restraining bolt 抑制螺栓
Restraining bolts are devices affixed to droids in order to better control their actions and enforce their obedience. A special applicator seals the bolt to a droid. Once affixed, the restraining bolt restricts a droid from wandering off and forces it to obey commands from a handheld control unit.
The scavenging Jawas of Tatooine often fit the droids they salvage with restraining bolts. They did so with Artoo-Detoo and See-Threepio. Once the droids were transferred to Owen Lars, so to was command of the bolts. The security systems at the Lars Homestead restricted any restrained droid from leaving the farm. Artoo-Detoo tricked Luke into removing the bolt, allowing him to sneak away at night to continue his search for Obi-Wan Kenobi.
Although there are many varieties of bolts with different levels of command, the ones used on Artoo and Threepio were relatively simple ones. The bolts, which were spot-welded onto the droid's surface, were paired with an "owner," or "caller," a hand-held device capable of three basic commands. The owner's three settings could call a droid forward (COME), force it to halt (STOP), or to enact the tasks that were just verbally spoken to it (ORDERS). A droid will not violate its basic programming when following orders, so the last setting can only be used to carry out tasks within the droid's operating parameters. Jawas also use restraining bolts as part of the recipe for their cobbled-together ionization blasters.
The bolts used by the Jawas in A New Hope were fairly visible, cylindrical affairs. The ones used in Jabba's Palace in Return of the Jedi must have been of a different model, since neither Artoo nor Threepio were seen bearing the same bolts they wore previously.