As for "voltage," I think there are machines that are supplied with a regulator, and there are things that use AC as is, but voltage is essential to operate machines. You can think of the regulator as a sensor as well.

Voltage fluctuations are a major factor leading to failures and malfunctions. Supplying a stable voltage is too commonplace, and it may not be recognized as a sensor.

"Current" may flow overcurrent or fall below the assumed current if the circuit is broken.
In particular, industrial robots often work in a noisy environment, and it is desirable to avoid noise-induced breakdowns as much as possible.

In such cases, using a current sensor changes the current that flows through the circuit during normal operation and during failure, allowing for quick detection of abnormalities. It is possible to detect anomalies not only in the vicinity of power supplies but also in the drive current circuits of motors and actuators.

"Temperature" measures the temperature of the machine and its surroundings.
Parts that are constantly in motion, such as motors and actuators, generate heat. In the case of industrial robot equipment, it is used for abnormal heat generation of the motor and temperature measurement of the CPU that controls the robot. In order to use the machine for a long time, it is very important to monitor the calorific value.

A temperature sensor is deep, and a general temperature sensor uses an ADC to sense the resistance value that changes with temperature depending on the material of the sensor part.

Recently, due to improvements in MEMS technology, temperature sensing using temperature sensors inside devices has increased. Since no external sensor material is required, the temperature that can be measured is often limited.

It may also be necessary to measure ambient temperature outside the machine. Construction machines often work outdoors, and if the outside temperature is too low, the machine cannot operate efficiently. Measuring the environmental temperature will be useful for future product development.

"Acceleration" sensors have exploded in popularity since they were installed in game consoles.

Recently, it has come to be mounted on a small evaluation board, and it has become easy to obtain. There are various types of acceleration sensors, from crystal oscillation types to MEMS products. The MEMS type is available at low cost and has come to be used in various applications.

The usage is a sensor to measure how much tilt has occurred from the offset position. It has become an essential sensor for industrial robots. It is also possible to detect positional information and weak vibrations that occur when a machine malfunctions. Signal analysis of abnormal vibrations leads to predictive maintenance.

There are many types of acceleration sensors, and when selecting a device, temperature characteristics and noise performance are of course important, but accuracy, power consumption, and response performance are also important. Depending on the type of industrial robot, selecting an analog output acceleration sensor is also an option.

The gyro sensor can calculate the current speed from the angular velocity of the rotation angle, and the distance traveled from the speed and time.

Distance can also be calculated using GPS signals, but in indoor areas where GPS cannot reach, acceleration and gyro sensors can be used as a substitute for GPS. Again, if the accuracy is poor, the position may shift.

If you are considering replacing GPS, selecting an IMU (inertial unit) eliminates the need for troublesome adjustments, and there are many products that have been calibrated at the time of shipment.

A ToF sensor is a sensor that recognizes height and distance by reflecting light.
Conventionally, we used ultrasonic sensors, pressure sensors, and air pressure sensors to implement this, but this is a mechanism that measures the time it takes for light to be reflected and received.

Since it does not depend on objects that reflect light, it is attracting attention as a type of sensor that can accurately measure depth and distance, and is expected to be used as a position sensor in the future.

There are many types of image sensors, but the number of pixels is one option.

If the angle of view is large, the image data will not be cut off, but image processing will require CPU power accordingly. If the number of pixels is small, it can be processed with relatively light CPU power.

Also important is the dynamic range of the image sensor. If the dynamic range is narrow, it may be difficult to detect the difference between the object and the background, as well as minor defects. A wide dynamic range is likely to result in a clean image, which can simplify further processing.

The external environment has many uses. Of course, the typical temperature sensor is different depending on what the industrial robot is working on.

• pressure sensor
• Strain gauge (weight sensor)
• illuminance sensor
• gas sensor
• Infrared sensor
• Temperature sensor for high temperature

These sensors differ depending on the usage environment of the industrial robot, but depending on the application, it is necessary to select a high-precision sensor.

A gesture sensor is one of the optical sensors and is a sensor used at a short distance. As a mechanism, it is possible to determine the distance and position from the reflection of the blocked light.

As an example of application, it is assumed to be used in factories where direct contact with equipment is not possible or in environments with strict hygiene control.

Voice-based operation may still be one of these technologies, but voice-based systems can be expected to be fully utilized as a new operation system if the CPU that controls them becomes inexpensive.

In that sense, it can be said that speech recognition is a promising field as a voice sensor.