly cross-linked by actin bundling protein scruin, straightens from a coiled conformation and extends from the cell to penetrate an egg in about five seconds. To identify the basis and mechanism for this movement, we examine the possible sources of chemical and mechanical energy and show that the stored elastic energy alone is sufficient to drive the reaction. We also provide an estimate of the maximum force generated during the uncoiling by stalling the bundle using an agarose gel to show the reaction produces enough force to penetrate the egg.