fix(robots): add retries while recording motor ranges (#4126)

* Add retries while recording motor ranges

* fix(motors): throttle calibration reads consistently

---------

Co-authored-by: tom-doerr <tomdoerr96@gmail.com>

src/lerobot/motors/motors_bus.py

@@ -23,6 +23,7 @@ from __future__ import annotations
 
 import abc
 import logging
+import time
 from collections.abc import Sequence
 from contextlib import contextmanager
 from dataclasses import dataclass
@@ -818,13 +819,13 @@ class SerialMotorsBus(MotorsBusBase):
         """
         motor_names = self._get_motors_list(motors)
 
-        start_positions = self.sync_read("Present_Position", motor_names, normalize=False)
+        start_positions = self.sync_read("Present_Position", motor_names, normalize=False, num_retry=5)
         mins = start_positions.copy()
         maxes = start_positions.copy()
 
         user_pressed_enter = False
         while not user_pressed_enter:
-            positions = self.sync_read("Present_Position", motor_names, normalize=False)
+            positions = self.sync_read("Present_Position", motor_names, normalize=False, num_retry=5)
             mins = {motor: min(positions[motor], min_) for motor, min_ in mins.items()}
             maxes = {motor: max(positions[motor], max_) for motor, max_ in maxes.items()}
 
@@ -837,9 +838,12 @@ class SerialMotorsBus(MotorsBusBase):
             if enter_pressed():
                 user_pressed_enter = True
 
-            if display_values and not user_pressed_enter:
-                # Move cursor up to overwrite the previous output
-                move_cursor_up(len(motor_names) + 3)
+            if not user_pressed_enter:
+                if display_values:
+                    # Move cursor up to overwrite the previous output
+                    move_cursor_up(len(motor_names) + 3)
+                # Throttle reads even when the live table is disabled.
+                time.sleep(0.02)
 
         same_min_max = [motor for motor in motor_names if mins[motor] == maxes[motor]]
         if same_min_max:

tests/motors/test_dynamixel.py

@@ -405,12 +405,18 @@ def test_record_ranges_of_motion(mock_motors, dummy_motors):
     read_pos_stub = mock_motors.build_sequential_sync_read_stub(
         *X_SERIES_CONTROL_TABLE["Present_Position"], positions
     )
-    with patch("lerobot.motors.motors_bus.enter_pressed", side_effect=[False, True]):
-        bus = DynamixelMotorsBus(port=mock_motors.port, motors=dummy_motors)
-        bus.connect(handshake=False)
+    bus = DynamixelMotorsBus(port=mock_motors.port, motors=dummy_motors)
+    bus.connect(handshake=False)
 
+    with (
+        patch("lerobot.motors.motors_bus.enter_pressed", side_effect=[False, True]),
+        patch("lerobot.motors.motors_bus.time.sleep") as mock_sleep,
+        patch.object(bus, "sync_read", wraps=bus.sync_read) as mock_sync_read,
+    ):
         mins, maxes = bus.record_ranges_of_motion(display_values=False)
 
     assert mock_motors.stubs[read_pos_stub].calls == 3
+    assert all(call.kwargs["num_retry"] == 5 for call in mock_sync_read.call_args_list)
+    mock_sleep.assert_called_once_with(0.02)
     assert mins == expected_mins
     assert maxes == expected_maxes

tests/motors/test_feetech.py

@@ -509,12 +509,18 @@ def test_record_ranges_of_motion(mock_motors, dummy_motors):
     stub = mock_motors.build_sequential_sync_read_stub(
         *STS_SMS_SERIES_CONTROL_TABLE["Present_Position"], positions
     )
-    with patch("lerobot.motors.motors_bus.enter_pressed", side_effect=[False, True]):
-        bus = FeetechMotorsBus(port=mock_motors.port, motors=dummy_motors)
-        bus.connect(handshake=False)
+    bus = FeetechMotorsBus(port=mock_motors.port, motors=dummy_motors)
+    bus.connect(handshake=False)
 
+    with (
+        patch("lerobot.motors.motors_bus.enter_pressed", side_effect=[False, True]),
+        patch("lerobot.motors.motors_bus.time.sleep") as mock_sleep,
+        patch.object(bus, "sync_read", wraps=bus.sync_read) as mock_sync_read,
+    ):
         mins, maxes = bus.record_ranges_of_motion(display_values=False)
 
     assert mock_motors.stubs[stub].calls == 3
+    assert all(call.kwargs["num_retry"] == 5 for call in mock_sync_read.call_args_list)
+    mock_sleep.assert_called_once_with(0.02)
     assert mins == expected_mins
     assert maxes == expected_maxes