UNDERSEA TECHNOLOGY 



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computer. The data will then be translated into displays for the DSRV 

 pilot and copilot. To control the vehicle the pUot and copilot will order 

 direction and rate and the ICAD computer will translate these signals and 

 provide exact control signals to the vehicle's individual propulsion con- 

 trol units. 



This vehicle control system must operate satisfactorily in the presence 

 of disturbances such as ocean currents. Other critical control problems 

 arise from crosscoupling between thrusters and from coupUng terms in 

 the equations of motion. The effect of the disturbances has been reduced 

 to a tolerable level by such compensation techniques as high rate-loop 

 gains and the use of decoupling networks. 



One of the difficult problems for submersible pilots is the relatively 

 slow vehicle response. To reduce this effect and to avoid limit cycling 

 which can arise from actuator saturation, the ship control system will use 

 both command-rate limiting and forward-feed decoupling. An assisted 

 manual control mode also helps the pilot hold station with respect to a 

 target which is visible on his TV screen. Here, the pilot will position a 

 synthetic marker over the desired location of the DSRV. 



In addition to the manual modes, the pilot can choose an automatic 

 altitude and position-hold mode or an automatic maneuvering mode, 

 where the DSRV is under the control of the central processor. When 

 under computer control, the pilot merely provides translational commands 

 to the computer. 



The search vehicle (DSSV) sensor, navigation, and control requirements 

 will be similar to those of the DSRV. The ship control requirements for 

 the DSSV will depend to some extent on the choice of vehicle design and 

 propulsion. A search submersible must hover and maneuver at least as 

 accurately as the DSRV. Side-looking sonar requires very low yaw and 

 roll rates to ensure proper coverage. Further, the DSSV is expected to 

 operate from a mother submarine, and thus must perform the same mating 

 operation as the DSRV. 



Although operator display and control panels for the DSSV will be 

 functionally similar to those of the DSRV, new sensors make an inte- 

 grated and well organized display even more important. Methods will be 

 developed to allow the operators to note possible sonar or optical targets, 

 record their position, and still follow a coordinated search plan. Human- 

 engineering techniques become important, since search missions are gen- 

 erally long, and physical size of vehicle may limit crew rotation. 



