Trocar simulation

Methods and devices are provided for supporting an elongate shaft on a surgical tool during robotic surgery. For example, a tool holder is provided with an elongate carrier arm configured to couple to a distal end of a surgical robotic arm. The tool holder has a housing that is removably mounted on the carrier arm and that is configured to be positioned adjacent to a tissue surface without extending into tissue. The tool holder thus simulates a trocar. The housing has an opening formed therethrough for receiving an elongate shaft of a surgical tool, and the opening has an inner diameter that is configured to dynamically adjust in size to adapt to and resist movement of elongate shafts of varying diameters inserted therethrough.