In-Situ Calibration Research Articles

In-Situ Calibration of Six-Axis Force/Torque Transducers on A Six-Legged Robot

Abstract Ground contact modeling for multi-legged locomotion is challenging due to the possibility of multiple slipping legs. To understand the interplay of contact forces among multiple legs, we integrated a robot with six high-precision 6-DoF force-torque sensors, and measured the wrenches (forces and torques) produced in practice. Here we present an in-situ calibration procedure for simultaneously measuring all foot contact wrenches of a hexapod using 6-DoF load cells installed at the hips. We characterized transducer offset, leg gravity offset and the wrench transformation error in our calibration model. Our calibration reduced the RSME by 63% for forces and 90% for torques in the residuals of the robot standing in different poses, compared with naive constant offset removal.

EasyCalib: Simple and Low-Cost In-Situ Calibration for Force Reconstruction With Vision-Based Tactile Sensors

EasyCalib: Simple and Low-Cost In-Situ Calibration for Force Reconstruction With Vision-Based Tactile Sensors

In-Situ Calibration and Trajectory Enhancement of UAV LiDAR Systems for Mapping Mechanized Agricultural Fields

In-Situ Calibration and Trajectory Enhancement of UAV LiDAR Systems for Mapping Mechanized Agricultural Fields

A Technique for In-Situ Calibration of Semiconductor Strain Gauges Used in Hopkinson Bar Tests

The semiconductor strain gauges (SCSGs) are widely introduced in Hopkinson bar technique to detect weak strain signals of low-impedance materials, just for its high gauge factor. But, the measurement accuracy is negatively affected by the instability of SCSGs’ specifications. A novel methodology is proposed to in-situ calibrate them and to interpret accurately the weak transmitted strain signals. And the dependence of the gauge resistance and factor on temperature and compressive/tensile loading conditions are calibrated with the stable electrical resistance strain gauges (ERSGs) as standard outputs. The results confirm that the properties present a high sensitivity to temperature, and even behave asymmetrically under tensile and compressive loadings. The experiments are carried out to verify the proposed in-situ calibration technique. Finally, the stress-strain curves of a shear thickening material are measured to demonstrate its reliability and detectability. This work will be useful to measure the dynamical mechanical properties of the soft and energy absorption materials like rubber and foams.

The Sound Power as a Reference for Sound Strength (<I>G</I>), Speech Level (<I>L</I>) and Support (<I>ST</I>): Uncertainty of Laboratory and In-Situ Calibration

The Sound Power as a Reference for Sound Strength (<I>G</I>), Speech Level (<I>L</I>) and Support (<I>ST</I>): Uncertainty of Laboratory and In-Situ Calibration

Establishment of Absolute Measurement Standards for In-Situ Calibration of Acoustic Emission Energy

Establishment of Absolute Measurement Standards for In-Situ Calibration of Acoustic Emission Energy

Establishment of Absolute Measurement Standards for In-Situ Calibration of Acoustic Emission Energy

To date acoustic emission (AE) monitoring has been undertaken without proper means of calibration and the actual AE measurement results are significantly affected by the experimental layout. As the use of AE monitoring increases, the need for more meaningful measurement to reflect the AE physical process becomes urgent and necessary, and this ultimately requires an absolute calibration for AE measurement systems in-situ. This paper outlines a possible hierarchy of measurement standards for AE energy calibration using artificial standard AE energy sources generated by the elastic impact of a bouncing-ball, the thermoelastic irradiation of a pulsed-laser, and the excitation of a conical piezoelectric transducer. The basic idea is to provide absolute standard AE energy sources for calibration of AE measurement systems in-situ.

In-Situ Calibration Technique for Laser-Induced Fluorescence Measurements of Nitric Oxide in High-Pressure, Direct-Injection, Swirling Spray Flames

We report spatially resolved laser-induced fluorescence (LIF) measurements of nitric oxide (NO) in a preheated, two-atmosphere, lean direct-injection (LDI) spray flame. The spray is produced by a hol-low-cone, pressure-atomized nozzle supplied with liquid heptane. NO is excited via the Q2(26.5) transition of the γ(0,0) band. Detection is performed in a 2-nm region centered on the γ (0,1) band. A complete scheme is developed by which quantitative NO concentrations in high-pressure LDI spray flames can be measured by applying linear LIF. Standard excitation and detection scans are performed to assess possible interferences and to verify a non-resonant wavelength for subtracting the influence of oxygen interferences and Mie scattering in the NO detection window. NO is doped into the reactants and convected through the flame with no apparent destruction, thus allowing an NO fluorescence calibration to be taken inside the flame environment. The in-situ calibration scheme is validated by comparisons to a reference flame. Relative axial calibration slopes are utilized in order to obtain radial profiles of absolute NO concentrations. These quantitative NO profiles are presented and analyzed so as to better understand the operation of lean-direct injectors for gas turbine combustors.

Mass Comparator for In-Situ Calibration of Large Mass Standards.

This paper describes a high precision electronic mass comparator with a range from 250 kg to 5,000 kg. It is suggested that it would be useful to transport the comparator to the test weights rather than to transport the weights to the comparator, the usual method, thus economizing time and monies.