Common Control Interface and MG400 Implementation Contract

The common control interface is defined by this family of projects and is shared conceptually across COBOTTA, Universal Robots (UR), and DOBOT. It is not a COBOTTA-specific interface adopted by DOBOT. Each robot has different physical capabilities: the presence of a method does not guarantee equivalent motion on every robot.

DobotCtrl exposes the public interface and delegates to DobotTcp. DobotTcp implements MG400-specific commands, feedback, and coordinate conversions. dobot_api.py contains the vendor API, while dobot_api_ext.py adds integration behavior. ese774_frame transparently publishes the public interface over the network; it does not define the robot interface itself.

Operation semantics and limitations

Common operation	MG400 implementation
`take_arm()` / `give_arm()`	No corresponding independent ownership command: return `True` without sending a robot command. Not equivalent to enabling the motors.
`turn_on_motor()` / `turn_off_motor()`	Map to `EnableRobot()` / `DisableRobot()`.
`servo_on`	Uses feedback `EnableStatus`.
`halt()` / `stop()` / `task_stop()`	Raise `NotImplementedError` because equivalent semantics have not been established. Do not use as emergency-stop functions.
`hand_stop()`	Not implemented until the attached hand is specified.
`set_decel()`	Returns `False`; no independent deceleration setting is implemented. `get_decel()` is unsupported.
`set_speed()`	Maps to `SpeedL`; `set_extspeed()` maps to `SpeedFactor`. These are distinct settings.
`get_speed()`	Returns the most recently configured value held by this library, not a measured velocity.

Cartesian and joint representations

The common Cartesian vector is [x, y, z, rx, ry, rz], while the MG400 uses [x, y, z, r]. _p_to_mg400() rejects nonzero rx or ry with ValueError and maps rz to r. Readback fills rx=ry=0.

The common joint vector is [j1, j2, j3, j4, j5, j6], while MG400 uses four joints. Input j5 and j6 must be zero; readback pads them with zeros. A six-element interface does not imply six physical degrees of freedom.

Remote invocation

The server uses FastApiServer(device_cls=DobotCtrl, router_cls=None, api_spec=None, object_name="dobot", ...). Both synchronous and asynchronous clients invoke the same server-side control layer. Completion of an HTTP request is distinct from completion of robot motion.

Source: supplied dobot_ctrl.py, dobot_tcp.py, server_fastapi/server.py, and ese774_frame implementation files.