Publications de Christian Köchli

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Magnetorheological (MR) valves attracted the interest of researchers across diverse fields, owing to the controllable nature of MR fluid. The use of MR fluid in valves enables fast response, energy efficiency, and robustness, while several studies designed ...

This publication presents the application of Non-Linear Programming (NLP) to the design of AC induction motors driving hydraulic pumps on commercial aircrafts. In addition to the usual constraints on the geometry or on the efficiency of the motor, the specifications for this application include conditions on the supply frequency, environment temperature and in-rush current, which are very difficult to meet. The NLP had to be adapted to support constraints on multiple operating points of the motor. A prototy

Fluidic systems enable actuation in various applications, such as automotive, medical, and industrial robotics. Miniaturized valves constitute a fundamental controlling element of modern fluidic systems, intriguing the interest of many researchers. This le ...

The valve mode is the most common operational mode of magnetorheological fluid (MRF) devices in engineering applications. Magnetorheological (MR) valves have been studied upon their self-sensing capabilities resulting from the electromagnetic induction phe ...

The brushless DC motors are normally built with rotor mounted PMs, which create the necessary back EMF voltage to produce a mechanical power. The shape of this back-EMF voltage is very important compared to the phase voltage supply one. Indeed, the electromechanical power is obtained by the product of the back-EMF and the phase current. Two possibilities are normally used to make the choice of the electronic supply. If the back-EMF is trapezoidal, the supply will be "block" (120 degrees, two-phase one mode)

Diabetic foot ulcers (DFUs) remain a major complication of diabetes mellitus, with significant human and economic costs. Plantar pressure (PP) is the most widely used surrogate to assess DFU risk. Existing PP measurement insoles are primarily designed for in-clinic assessments using external instrumentation to guide passive offloading strategies. However, reliance on brief clinical measurements limits their ability to capture real-world loading patterns, motivating the development of sensing systems capable

Permanent magnet axial flux motors are very well adapted to applications requiring a very short active length and a big diameter. They also have been used for micro-motors. Because of their size, these motors require the use of a permanent magnet and their ...

Inductive detection with double-balanced coils and a spatial phase profile were used to identify copper and steel rods in a composite target. The electromagnetic detection system was designed and validated using a dipole model. Simulations and experiments ...

The high prevalence of lower extremity ulceration and amputation in people with diabetes is strongly linked to difficulties in achieving and maintaining a reduction of high plantar pressures (PPs) which remains an important risk factor. The effectiveness o ...

Synchronous motors require sensors in order to control these devices in speed and/or position. Basically, the auto-commutation needs 3 sensors for a 3-phase type actuator. In micro-motors, as there is no more room to place the sensors, self-sensing approach must be used. The motor becomes a sensor it-self and electromagnetic phenomena are analyzed to detect the position of the rotor. These phenomena are magnetic saturation, back-EMF detection, Eddy current analysis and/or magnetic anisotropy variation. The

Plantar pressure plays a crucial role in the pathogenesis of foot ulcers among patients with diabetes and peripheral polyneuropathy. Pressure relief is a key requirement for both the prevention and treatment of plantar ulcers. Conventional medical practice ...

This paper presents an analytical model for the calculation of the flux density in PM synchronous motors. Parallel and radial magnetization of surface-mounted magnets and finite permeability of the iron are taken into account. © 2006 IEEE.

The paper presents a method to determine hysteresis losses in synchronous permanent magnet (M) slotless motors. The method comprises four steps: (1) experimental determination of the B-H loop, () analytical modeling of the B-H loop by applying different models, (3) analytical modeling of the hysteresis losses, and (4) determination of the hysteresis losses in a synchronous PM motor, and results verification using an experiment and an FEM software. This paper also presents an innovative and simple way to tak

In this paper, a MEMs relay for high power application is investigated. This relay has to hold a current of the order of magnitude of the Ampere and is subject to harsh environment such as high temperature or vibrations which can lead to a premature dysfun ...

The paper presents a method to determine hysteresis losses in synchronous permanent magnet (PM) motors. The method comprises four steps: (1) experimental determination of the B-H loop, (2) analytical modeling of the B-H loop by applying different models, (3) analytical modeling of the hysteresis losses, and (4) determination of the hysteresis losses in a synchronous PM motor, and results' verification using an experiment and an FEM software. © 2006 IEEE.

This paper addresses the design of a new hybrid MEMS micromotor. It is a small 3-phases axial flux BLDC motor. The stator is realized following the almost CMOS technology rules used for MEMS manufacture and the coils have two copper layers. The rotor is ma ...

This paper addresses the design of a new hybrid microelectromechanical systems (MEMS) micromotor. It is a small three-phase axial flux brushless dc (BLDC) motor. The stator is developed following the almost-standard CMOS technology rules used for MEMS manu ...

Low-frequency electromagnetic scattering from conductive and permeable bodies is the main principle of detection devices. To be able to classify the objects in the base material, a fast forward model based on the dipolar approximation was developed and ver ...

The present invention relates to a valve (10) comprising a housing (11) having a peripheral structure (12) made of a magnetic field conductive material and a core (13) disposed in said housing (11) The core (13) and the peripheral structure (12) delimit a ...

This paper addresses the design of a new hybrid MEMS micromotor. It gives insights on the choices, which led to the fabrication of a small 3-phases axial flux BLDC motor. The stator is developed following the almost CMOS technology rules used for MEMS manufacturing and the coils have two copper layers. The rotor is made of a ring permanent magnet assembled over the stator chip. The stator design has been performed using an analytical model presented in the paper and validated using finite elements and measu

Christian Köchli

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Modeling and experimental study of a miniaturized magnetorheological valve with high performance

Design optimization of induction motors for aerospace applications

Highly Efficient Miniaturized Magnetorheological Valves Using Electropermanent Magnets

Microfluidic device for analysis of magnetorheological fluids' properties

Modification of brushless DC motor back-EMF shape-application to noise reduction

P-MAPS: A Custom-Topology Velostat Insole for Pressure Redistribution in Diabetic Foot Care

Analytical Model for Slotless Permanent Magnet Axial Flux Motors

Geometrically Balanced Metal Detector Based on Optimized Frequencies and Spatial Phase Profile Responses to Discriminate Different Metal Rods Features

Intelligent plantar pressure offloading for the prevention of diabetic foot ulcers and amputations

Self-sensing methods to drive micro-machines

A Tunable Self-Offloading Module for Plantar Pressure Regulation in Diabetic Patients

Analytical modeling of the flux density in permanent magnet motors

Modeling of Hysteresis Losses Applied to Slotless Permanent Magnet Motors

Electrostatically actuated MEMs relay for high power applications

Analysis of hysteresis losses in synchronous permanent magnet motors

Development of a Hybrid MEMS BLDC Micromotor

Development of a Hybrid MEMS BLDC Micromotor

Validity Tests of Superposition Principle Based on Forward Model for Electromagnetic Induction Scattering

Magnetorheological valve

Modeling and design of a hybrid MEMS motor