Bernard Pottier

Performance of wavelet denoising in vibration analysis: highlighting

This paper proposes to highlight two aspects of denoising in vibration analysis. The first aspect aims to reveal the singularities, and the second eliminates the noise in order to keep the useful signal. These two aspects are the cause of the surjection of denoising, especially due to the choice of the performance criteria. This paper highlights the use of denoising through these aspects, and then proposes a performance criterion suitable for vibration analysis as part of a noise suppression, to apply a processing method. This paper provides a reflection on the use of discrete wavelet transform through the various parameters which are used during processing.

A Novel Capacitive Safety Device for Target Localization and Identification

A novel capacitive device dedicated to the safety of people working on automated production sites has been developed. It can be implemented on an articulated mechanical system (robot, press) to estimate the distance between sensors that are fixed on such a system and a mobile target. An interdigital sensor has been fabricated to identify the target nature among them (human beings or objects). The variable geometry of the system is taken into account as well as its motion relatively towards the ground by means of an ingenious sensitive element design. Furthermore, the sensors are made of conducting paint, thus providing low weight and negligible space hindrance devices. Results show this novel low-cost sensing setup has a great potential to estimate the distance and to discriminate targets.

Capacitive Sensor Device for Measuring Loads on Bearings

This paper aims to present an experimental device, which measures the displacement of an outer ring of a roller bearing subjected to two loads: a stationary load and a rotational load. This displacement is measured with a very high degree of accuracy, by means of a capacitive probe. The probe and its associated electronics convert the displacement into a proportional voltage. The relation displacement/load is proportional since linear elasticity domain of the material is not exceeded. The empirical mode decomposition applied to the measured signal allows discriminating the stationary and rotational loads and thus gives an easy access to the value of the load. Both the numerical simulations and prototype testing confirm the relevance of the device. The applications are numerous: 1) located on the wheels of motor vehicles, potential optimization of the information received by the integrated safety devices; 2) opportunity to measure the load on lifting equipments; and 3) possibility to monitor the defects of machines through vibratory analysis.

Static Stress Measurement Based on Capacitive Probes Integrated Inside Rolling Rings

An experimental setup has been conceived to measure the deformation of a rolling ring subjected by stress. This deformation is measured by means of a capacitive sensor. Such a sensor behaves like a displacement sensor that translates the displacement into an electrical signal. Mechanical and electrical operating points determine the sensitivity of the probe and its measurement range. Numerical simulations and tests performed on a prototype confirm the relevance of the device. Applications are numerous: i) mounted on the wheels of motorized vehicles, such sensors allow one to improve the quality information transmitted to integrated safety devices and ii) placed on devices of lift, they measure the load.

Numerical determination of the mechanical stiffness of a force measurement device based on capacitive probes: Application to roller bearings

Abstract Bearings allow external loadings to be transferred from one raceway to the other through rolling elements, which induces strains in the bearing constituents. In order to measure the radial component of these forces, the fixed ring is inserted within a housing equipped with capacitive probes able to measure displacements with very high sensitivity. This work mainly focuses on determining the optimal housing shape using FE simulations and their influence on the global stress state undergone by the structure. Finally, an averaged global stiffness is computed, allowing proper calculation of the contact forces involved in the bearing.

Capacitive protection system for robot dedicated to the safety of humans

This protection system is dedicated to the safety of people working on automated sites of production. The system is implemented on an articulated mechanical system, (robot, press...). Capacitive sensors exploit the properties of an electric field to estimate the distance between a detected target and themselves. By the way, it makes it possible to discriminate the presence of human beings or objects in their environment and to give information about their distance. Moreover, the system takes into account the capacitive variations which are induced on itself due to its variable geometry (interactions between the various elements of the articulated mechanical system and the relative approach of the ground). The sensitive elements of detection are of a low cost because they are made with a conducting paint put on the dangerous parts of the machine. Their weight and their space hindrance are negligible, this is essential for an embarked tool of a robot.

Capacitive Sensor Dedicated to Pedestrians Protection

In the case of an unavoidable frontal collision between a vehicle and a pedestrian, the activation of a protection system can reduce the severity of injuries caused by the collision. However, to fulfill this objective, it is necessary to determine when the shock will occur. To overcome this problem, we place inside the front bumper a metallic sheet that emits an electric field. This field is oriented toward the front of the vehicle by means of various guard screens. The intrusion into the emitted electric field induces a capacitive coupling with the sensor. Which will enable the electronic device to detect the presence of the pedestrian at a distance of 1 m. To avoid slow drifts in time, the change in capacity is measured every millisecond. The last hundred acquisitions are considered as a history. This history is compared with the signature of a pedestrian who was established in the laboratory. When the pedestrian is about a thirty centimeters of the vehicle and the shock is inevitable, the protection systems are activated. When the vehicle is at very low speed, this device can be used as parking assistance.

Pedestrian Detection Strategy in Urban Area: Capacitance Probes and Pedestrians’ Signature

Every year, lives of millions of people are cut short or considerably affected by road accidents. Most of them happen in urban areas where the speed limit is supposed to be below

Numerical Model of the Capacitive Probe's Capacitance for Measuring the External Loads Transmitted by the Bearing's Rolling Elements of Rotating Machines

50~km/h

Determination of loads transmitted by rolling elements in a roller bearing using capacitive probes: Finite element validation

. Active protection devices (such as airbags) attached at the front of the vehicle can help reduce the severity of injuries inflicted in such circumstances. However, the effectiveness of such strategies depends greatly on how well we can anticipate the impact moment of the accident. The physical principle of capacitive coupling can be used to anticipate the impact by detecting the intrusion of the pedestrian in the detection volume of the probe. However, any intrusion into the sensing volume of probe can increase its capacitance like dust deposits on the surface of the capacitive probe, the variation of the air humidity, the air friction on the car’s body, which makes the common voltage float among others that influence the capacitance of the probe and make the voltage carried by the probe vary over time. To overcome this problem, we define the concept of “pedestrian signature.” This concept can help us distinguish the presence of a pedestrian in the sensing volume of the probe from any other perturbations. Thus, we can anticipate the moment of impact early enough to trigger protection systems. The analog electronic device, we present in this paper, along with the pedestrian signature can help trigger protection devices to react at the right moment. The same device can also be used as parking aid when the vehicle speed is less than