Tietronix lends a hand with RSAD: Making an Astronauts’ jobs easier

RSAD, RMS Situational Awareness Display, is a MFC based software developed to provide the crew with visual steering cues and other robotics information when manipulating a robotic arm (Remote manipulating system, RMS) on board the Space Shuttle or the International Space station.

RSAD gets its data from several sources onboard (Telemetry, Space Vision System, MCIU) to give astronauts different tools that will help him/her to have a good idea of what's going on with the arm. Here are the main displays that we developed :

The Combo Display is used for generic operations. It groups three different components. The first component, the Joint Information Display, gives real time the status of each joint and indicates whether or not the arm is or will be soon in a singularity position. The second component, the Hand Controller Display, help the astronaut to move the arm to a defined target, using a green square as the representation of translations and a circle as a representation of rotations. The goal is to bring

both circle and square in good shape in the center of the display. The third component, the POR Display, indicates the current and targeted position of the arm from all sources available. Onboard the shuttle, a maximum of 3 digitals can be displayed at the same time on the control panel and RSAD makes available all the digitals at the same location.

The Single Joint Display is used to mate, berth or grapple a payload. In a given situation an astronaut would use this display to fly the arm in a straight direction using only one joint at a time. The philosophy is to define a cylinder envelope that helps the user see the “corridor” the arm needs to remain inside, rendered on the six arm joints. Since no one joint can go all the way to its target, each joint will be moved close to the envelope border found between the current position and the

target, and then the next joint will be moved in the same fashion, until ultimately all joints can move to the target without violating the envelope.

The Dependency Display is used for generic operations. It allows the user to see the effect of a hand controller command on the joint angles or the effect of a single joint command on the POR position and attitude. The main goal is to give enough information to the astronaut to fly away from a singularity in a direction that will bring the arm closer to its targeted position.

The Path Planning Display is used for generic operations. It provides a table of waypoints for a path between the current and target position. Two types of paths are provided: constrained and unconstrained. The unconstrained path is simply the straight line path between the current and target position. It shows the user where if and where he will meet a singularity or a joint's reach limit. The constrained path attempts to modify the straight line path to

avoid proximity to reach limits and singularities.

The Mating Corridor Display is used during mating operations. It provides digital and graphical cues for maneuvering within the mating corridor. The two most significant components of the MCD are the reticles, seen as a green circle and a blue square, near the white crosshair (target) in the center of the display. The green circle is the rotational reticle, which indicates how the operator should direct the Rotational Hand Controller.

The blue square is the translational reticle, which indicates how the operator should direct the Translational Hand Controller. The mating corridor is represented by a green circle for the wobble (pitch-yaw) constraint, a blue circle for the lateral (y-z) constraint and the “ears” on the rotational reticle for the axial (roll) constraint. Digital data for the mating corridor appear in the upper right hand corner of the display

The Graphical Plot Display is used during generic operations. The GPD provides a graphical display of the time history of the arm's position and attitude components from the various enabled data sources and the POHS position and attitude errors from the primary data source. A graph is provided for each component (x, y, z, pitch, yaw and roll), co-plotting the data for up to three data sources: (Telemetry, MCIU, Space Vision system).

Each graph will auto rescale to contain the current data plus a constant pad.

Apart from NASA, Tietronix has developed as an internal research a version of this software on Palm OS and Pocket PC, allowing the user to receive through a wireless connection, the shuttle arm's main data sent by RSAD from a laptop.