Page 153 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

Power and Telemetry 7 CHAPTER CONTENTS
7.1 Electrical considerations...............................................................................................................142
7.1.1 “So you wanna design an ROV—are you sure?” ........................................................... 142
7.1.2 Power systems (general)............................................................................................142
7.1.3 Power system arrangements ...................................................................................... 144
7.1.4 Rotary joints (a/k/a “slip rings”) ................................................................................. 145
7.1.4.1 Electricalslipring.................................................................................................145
7.1.4.2 Fiber-optic rotary joints ......................................................................................... 146
7.1.5 The ubiquitous ground fault....................................................................................... 149
7.1.6 The tether................................................................................................................150
7.1.7 Powersource............................................................................................................153
7.1.7.1 Electricalpower....................................................................................................153
7.1.7.2 Electrohydraulic power ......................................................................................... 155
7.2 Control systems ............................................................................................................................156
7.2.1 The control station.................................................................................................... 156
7.2.2 Motor control electronics........................................................................................... 157 7.2.2.1 Inductors.............................................................................................................157 7.2.2.2 The H-bridge........................................................................................................ 159 7.2.2.3 PWMcontrol........................................................................................................160
“Failure is not an option!”
In the 1995 Hollywood movie “Apollo 13,” actor Gary Sinise plays astronaut Ken Mattingly as he sits in a simulator on the ground desperately attempting to come up with a power budget to operate the stricken craft in space (commanded by astronaut Jim Lovell). The tension builds as the hours wear on and the batteries continue to deplete. The spacecraft has lost a majority of its power—and when it is gone, there will be no power to run the life support systems. There is a finite amount of power left. Each switch on the control panel energizes a system, depleting precious stored energy. On the one side of the power account is the limited power available, and on the other side is the power consumed. They must decide upon which systems are essential and which ones are not while prioritizing based upon the system’s consumption versus its critical need. It is a simple math equation, but if they choose incorrectly . . . Will they make it (see Figure 7.1)?
The ROV Manual.
© 2014 Robert D Christ and Robert L Wernli. Published by Elsevier Ltd. All rights reserved.
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