A computer-implemented method for dynamically manipulating an assembly of objects in a three-dimensional scene of a system of computer-aided design, the method comprising the steps of: - providing the assembly of objects with information relative to kinematic joints linking objects of the assembly; - providing a dynamic manipulating tool embedded in the scene, comprising a referential with three axes allowing for each axis a degree of freedom in translation and a degree of freedom in rotation; - attaching said dynamic manipulating tool to one object of the assembly; - selecting a degree of freedom of the dynamic manipulating tool attached to the object of the assembly; - selecting (S5d) if the axes of the dynamic manipulating tool rotate with the object of the assembly to which the dynamic manipulating tool is attached or not; - performing a movement using a mouse with a pressed button or with a contact of a finger on a screen of displaying; - converting the said movement into a load value, the load being a force or a torque, said conversion taking into account a speed for a movement of translation according to an axis or an acceleration for a movement of rotation according to an axis, - applying the load to the object, the load having said value and the direction of the axis of the selected degree of freedom, said direction keeping either a fixed orientation in a world reference frame or rotating with the object according to said selecting (S5d) if the axes of the dynamic tool rotate with the object of the assembly to which the dynamic manipulating tool is attached; and - calculating and displaying in real-time the result of a dynamic simulation of applying said load wherein, during said calculating and displaying in real-time the result of a dynamic simulation, the dynamic manipulator follows the part of said object of the assembly to which it is attached. - providing the assembly of objects with information relative to kinematic joints linking objects of the assembly; - providing a dynamic manipulating tool embedded in the scene, comprising a referential with three axes allowing for each axis a degree of freedom in translation and a degree of freedom in rotation; - attaching said dynamic manipulating tool to one object of the assembly; - selecting a degree of freedom of the dynamic manipulating tool attached to the object of the assembly; - selecting (S5d) if the axes of the dynamic manipulating tool rotate with the object of the assembly to which the dynamic manipulating tool is attached or not; - performing a movement using a mouse with a pressed button or with a contact of a finger on a screen of displaying; - converting the said movement into a load value, the load being a force or a torque, said conversion taking into account a speed for a movement of translation according to an axis or an acceleration for a movement of rotation according to an axis, - applying the load to the object, the load having said value and the direction of the axis of the selected degree of freedom, said direction keeping either a fixed orientation in a world reference frame or rotating with the object according to said selecting (S5d) if the axes of the dynamic tool rotate with the object of the assembly to which the dynamic manipulating tool is attached; and - calculating and displaying in real-time the result of a dynamic simulation of applying said load