Civil analysis — Collision analysis (Single-axis trackers)

Introduction to Collision analysis

To start working on collision analysis, open the Civil analysis menu. In the second tab, Collision & Grading, you will find the Collision analysis menu.

In the Collision & Grading tab, you can:

• Define constraints for minimum ground clearance and/or pile reveal length
  
  
• Highlight frames and see detailed height of frames that don't meet the defined criteria with Indicate and Show details

• Correct the terrain beneath the frames to meet the established criteria with Grade and see the Ground grading volume:
  
  

Pile reveal range

When working with Single-axis trackers, it can be beneficial to review the collision analysis through the scope of the Pile reveal range; however, we will also examine the Ground clearance option. It is also possible to do both simultaneously.

Pile reveal is the part of the pole above the terrain surface.

With the Pile reveal range analysis, you may specify the lower and upper limit for the pile reveal length and use the tool to highlight the affected frames and their specific poles.

Usually, the criteria to be applied here are given by the structure supplier, based on the mechanical specifications of the equipment. In this example, the pile reveal needs to be between 1.3 and 1.5 meters.
That is why, when generating the initial layout, we set a reference pile reveal (flat terrain) of 1.4 meters. This way, we have 10 cm of tolerance in both directions.

Once you click on Indicate, the software will mark any frame that has piling outside our specified range.

Trackers with poles that are shorter than 1.3 meters will be colored pink while frames with poles longer than 1.5 meters will be marked purple.

The software uses millesimal resolution, meaning it is accurate to one-thousandth of a meter. There is no allowance for minor deviation, so anything beyond these values will be marked as not meeting or exceeding the pole length respectively.

You may also go further into the Pile reveal range analysis and inspect the calculated individual pole lengths, by clicking Show Details. PVcase populates the frame drawing with text labels indicating the length of the individual poles of the frames. This is similar to the Piling information function.

PVcase places frames so that middle points at both extremes of the tracker are at the reference height that was set in Frame and park settings.

However, the software does not account for the terrain underneath the frame between the two extremes; piles placed on a bump are shorter, the ones placed in a valley, longer. It is possible that no single pile is as long as the defined reference height, and there may be intermediate positions where the pile length may be out of the allowed range.

The Piling range analysis allows you to test if the placed frames have areas where they are outside the given pole range.

If you zoom in on one of the affected frames, you'll see that this particular frame is colored pink, meaning that the pole reveal is less than 1.3 meters which is the lower limit. If you click on Show details and select one or several frames, you'll see that the piles shorter than 1.3 are highlighted in red.

Similarly, the purple one indicates that the Pile reveals exceed the upper limit of 1.5 meters.

Tables and pile values colored in blue are within the acceptable range.

Front view

This can be best illustrated by using the Front view option on the frame and measuring its distance from the terrain:
1. Select the Front view option from the drop-down menu (next to the Cross-section function)
2. Select the PV area boundary line
3. Draw the desired front view
4. Click to place the front-view drawing

To manually measure the frame height, go to AutoCAD's Home tab and select the measuring tool (Dimension tab). Alternatively, you can use the DIM command.
If you click on this part of the frame and draw a perpendicular line to the terrain and finish placing the dimension, you'll see that the resulting value matches the manually measured value shown in the Collision analysis.

Ground clearance

Instead of a piling reveal range, we can also input a minimum value for our Ground clearance.

Ground clearance distance is measured from the terrain to the lower edge of the table at its maximum rotation (i.e. 55º, depending on the setting in "Frame creation"), as marked with the blue lines:

You may specify the minimum requirement for the ground clearance and use the tool to highlight the affected frames. In this example, the lowest permissible height from the bottom of the frame to the terrain is set to 0.4 meters.

Now that the acceptable range has been specified, click on Indicate to see if your frames are in accordance with the given clearance range. Frames with clearance points of less than 0.4 meters will be highlighted in orange.

Click on Show details to get further insights. Once you select the specific frame you want to observe, press Space or Enter on the keyboard.

If you zoom in on one of the affected frames, you'll see that this particular point is colored orange, meaning that the clearance is less than 0.4 meters.

Points with black text are within the acceptable range.

It is also possible to combine the analysis for Ground clearance and pile reveal length by activating both check boxes, and it might make sense to choose 3 different colors.

When multiple constraint violations are detected for the same frame, the coloring will be applied for the active constraints in the same order you see in the interface: clearance first, pile reveals later.

Show details will give you the values for both clearance and pile reveal.

Increase or decrease tracker height

The options discussed above will not modify the height of the tracker, they are mere analysis functions. If, on the other hand, you would like to change frame height, there are two options:

Option 1: Change the reference height in Park settings, then use Adapt to positions on individual frames or the whole area:

Option 2: Use our Prototype function Adapt with pile range:

1. Input the command PVcaseAdaptWithPileRange in the AutoCAD command line.

2. Enter the positive extra amount and negative extra amount - referred to as "delta" - that can be applied to the reference pile reveal height. In our example from above where reference pile reveal was set to 1.4 m and our acceptable range is 1.3 - 1.5 m, our tolerance or delta is 10 cm in both directions.

3. Choose the frames you wish to adjust. If feasible, these frames will be raised or lowered accordingly.

In cases where a suitable adjustment can't be made (when it’s impossible to meet both criteria simultaneously), you will receive a notification, and the frames with issues will be highlighted. For these frames, the height will not be modified at all.

After modifying the frame height, you can run the collision analysis again to check the improvement.
In a further step, we can use the Ground grading tool to modify the terrain, so the set criteria are met.