To build autonomous robots capable to plan and control tasks in human environments, we need a description of trajectories that allows the robot to reason on his moves. In this paper we propose to use series of cubic polynomial curves to define the trajectories with bounded jerk, acceleration and velocity. This solution is well adapted to plan safe and acceptable moves of the robot in the vicinity of humans. It is also a simple solution to approximate any trajectory and synchronize different robots or element of the robots. These curves have a simple representation, can be computed quickly and when used in a fitting algorithm can build controller.