a remote center compliance system for compliantly connecting a robot support arm interface to an operator device interface comprises at least three gas - tight spring bellows interconnecting the interfaces and a connection means for connecting the interiors of the bellows in common to an external variable pressure source . the compliance of the system , both rotational and lateral , may be controlled by the applied pressure . the bellows may also be evacuated so that their resultant collapse locks the support structure and operator device together .