User Manual

Warning: It is extremely important that the calibration grid is attached securely to the robot such that it
does not change its relative position w.r.t. the user-defined robot frame during step 2 of the Calibration
routine (Section 6.7.3).
Securely preventing unintended position changes such as those caused by vibrations, for example by
mounting the calibration grid itself on a wooden support (suggested thickness min. 1 cm), which can
then be screwed to the robot structure, e.g., its flange or tool, is therefore strongly recommended.
In this use case, the result of the calibration (step 3 of the Calibration routine, Section 6.7.3) is the pose
T
ext
camera
describing the (previoulsy unknown) relative positional and rotational transformation between the
rc_visard’s camera frame and the user-selected external reference frame ext such that
p
ext
= R

T
ext
camera

· p
camera
+ t

T
ext
camera

,
(6.7.2)
where p
ext
= (𝑥, 𝑦, 𝑧)
𝑇
is a 3D point with its coordinates expressed in the external reference frame ext,
p
camera
is the same point represented in the camera coordinate frame, and R(T) as well as t(T) are the
corresponding 3 × 3 rotation matrix and 3 × 1 translation vector to a pose T, respectively.
robot
ext
camera
T
robot
ext
T
camera
ext
Calibration
grid
Fig. 6.7.2: Important frames and transformations for calibrating a statically mounted rc_visard: The sensor is
mounted with a fixed position relative to a user-defined external reference frame ext (e.g., the world coordinate
frame or the robot’s mounting point). It is important that the pose T
ext
robot
of the user-defined robot frame w.r.t. this
frame is observable during the calibration routine. The result of the calibration process is the desired calibration
transformation T
ext
camera
, i.e., the pose of the camera frame in the user-defined external reference frame ext.
robot
camera
robot
camera
Fig. 6.7.3: Alternate mounting options for attaching the calibration grid to the robot
6.7. Hand-eye calibration 56