Gravity Compensation

Hold the arms weightless so you can move them by hand — from the web control panel or the CLI.

Gravity compensation holds both arms weightless so you can move them freely by hand. Each free joint is commanded with zero stiffness, velocity damping, and a feedforward torque that cancels the arm’s modelled gravity — so the arm neither sags nor springs back. It’s the easiest way to pose the robot, check its range of motion, or hand-guide it.

You can run it from the web control panel or the CLI (axol gravity-comp).

Before you start

• Axol installed (one-command install) and the robot powered on.
• CAN up and motors verified. The control panel handles this on connect; on the CLI run axol can.setup once, then check a motor with axol motor.info.

The arms go compliant the moment this starts — be ready to support them so they don’t drop.

Run it

Control Panel

1. Connect the robot

   Connect the Axol Host — the panel connects the robot automatically (press Connect on the Axol tile if needed). Gravity comp needs only the robot connection — no cameras. See the Web Control Panel guide.

2. Select Gravity Compensation and Start

   Pick Gravity Compensation from the operation selector and press Start. The arms go weightless immediately. Press Stop to hold them rigid again.

   To record the hand-guided session, set a recording name on the panel before starting — the capture is written when the session stops, and Build motion in the diagnostics dashboard turns it into a replayable reference motion.

CLI

On the robot machine:

axol gravity-comp                                 # all 7 joints free, both arms
axol gravity-comp --right_channel null            # left arm only
axol gravity-comp --kd 1.0                        # heavier damping (less floppy)
axol gravity-comp --free_joints [WRIST_3]         # only WRIST_3 free; the rest held rigid
axol gravity-comp --record demo1                  # capture the hand-guided motion

Press Ctrl+C to stop. Use --free_joints to float only the named joints while the rest of the arm holds its pose — handy for isolating one joint at a time. --record captures the hand-guided session so motion.build can turn it into a replayable reference motion. See the gravity-comp reference for every flag.

If an arm sags or pushes back, the gravity model needs tuning — adjust the per-joint mass and com fields on AxolConfig. See Gravity compensation.

Next steps

Config Parameters

Every setting for gravity comp, with its default.

Teleoperation

Drive the arms from a VR headset instead of by hand.

gravity-comp reference

Every flag — free joints, damping, per-arm channels.