A system is provided that includes a mounting module configured to be coupled to a support frame and an object-support module configured to support an object. The mounting module comprises an area configured to allow at least a portion of an object supported by the object-support module to pass through the area. The system further includes a motion-guiding module coupled to the object-support module and the mounting module. The motion-guiding module is configured to guide motion of the object-support module along a first axis of the system toward the mounting module in response to a threshold force applied to the object-support module along the first axis. The motion-guiding module is configured to resist motion of the object-support module along a second axis of the system that is perpendicular to the first axis of the system.