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API and examples

Examples are in Python; the C++ interfaces share the names, and help(t.FollowerGripper) has the full reference. Installation: Setup and self-check; motion: Motion control.

import xense.taccap as t

Opening the follower gripper

With one connected:

g = t.FollowerGripper(t.find_follower().mcu_device)

With several, pick by side and role:

ep = next(e for e in t.scan_grippers()
          if e.side == t.Side.Left and e.role == t.Role.Follower)
g = t.FollowerGripper(ep.mcu_device)

Follower serials end in s; see Serial number.

Scanning interrupts other programs

It stops other programs' gripper data streams, and a holding follower releases its torque; scan only once, at start-up.

Controllers

Impedance control (default) Force-position control
Controller ImpedanceController ForcePositionController
Config ImpedanceConfig.for_spec(g.motor.get_spec()) ForcePositionConfig.for_spec(g.motor.get_spec())
Tunable Usually left alone grasp_torque_nm (grip force, ≤ 1.1N·m)
Common set_target(opening) set_target(opening), release(), hold_position()

Both have start() / stop() (or with), snapshot() and reset(). Order:

g.motor.clear_fault() → start the controller → g.motor.enable() → set_target() → stop the controller

Code: Control from a program.

Reading state

When Interface Contents
While controlling c.snapshot().observation position (opening), velocity, torque (positive = closing), motor_temp_c
While controlling c.snapshot().holding Holding (force-position control)
Not controlling g.position() Opening
Any time g.motor.motor_version() See Motor firmware version

While controlling, read only through snapshot(); reading the motor separately competes for the link.

Low-level motor interfaces

g.motor.submit_* and other low-level interfaces bypass the controller's protection. Use a controller.

These rewrite gripper or motor configuration; only under technical support's guidance: set_model(), set_startup_limit_torque(), switch_protocol(), set_can_id(), set_private_param(), set_zero(), set_gripper_config(), set_envelope(), set_auto_cal_config(), set_motor_fw_version().

Wrist camera

Off by default; enable it the same way as on the leader gripper, see Wrist camera and fisheye undistortion.

Example scripts

  • Scripts are in python/examples/; run them from the SDK source directory (the collection repository's third_party/taccap-gripper, or a standalone TacCap-Gripper).
  • Pick the gripper with left, right or the full serial, optional with only one connected; options via --help.
Script Purpose Effect
follower_status.py Self-check Read-only
gripper_console.py Keyboard control Moves motor
impedance_control.py Impedance test; view / write the motion safety envelope Moves motor; --set-envelope rewrites the gripper
force_position_control.py Force-position grasp test Moves motor
control_and_read.py Read state while controlling Moves motor
control_ripple.py Measure motion smoothness Moves motor
ota_update.py Gripper firmware upgrade Flashes
motor_ota_update.py Motor firmware upgrade Flashes 
python python/examples/follower_status.py left
python python/examples/gripper_console.py left
python python/examples/impedance_control.py left
python python/examples/force_position_control.py left --grasp-torque 0.6
python python/examples/control_and_read.py left

Before running the examples