problem with Libfranka.JointPositions

[vincentkeino]

hi , thanks for releasing code! while i use libfranka control method in this way:

target_joint_positions = [0.0, -0.78539816, 0.0, -2.35619449, 0.0, 1.57079633, 1.57079633]

def motion_generator(state: RobotState, period: Duration) -> JointPositions:
global start_time
current_joint_positions = state.q
elapsed_time = time.time() - start_time
interpolation_ratio = min(elapsed_time / motion_duration, 1.0)
desired_joint_positions = current_joint_positions + interpolation_ratio * (
np.array(target_joint_positions) - np.array(current_joint_positions)
)
joint_positions = JointPositions(desired_joint_positions.tolist())
if elapsed_time >= motion_duration:
joint_positions.motion_finished = True
else:
joint_positions.motion_finished = False
return joint_positions

motion_duration = 5.0
start_time = time.time()

try:
print("Starting motion...")
robot.control(motion_generator)
except Exception as e:
print(f"Motion failed: {e}")
finally:
print("Stopping motion...")
robot.stop()

it remind me that:Motion failed: Unable to cast Python instance of type <class 'panda_py.libfranka.JointPositions'> to C++ type '?' (#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for details)

could u help me ? i cannot fix it . thank you!!!!