Units and Pose Representation

Public units

URCtrl standardizes its public units for convenient use in experimental scripts by researchers.

Type	Representation	Unit
P coordinates	`[x, y, z, rx, ry, rz]`	mm, degree
J coordinates	`[j1, j2, j3, j4, j5, j6]`	degree
speed	`0 < value <= 100`	%
jspeed	`0 < value <= 100`	%
accel	`0 < value <= 100`	%
decel	`0 < value <= 100`	%
`move_path()` blend	float	m

Internal UR units

UR RTDE uses m / rad. URCtrl converts values at the boundary between the public interface and RTDE.

Public interface
    mm / degree / %
        ↓
URCtrl
        ↓
RTDE
    m / rad / SI

P coordinates

P coordinates contain the following six components:

[x, y, z, rx, ry, rz]

x, y, z are expressed in mm.

rx, ry, rz form a rotation vector expressed in degrees.

Rotation vector

UR orientations are not Euler angles.

rx, ry, rz form a rotation vector: three components obtained by multiplying the rotation axis by the rotation angle.

URCtrl exposes each rotation-vector component in degrees. These are not roll / pitch / yaw angles in degrees.

J coordinates

J coordinates contain six joint angles:

[j1, j2, j3, j4, j5, j6]

The public unit is degree.

speed / accel

speed, jspeed, accel, and decel are all percentages.

Internally, they are converted to physical speeds and accelerations as follows:

linear speed = UR_MAX_LINEAR_SPEED * speed / 100
joint speed  = UR_MAX_JOINT_SPEED  * jspeed / 100
linear accel = UR_MAX_LINEAR_ACCELERATION * accel / 100
joint accel  = UR_MAX_JOINT_ACCELERATION  * accel / 100

Default values

Setting	Default
`UR_MAX_LINEAR_SPEED`	0.25 m/s
`UR_MAX_LINEAR_ACCELERATION`	1.2 m/s²
`UR_MAX_JOINT_SPEED`	1.05 rad/s
`UR_MAX_JOINT_ACCELERATION`	1.4 rad/s²
`UR_DEFAULT_BLEND_RADIUS`	0.005 m

These values can be overridden in the configuration.