Motors · Leader arm
Motor 5 · wrist roll
Wrist roll. Motor 5's joint. "Roll" means turning about its own axis; it rotates the gripper.Source: lerobot/docs/source/so101.mdx#2-set-the-motors-ids-and-baudrates · lerobot/docs/source/so101.mdx#gripper--handle
wrist roll
Wrist roll. Motor 5's joint. "Roll" means turning about its own axis; it rotates the gripper.Source: lerobot/docs/source/so101.mdx#2-set-the-motors-ids-and-baudrates · lerobot/docs/source/so101.mdx#gripper--handleWhich motor goes here
- Use the motor you labelled 5. It must be a STS3215 motor, gear, code C046.
1:147
Gear ratio. The number on the motor's label, such as 1:345. The motor inside turns 345 times for one turn of the output. The follower arm uses 1:345 at all six joints. The leader arm mixes 1:191, 1:345 and 1:147, so check the label before fitting a motor.Source: lerobot/docs/source/so101.mdx#step-by-step-assembly-instructions · SO-ARM100/README.md#sourcing-parts - Power it from a 5V supply; that is the supply for the standard 7.4V motor.
- Joint: wrist_roll · bus ID 5 · STS3215 1:147
- Default part: Feetech STS3215 servo, 7.4V, 1:147 gear (C046)
servo-sts3215-c046-147 - Standard: Feetech STS3215 servo, 7.4V, 1:147 gear (C046)
servo-sts3215-c046-147, 7.4V servo, 5V supply. Leader arm is always 7.4V on the 5V supply; no 12V variant exists for it (README).
Steps for this motor
- L-050 Insert motor 5 into the wrist holder
- L-051 Fit one horn only on motor 5 (wrist roll)
- L-060 Mount the leader holder on the wrist
Sources (4)
- lerobot/docs/source/so101.mdx#step-by-step-assembly-instructions — leader table row "Wrist Roll": motor 5, 1 / 147
- wiki.seeedstudio.com (retrieved 2026-09-07) — servo table: L5 = 1:147
- SO-ARM100/README.md#sourcing-parts — leader bundle footnote
- SO-ARM100/README.md#sourcing-parts — 7.4V servos; 5V power supply