Frequently asked Questions.
Change a Measurement File
The change of a measurement file is not planned. However, you can load data from a previous measurement with the menu item “template from file” in the software and save it as a new measurement.
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Selection of Damping Elements
The assignment of the damping elements to the individual body zones is displayed in the CoboSafe-Vision software.
The selection is made according to the letter of the DGUV: “FB HM 080” (August 2017), chapter 6.
Positioning the Measuring System
Place the measuring system at the collision point so that the measuring surface is perpendicular to the direction of movement of the robot.
For precise alignment of the handheld measuring devices you can use our mounting foot with ball joint.
Example of a Measuring System for Force and Pressure
The spring rate of a spring is usually not linear. The springs we use are specially selected and have the prescribed spring rate in the work area of MRK applications.
For the measurement of the biomechanical limit values a corresponding measuring system should be used. The possibility of simultaneous or sequential measurements of force and pressure must be against.
The target of a measurement is to realistically assess the collision between a human and a robot. The maximum permissible forces and pressures of a collision according to ISO / TS 15066 were defined as limit values. In order to make a reliable statement about collision forces and pressures, we provide you with a selection of different biofidel measuring devices. These substitute a subject with a suitable measuring system consisting of sensors, springs and damping elements.
The assignment of the spring strength (NM) to the individual body zones is displayed in the CoboSafe-Vision software. The selection is made according to the letter of the DGUV: “FB HM 080” (August 2017), chapter 6.
Damping elements are selected on the basis of DUGV Recommendation “FB HM 080” (August 2017), Chapter 6. There is no obligation to place these elements in a test on the measuring instrument – but with the help of this, much more realistic pressure values are determined. The measurements show the result of a collision with and without a damping element. The maximum pressure was reduced to about one third.
The microfiber cloth (≤ 0.5 mm) can be used for compensation, for surface correction and as an additional / variable damping element on the measuring surface.
Replacement of the Damping Elements
We recommend replacing the damping elements after one year at the latest. Likewise, an exchange should be made if the material has taken visible damage, or worsen the damping properties. Check this with a simple ‘Shore A hardness measurement’.
In order to maintain the functionality, the conformity to standards and the measuring accuracy of the devices, GTE Industrieelektronik GmbH offers a calibration service, which must be carried out once a year. The next due date can be found on the stickers on your devices. Alternatively, a calibration by a laboratory accredited according to DIN EN ISO / IEC 17025 is possible (DAkkS).
The measured force of a collision is usually the limiting factor only for fast heavy robots. The graphic shows a typical force curve of a collision measurement.
The measured pressure of a collision is usually the limiting factor only for fast heavy robots. The graphic shows a typical force curve of a collision measurement.
FUJI Pressure Measurement – handling the Sensor Foils
The rough measuring surfaces of the films should have no contact with foreign bodies in the experimental preparation. In particular, you should be careful to avoid contact with moist surfaces such as human skin, as this increases the chemical reaction caused by the action of the film and thus falsifies the measurement results.
The slides should be scanned immediately after the measurement to avoid a measurement error. For storage, a dry and light-tight place is recommended.
FUJI Pressure Measurement – Scan Slides, process later
You can scan the samples with the calibration sheet and process them later with the FPM Vision program.
Use the following scan settings:
Resolution: 200 DPI
However, the tests of the sample and the scan are done here only when you load the data in the software.
FUJI Pressure Measurement – Maximum Pressure
The FUJI Prescale pressure measurement determines the maximum pressure distribution. A temporal resolution is not possible, thus no separation between the maximum pressure and the clamping pressure. Comparative measurements with the time-resolved pressure measuring system TekScan have shown that a correlation to the force is not given, and therefore a conversion is uncertain.
The relationship: ∫▒ 〖p (A) dA = F〗 can not be used with the result of a FUJI pressure evaluation because the values determined are the maximum values from the entire measurement duration.
Pressure Measurement with Filter
For a realistic view of the measurement data of the pressure measurements an “Average Filter” is used. This was also used by the Institute for Occupational Safety and Health (IFA) to determine the limits and is allowed for the measurements.
Force Measurement with Filter
The force measurement data are filtered according to the recommendation letter of the DGUV: “FB HM 080”: “The measured signals are to be filtered with a Butterworth low-pass filter with a limit frequency of 11 Hz (at 3dB) and a slope of 24dB / oct.” FB HM 080 ( August 2017), chapter 6.
Measurement with the 75N/mm Spring
According to the letter of recommendation of the DGUV: “FB HM 080” measurements for all body zones except the head can be performed with a measuring device with a 75N/mm spring. Our measuring devices KMG 500 and KMG 300 are each equipped with such a spring and allow an easy and fast determination and evaluation of the collision loads.
Measurement of the critical Zones
According to ISO/TS 15066, the table of limit values in the area of the head and larynx can be called “not applicable”. Likewise, this critical area is marked in the letter of the DGUV: “FB HM 080” with “none”.
This means that no factor is to be used for the calculation of the transient limit value. Thus, the specified static limit value must not be exceeded at any time during a measurement. It should be noted in a risk assessment that the eyes, ears and larynx are particularly critical zones and can not be protected by a simple force limitation.
To control the robot, they define simple, easy-to-measure points. Detect collision loads at these points and look at the course of the measurement results. When climbing, they should check the mechanics and sensors of the robot.
By means of the KDMG, loads can be determined and subsequently adjusted by means of control measurements with the CBSF-75-Basic, or used as references.
Subject to the exclusion of the head and neck from the working area of the robot system, it is sufficient within the scope of its intended use and foreseeable misuse to use only the worst (spring) spring of 75N/mm. Should it be necessary in the context of the foreseeable misuse, also a contact e.g. in the area of the forehead, use a spring of 150N/mm.
Measurement with 75 N/mm
Subject to the exclusion of the head and neck from the working area of the robot system, it is sufficient within the scope of its intended use and foreseeable misuse to use only the worst (spring) spring of 75N/mm.
As soon as one of the limit values force or pressure is exceeded, the requirements are to be assessed as not fulfilled. As a rule, the safety limits set for the force in conjunction with the safely monitored speed must then be reduced. If so afterwards, e.g. the pressure values are still exceeded, the design must be changed, e.g. through larger surfaces, padding, spring-loaded grippers, etc.
Comply with Limit Values
Depending on the clamping situation, additional tips may occur. These must not exceed the limits for short-term effects!