Kin_Tripod_Rotary (FB)¶

FUNCTION_BLOCK Kin_Tripod_Rotary IMPLEMENTS ISMPositionKinematics_Offset,

ISMPositionKinematicsInternal, ISMKinematicWithInfo2, ISMKinematicWithInitialization

Transformation FB for Tripod kinematics with rotary axes

In the kinematic design for a tripod with rotary drives, three rotary drives are connected to the tool plate by arms and connecting rods.

Machine coordinate system (MCS)
Origin	Defined as the midpoint of the tool plate when all three upper arms (i.e. the ones directly connected to A0, A1, and A2 respectively) are in horizontal position.
X	Points from the origin and away from the point P of the first axis (A0).
Y	Defined by X and Z so that the MCS becomes right-handed.
Z	Orthogonal to the tool plate. Points from the tool plate towards the motors.

The location of the tool coordinate system (TCS) relative to the MCS in zero position:

Tool coordinate system (TCS)
X	Along the X-Axis of the MCS in positive direction
Y	Along the Y-Axis of the MCS in positive direction
Z	Along the Z-Axis of the MCS in positive direction

The image shows the zero position of all axes (the three upper arms are horizontal). The MCS is displayed in the tool plate. Additionally, the arrows at the axes A0, A1, and A2 show the direction of rotation according to the right-hand-rule.

Mechanical requirements:

• The lengths of all three arms must be equal.

• The lengths of all connecting rods must be equal.

• The distance between the two connecting rods in each pair must be equal.

The members of AXISPOS_REF have the following interpretation:

Attributes:

sm_kin_libdoc

InOut:

Scope	Name	Type	Initial	Comment
Input	dArmLength1	LREAL		Length of the upper arm connected to the motor.
	dArmLength2	LREAL		Length of the lower arm (from the upper arm to the tool plate).
	dArm1Radius	LREAL		The radius of the circle that is established by the three points P of the drives.
	dStewartRadius	LREAL	0	The radius of the circle that is established by the six points where the connecting rods connect to the tool plate.
	dDistance	LREAL		Distance between the two connecting rods in one pair.
	dMaxAngleBallJoint	LREAL	45	Maximum angle in +/- for the ball joints.

Properties:

NumAxes

Methods:

AxesToCartesian

AxesToOrientation

CartesianToAxes

CartesianToAxes_Offset

GetAxisProperties

GetKinematicsName

GetOrientationImage

Initialize

IsInitialized

IsSingularity

ProjectPosition

Structure: