Gravity Compensation

Gravity compensation holds both arms weightless so you can move them by hand. The arms don’t sag and don’t spring back. Use it to pose the robot, check its range of motion or guide it by hand. Start it from the web control panel or with axol gravity-comp.

Before you start

Install Axol with the one-command install and power on the robot.
Bring up CAN and check the motors. The control panel does this when it connects. On the CLI, run axol can.setup once, then check a motor with axol motor.info.

The arms go limp as soon as gravity compensation starts. Be ready to support them so they don’t drop.

Run it

Control Panel
CLI

Connect the robot

Connect the Axol Host. The panel connects the robot. If it doesn’t, press Connect on the Axol tile. No cameras are needed. See Connections.

Select Gravity compensation and Start

Pick Gravity compensation from the operation selector and press Start. The arms go weightless. Press Stop to hold them stiff again.To record what you do by hand, fill in Record before you start. The recording is saved when you stop. Press Build motion in the diagnostics dashboard to turn it into a reference motion you can replay.

On the robot’s computer:

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.

--free_joints frees only the joints you name. The rest of the arm holds its pose, so you can test one joint at a time.
--record saves the session so motion.build can turn it into a reference motion.

See gravity-comp for every flag.

If an arm sags or pushes back, 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, including free joints, damping and per-arm channels.

Get Started

Operations

Mantis

Remote Teleop

Web Interfaces

Advanced

Gravity Compensation

Before you start

Run it

Next steps

Config Parameters

Teleoperation

gravity-comp reference

​Before you start

​Run it

​Next steps

Config Parameters

Teleoperation

gravity-comp reference

Before you start

Run it

Next steps