pib-sdk 0.2

Forward & inverse kinematics helpers for pib's robot arms

pib-sdk

SDK for pib including forward, inverse kinematics and trajectory generation

Features

• One‑liner FK / IK for the right & left arm using Robotics Toolbox under the hood
• Ready‑made Denavit‑Hartenberg (DH) parameters for pib
• Multi point trajectory generation
• Numeric Jacobian and analytical pose error utilities
• Zero ROS / Gazebo dependencies – pure Python ≥ 3.9
• Writing joint values to ROS topic without ROS enbironment requirement

Installation

pip install pib-sdk

Usage

from pib_sdk.kinematics import fk, ik
'''
fk for Forward kinematics, returns pose of end effector from given angles
ik for inverse kinematics, returns joint angles from given end effector position [xyz] and orientation [rpy] (optional)
Specify right or left to calculate for designated pib arm
'''
print('FK pose:', fk('right', [0,45,0,0,90,0]))
print('IK angles:', ik('right', xyz=[150,0,350]))
# To write or read values from joints
write('shoulder_vertical_right', position=20, velocity=5000)
read('shoulder_horizontal_left')

Getting started

from pib_sdk.control import *
from pib_sdk.kinematics import ik, fk

# Control client
w = Write(debug=True)  # connects to rosbridge (localhost:9090 by default)

# Move a couple of joints with the same angle
w.move("shoulder_vertical_right", "elbow_right", -30.0)

# Broadcast to all
w.move(All, -45.0)
w.move(All, zero_position)        # every motor to 0°
w.move(All, resting_position)     # special: elbows=5000 internal, fingers=-9000, others=0

Hand presets

w.move(open_hand_left)   # all left fingers (endswith *_stretch) to -90°
w.move(close_hand_right) # all right fingers to +90°

Arm groups

# All non-finger, non-thumb-opposition joints whose names end with _right / _left
w.move(right_arm, -20.0)
w.move(left_arm,  15.0)

Naming rule recap

• Fingers: name ends with _stretch
• Right/Left: motor name ends with _right / _left

Per-motor angles (one call)

w.move("shoulder_vertical_right", "shoulder_horizontal_right", "elbow_right",
       -30.0, 10.0, 5.0)

---

Settings API

Apply settings to one or more motors:

w.set("shoulder_vertical_right",
      turned_on=True, velocity=6000, acceleration=10000,
      deceleration=5000, period=19500,
      pulse_width_min=700, pulse_width_max=2500,
      rotation_range_min=-9000, rotation_range_max=9000,
      visible=True, invert=False)

Multiple motors, same settings:

w.set("shoulder_vertical_right", "wrist_right", velocity=6000, acceleration=10000)

All motors, default preset (you can override any field inline):

w.set(All, default)                   # or w.set(All, default=True)
w.set(All, default=True, velocity=12_000)  # override velocity only

Default preset (applied by default):

turned_on=True
velocity=16000
acceleration=10000
deceleration=5000
period=19500
pulse_width_min=700
pulse_width_max=2500
rotation_range_min=-9000
rotation_range_max=9000
visible=True
invert=False

---

IK / FK

kinematics.py provides one-liners around your pib_DH models.

from pib_sdk.kinematics import ik, fk

# Inverse kinematics: position-only (mm)
q_deg = ik("right", xyz=[150, 0, 350])         # returns np.ndarray of degrees (len = DOF)

# Move the whole right arm using that IK (broadcasting one angle per joint)
from pib_sdk.control import Write, right_arm
w = Write()
w.move(right_arm, *q_deg)

# Forward kinematics
pose = fk("right", q_deg=[0, 45, 0, 0, 90, 0]) # returns SE3
print(pose)

Notes

• If your arm has more joints than the IK vector, slice: w.move(right_arm, *q_deg[:N]).
• IK defaults to position-only (RPY ignored); pass rpy_deg=[roll, pitch, yaw] to constrain orientation.
• ik(..., q0_deg=[...]) sets an initial guess (deg). Convergence settings: tol, max_steps, custom_mask.

---

Motor discovery & database

Write builds the motor list from two sources:

1. SQLite DB (optional): looks for table motor(name) in
   /home/pib/app/pib-backend/pib_api/flask/pibdata.db
   Override via:
   • env var: PIB_MOTOR_DB=/path/to/pibdata.db, or
   • constructor: Write(db_path="/path/to/pibdata.db")
2. Telemetry: any name seen on /motor_settings is cached.

You can inspect what’s known:

print(w._get_all_motors())

---

CLI (optional)

A tiny CLI is included:

python -m pib_sdk.control send --motor elbow_right --position-deg -30
python -m pib_sdk.control echo --motor elbow_right

Common flags:

• --turn-on, --set-defaults
• --velocity, --acceleration, --deceleration, --period
• --verify-echo (waits for /motor_settings echo), --echo-timeout

---

Troubleshooting

• “Only the first joint moved”
  Some servers ignore multi-joint trajectories. The SDK sends one service call per joint for multi-motor moves to guarantee motion.

• “No motors known yet”
  Provide the DB path/env var or let one /motor_settings message flow to seed names.

• ValueError: degrees range
  Angles must be within −90 … +90.

• Arm groups empty / missing joints
  Check your naming: arm members must end with _right / _left. Fingers end with _stretch (excluded). Thumb opposition joints (contain both thumb and opposition) are excluded.

---

Examples cheat-sheet

# All to -90
w.move(All, -90)

# All to 0
w.move(All, zero_position)

# Resting
w.move(All, resting_position)

# Open/close hands
w.move(open_hand_left)
w.move(close_hand_right)

# Right/left arm broadcast
w.move(right_arm, -15)
w.move(left_arm,  20)

# Per-joint list
w.move("shoulder_vertical_right", "shoulder_horizontal_right", "elbow_right",
       -30, 5, 10)

# Apply defaults to all
w.set(All, default)

# Apply custom velocity to two joints
w.set("shoulder_vertical_right", "wrist_right", velocity=8000)