Hands-On Artificial Intelligence for IoT

Gated recurrent unit

Gated recurrent unit (GRU) is another modification of RNN. It has a simplified architecture compared to LSTM and overcomes the vanishing gradient problem. It takes only two inputs, the input x_t at time t and memory h_t-1 from time t-1. There are only two gates, Update Gate and Reset Gate, shown in the following diagram:

The architecture of a basic GRU cell

The update gate controls how much previous memory to keep, and the reset gate determines how to combine the new input with previous memory. We can define the complete GRU cell by the following four equations:

Both GRU and LSTM give a comparable performance, but ...