Your first hand integration: signals before motion
Establish what commands and feedback mean before attempting a complete grasp.
Create a checkable map between commands, measured state and the target hand.
Identify the system you actually have
Record the hand revision, left or right side, firmware, controller, connection and SDK release. Start from the manufacturer’s example for that combination. A repository mentioning the same brand does not establish support for your device. Keep manufacturer setup, stopping and operating instructions alongside your integration notes.
Make a signal dictionary
For every command and observation, record its name, order, unit, coordinate frame and meaning. Is the target an absolute position or an increment? Does the reported value come from an encoder, an estimate or the last command? ROS conventions use SI units, but a vendor interface may use degrees or device-specific counts. Convert explicitly at that boundary.
Start with read-only observations
Use documented read-only functions to inspect device identity, state and error reporting. Record timestamps and how old each observation is. A successful connection does not establish a healthy feedback loop. If a joint position exactly repeats the last command, confirm whether it is a measurement or an echoed target.
Check the mapping away from the physical robot
Use a documented simulator or visualizer to check one named joint, its direction, range and left/right interpretation. Map by names instead of assuming that two arrays use the same ordering. For ROS 2 setups, check which state and command interfaces the driver exposes. A position controller cannot assume an effort interface exists.
Define the next controlled test
Write down the expected observation, allowed operating conditions and stop procedure before moving hardware. Follow the manufacturer’s validated commissioning sequence with the appropriate operator. Keep the first physical check separate from object manipulation. This lesson is an integration planning exercise, not a replacement for the device’s commissioning procedure.
Worked example: trace one command
| Check | Example mismatch | What to verify |
|---|---|---|
| Unit | 30 interpreted as radians instead of degrees | Document and test the conversion boundary |
| Ordering | Thumb target reaches an index joint | Map named joints across all interfaces |
| Feedback | Target value mistaken for measured position | Identify the signal’s actual source |
| Timing | Old state displayed as current | Inspect timestamps and stale-data behavior |
Try it yourself
Your practical task
- Find the exact model’s official setup guide and supported SDK release.
- Make a signal dictionary with names, units, ordering and timestamps.
- Inspect documented read-only feedback or recorded logs.
- Check the named-joint mapping in a documented simulator before planning physical tests.
What to produce: An interface sheet with unresolved items and the next manufacturer-approved check.
Check your understanding
Original sources & next steps
ROS REP-103: units and coordinate conventions ↗ros2_control: state and command interfaces ↗Dex Retargeting: joint ordering and mapping ↗Original Dexhands teaching material. Lesson and linked references reviewed 2026-09-24. Research links are not endorsements or evidence of hardware compatibility.