The 'Anymal' robot from Anybotics, whose movements resemble those of an animal, is used to search for people, among other things. The technology is mounted on four flexible legs - for example batteries for two to four hours of operation or sensors that give it autonomy. The four legs and the mobility of its joints, which can be rotated through 360°, enable Anymal to climb, jump, run, crawl or even dance. It is therefore particularly suitable for use in rough terrain: the robot can be used after earthquakes, for example, when scattered rubble makes it difficult to access buried people. A large number of sensors provide the robot with a precise sense of detection so that it can quickly and specifically search for people during mountain rescue, bomb disposal or after earthquakes - especially in places where it is too dangerous to use people for rescue.

Weighing just 30 kg, the Anymal operates completely autonomously. Among other things, it has been fitted with laser sensors to enable it to move around safely; with their help, the robot detects obstacles.

... the 'thermoImager TIM 160' thermal imaging camera from Micro-Epsilon. It is used for non-contact temperature measurement.

© Anybotics

In contrast to pyrometers, thermal imaging cameras do not detect and measure temperatures at a point, but on a surface. They work like digital cameras and have a field of view (FOV). This can be adapted to the application by selecting a suitable lens. In the infrared range, thermal radiation can only be focused by optics made of germanium or with surface mirrors. Compared to conventional, mass-produced lenses in the visible spectral range, such coated optics are a considerable cost factor for thermal imaging cameras, as they are designed as spherical 3-lens or aspherical 2-lens lenses and must be calibrated for thermometrically correct measurements, especially for cameras with interchangeable lenses, with regard to their influence on each individual pixel.

Infrared radiation is emitted by any body whose temperature is above absolute zero. In a detector, the energy of the infrared radiation is converted into electrical signals, which are then converted into temperature values based on the calibration of the sensor and the set emissivity.

Contactless measurement

Based on this evaluation, the measured temperature can be shown on a display, output as an analog signal or shown on a computer via a digital output. The measurement is contactless, which enables fast and reliable temperature measurements of moving, hot or hard-to-reach objects. While a contact temperature sensor could influence the temperature of a measured object and possibly damage or contaminate it, the non-contact method guarantees precise measured values at all times without contact.

Authors:
Péter Fankhauser is Robotics Software Engineer at Anybotics in Zurich;
Manfred Pfadt is Product Manager Sensors at Micro-Epsilon Messtechnik in Ortenburg.

The beginnings of thermography

The discovery of thermal radiation dates back to 1800, when the astronomer and musician Wilhelm Herschel directed sunlight through a prism. Using a thermometer, he examined the area behind the red end of the visible spectrum. The temperature there rose and he concluded that some kind of invisible energy must prevail. The term 'thermal radiation' was coined, which is still in common use today, but was later replaced by 'infrared'. Over the years, lenses made of rock salt and arrangements of thermopiles were used, which formed the basis of the first thermal cameras.

In 1840, the temperature distribution on surfaces was made visible by Herschel using different evaporation rates of a thin film of oil. Thermal paper, which changed color through direct contact with warm surfaces, was also used for visualization. The breakthrough in non-contact measurement came in 1880 with Samuel Pierpont Langley's invention of the bolometer, which was used to detect icebergs or for rescuing people.