EoAT Settings

The RoArm-M2-S supports interchangeable End of Arm Tooling (EoAT). The firmware needs to know which tooling is installed and how it’s mounted so that forward/inverse kinematics calculate correctly.

EoAT Modes

Mode	Code	Description
Gripper	0	Parallel-jaw gripper (default)
Wrist	1	Rotary wrist joint

Switch modes:

{"T":1,"mode":0}

{"T":1,"mode":1}

Image: Waveshare

EoAT Assembly Configuration

The firmware uses link-length parameters to compute kinematics. When you change the EoAT mounting position or add extensions, you need to update these dimensions.

The arm geometry from the firmware source:

  -------L3A-----------O==L2B===
  |                    ^       ||
 L3B                   |       ||
  |              ELBOW_JOINT   ||
  pos->X--L4A---O              L2A
       |                       ||
  |   L4B                      ||
/      |                       ||
PI X-EA-X       SHOULDER_JOINT -> OO
\ |                            [||]
 EB                             L1
  |                            [||]
 --------            BASE_JOINT -> XX

Configure Assembly

{"T":2,"pos":3,"ea":0,"eb":20}

Parameter	Description
pos	Mounting position: 0=edge, 1=D-3.2, 2=D-4.2, 3=D-10.2
ea	Extension A length (mm) — horizontal offset from gripper center
eb	Extension B length (mm) — vertical offset below gripper

Tip

The mounting position pos selects from predefined hole patterns on the expansion plate. Position 3 (D-10.2) is the default for the standard gripper.

Gripper Control

Open and close the gripper using radian values:

Release (open):

{"T":106,"cmd":1.57,"spd":0,"acc":0}

Grab (close):

{"T":106,"cmd":3.14,"spd":0,"acc":0}

Specific angle:

{"T":106,"cmd":4.0,"spd":0,"acc":0}

The cmd parameter is the target angle in radians. The range depends on the installed EoAT.

Grab Torque

Set the maximum grip force:

{"T":107,"tor":200}

Parameter	Description
tor	Torque limit (0–1000). Higher = stronger grip

Caution

Setting torque too high with small or fragile objects can damage them. Start low (100–200) and increase as needed.

Custom EoAT Design

The expansion plate supports custom end-effectors. Key constraints:

• Maximum payload at full extension: 0.5kg
• Servo bus connector available at the wrist for powered tooling
• 12V switched output available via {"T":113} for external actuators
• Mounting hole patterns: M3 threads on 3.2mm, 4.2mm, and 10.2mm spacing

When designing custom tooling, update the assembly parameters (T:2) to match your new link lengths so the kinematics remain accurate.

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EoAT reference from firmware source json_cmd.h and Waveshare Wiki.