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Gran, R.

Publications and source records attributed to Gran, R..

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Control of flexible structures: A systematic overview of the problem

A way of designing a control system using a finite model that accounts for the distributed nature of the control problem in a systematic way is described. This is accomplished by using a mode description of the system and from that description determining the number of modes that must be retained based on the performance and the disturbance descriptions. The design then uses a full order model that includes all of the dynamics: sensor, actuator, disturbance and flexible motion. The designs that result are simple, robust, perform well and have the added distinction of being easy to implement.

Gran, R.↗
NASA NTRS1983

A robot in space as a large space structures control experiment

The control systems design issues for large space structures can be addressed by a robotics experiment which defines a teleoperator or a robot or uses the RMS. The robotics control demonstration brings the large space structures control technology to an effective state of readiness and provides a useful robot when the experiment is finished. Three major options in such an experiment are the RMS, a flexible arm that is going to be put on the Shuttle for other reasons, or a dexetrous manipulator or teleoperator.

Gran, R.↗
NASA NTRS1980

A modern control approach to the design of the SPS control system

The structural dynamics of the solar power satellite were considered. The requirements on the vibration of the microwave antenna and the possibility of thermal induced vibration and severe structural-thermal interactions were considered. The possibility of using an active control system and modern control methods to mitigate structural problems is discussed.

Gran, R.↗
NASA NTRS1979

Control of large space structures

The control of large space structures was studied to determine what, if any, limitations are imposed on the size of spacecraft which may be controlled using current control system design technology. Using a typical structure in the 35 to 70 meter size category, a control system design that used actuators that are currently available was designed. The amount of control power required to maintain the vehicle in a stabilized gravity gradient pointing orientation that also damped various structural motions was determined. The moment of inertia and mass properties of this structure were varied to verify that stability and performance were maintained. The study concludes that the structure's size is required to change by at least a factor of two before any stability problems arise. The stability margin that is lost is due to the scaling of the gravity gradient torques (the rigid body control) and as such can easily be corrected by changing the control gains associated with the rigid body control. A secondary conclusion from the study is that the control design that accommodates the structural motions (to damp them) is a little more sensitive than the design that works on attitude control of the rigid body only.

Gran, R.↗