Application of automated robot sensors

The degree of intelligence continues to improve, the development of flexibility, robot vision, force sense, and touch have become more and more important, and sensors have entered many applications. In this article, the pilot automation editor takes you to understand the various robot sensors on the market.

1) Vision sensor

This is a very widely used external sensor, given that its content is very rich, and machine vision often forms products independently, and is closely related to software technology.

2) Position (displacement) sensor

There are two kinds of linear moving sensor: potentiometer sensor and adjustable transformer. The angular displacement sensor has three kinds: potentiometer type, adjustable transformer (rotating transformer) and photoelectric encoder, among which the photoelectric encoder has incremental encoder and absolute encoder. The incremental encoder is generally used for zero position servo control with uncertainty, and the absolute encoder can obtain the instantaneous Angle value of the drive shaft corresponding to the initial locking position of the encoder. When the device is under pressure, as long as the reading of each joint encoder is read, the given value of the servo control can be adjusted to prevent the robot from having a violent movement when starting.

3) Speed and acceleration sensors

There are two kinds of speed sensors to measure translational and rotational motion speed, but in most cases, it is limited to measuring rotational speed. Using the derivative of displacement, especially the photoelectric method to let the light illuminate the rotating disk, detect the rotation frequency and the number of pulses, in order to find the rotation Angle, and the use of the disk to make a gap, through two photodiodes to identify the angular speed, that is, the photoelectric pulse speed sensor. In addition, there are tachometer generators for speed measurement.

A strain gauge is a stretch gauge, also a stress sensor, used for acceleration measurement. Acceleration sensors are used to measure the dynamic control signals of industrial robots. Generally, the force generated by the acceleration of the known mass object is deduced from the velocity measurement, that is, the force is measured by the strain gauge, and the following method is described:

The force associated with the measured acceleration may be generated by a known mass. This force can be electromagnetic force or electric force, and ultimately simplified to the measurement of current, which is the servo return sensor, and actually can have a variety of vibration acceleration sensors.

4) Internal sensor

The internal sensor and motor, shaft and other mechanical parts or mechanical structures such as Arm (Arm), Wrist (Wrist) are installed together to complete the measurement of position, speed, and force to achieve servo control.

5) External sensor

External sensor is the realization of external sensory ability. For example, multi-joint robots, mobile robots, and intelligent robots require the ability to correct and react to environmental changes.

6) Tactile sensors

Microswitches are the most common type of contact sensors, and there are isolated two-state contact sensors (that is, bistable switching semiconductor circuits), single analog sensors, matrix sensors (matrix sensors for piezoelectric components, artificial skin - variable conductivity polymers, light reflection tactile sensors, etc.).

7) Force sensor

The force sensor is used to measure the three components of the force and the three components of the moment between two objects. The ideal sensor in the robot is a semiconductor stress meter glued to the compliant part. Specific metal resistance type force sensor, semiconductor type force sensor, other magnetic pressure type and the use of string vibration principle made of force sensor.

8) Stress sensor

For example, the linear module needs to know the actual existence of the contact, the position of the contact point (positioning), the characteristics of the contact, that is, the estimated force received (representation), these three conditions, so the strain gauge pointed out in the upper section combined with the basic assumptions of specific stress detection, such as the force between the workbench and the object. Specific methods include installing sensors on the environment and installing a driving device for a tester on the robot wrist as a sensor.

9) Proximity sensor

Due to the increase of the robot's motion speed and the possible damage caused by loading and unloading of objects, it is necessary to know the prior information of the object's location in the robot's work site and appropriate trajectory planning, so it is necessary to apply the remote sensing method to measure the proximity. Proximity sensors are divided into passive sensors and active sensors, so in addition to natural signal sources, artificial signal transmitters and receivers may be required.

Ultrasonic proximity sensors are used to detect the presence of objects and measure distances. It can not be used to measure a distance of less than 30~50cm, and the ranging range is large, it can be used in mobile robots, but also can be used in the grip of large robots. It can also be used as an ultrasonic navigation system.

10) Acoustic sensor

For sensing and interpreting sound waves in gases (non-contact sensing), liquids or solids (contact sensing). Acoustic sensors can range in sophistication from simple acoustic presence detection to complex acoustic frequency analysis to the identification of individual sounds and words in continuous natural language.

Contact or non-contact temperature sensor

In recent years, it has been widely used in robots, and in addition to commonly used thermal resistors (thermistors), thermocouples, etc., progress has also been made in thermoelectric TV cameras to measure and sense temperature images.