Engineering topics
Publications and source records attributed to Dendy, J. B..
High accuracy is obtained by combining analog and digital corrections. Proximity-sensor linearization circuit has two stages. First-stage linearization is accurate to about 3 percent; accuracy of final output is better than 0.5 percent. By modifying contents of the Programable Read-Only Memory (PROM), circuit can also be used to derive a nonlinear output.
Magnetic suspensions offer several advantages over conventional bearings, arising because of the contactless nature of the load support. In application to spacecraft reaction wheels, the advantages are low drag torque, wearfree, unlubricated, vacuum-compatible operation, and unlimited life. By the provision of redundancy in the control electronics, single-point failures are eliminated. The rational for selection of a passive radial, active axial, dc magnetic suspension is presented, and the relative merits of 3-loop and single-loop magnetic suspensions are discussed. The design of a .678 N-m-sec (.5 ft-lb-sec) reaction wheel using the single loop magnetic suspension was developed; the design compares favorably with current ball bearing wheels in terms of weight and power.