The disclosure relates to a force measurement device including central portion, fixing portion, first and second sensing portions, and first and second electromechanical elements. The first sensing portion has first natural frequency. The first sensing portion is connected to the central portion. The second sensing portion has a second natural frequency. The second sensing portion is connected to the first sensing portion and the fixing portion. The first electromechanical element is disposed on the first sensing portion to measure a first vibration amplitude. The second electromechanical element is disposed on the second sensing portion to measure a second vibration amplitude. When the central portion is subjected to a first force, the first vibration amplitude is larger than the second vibration amplitude. When the central portion is subjected to a second force, the first vibration amplitude is smaller than the second vibration amplitude.

A vehicle brake pad (100) comprising: a support plate (21); a friction pad (20); at least a shear force sensing device; and an electrical circuit configured to collect signals from the shear force sensing device (1); wherein the shear force sensing device (1) comprises: a sheet (2) of piezoelectric material having a first and a second main faces (3, 4) parallel to each other identifying a shear stress direction (S); at least a first digitated reading electrode (5) located on the first main face (3); at least a second digitated reading electrode (6) located on the second main face (4), the first and second reading electrodes (5, 6) having digits (5a, 6a) aligned along a reading direction (R) orthogonal to the stress shear direction (S); at least a first digitated polarizing electrode (7) located on the first main face (3) and interdigitated with the first digitated reading electrode (5); and at least a second digitated polarizing electrode (8) located on the second main face (4) and interdigitated with the second digitated reading electrode (6); and wherein the piezoelectric material has a bulk electric polarization with vector field (E) transversally oriented to the reading direction (R), each pair of aligned digits (5a, 6a) of the first and second reading electrodes (5, 6) enclosing a respective zone (2a) of the piezoelectric material having the

The disclosure provides a method, system, device and medium for online monitoring of a plane stress field without baseline data based on a piezoelectric transducer array. Since Lamb waves have complex multi-mode characteristics, a suitable excitation frequency needs to be selected according to geometric dimensions of the structure to be measured, and then, only low-order mode Lamb waves are excited inside the measured structure to avoid serious waveform aliasing. For isotropic measured objects, anisotropic characteristics will be generated under the action of pre-stresses, that is, the propagation velocities of ultrasonic waves in all directions are different, but there is a linear relationship between velocity changes in different propagation directions and stresses. Therefore, there is still a linear relationship between the difference of velocity changes in different propagation directions and the stress. According to this characteristic, a characterization method of an absolute stress field without baseline data can be implemented. The method of the disclosure can make full use of the low attenuation characteristics of the Lamb waves to realize online monitoring of the plane stress field with a large coverage area.

The disclosure provides a method, system, device and medium for online monitoring of a plane stress field without baseline data based on a piezoelectric transducer array. Since Lamb waves have complex multi-mode characteristics, a suitable excitation frequency needs to be selected according to geometric dimensions of the structure to be measured, and then, only low-order mode Lamb waves are excited inside the measured structure to avoid serious waveform aliasing. For isotropic measured objects, anisotropic characteristics will be generated under the action of pre-stresses, that is, the propagation velocities of ultrasonic waves in all directions are different, but there is a linear relationship between velocity changes in different propagation directions and stresses. Therefore, there is still a linear relationship between the difference of velocity changes in different propagation directions and the stress. According to this characteristic, a characterization method of an absolute stress field without baseline data can be implemented. The method of the disclosure can make full use of the low attenuation characteristics of the Lamb waves to realize online monitoring of the plane stress field with a large coverage area.

A piezoelectric sensor includes an elastic body having a first surface, a regulatory section which is disposed at a position where the regulatory section faces the first surface of the elastic body, and which is configured to limit a deformation of the elastic body, and a first piezoelectric element which is partially fixed to the regulatory section, and which deforms in accordance with the deformation of the elastic body, wherein the first piezoelectric element outputs a voltage signal which increases and decreases from a reference voltage in accordance with a direction of the deformation.

A piezoelectric sensor includes an elastic body having a first surface, a regulatory section which is disposed at a position where the regulatory section faces the first surface of the elastic body, and which is configured to limit a deformation of the elastic body, and a first piezoelectric element which is partially fixed to the regulatory section, and which deforms in accordance with the deformation of the elastic body, wherein the first piezoelectric element outputs a voltage signal which increases and decreases from a reference voltage in accordance with a direction of the deformation.

A force sensing system for determining if a user input has occurred, the system comprising: an input channel, to receive an input from at least one force sensor; an activity detection stage, to monitor an activity level of the input from the at least one force sensor and, responsive to an activity level which may be indicative of a user input being reached, to generate an indication that an activity has occurred at the force sensor; and an event detection stage to receive said indication, and to determine if a user input has occurred based on the received input from the at least one force sensor.

A force detection system includes first and second sets of pressure sensors, memory, and a processing module. The first set of pressure sensors are in an insole of a shoe and the second set of pressure sensors are in an outsole of a shoe. The processing module receives first data regarding the first set of pressure sensors and generates a first digital representation of the first data. The processing module also receives second data regarding the second set of pressure sensors and generates a second digital representation of the second data. The processing module also writes the first and second digital representations to the memory.

A force detection system includes first and second sets of pressure sensors, memory, and a processing module. The first set of pressure sensors are in an insole of a shoe and the second set of pressure sensors are in an outsole of a shoe. The processing module receives first data regarding the first set of pressure sensors and generates a first digital representation of the first data. The processing module also receives second data regarding the second set of pressure sensors and generates a second digital representation of the second data. The processing module also writes the first and second digital representations to the memory.

A force detection apparatus includes first and second force sensors each including a force detection device having a force detection axis, a first inertial sensor disposed in the vicinity of the first force sensor and having an inertia detection axis extending along the force detection axis of the first force sensor, and a second inertial sensor disposed in the vicinity of the second force sensor and having an inertia detection axis extending along the force detection axis of the second force sensor.