Trajectory: Joint Position
Note
The Streaming Mode ID for this mode is 1.
Streaming Message Format
In Pos mode, the robot is controlled by commanding the desired position for each joint.
In order to use this mode, a trajectory generation algorithm is required that generates a feasible trajectory satisfying each joint’s dynamic limits. Please see below for suggested limits in streaming mode:
Joint Limits
1Joint Position: ±270 deg
2Joint Velocity:
3 Drive 193: ±1.25 [rad / s]
4 Drive 148: ±2.00 [rad / s]
5 Drive 116: ±4.00 [rad / s]
6 Drive 86: ±5.00 [rad / s]
7Joint Acceleration: ± 4.0 [rad / s2]
8Joint Jerk: ± 100.0 [rad / s3]
The controller will receive the streaming messages and store them in a buffer (the size can be adjusted via the streaming enable API message, see Start Streaming).
Based on the four most recent entries of the buffer, a B-Spline interpolation is calculated to obtain smooth values for the first two derivatives.
In some cases - for example due to rounding errors or packet loss - larger jumps can occur, specifically in the derivatives. Therefore, to guarantee best possible robustness, the commanded joint properties are post processed and the controller is aiming to best possibly follow the commanded joint trajectory. However, this postprocessing assumes the trajectory is valid, i.e. it respects the feasibility limits for joint position, velocity and acceleration.