The ExpandDims layer was implemented by "Reshape layer."
The following code will generate the ExpandDims layer:

expand_dim = tf.expand_dims(input, -1)
# or
expand_dim = tf.expand_dims(input, 2)

Related test data could be found at PR in opencv_extra.

There are still some unresolved issues here:

• 1. Currently, this code can only handle when the dimension input layer dimension is 4., since the different Datalayout between OpenCV and Tensorflow.(Solved.)
• 2. Since the implementation uses the dstNet.getLayerShapes() function. This implementation can not handle this model.

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or other license that is incompatible with OpenCV
• The PR is proposed to proper branch
• There is reference to original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

opencv_extra=tf_expand_dim_layer