ATCRM

Other corner recognition methods start by having the user check the orientation of the four stickers that should be facing upwards on the U layer. The ones that match the U center. Then a pattern of 3 or 4 additional fixed position stickers is checked on the four corners. ACRM works differently. First the user finds the orientation of the stickers that should be oriented to the left and right sides of the cube. Then just two fixed position stickers are checked. Below is a more detailed explanation.

On the left side of your cube you have one color and on the right side of your cube you have another color. In a solve, when you get to the step where you want to solve the final corners, you will look for those four stickers. They will have one of eight possible orientations that is the same as in a recognition method that has the user look for the U sticker orientation. Sune, Anti-Sune, T, U, L, Pi, H, or O. One difference is that among each of those orientations there are two or three sub-orientations. These come from the positions of the left side stickers and the right side stickers within the main orientation.

Non-matching blocks

When finding the orientation case with non-matching blocks, there is no difference. The orientations are all the same.

Transformation

In a solve where transformation was used, there is one additional rule. When doing the transformation, there will be a corner that you placed on the D layer to cause the transformation. This also causes there to be three U layer corners on the U layer and one D layer corner on the U layer. While placing the corner on the D layer during the solve before the corner step, check the sticker that is on the R layer. If that sticker contains an L or R layer color, the orientation recognition of the last four corners will be the same as usual. If that sticker is not an L or R layer color, then you will instead look for the F and B layer stickers on the three corners on the U layer that are U layer corners. For the D layer corner that is on the U layer, you will find the L or R layer color. However, you can skip checking that D layer corner that is on the U layer since the full orientation can be determined by just checking the three U layer corners.

The images on the left in the above images show a normal H orientation. The images in the middle in the above image show what happens when you do a U2 R transformation. The left and right side colors are still the same colors. The number of a certain color is all that changes. In the images on the right, it shows the result of a U R transformation. The first image of a 3D cube has a corner at DBR with a green sticker on the right. It is not an L or R layer color, so you look for the F and B colors of the three U layer corners. These colors are at LFU, LBU, and RBU. Then we look for the L or R layer color on the D layer corner that is on the U layer. Here it is at RFU. If you do U R on a solved cube you can see that the DFR corner is brought to UFR. This is the D layer corner that is on the U layer in the images. As mentioned above, it isn't necessary to check this corner for the orientation. The full orientation can be determined by just checking the other three corners.

Next you will check two stickers. Each sub-orientation has two fixed sticker positions to be checked. So you will know in every solve exactly where to look. There is one rule to be learned for this step. If you have an R or R' non-matching block or used transformation, then if you see a U or D layer color on the sticker position you are checking imagine that it isn't a U or D color. If it isn't a U or D color, then imagine it is.

Let's use the first H orientation as an example. For this orientation you check the UFL and UFR stickers.

Normal

In a normal solve, you simply check if one, both, or neither of the two sticker positions contains a sticker that matches the U layer center.

Here we have two cases. The solved case and the case solved by F R U R' U' R U R' U' R U R' U' F'. In the first image if you check the sticker labeled 1, you see that it is a U layer sticker. The sticker labeled 2 is also a U layer sticker. So checking in the document linked above shows us that this is H1 - UU -  the solved case. In the second image, the sticker labeled 1 isn't a U sticker and neither is the sticker labeled 2. The document gives us H1 - NN.

Non-matching blocks

In a non-matching blocks solve, there is an additional rule. Recall that there are various sub-orientations. Imagine a line going between the two corners that have the L layer colors in the orientation and a line going between the two corners that have the R layer colors. The two corners that have the L layer colors are the two corners that belong on the L layer and the two corners that have the R layer colors belong on the R layer. In this step of checking two stickers, for the sticker that you check that is on one of the two R layer corners, if that sticker is a U layer or a D layer color, pretend that it isn't a U or D layer color. If it isn't a U or D layer color, pretend that it is. Or, more specifically, pretend that it is just a U layer color. This rule doesn't apply to R2 non-matching blocks. The sticker that you check on one of the two L layer corners is just as in a normal solve. No need to pretend that stickers are different. The U and D stickers in these images will be yellow and white since the U center is yellow which makes the D center white.

These are the same two cases as in the Normal section just above. Checking the sticker labeled 1 gives us a U layer sticker and it is on a corner that has one of the two orientation stickers (orange) that belong on the left side of the cube. So it works just as normal. Checking the sticker labeled 2 gives us a sticker that isn't a U layer sticker or a D layer sticker and it is on a corner that has one of the two orientation stickers that belong on the right side of the cube (red). Based on the rules for non-matching blocks, when checking a sticker for the corners that belong on the right side, we pretend that U/D stickers are not U/D stickers and that non-U/D stickers are U/D stickers. So the sticker labeled 2 isn't currently a U/D sticker but we will pretend that it is. This means that both stickers 1 and 2 are U stickers, giving us the solved case.

In the second image, we have a non-U layer sticker in the 1 position and it is on a corner that belongs on the left side (orange). So it works as normal. Then the sticker labeled 2 is a U sticker and is on a corner that belongs on the right side of the cube. Because it is on a corner that belongs on the right side we flip the meaning of the colors to give us no U/D sticker in the 2 position. So neither stickers 1 and 2 contain U/D stickers, giving us the H1 - NN case. The same as in the Normal section above.

Transformation

In a solve with transformation, the rules are all the same as above.