Fix bug in normalize to avoid divide by zero (#239)

Co-authored-by: rj <[email protected]>
Co-authored-by: Remi <[email protected]>

Author: 3 people

lerobot/common/policies/normalize.py

@@ -147,7 +147,7 @@ def forward(self, batch: dict[str, Tensor]) -> dict[str, Tensor]:
                 assert not torch.isinf(min).any(), _no_stats_error_str("min")
                 assert not torch.isinf(max).any(), _no_stats_error_str("max")
                 # normalize to [0,1]
-                batch[key] = (batch[key] - min) / (max - min)
+                batch[key] = (batch[key] - min) / (max - min + 1e-8)
                 # normalize to [-1, 1]
                 batch[key] = batch[key] * 2 - 1
             else: