1. A method comprising: causing, by a control system, a robotic manipulator to pick up an object in an environment with an end effector; causing, by the control system, the robotic manipulator to pivot the object around an edge of the object in contact with a surface in the environment; while causing the robotic manipulator to pivot the object, using sensor data from a force-torque sensor to cause, by the control system, the robotic manipulator to follow a trajectory that maintains contact between the edge of the object and the surface in the environment; determining, by the control system, a radius of the trajectory followed by the robotic manipulator in pivoting the object around the edge of the object; and determining, by the control system, at least one unknown dimension of the object based on the radius of the trajectory followed by the robotic manipulator.