Christophe Winter

Optimal design of a squeeze film actuator for friction feedback

Sense of touch belongs to one of the five Human Senses. Whereas blind people largely use feeling in everyday life, sighted person mainly focus on hearing and vision. However, haptic interface started being introduced in customers applications, such as smartphone, to propose new opportunities to users. A surface put in vibration nearby another can modify the friction coefficient measured between the two objects. This is known as the squeeze film effect. The aim of this paper is to present the optimization of a piezoelectric actuator for friction feedback. Since the computation of the Squeeze film Finite Element (FE) model is time-consuming, it is also proposed to focus only on the mechanical simulations. Indeed, a correlation between the force of the actuator and the volume swept by the travel of the vibrating surface is brought out. Finally, a couple of optimization results are presented for different topologies of actuators.

Design of a resonant power inverter for a piezoelectric actuator

The power stage of a resonant piezoelectric actuators is difficult to design due to the high static capacitance of the actuator. It creates a lot of reactive power to compensate and can cause stability issues. This work presents a design of a resonant current inverter to drive actuators with a sine excitation biased with a DC offset with voltages and frequency in the range of 300 Vpk and 40 kHz.

Empirical Modeling of a Squeeze Film Haptic Actuator

In the analysis of squeeze film haptic tactile feedback actuators, attention is focused on establishing an empirical model of the force generated on the users finger. The model is based on finite-element simulations which take into account the real motion of the actuator. As analytical models exist for very few special cases, a methodology is exposed to establish an empirical model of the force created between a finger and an actuator aided by an optimal design-of-experiment plan. Then, an example of an actuator which generates a sinc profile amplitude of vibration is treated.

Optimal design of inductive coupled power transfer systems with applications to electric cars

This paper presents the multi-objective optimisation of an Inductive Coupled Power Transfer (ICPT) device. A setup as complicated as the one at hand in this paper is extremely hard to model analytically. To acquire some knowledge about the influence of the geometric factors, a sensitivity analysis is first performed using design of experiment (DoE) and finite-element modelling (FEM). It allows to validate that the choice of the free factors is relevant. This being done, the optimisation itself is performed using a genetic algorithm (GA), with two objectives and a strict functioning constraint.

A Novel winding topology applied for a self-shielding induction cooker

In this paper, the magnetic coupling between an induction cooker and a metallic pot is studied for various winding topologies. Effects of the winding orientation on the power transfer capability and on the emitted magnetic field under the cooker are discussed and compared. A novel topology inspired by permanent magnet Halbach array is proposed. This consists in coupling in both horizontal and vertical directions and to create an asymmetric field in order to reduce the emission under the cooker.

Haptic tactile interface (HTI): Friction coefficient measurements

An haptic tactile interface (HTI) is presented with its modeling. Its design is dedicated to perform friction coefficient measurement to characterize reachable feelings with that kind of interface. Friction measurements are presented and discussed.

Haptic tactile interface: A novel click-wheel user experience

An haptic tactile interface (HTI) feedback device is presented. Its finite element (FE) model is presented and explained. Comparison between FE predictions and measurements are performed in order to validate the modeling approach. Finally a functional demonstrator is built allowing users to feel a new experience of touch control electronic devices.

Haptic tactile interface (HTI): Design of the power supply stage

The driving electronics of an haptic tactile interface (HTI) is presented. The stability of its linear power amplifier under the capacitive load of the HTI piezoelectric actuator is analysed and ensured. As the HTI actuator is a resonant one, a topology to compensate its reactive power is presented allowing to reduce the size and the thermal heating of the power stage.