An effector system comprises: an effector assembly including: a first segment having a conduit between a proximal end and a distal end, an inner surface of the conduit having a conductive portion and a resistive portion; an output member slidable within the conduit, the output member having a conductive exterior contacting the inner surface; a first shape-memory transducer affixed between the proximal end and the output member; and a second shape-memory transducer affixed between the distal end and the output member; and a controller configured to: selectively energize: (i) the first shape-memory transducer to slide the output member in a first direction, (ii) the second shape-memory transducer to slide the output member in a second direction, or (iii) the resistive portion of the inner surface; and in response to energizing the resistive portion, determine a position of the output member.