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Flow Base

✓ Python SDK ✓ Omnidirectional ✓ Remote Control ✓ Raspberry Pi On-board

Flow Base is I2RT's omnidirectional holonomic mobile platform. Designed to pair with YAM arms, it enables precise whole-body mobile manipulation for tasks that demand exact positioning and free orientation.

Tagline

"It likes to move it move it" — precise, omnidirectional control for tasks where positioning and stability are critical.

Key Features

  • Holonomic drive — simultaneous XY translation and rotation with no kinematic constraints
  • On-board Raspberry Pi — pre-configured with i2rt SDK; SSH-accessible over Wi-Fi or Ethernet
  • CAN bus motor control — same DM-series protocol as YAM arms
  • Remote controller — joystick remote included for manual operation
  • API control — full network Python API via FlowBaseClient
  • Odometry — wheel odometry with reset; external sensor integration supported
  • Safety — E-stop, velocity timeout (0.25 s), remote override

Specifications

Parameter Value
Drive Holonomic (4-wheel)
Communication (external) Ethernet (static IP 172.6.2.20) / Wi-Fi
Communication (motors) CAN bus
On-board computer Raspberry Pi
Power Internal battery
SSH credentials i2rt / root
API port 11323
Velocity timeout 0.25 s

Photos & Videos

Remote Control Layout

Input Function
Left joystick XY translation
Right joystick X Rotation (yaw)
Right joystick Y Linear rail lift (if equipped)
Left1 Reset odometry
Mode Toggle local ↔ global frame
Left2 Override API commands (safety)

Getting Started

1. Unbox & power on

Follow the unboxing guide. Ensure:

  • Battery is connected and charged
  • E-stop is not pressed
  • CAN selector switch is in the UP position

2. SSH in

# Wired (Ethernet, static IP)
ssh i2rt@172.6.2.20

# Or find the Pi on your LAN after Wi-Fi setup
ssh i2rt@<pi-ip>
# Password: root

3. Run joystick demo

python i2rt/flow_base/flow_base_controller.py

4. Python API

from i2rt.flow_base.flow_base_controller import Vehicle
import time

vehicle = Vehicle()
vehicle.start_control()

# Move forward at 0.1 m/s for 1 second
start = time.time()
while time.time() - start < 1.0:
    vehicle.set_target_velocity((0.1, 0.0, 0.0), frame="local")

Coordinate Systems

The base supports two control frames toggled with the Mode button on the remote:

Mode Behaviour
Local XY motion is relative to the base's current heading
Global XY motion is relative to the world frame (headless mode)

::: warning Odometry drift Wheel odometry accumulates error, especially during aggressive movements. For precise mobile manipulation, integrate a visual odometry sensor (RealSense T265, ZED Camera). Press Left1 to reset odometry at any time. :::

API Reference

from i2rt.flow_base.flow_base_client import FlowBaseClient

client = FlowBaseClient(host="172.6.2.20")

# Read wheel odometry
odom = client.get_odometry()
# {'translation': array([x, y]), 'rotation': array([theta])}

# Reset odometry
client.reset_odometry()

# Command velocity [x, y, theta] in m/s and rad/s
client.set_target_velocity([0.1, 0.0, 0.0], frame="local")

Linear Rail (if equipped)

client = FlowBaseClient(host="172.6.2.20", with_linear_rail=True)

# Get rail state (position, velocity, limit switches)
state = client.get_linear_rail_state()

# Set rail velocity (rad/s)
client.set_linear_rail_velocity(0.5)

# Combined base + rail command [x, y, theta, rail_vel]
client.set_target_velocity([0.1, 0.0, 0.0, 0.2], frame="local")

::: tip Linear rail safety The rail homes to the lower limit on init and has hardware limit switches. Set velocity to 0.0 to stop — do not control the brake directly. Commands time out after 0.25 s of inactivity. :::

External CAN Control

To bypass the on-board Pi and control the base from an external computer:

  1. Connect your CAN adapter to the external CAN connector
  2. Set the CAN selector switch to the DOWN position
  3. Clone the i2rt repo on your external machine and control via CAN directly

Troubleshooting

Symptom Fix
Remote unresponsive Toggle remote off and on to wake from sleep
Slow boot Normal — screen firmware adds delay, SSH is available quickly
Inaccurate odometry Expected with wheel odometry; use external visual sensor for precision
Linear rail not homing Check GPIO connections and limit switches
Linear rail stuck at limit Run get_linear_rail_state() to check switch status

See Also

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