Abstract: A control system comprising a control input device having a movable magnet, a pole-piece frame arrangement positioned about the magnet and positioned therein at least two magnetic flux sensors for sensing movement of the magnet in a given direction. The control system further comprises a monitoring arrangement for monitoring the output signal of each of the sensors and permits the input device to control the system only when the output of the sensors are within a predefined range. This multiple sensing provides a fail-safe in the event that one of the sensors generates an erroneous signal.

Abstract: A joystick controller has a body 12 including an end wall 18 in which is secured a resilient arm 10. The resilient arm 10 has secured to its top a tube 90 and a handle 94. The tube 90 surrounds to arm and mounts an annular magnet 38 at the level of a pivot point 96 about which the arm 10 flexes. The outputs of Hall effect probes 26 are affected by the position of the magnet 38 to give an indication of the position of the arm 10. The angular position of a rotary handle 80 is sensed using a magnet 110 which is connected for movement with the handle 80 relative to further Hall effect probes 116 (FIG. 9).

Abstract: A rotary variable differential transducer has first and second coil portions (50a and 50b) of a primary coil overwound by respective secondary coils (52 and 54). Pole pieces (42 and 44) are asymmetrically arranged about the axis of rotor (16) and are inductively associated with the first and second coil portions (50a and 50b), respectively. The rotor (16) has first and second formations which are respectively defined by front and rear arcuate portions (70b and 70c) associated with the pole pieces (42 and 44), respectively. The pole pieces (42 and 44) are mutually angularly displaced about the axis of the rotor (16). The first and second coil portions (50a and 50b) are mutually axially displaced relative to the rotor (16) and an intermediate common pole piece (32b) is disposed between them.

Abstract: This invention is concerned with generating line symbols (e.g. straight lines, circles) on cathode ray tube displays with TV-type scans. A tube 10 has the normal line and frame deflection waveform generators 12 and 13 and a normal video amplifier 15. A symbol generator 20, 20', 20", etc. is provided for each symbol; the generators may be controlled by a computer 21 which defines the parameters of the symbol (e.g. slope and position of a straight line). Each symbol generator contains two waveform generators--line and frame frequency waveform generators synchronised by the line and frame synch pulses LSV and FSV--and a comparator which produces output pulses when the voltages from the two generators are equal. These pulses are fed to the video amplifier 15. The waveforms generated by the two generators are chosen to give the desired symbols; e.g. sawtooths for straight lines, parabolic waveforms for ellipses. The output pulses have substantially vertical leading and trailing edges.