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picoScan150: Possible challenges and countermeasures in outdoor applications
Article No: KA-09881
Version: 1.16
Subject to change without notice
This page considers outdoor conditions and lists the corresponding specifications and integrated measures. Then, possible additional measures are explained
Related Products
picoScan100
Table of Contents
General information
The picoScan150 is a robust outdoor device designed for outdoor use and can therefore withstand harsh environmental conditions. Depending on the conditions, however, certain measures must be taken to achieve the best possible measurement result. This page considers various outdoor conditions and lists the corresponding specifications and integrated measures. Finally, possible additional measures are explained.
This document refers to firmware V2.1.0 or higher.
Some features are license-based and may not included in your variant.
It is recommended to use only the accessories provided by SICK.
Temperature
Extreme temperatures can influence the function of the picoScan150 (e.g. overheating, condensation, ice on the optical hood). Depending on the ambient temperature, different measures are required to ensure reliable performance.
Specification
Operating temperature: -33 °C to +50 °C
Storage temperature: -40 °C to +70 °C
Humid heat: +25 °C ... +55 °C at 95 % rH
Measures by design
Built in ventilation element for air-heat exchange and humidity regulation (see figure) to protect the seal.
Thermal connections between electronics and mechanical structure for better heat dissipation.
Additional measures
If you use the device in low temperature environments, leave the sensor switched on permanently to prevent it from falling below the minimum operating temperature.
Avoid large temperature fluctuations to prevent moisture condensation or use a fan to minimize misting on the hood.
Direct exposure to sunlight should be avoided to prevent additional thermal stress.
Use of the picoScan150 weather protection hood (item number: 2140840, https://www.sick.com/2140840) to protect the sensor from excessive heating by the sun.
If you expect high ambient temperatures, ensure efficient heat dissipation through a large-area connection, e.g. all five mounting points to the heat dissipation surface.
Using a dedicated mounting bracket (e.g. 2134874) is preferred, as it supports heat transfer
Application of a thermal interface material (thermal pad or paste) between the housing bottom and the bracket is recommended to enhance thermal conductivity.
Rain
Rain can affect the measuring accuracy of the picoScan150. On the one hand, water in the air can scatter or absorb the emitted laser light. Additional, water droplets on the optics can impair the signal quality.
Specification
IP65 (IEC 60529:1989+AMD1:1999+AMD2:2013): Protected against dust ingress and water jets from any angle
IP67 (IEC 60529:1989+AMD1:1999+AMD2:2013): Protected against dust ingress and temporary submersion
Device is protected against water with a seal between hood, housing and systemplug. In addition, the sealing is checked with overpressure after production.
Device is designed that no water remains on surface.
Provides additional protection in the event of heavy or prolonged exposure to precipitation.
Prevent rain from above and splash water from below, e.g. with a weather protection hood.
Figure: Weather protection hood
If compressed air is already available at the installation site, an air shower, for example, can be installed to remove waterdrops from the hood.
Select a suitable installation location to avoid too low a mounting height and the associated soiling from splashing water from the ground.
Avoid overhead installation to protect the connections from direct water ingress.
Use of multi-echo evaluation to improve robustness (see figure) (SOPASair: Configuration → Filter → Echo filter → Last echo).
Activation of particle filter to minimize interference from raindrops (SOPASair: Configuration → Filter → Particle filter). → Attention: With activation of the particle filter, measurement data is output with a delay.
Use of the contamination measurement feature (see figure) to detect optical impairments caused by water or dirt deposits on the lens. → For more information, see the operating instructions at https://www.sick.com/8028322.
If 2D object detection is used, define higher blanking variables in the field adjustment to optimize the measurement ranges. Also adjust the evaluation time to better compensate for measurement errors caused by rain.
Test measurements
The test measurements were recorded in the SICK Outdoor Technology Center (OTC). This is used to test the measurement performance of various SICK devices. The test setup shows how robustly the picoScan150 delivers measurement data in rainy weather conditions.
Note: The weather station is not directly next to the LiDAR’s, but close to them. This can cause small differences in the measurement.
Figure: The picoScan150 Pro is aimed at four measurement targets at different distances of 5 m, 10 m, 15 m and 20 m from the traverse. Each target has 3 differently colored areas. Starting from the left, these are black (10 % Remission), gray (20 % Remission) and white (90 % Remission) to be able to carry out measurements at different reflectance values. The video shows the rain conditions under which the tests were carried out.
Video: Rain intensity: 3,5 mm/h
Figure: Temporal course of the rainfall in millimeters per hour over a period of approximately two hours. The time is plotted on the horizontal axis. The vertical axis represents the rain intensity in mm/h. The video above shows the rain intensity at the measured weather conditions in the diagram.
Figure: The diagram shows the distance measurement (last echo) of the picoScan150 over time, which recorded a measuring point once per minute. The time is shown on the horizontal axis and the measured distance in mm on the vertical axis.
In general, the measurements on target 2 (line 2) and target 4 (line 4) were recorded without occurrence. At target 3 (line 3), a short dip to the gray target can be seen at around 2:33:14. A further dip in the measurement data can be seen at target 1 (line 1) at around 3:33:56. These brief measurement events may have been caused by raindrops that were in the path of the laser beam or on the target at the time of measurement. rain drops reflect the output laser signal differently and therefore affect the measurement, as can be seen in the diagram.
Figure: The RSSI value (received signal strength indicator) indicates the strength of the measurement signal. It depends on the reflectance value of the surface and environmental influences.
As can be seen in the diagram, there is a lower range (1) and an upper range (2). This is because the picoScan150 works with two different sensitivities for measuring the RSSI value. The lower range (1) is measured with the "sensitive channel" and the upper range (2) with the "insensitive channel". The strong fluctuations in the RSSI value of Target_4_White are due to switching between the different measurement channels.
Figure: The diagram shows the distance measurement (last echo) of the LMS511 over time, which recorded a measuring point once per minute. The time is shown on the horizontal axis and the measured distance in mm on the vertical axis.
In general, the measurements at target 2,3 and 4 in lines 2, 3, and 4 were recorded without any occurrences. At target 1 in line 1, multiple dips to the black target can be observed between approximately 02:24:05 and 03:44:53. These brief measurement events may have been caused by a rain drop that were in the path of the laser beam or on the target at the time of measurement. Such obstructions reflect the output laser signal differently and therefore affect the measurement, as can be seen in the diagram.
Figure: The RSSI value indicates the strength of the measurement signal. It depends on the reflectance value of the surface and environmental influences.
As can be seen in the diagram, the LMS511 measures the RSSI values stable - except for the value of Target_1_Black. This is because no measured values could be recorded for this target. The dips in the RSSI value correlate with the dips in the measurement errors in the distance measurement.
Conclusion: The picoScan150 provides very robust measurement data and is therefore suitable for outdoor use. This can be recognized by the stable distance measurements. Only two small drops in distance can be seen on the diagrams (5 and 6). The RSSI value also shows that the sensor detects environmental influences, but that these do not affect the measurement accuracy. Especially in direct comparison to the LMS511, the picoScan150 shows a very good measurement performance in rain. The LMS511 fluctuates when measuring the first target, which can be seen from the drop in distance values. In contrast, the picoScan150 delivers consistently correct measured values.
In addition to the test in the SICK Outdoor Technology Center (OTC), the video shows a comparison between the LMS111 (left, all echoes) and the picoScan150 (right, all echoes), and in the SICK rain chamber. Both devices measure on a moving black (10%) and white target (90%). The picoScan150 can cope very well with the rain influences.
Snow
Snow scatters the light more than rain, which makes it more difficult to detect objects behind the snowfall. Snowflakes in the air and deposits on the optics or the housing can impair the measurement accuracy.
Specification
IP65: Protected against dust ingress and water jets from any angle
IP67: Protected against dust ingress and temporary submersion
Operating temperature: down to -33 °C
Storage temperature: down to -40 °C
Measures by design
Device is protected against moisture from snow in accordance with IP65 and IP67.
Additional measures
Attach a weather protection hood to prevent snow deposits on the hood.
Keeping the ventilation element of the sensor clear to avoid moisture problems caused by blockage.
Selecting a suitable installation location to avoid low mounting and associated snow coverage.
Avoiding overhead mounting to protect the connections from moisture and ice formation.
Use of multi-echo evaluation as well as echo and particle filters to suppress interfering reflections from snowflakes (SOPASair: Configuration → Filter → Echo filter / Particle filter).
Use of the contamination measurement feature for early detection of visual impairments caused by snow deposits (SOPASair: Configuration → Contamination indication).
Definition of higher blanking values and adjustment of the evaluation time in the field adjustment for better compensation of measurement errors due to snowflakes or snow layers.
Fog
Fog consists of fine water droplets in the air that scatter and absorb the laser light. These water droplets can reduce the signal strength. This can result in reduced range and accuracy, as well as false reflections.
Specification
IP65: Protected against dust ingress and water jets from any angle
IP67: Protected against dust ingress and temporary submersion
Measures by design
Mechanical protection of the sensor through IP65 and IP67 certification against moisture.
Additional measures
Use of the weather protection hood to reduce direct moisture deposits.
Keeping the ventilation element clear to avoid problems caused by fog precipitation or freezing moisture.
Avoid overhead mounting to protect the connections from moisture ingress.
Use of multi-echo evaluation to minimize the effects of fog.
Set sensitivity level to robust.
Activation of the fog filter (SOPASair: Configuration → Filter → Fog filter) to reduce disturbing reflections caused by water droplets.
Test measurements
The test measurements were recorded in the SICK Outdoor Technology Center (OTC). This is used to test the measurement performance of various SICK devices. The test setup shows how robustly the picoScan150 delivers measurement data in foggy weather conditions.
Note: The weather station is not directly next to the LiDAR’s, but close to them. This can cause small differences in the measurement.
Figure: Test setup at clear view
The picoScan150 Pro is aimed at four measurement targets at different distances of 5 m, 10 m, 15 m and 20 m from the traverse. Each target has 3 differently colored areas. Starting from the left, these are black (10 % Remission), gray (20 % Remission) and white (90 % Remission) to be able to carry out measurements at different reflectance values. The image shows the fog conditions under which the tests were carried out. The average visibility over the period of the measurement shown was 85 m.
Figure: Foggy conditions at visibility of aprox. 81 m
Figure: The diagram shows the temporal course of the visibility in meters over a period of approximately two hours. The time is plotted on the horizontal axis. The vertical axis represents the visibility in meters. The graph fluctuates significantly, indicating varying weather conditions affecting visibility during this period. Visibility is affected by the fog and varies between approx. 35 m and a maximum of 130 m.
Figure: The diagram shows the distance measurement of the picoScan150 over time, which recorded a measuring point once per minute. The time is shown on the horizontal axis and the measured distance in mm on the vertical axis.
In general, the measurements at all four targets at all three remissions were recorded without anomalies. As can be seen from the almost straight lines on the diagram, the fog does not affect the measuring accuracy of the distance with the picoScan150 at all.
Figure: The RSSI value indicates the strength of the measurement signal. It depends on the reflectance value of the surface and environmental influences.
As can be seen in the diagram, the picoScan150 measures very constant RSSI values. Only two small peaks (1 and 2) can be seen for Target_2 on black. This can happen temporarily due to the wetting of the target by the fog, as this can cause a glossy effect and thus increase the reflected energy compared to the black surface of the target.
Figure: The diagram shows the distance measurement of the LMS511 over time, which recorded a measuring point once per minute. The time is shown on the horizontal axis and the measured distance in mm on the vertical axis.
In general, the measurements at all four targets at all three remission values were recorded without anomalies and are unaffected by the fog.
Figure: LMS511 RSSI values with a stable level
Conclusion: Even when visibility is restricted by fog, the picoScan150 shows excellent measurement characteristics and ignores the optical measurement influences. The two LiDARs have no problems with fog and are therefore suitable for such a foggy location. A failure would cause the distance to collapse and thus show a drop in the characteristic curve.
Dust and dirt
Dust and dirt particles can scatter and absorb the laser light from the sensor, which can reduce the signal strength, range and measurement accuracy. Fine particles amplify scattering, large particles block the light. Condensed dust on the cover can also cause permanent measurement errors. Dry particles are easier to remove, while damp or sticky dust can impair the lens in the long term.
Specification
IP65: Protected against dust ingress and water jets from any angle
IP67: Protected against dust ingress and temporary submersion
Measures by design
Mechanical protection through IP65 and IP67 certification against dust.
Hood with anti-scratch coating to minimize unwanted reflections.
Additional measures
Taking protective measures to avoid heavy soiling of the optics, such as special protective housings or clean locations.
Use of the weather protection hood to reduce dust and dirt on the hood.
Use of air showers for active cleaning of the protective cover using compressed air or water.
Possibility of manual cleaning of the protective hood.
Activation of particle filter and echo filter to filter out interfering reflections caused by suspended particles.
Measurement of the contamination of the protective hood during operation and output of warnings or error messages in the event of critical optical impairment.
Use of the last echo for the measurement.
Test measurements
The measurements were taken in a certified external test center. The test setup shows how robustly the picoScan150 delivers measurement data in dusty environments.
Figure: Test chamber without particle load
A total of seven targets were set up in the dust chamber. These are divided into three areas with different reflectance values. Black has 10% reflectance, gray 20% and white 90%. One of the targets is a reflector. The targets are also positioned at different distances and angles to the sensors. As a test medium, clay dust was distributed in varying concentrations in the air of the test room.
Figure: Test chamber loaded with particles and a visibility of 30 m.
Figure: The visibility is shown on the horizontal axis and the detectability on the vertical axis at the 3.5 m target on white.
As can be seen in the diagram, the detectability of the LMS511 (blue) fluctuates slightly at lower visibility and then settles at around 98% detectability, as one measuring point is on the edge of the target and is therefore not fully evaluated. The picoScan150 (green) is already at almost 100% detectability at a visibility of approx. 80 m and more.
Figure: The visibility is shown on the horizontal axis and the detectability on the vertical axis at the 3.5 m target on black.
The diagram shows that the picoScan150 (green) already shows stable 100 % detectability at a visibility of approx. 60 m, whereas the LMS511 (blue) still fluctuates up to a visibility of approx. 190 m, caused by a measuring point on the edge. Both LiDAR’s offer good measurement results in dusty environments, but a direct comparison shows that the picoScan150 detects the measurement target more reliably and therefore offers more reliable measurement values in dusty environments than the LMS511.
Figure: Comparison LMS511 vs. picoScan150 at a visibility of approx. 30 m
The pictures show the complete measurement with dust blown in (LMS511 left; picoScan150 right). The outer lines show the measured outlines of the dust chamber. The individual angled lines are the targets that are detected. The picoScan150 (right) detects significantly more targets than the LMS511 (left) in the same test environment. The picoScan150 (right) can also record significantly more measuring points per target.
Moisture
Moisture can affect the performance of the picoScan150. High humidity in combination with temperature fluctuations can lead to condensation forming on the optical hood.
Specification
IP65 (IEC 60529:1989+AMD1:1999+AMD2:2013): Protected against dust ingress and water jets from any angle
IP67 (IEC 60529:1989+AMD1:1999+AMD2:2013): Protected against dust ingress and temporary submersion
Operate the sensor at a maximum relative humidity of 80 % (non-condensing) and up to 90 % when switched off.
Humid heat: +25 °C ... +55 °C at 95 % rH
Additional measures
Avoid rapid temperature changes to reduce condensation.
Minimize condensation on the hood through continuous air exchange (e.g. fan). This increases air circulation and removes moist air. As a result, the moisture evaporates quickly.
Ensure that the ventilation element is not trapped or blocked and that no water collects on it.
Suitable installation and specific shielding measures to minimize the influence of moisture.
Vegetation
Dense variable vegetation can impair the performance of the picoScan150, when it grows into the sensor's field of vision over time.
Additional measures
Install the sensor in a location that is not regularly affected by overgrown vegetation.
Ensure that no vegetation interferes with the 2D object detection field.
Remove plants or branches that could interfere with the sensor.
Check that there is no shadowing in monitoring areas.
During field evaluation, the teach-in function can help to determine precise field dimensions with sufficient distance from the vegetation.
Sunlight (ambient light)
Direct sunlight can impair the measuring accuracy of the picoScan150, as the intense light can enter the sensor's receiving unit area and worsen the signal-to-noise ratio. Low standing sun is particularly problematic, as it can shine directly into the sensor and thus cause measurement noise.
Indirect ambient light can influence the measuring accuracy of the picoScan150, especially if strong light enters the target area.
Specification
Robustness of the picoScan150 up to an indirect ambient light immunity of 100 klx.
Measures by design
No influence from static light sources such as LED lighting because of the integrated optical bandpass filter.
Minimization of interference from pulsed light sources because of the HDDM+ technology (High-Definition Distance Measurement Plus).
Additional measures
Use of a weather protection hood to shield against direct ambient light, protect against overheating, reduce reflections and disturbing light on the sensor.
Install the sensor in a suitable mounting position that avoids direct sunlight, stray light and potential interference.
Switching the sensitivity of the picoScan150 to standard or optimized for robustness to reduce sensitivity to interference.
Mutual optical interference from other picoScan150 devices
If several picoScan150 devices working close together, there is a chance of them interfering with each other. This is because the laser beams emitted by one sensor can be picked up by the receiver of another sensor. This could lead to reduced measurement accuracy.
Measures by design
picoScan150 is designed using a patented process (HDDM+) to minimize the mutual interference of several devices. → For more information, see https://support.sick.com/sick-knowledgebase/article/?code=KA-09734. Therefore, only small measurement deviations are to be expected.
Additional measures
Mount the picoScan150 outside the direct field of view of other LiDAR sensors to avoid interference (α = Tilt angle; α ≥ 6°).
Slight tilting of the laser line or overhead mounting to reduce the probability of picking up extraneous laser beams (x = distance; x ≥ 200 mm).
Mechanical loads and vibrations
Mechanical loads such as vibrations, shocks or abrupt changes in movement like on machines or vehicles can change the alignment of the sensors and distort the measurements.
Specification
Vibration resistance of the sensor tested according to IEC 60068-2-6:2007-12 and IEC 60068-2-64:2008.
Shock resistance of the sensor tested according to IEC 60068-2-27:2008-02, IEC 60068-2-75: 2014 and IEC 61010-1: 2017.
Shock and vibration-free mounting of the sensor, or free, decoupled mounting to absorb shocks and vibrations.
Use of the lower three fastening points in case of extreme vibrations for higher load capacity and stable fastening, because the floor offers more stable screw points than the back wall.
