Weighing technology has been valued by people since ancient times. As a means of measurement, it is widely used in various fields such as industry, agriculture, scientific research, transportation, domestic and foreign trade, and is closely connected with people's lives. Electronic automatic scales are one type of electronic weighing instruments. Weighing instruments are national legal measuring instruments. They are indispensable measuring equipment for national defense construction, national economy and people's livelihood, domestic and foreign trade, and scientific research. The technical level of weighing instrument products will directly affect all walks of life. improvement of the level of modernization. The weighing device is not only a single instrument that provides weight data, but also serves as an integral part of the industrial control system and business management system, promoting the automation and management modernization of industrial production. Advanced and precise electronic sorting scales will definitely shorten operating time, improve operating conditions, reduce energy and material consumption, improve product quality, strengthen corporate management, and improve business management. The application of weighing devices has spread to all fields of the national economy and has achieved significant economic benefits. At present, our country has moved from traditional mechanical weighing instruments to the development stage of electronic weighing instruments integrating sensors, microelectronics technology, computer technology and integration. Because electronic scales have the characteristics of fast weighing, easy reading, the ability to work under harsh conditions, and the ease of combining with computer technology to realize the automation of weighing technology and process control, they have been widely used in industrial and mining enterprises, energy transportation, commercial trade and science. Technology and other various directions. This article is based on the current wide application of weighing sensors and selects the current
How to choose suitable sensors in manipulators. Sensor selection is a very complex issue, and whether it is correct or not will directly affect the success or failure of the test system. Usually we start from factors such as sensitivity, maximum and minimum graduation values, etc.
Consider it.
2 Selection of sensor quantity and range
The selection of the number of sensors depends on the purpose of the electronic scale and the number of support points required for the scale body. Generally speaking, if there are several support points, use several load cells. The measuring range of the sensor is based on the number of sensors and the maximum scale
Determined by the weighing value, the self-weight of the scale, and dynamic load factors.
The following is a calculation formula derived from a large amount of experience: C=K0×K1×K2×K3 (Wmax+W)/N
In the formula: C the rated range of the sensor W the self-weight of the scale body Wmax the maximum net weight of the object being measured; N the number of support points of the scale body K0 wind pressure coefficient K1 insurance coefficient K2 impact coefficient K3 center of gravity offset coefficient
Choose the solution for the sensor on the robot:
Solution 1 Piezoelectric sensor
Piezoelectric sensor is a typical active sensor, also known as self-generating sensor. Its working principle is based on the fact that certain materials are affected by
The piezoelectric effect produces charges on its corresponding specific surface after force. Piezoelectric sensors are small in size, light in weight, simple in structure, and reliable in operation. They are suitable for measuring dynamic mechanical quantities. They are not suitable for measuring objects with too low frequency, let alone measuring static quantities. Currently it is mostly used for the measurement of acceleration and dynamic force or pressure. Weaknesses of piezoelectric devices: high internal resistance, low power, weak output energy, distributed capacitance of cables and noise interference affect the output characteristics, which places high demands on external circuits.
Option 2 Capacitive sensor
Capacitive sensor is a sensor that converts changes in measured non-electricity into changes in capacitance. It has good dynamic response, simple structure, high sensitivity, can realize non-contact measurement, and has the phenomenon that the average conductor resistance changes with mechanical deformation, which is called the resistance strain effect. After the resistance strain gauge converts the signal into △R/R, due to the corresponding Resistance changes are generally very small, difficult to measure directly and accurately, and inconvenient to handle. Therefore, a conversion circuit is required to convert △R/R changes into changes in current or voltage. The conversion circuit usually uses a bridge circuit.

Option 3 Resistance strain gauge sensor
The resistance strain sensor is a structural sensor that uses the resistance strain effect to convert various mechanical quantities into electrical signals. The core component of the resistance strain gauge type resistance strain sensor, its working principle is based on the resistance strain effect of the material. The resistance strain gauge can be used as a sensor alone, and can also be combined with elastic elements to form a mechanical sensor.