German SKI sensor SKI model SKI price

SKI sensors are used in robots to mimic tactile functions. Touch is an important sensory function when humans come into direct contact with the external environment. Developing tactile sensors that meet requirements is one of the key technologies in robot development. With the development of microelectronics and the emergence of various organic materials, a variety of development plans for tactile sensors have been proposed, but most are currently in the laboratory stage, with few reaching commercialization. Tactile sensors can be roughly classified by function into contact sensors, force-torque sensors, pressure sensors, and slip sensors.

SKI sensor classification

1) Contact type: The sensing element of a contact temperature sensor has good contact with the object being measured; it is also called a thermometer. The thermometer reaches thermal equilibrium through conduction or convection, so that its reading directly indicates the temperature of the object being measured. Generally, the measurement accuracy is high. Within a certain temperature range, the thermometer can also measure the internal temperature distribution of an object. However, significant measurement errors occur for moving bodies, small targets, or objects with very small heat capacity. Commonly used thermometers include bimetal thermometers, glass liquid-in-glass thermometers, pressure-spring thermometers, resistance thermometers, thermistors, and thermocouples. They are widely used in industrial, agricultural, commercial, and other sectors. These thermometers are also frequently used in daily life. With the extensive application of cryogenic technology in national defense engineering, space technology, metallurgy, electronics, food, medicine, petrochemicals, and research into superconductivity, cryogenic thermometers for measuring temperatures below 120K have been developed, such as low-temperature gas thermometers, vapor-pressure thermometers, acoustic thermometers, paramagnetic salt thermometers, quantum thermometers, low-temperature resistance thermometers, and low-temperature thermocouples. Cryogenic thermometers require sensing elements that are small in size, highly accurate, and offer good reproducibility and stability. A carburized glass resistance thermometer, made by carburizing and sintering porous high-silica glass, is one type of sensing element for cryogenic thermometers and can be used to measure temperatures in the range of 1.6 to 300K. 2) Non-contact type: Its sensing element does not come into contact with the object being measured; it is also called a non-contact temperature measuring instrument. This instrument can be used to measure the surface temperature of moving objects, small targets, objects with small heat capacity, or objects with rapid (transient) temperature changes, and can also be used to measure temperature field distribution. The most commonly used non-contact temperature measuring instruments are based on the basic laws of blackbody radiation and are called radiation thermometers. Radiation thermometry includes the brightness method (see optical pyrometer), the radiation method (see radiation pyrometer), and the colorimetric method (see colorimetric thermometer). Various radiation thermometry methods can only measure the corresponding brightness temperature, radiation temperature, or colorimetric temperature. Only the temperature measured for a blackbody (an object that absorbs all radiation and reflects no light) is the true temperature. To determine the true temperature of an object, correction for the material's surface emissivity is required. However, material surface emissivity depends not only on temperature and wavelength but also on surface condition, coating, and microstructure, making precise measurement difficult. In automated production, radiation thermometry is often used to measure or control the surface temperature of certain objects, such as the rolling temperature of steel strips, roll temperature, forging temperature, and the temperature of various molten metals in smelting furnaces or crucibles in metallurgy. In these specific cases, measuring the surface emissivity of the object is quite difficult. For automatic measurement and control of solid surface temperature, an additional mirror can be used to form a blackbody cavity together with the measured surface. The influence of additional radiation can increase the effective radiation and effective emissivity of the measured surface. By using the effective emissivity to correct the measured temperature via the instrument, the true temperature of the measured surface can ultimately be obtained. The most typical additional mirror is a hemispherical mirror. Diffuse radiation from the measured surface near the center of the sphere is reflected back to the surface by the hemispherical mirror, forming additional radiation and thereby increasing the effective emissivity, where ε is the material surface emissivity and ρ is the reflectivity of the mirror. For radiation measurement of the true temperature of gaseous and liquid media, a method involving inserting a heat-resistant material tube to a certain depth to form a blackbody cavity can be used. The effective emissivity of the cylindrical cavity after reaching thermal equilibrium with the medium is calculated. In automatic measurement and control, this value can be used to correct the measured temperature at the bottom of the cavity (i.e., the medium temperature) to obtain the true temperature of the medium.

SKI sensor usage precautions

1) Errors introduced by improper installation: For example, the installation position and insertion depth of the thermocouple cannot reflect the true temperature of the furnace chamber. In other words, the thermocouple should not be installed too close to the door and heating areas, and the insertion depth should be at least 8 to 10 times the diameter of the protection tube; the gap between the thermocouple protection tube and the wall is not filled with insulating material, causing heat to escape from the furnace or cold air to enter. Therefore, the gap between the thermocouple protection tube and the furnace wall hole should be blocked with insulating materials such as refractory mud or asbestos rope to prevent convection of hot and cold air from affecting the accuracy of temperature measurement; the cold end of the thermocouple is too close to the furnace body, causing the temperature to exceed 100℃; the installation of the thermocouple should avoid strong magnetic fields and strong electric fields as much as possible, so the thermocouple and power cables should not be installed in the same conduit to avoid introducing interference and causing errors; the thermocouple cannot be installed in areas where the measured medium flows very little. When using a thermocouple to measure the temperature of gas in a pipe, the thermocouple must be installed against the flow direction and in full contact with the gas. 2) Errors introduced by poor insulation: If the thermocouple is insulated, excessive dirt or salt residue on the protection tube and pull plate causes poor insulation between the thermocouple poles and the furnace wall, which is more serious at high temperatures. This not only causes loss of thermoelectric potential but also introduces interference, and the resulting error can sometimes reach hundreds of degrees. 3) Errors introduced by thermal inertia: Due to the thermal inertia of the thermocouple, the instrument's indication lags behind changes in the measured temperature, and this effect is particularly prominent during rapid measurements. Therefore, thermocouples with thinner thermoelectrodes and smaller protection tube diameters should be used as much as possible. When the temperature measurement environment permits, the protection tube can even be removed. Due to measurement lag, the amplitude of temperature fluctuations detected by the thermocouple is smaller than the amplitude of furnace temperature fluctuations. The greater the measurement lag, the smaller the amplitude of the thermocouple fluctuation, and the greater the difference from the actual furnace temperature. When using a thermocouple with a large time constant for temperature measurement or control, although the temperature displayed by the instrument fluctuates very little, the actual furnace temperature may fluctuate significantly. To accurately measure temperature, a thermocouple with a small time constant should be selected. The time constant is inversely proportional to the heat transfer coefficient and directly proportional to the diameter of the thermocouple's hot end, the density of the material, and the specific heat. To reduce the time constant, in addition to increasing the heat transfer coefficient, the most effective method is to minimize the size of the hot end. In use, materials with good thermal conductivity, thin-walled tubes, and small inner diameter protection sleeves are usually used. In more precise temperature measurements, bare-wire thermocouples without protection sleeves are used, but thermocouples are easily damaged and should be calibrated and replaced in time. 4) Thermal resistance error: At high temperatures, if there is a layer of coal ash or dust attached to the protection tube, the thermal resistance increases, hindering heat conduction, and the temperature reading is lower than the true value of the measured temperature. Therefore, the exterior of the thermocouple protection tube should be kept clean to reduce errors.

SKI sensor industry applications

Temperature sensors are the earliest developed and most widely used type of sensor. The market share of temperature sensors greatly exceeds that of other sensors. People began to use temperature for measurement in the early 17 century. Supported by semiconductor technology, semiconductor thermocouple sensors, PN junction temperature sensors, and integrated temperature sensors were successively developed in this century. Two conductors of different materials, if connected together at a point and heated at this connection point, will produce a potential difference at their unheated parts. The value of this potential difference is related to the temperature of the measurement point at the unheated part and the material of these two conductors. This phenomenon can occur over a wide temperature range. If this potential difference is measured precisely, and the ambient temperature of the unheated part is measured, the temperature of the heating point can be accurately known. Because it requires two conductors of different materials, it is called a "thermocouple". Thermocouples made of different materials are used in different temperature ranges, and their sensitivities vary. Thermocouple sensors have their own advantages and disadvantages; their sensitivity is relatively low, they are easily affected by environmental interference signals, and they are also easily affected by the temperature drift of the preamplifier, so they are not suitable for measuring tiny temperature changes. Since the sensitivity of thermocouple temperature sensors is unrelated to the thickness of the material.

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