bump version to 0.3.7

- Add zero_ft_sensor() to zero the robot's force/torque sensor
- Add zero_first=True parameter to move_until_contact (zeros FT sensor by default)
- Rename activate_gripper() to _activate_gripper() (private), use gripper.activate() as public API
- Fix time import inconsistency in motion.py (was _time, now matches project style)

Author: rodolfo-verde

CHANGELOG.md

@@ -5,6 +5,15 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.3.7] — 2026-07-07
+
+### Added
+- `zero_ft_sensor()` — zero the robot's force/torque sensor (wraps `rtde_control.zeroFtSensor()`)
+- `move_until_contact(zero_first=True)` — new parameter to zero FT sensor before contact detection (default True)
+
+### Changed
+- `activate_gripper()` renamed to `_activate_gripper()` (private) — use `robot.gripper.activate()` directly as the public API
+
 ## [0.3.6] — 2026-07-07
 
 ### Changed

README.md

@@ -428,7 +428,17 @@ robot.move_sequence(["a", "b", "c"], blend_radius=0.02)
 #### Contact Detection
 
 ```python
+# Zeros FT sensor automatically, then moves until force exceeds threshold
 robot.move_until_contact([0, 0, -0.02, 0, 0, 0])
+
+# Custom threshold (default: 5.0 N/Nm)
+robot.move_until_contact([0, 0, -0.02, 0, 0, 0], threshold=10.0)
+
+# Skip zeroing if you need absolute force values
+robot.move_until_contact([0, 0, -0.02, 0, 0, 0], zero_first=False)
+
+# Manual zero (e.g. before custom force-based logic)
+robot.zero_ft_sensor()
 ```
 
 #### Velocity Control

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "urkit"
-version = "0.3.6"
+version = "0.3.7"
 description = "Universal Robots e-Series control toolkit built on ur_rtde"
 readme = "README.md"
 license = {text = "MIT"}

src/urkit/__init__.py

@@ -24,7 +24,7 @@
 
 from __future__ import annotations
 
-__version__ = "0.3.6"
+__version__ = "0.3.7"
 
 from urkit.config import load_config, resolve_config
 from urkit.exceptions import (

src/urkit/cli/teach.py

@@ -1441,7 +1441,7 @@ def teach_command(args) -> None:
             **gripper_kwargs,
         )
         print("  Connected.", flush=True)
-        if robot.activate_gripper():
+        if robot._activate_gripper():
             print("  Gripper activated.", flush=True)
     except ConnectionError as e:
         print(f"Connection error: {e}")

src/urkit/motion.py

@@ -10,7 +10,7 @@
 import logging
 import os
 import sys
-import time as _time
+import time
 from contextlib import contextmanager
 from enum import IntEnum
 from typing import Iterator
@@ -255,12 +255,28 @@ def move_by(
                 f"Relative move failed: {e}"
             )
 
+    def zero_ft_sensor(self) -> None:
+        """Zero the robot's force/torque sensor.
+
+        Clears the baseline so that subsequent ``getActualTCPForce()``
+        readings reflect only forces applied after this call. Call before
+        ``move_until_contact()`` or any force-based operation.
+
+        Raises:
+            MotionError: If the command fails.
+        """
+        try:
+            self._rtde_c.zeroFtSensor()
+        except Exception as e:
+            raise MotionError(f"Failed to zero FT sensor: {e}")
+
     def move_until_contact(
         self,
         speed_vector: list[float],
         *,
         threshold: float = 5.0,
         acceleration: float = 0.1,
+        zero_first: bool = True,
     ) -> None:
         """Move until contact is detected via TCP force sensing.
 
@@ -280,12 +296,15 @@ def move_until_contact(
                 Contact fires when any of the 6 wrench components changes
                 by more than this value from the baseline reading.
             acceleration: Acceleration limit passed to ``speedL()`` in m/s².
+            zero_first: If True (default), zero the FT sensor before reading
+                the baseline. Set to False if you need absolute force values
+                rather than delta from zero.
 
         Raises:
             MotionError: If the command fails or the vector is invalid.
 
         Example:
-            >>> # Move straight down until contact
+            >>> # Move straight down until contact (zeros FT sensor first)
             >>> motion.move_until_contact([0, 0, -0.02, 0, 0, 0])
             >>> # Move down while rotating, higher threshold
             >>> motion.move_until_contact([0, 0, -0.02, 0, 0.1, 0], threshold=10.0)
@@ -303,6 +322,11 @@ def move_until_contact(
                 speed_vector, threshold,
             )
 
+            # Zero FT sensor to clear gravity bias before reading baseline
+            if zero_first:
+                self.zero_ft_sensor()
+                time.sleep(0.05)  # let sensor settle after zero
+
             # Baseline force reading before the loop
             baseline = list(self._rtde_r.getActualTCPForce())
 
@@ -387,9 +411,9 @@ def move_velocity(
             raise MotionError(f"Duration must be > 0, got {duration}.")
 
         try:
-            start = _time.monotonic()
+            start = time.monotonic()
             while True:
-                elapsed = _time.monotonic() - start
+                elapsed = time.monotonic() - start
                 if elapsed >= duration:
                     break
                 if not self._rtde_c.isConnected():

src/urkit/robot.py

@@ -254,19 +254,19 @@ def __init__(
 
         logger.info("URRobot initialized at %s", ip)
 
-    def activate_gripper(self, *, timeout: float = 10.0) -> bool:
-        """Activate the gripper with a timeout.
+    def _activate_gripper(self, *, timeout: float = 10.0) -> bool:
+        """Activate the gripper with error handling (internal use).
 
         Tries to activate the configured gripper. If activation fails
         or times out (e.g., gripper not physically connected), disconnects
         the gripper, nulls out ``self._gripper``, and returns ``False``.
 
-        This is the single place that handles gripper activation — the
-        CLI and library code should call this rather than touching
-        ``gripper.activate()`` directly.
+        Users should call ``robot.gripper.activate()`` directly instead.
+        This method exists for the CLI which needs graceful fallback
+        when the gripper isn't connected.
 
         Args:
-            timeout: Maximum seconds to wait for activation (default 5.0).
+            timeout: Maximum seconds to wait for activation (default 10.0).
 
         Returns:
             ``True`` if the gripper was activated successfully,
@@ -1113,16 +1113,31 @@ def move_sequence(
         except Exception as e:
             raise MotionError(f"move_sequence failed: {e}")
 
+    def zero_ft_sensor(self) -> None:
+        """Zero the robot's force/torque sensor.
+
+        Clears the baseline so that subsequent force/torque readings
+        reflect only forces applied after this call. Call before
+        ``move_until_contact()`` or any force-based operation.
+
+        Raises:
+            MotionError: If the command fails.
+        """
+        self._check_connection()
+        self._motion.zero_ft_sensor()
+
     def move_until_contact(
         self,
         speed_vector: list[float],
         *,
         threshold: float = 5.0,
         acceleration: float = 0.1,
+        zero_first: bool = True,
     ) -> None:
         """Move until contact is detected via TCP force sensing.
 
         Runs an interruptible control loop — press Ctrl+C to stop at any time.
+        Zeros the FT sensor by default before reading the baseline.
 
         Args:
             speed_vector: 6-element speed vector
@@ -1131,17 +1146,22 @@ def move_until_contact(
                 Contact fires when any wrench component changes by more
                 than this value from the baseline reading.
             acceleration: Acceleration limit passed to ``speedL()`` in m/s².
+            zero_first: If True (default), zero the FT sensor before reading
+                the baseline. Set to False if you need absolute force values.
 
         Example:
-            >>> # Move straight down until contact
+            >>> # Move straight down until contact (zeros FT sensor first)
             >>> robot.move_until_contact([0, 0, -0.02, 0, 0, 0])
             >>> # Higher threshold for heavier contact
             >>> robot.move_until_contact([0, 0, -0.02, 0, 0, 0], threshold=10.0)
         """
         self._check_connection()
         self._disable_freedrive_guard()
         self._motion.move_until_contact(
-            speed_vector, threshold=threshold, acceleration=acceleration
+            speed_vector,
+            threshold=threshold,
+            acceleration=acceleration,
+            zero_first=zero_first,
         )
 
     def move_velocity(