> ## Documentation Index
> Fetch the complete documentation index at: https://docs.almond.bot/llms.txt
> Use this file to discover all available pages before exploring further.
# Gravity Compensation Config Parameters
> Every setting for axol gravity-comp — what it does and its default.
export const F = ({children}) => {children};
export const prefix_0 = "axol."
Every setting for `axol gravity-comp`. Add any flag below to the command, or set it once in the control panel — see [Command configuration](/cli/configuration) for config files and syntax details.
```bash theme={null}
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/_*.npz` so [`motion.build`](/cli/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 |
| --------------------------------------------- | --------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| --{prefix_0}left\_stiffness | `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`. |
| --{prefix_0}right\_stiffness | `1.0` | Same, for the right arm. |
| --{prefix_0}has\_gripper | `true` | Set `false` on the gripperless model. The gripper motors are never enabled and datasets record 7 channels per arm instead of 8. |
| --{prefix_0}max\_step\_rad | `0.5` | Largest joint move (rad) allowed between two consecutive commands. Bigger moves are dropped with a warning. `inf` disables. |
| --{prefix_0}left.gripper.torque\_limit | `0.5` | Grip force — peak gripper torque (Nm). |
| --{prefix_0}left.gripper.max\_speed | `10.0` | Maximum gripper speed (rad/s). |
| --{prefix_0}left.elbow\.kp | per joint | Position stiffness of one joint, in `[0, 500]`. This is the stiffness-`1` value. |
| --{prefix_0}left.elbow\.kd | per joint | Velocity damping in the motor firmware, in `[0, 5]`. |
| --{prefix_0}left.elbow\.kd\_host | 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. |
| --{prefix_0}left.elbow\.kd\_host\_hz | `null` | Centre frequency (Hz) of the band the host damping acts in. `null` tracks the arm's pose automatically. |
| --{prefix_0}left.elbow\.kd\_host\_q | `null` | Width of that band (bandwidth = centre ÷ q). `null` uses `0.8`. |
| --{prefix_0}left.elbow\.j\_eff | per joint | Effective inertia (kg·m²) used for acceleration feed-forward. |
| --{prefix_0}left.elbow\.mass | per joint | Mass (kg) of the link, used for gravity compensation. Tune if an arm sags or pushes back in [gravity comp](/operations/gravity-comp). |
| --{prefix_0}left.elbow\.com | per joint | Centre of mass `[x, y, z]` (m) of the link. |
| --{prefix_0}left.elbow\.friction.fc | per motor | Coulomb friction (Nm). Measured per motor with [`tune.friction`](/cli/tune-friction). |
| --{prefix_0}left.elbow\.friction.k | per motor | Friction curve sharpness. |
| --{prefix_0}left.elbow\.friction.fv | per motor | Viscous friction (Nm·s/rad). |
| --{prefix_0}left.elbow\.friction.fo | 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`](/cli/tune-pid), [`tune.friction --save`](/cli/tune-friction), or [`tune.gravity --save`](/cli/tune-gravity) uses its own measured values (from `~/.almond/calibration.json`) instead of the defaults below. Flags you pass still override both.
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 |
Fallback values of `fc`, `k`, `fv`, `fo` for each motor, measured on the reference robot with [`tune.friction`](/cli/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` |