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TCP

A Tool can be anything that is attached to the last detected module of the Robot, e.g. a welding gun (see image below), screwdriver or any gripper. The Tool is defined by the Tool Center Point, the Mass and the Center of Mass.

Tool Center Point​

The Tool Center Point (TCP) defines the working point of the Robot and is used to determine the Robot's positional Cartesian coordinates. The TCP is defined with respect to the coordinate system of the last Robot module (e.g. the Flange). The x- and y-axis of that frame are marked on the PCB of the last module. The z-axis points outwards, perpendicular to the (x,y)-plane as shown in the figure below. All coordinate frames are right-handed.

tcp-shift

Please follow the subsequent instructions to define the TCP:

  1. Define the position of the origin of the TCP frame with respect to the last Robot module (x,y,z)
    In the example above the origin of the TCP frame is shifted by 15cm along the z-axis and 5cm along the y-axis of the Flange frame. Therefore, the position is defined as (x,y,z) = (0, 0.05, 0.15) m.

  2. Define the rotation of the TCP frame with respect to the last Robot module (rz,ry,rx)
    The rotation is defined based on the intrinsic zyx euler convention. The order of the elemental rotation is as follows:

    1. Rotation around z-axis
    2. Rotation around y-axis
    3. Rotation around x-axis

    Note that each elemental rotation is performed on the coordinate system as rotated by the previous rotation.
    In the example above there is only a negative rotation around the x-axis of the Flange frame. Therefore the rotation is defined as (rz, ry, rx) = (0, 0, -45) °.

Mass Dynamics​

Additionally, the Mass and Center of Mass of the Tool needs to be defined. This is important to keep the performance of the controller high.
The Mass is the total weight of the Tool in kilograms. The value can be determined by weighing the Tool on a scale.
The Center of Mass is specified as a vector (x,y,z) from the last module (e.g. the Flange). The coordinate system is marked on the PCB of the last module.