Trained Tensorflow Model Always Outputs Zero

I am training an autonomous driving convolutional neural network in TensorFlow. It is a simple regression network that takes an image and outputs a single value (a steering angle).

Solution 1:

That dropout regularization might be the culprit:

dropout = tf.layers.dropout(
        inputs=dense1,
        rate=0.4,
        training=mode == learn.ModeKeys.TRAIN
    )

What you are describing, the weights failing to adequately converge or falling close to zero, is highly descriptive of a high-bias problem. Removing or reducing the degree of regularization, adding more parameters to your network, or otherwise increasing the variance are common ways to fix this type of problem.