None value with variable "qd" and "qdd" in function "mstraj" return

[yang-si-hang]

Describe the bug
I applied the function "mstraj" in my code,

Version information
Installation from Conda channel "conda-forge"

To Reproduce
The python code is below:

q_start = np.array([0, 0, 0, 0, 0, 0])
q_via1 = np.array([0.5, -0.5, 0.2, 0, 0, 0])
q_via2 = np.array([1.0, 0.5, 0.9, 0.5, -0.2, 0])
q_end = np.array([1.5, 0, 0, 0, 0, 0])
waypoints = np.array([q_start, q_via1, q_via2, q_end])

dt = 0.02
t_acc = 0.5
q_vel = 2

traj = rtb.mstraj(waypoints, dt=dt, tacc=t_acc, qdmax=q_vel)

# None in variable "qd" and "qdd"
print(traj.qd)
print(traj.qdd)

The output of the code:

None
None

Expected behavior
I expected the meaningful value of varibale "qd" and "qdd" but returns "None".

Screenshots

Environment (please complete the following information):

• Linux (Ubuntu 22.04).
• python==3.11.11

Additional context