WidowX-250 6DOF

Overview

The WidowX-250 6DOF Robot Arm belongs to the Interbotix X-Series family of arms featuring the DYNAMIXEL X-Series Actuators from Robotis. The X-Series actuators offer higher torque, more efficient heat dissipation and better durability all at a smaller form factor over previous DYNAMIXEL servos. The DYNAMIXEL XM430-W350 & DYNAMIXEL XL430-W250 servos offer high resolution of 4096 positions and user definable PID parameters, temperature monitoring, positional feedback, as well as voltage levels, load, and compliance settings are user accessible as well. At the heart of the WidowX-250 6DOF is the Robotis DYNAMIXEL U2D2 which enables easy access to DYNAMIXEL Wizard software as well as ROS. The WidowX-250 6DOF offers 6 degree of freedom and a full 360 degree of rotation.

The main advantage to using a 6 degree of freedom arm is the increased maneuverability it provides. In general, the pose of an arm’s end-effector can be described by its position (x, y, z) and orientation (roll, pitch, yaw) in 3D space. While each of these six factors can be controlled independently with a 6DOF arm, one or more of them must be constrained with lower dof arms.

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WidowX-250 6DOF
Degrees of Freedom 6
Reach 650mm
Total Span 1300mm
Repeatability 1mm
Accuracy 5 - 8mm
Working Payload 250g*
Total Servos 9
Wrist Rotate Yes

Note

* Working Payload for the WidowX-250 6DOF is inside its maximum reach, if intending to use a 250g weight we recommend no more than a 50% extension of the arm.

Default Joint Limits

Default joint limits are the safe range of operation for each joint. These are set in the firmware, defined as degrees from Zero (servo centered).

Joint Min Max Servo ID(s)
Waist -180 180 1
Shoulder -108 114 2+3
Elbow -123 92 4+5
Forearm Roll -180 180 6
Wrist Angle -100 123 7
Wrist Rotate -180 180 8
Gripper 30mm 74mm 9

Default Servo Configurations

ID Joint Name Servo Baudrate
1 waist XM430-W350 1Mbps
2 shoulder XM430-W350 1Mbps
3 shoulder_shadow XM430-W350 1Mbps
4 elbow XM430-W350 1Mbps
5 elbow_shadow XM430-W350 1Mbps
6 forearm_roll XM430-W350 1Mbps
7 wrist_angle XM430-W350 1Mbps
8 wrist_rotate XL430-W250 1Mbps
9 gripper XL430-W250 1Mbps

Kinematic Properties

Product of Exponentials [Learn More]

\[\begin{split}M & = \begin{bmatrix} 1.0 & 0.0 & 0.0 & 0.458325 \\ 0.0 & 1.0 & 0.0 & 0.0 \\ 0.0 & 0.0 & 1.0 & 0.36065 \\ 0.0 & 0.0 & 0.0 & 1.0 \end{bmatrix}\end{split}\]
\[\begin{split}Slist & = \begin{bmatrix} 0.0 & 0.0 & 1.0 & 0.0 & 0.0 & 0.0 \\ 0.0 & 1.0 & 0.0 & -0.11065 & 0.0 & 0.0 \\ 0.0 & 1.0 & 0.0 & -0.36065 & 0.0 & 0.04975 \\ 1.0 & 0.0 & 0.0 & 0.0 & 0.36065 & 0.0 \\ 0.0 & 1.0 & 0.0 & -0.36065 & 0.0 & 0.29975 \\ 1.0 & 0.0 & 0.0 & 0.0 & 0.36065 & 0.0 \end{bmatrix}^T\end{split}\]