Abstract: A computer system displays a first object that includes at least a first portion of the first object and a second portion of the first object and detects a first gaze input that meets first criteria, wherein the first criteria require that the first gaze input is directed to the first portion of the first object in order for the first criteria to be met. In response, the computer system displays a first control element that corresponds to a first operation associated with the first object, wherein the first control element was not displayed prior to detecting that the first gaze input met the first criteria, and detects a first user input directed to the first control element. In response to detecting the first user input directed to the first control element, the computer system performs the first operation with respect to the first object.

Abstract: A drill pipe speed sensor includes a roller head assembly including an incremental encoder, a roller to contact a drill pipe, and first and second rotating members. The first rotating member is coupled to the roller, the second rotating member is coupled to the incremental encoder, and the first rotating member is coupled to the second rotating member. The sensor also includes a pivot assembly having mounting plates, pivotal arms, first and second mounting members, and a biasing member. The first and second mounting members extend between the mounting plates, which are parallel to each other. The biasing member contacts the mounting members and extends between the mounting members, and the biasing member is parallel to the mounting plates. The pivotal arms extend from the mounting plates to the roller head assembly and pivot relative to the mounting plates, and the first mounting member is coupled to two pivotal arms.