1. A system comprising: a robotic manipulator; a gripper coupled to the robotic manipulator; at least one processor; and data storage comprising instructions executable by the at least one processor to cause the system to perform operations comprising: receiving data representative of a plurality of trajectories along which the robotic manipulator, while gripping one or more physical objects using the gripper, previously moved the one or more physical objects without dropping the one or more physical objects, determining a set of force vectors corresponding to the plurality of trajectories, determining a virtual model of the set of force vectors, wherein boundaries of the virtual model are representative of constraints on magnitudes of forces that are applied in a given direction to perform the plurality of trajectories, and determining one or more subsequent trajectories corresponding to a subsequent set of force vectors that are within the boundaries of the virtual model, wherein the determined one or more subsequent trajectories represent trajectories that enable the robotic manipulator to move a subsequent physical object at particular accelerations along the subsequent trajectories without dropping the subsequent physical object.