Gravity Compensation Config Parameters

Every setting for axol gravity-comp. Add any flag below to the command, or set it once in the control panel — see Command configuration for config files and syntax details.

axol gravity-comp --kd 0.8 --axol.left.elbow.mass 0.3

General

Flag	Default	Description
`--left_channel`	`can_alm_axol_l`	CAN interface for the left arm. `null` disables the arm.
`--right_channel`	`can_alm_axol_r`	CAN interface for the right arm. `null` disables the arm.
`--free_joints`	`null` (all)	Joints to gravity-compensate, e.g. `[WRIST_3]` or `[SHOULDER_1,ELBOW]`. Other joints hold rigidly. `null` frees all seven.
`--kd`	`0.5`	Damping (Nm·s/rad) on freed joints. Higher is less floppy.
`--record`	`null`	Record the hand-guided motion to `~/.almond/recordings/<name>_*.npz` so `motion.build` can turn it into a reference motion.
`--rate_hz`	`250.0`	Control-loop rate (Hz).
`--log_level`	`INFO`	`DEBUG`, `INFO`, `WARNING`, or `ERROR`.
`--config_path`	—	Load a JSON/YAML config file. Flags override it.

Robot

Arm stiffness, gripper limits, and per-joint gains. The mass and com values are what gravity comp uses to hold the arm weightless — tune them if an arm sags or pushes back.

Flag	Default	Description
	`1.0`	How stiff the left arm is, from `0` (soft, hand-guidable) to `1` (the tuned gains). Lower values only add compliance — the arm tracks a little less tightly but yields more to obstacles. One number applies to every joint; a 7-element list sets each joint in the order `shoulder_1, shoulder_2, shoulder_3, elbow, wrist_1, wrist_2, wrist_3`.
	`1.0`	Same, for the right arm.
	`true`	Set `false` on the gripperless model. The gripper motors are never enabled and datasets record 7 channels per arm instead of 8.
	`0.5`	Largest joint move (rad) allowed between two consecutive commands. Bigger moves are dropped with a warning. `inf` disables.
	`0.5`	Grip force — peak gripper torque (Nm).
	`10.0`	Maximum gripper speed (rad/s).
	per joint	Position stiffness of one joint, in `[0, 500]`. This is the stiffness-`1` value.
	per joint	Velocity damping in the motor firmware, in `[0, 5]`.
	per joint	Extra damping (Nm·s/rad) applied by the host, for the slow shoulder resonance the firmware can’t damp. Scaled down automatically in poses where the joint carries less inertia. `0` on joints whose firmware damping is enough.
	`null`	Centre frequency (Hz) of the band the host damping acts in. `null` tracks the arm’s pose automatically.
	`null`	Width of that band (bandwidth = centre ÷ q). `null` uses `0.8`.
	per joint	Effective inertia (kg·m²) used for acceleration feed-forward.
	per joint	Mass (kg) of the link, used for gravity compensation. Tune if an arm sags or pushes back in gravity comp.
	per joint	Centre of mass `[x, y, z]` (m) of the link.
	per motor	Coulomb friction (Nm). Measured per motor with `tune.friction`.
	per motor	Friction curve sharpness.
	per motor	Viscous friction (Nm·s/rad).
	per motor	Constant torque offset (Nm).

Per-arm and per-joint flags are shown for left / elbow. Swap in right, or any joint: shoulder_1, shoulder_2, shoulder_3, elbow, wrist_1, wrist_2, wrist_3.

A robot calibrated with tune.pid --save, tune.friction --save, or tune.gravity --save uses its own measured values (from ~/.almond/calibration.json) instead of the defaults below. Flags you pass still override both.

Per-joint defaults

Both arms share these. kp/kd are the stiffness-1 values (the default); the soft columns are what stiffness 0 blends toward. shoulder_1 also sets kd_host_q to 3.0; every other joint leaves it null.

Joint	`kp`	`kd`	`kd_host`	`j_eff`	`mass` (kg)	soft `kp`	soft `kd`
`shoulder_1`	250	3.5	40	1.27	1.80	40	1.4
`shoulder_2`	250	3.5	35	1.1	1.00	50	1.57
`shoulder_3`	180	5.0	0	0.25	3.75	45	1.0
`elbow`	130	5.0	0	0.6	0.25	40	2.22
`wrist_1`	180	1.7	0	0	0.25	30	0.69
`wrist_2`	130	3.5	0	0	0.65	25	1.5
`wrist_3`	130	2.0	0	0	0.75	25	0.9

Per-motor friction defaults

Fallback values of fc, k, fv, fo for each motor, measured on the reference robot with tune.friction.

Joint	Left arm	Right arm
`shoulder_1`	`0.9091, 799.59, 0, 0.37`	`1.2972, 742.11, 0, −0.1557`
`shoulder_2`	`1.1378, 756.76, 0, −0.3969`	`1.3950, 768.06, 0, 0.2082`
`shoulder_3`	`0.3599, 835.51, 0, −0.0133`	`0.4377, 107.94, 0.0853, −0.0147`
`elbow`	`0.6023, 855.95, 0, −0.072`	`0.6066, 784.78, 0, 0.049`
`wrist_1`	`0.3765, 88.91, 0.0298, −0.0115`	`0.5245, 98.58, 0.3062, −0.0097`
`wrist_2`	`0.1521, 780.31, 0, −0.0152`	`0.1092, 899.67, 0, 0.0021`
`wrist_3`	`0.0714, 927.26, 0, 0.0042`	`0.1172, 204.46, 0, 0.0042`

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Gravity Compensation Config Parameters

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