Patent GB-1366998-A (GB)
Title: Vehicle systems comprising a track with toy or other vehicles  thereon
IPC: A63H18/12
Filed: 1972-01-13
Abstract: 1366998 Controlling vehicles A SARGEANT 5 Jan 1973 [13 Jan 1972] 1620/72 Heading B7H [Also in Division A6] A vehicle system comprises one or more vehicles on a track having an elongate planar upper surface and made of a material which is either electrically conductive or has an electrically conductive upper surface, electrical conductors extending along two opposite edges of the material which has a resistance in the transverse direction between the conductors substantially greater than the resistance of the conductors along their lengths, an adjustable potential being applied to the conductors to establish a potential gradient across the track and the or each vehicle including pick-ups to sense the potential gradient and thus actuate a control in command of a function of its associated vehicle. The track may be rigid, and the vehicles are wheeled. More than one vehicle may be controlled simultaneously and independently upon the track. The applied potential may be A.C. or D.C. In one form, a vehicle has contacts 20 ... 23, Fig. 1, connected through rectifiers 24, &c. 27, &c. to lines 26, 29 controlling a function of the vehicle, e.g. its steering, the vehicle being battery powered. The contacts 20, 21 are underneath and on one side of the vehicle, or may be its wheels, and the contacts 22, 23 are on its other side. The vehicle is used on a track of resistive conductive material 10, e.g. an insulator covered with conducting material such as paper or fabric impregnated with a conducting compound. Glass cloth coated with conducting silicone rubber is suitable. Low resistance metal strips 11, 12 along opposite edges of the conductive material 10 are connected to a controlled power supply 13. Four contacts 20, &c. instead of two only, prevent twisting of the vehicle relative to its direction of motion from producing a substantial change in sensed potential gradient. If the vehicle is to operate in either direction of motion along the track, instead of one direction only, then three contacts 30 ... 32, Fig. 2, connected through rectifiers 33, &c., 37 &c. of opposite polarity to lines 36, 40 may be used. In another form, Fig. 3 (not shown), the vehicle has two contacts (42, 43) on one side connected through rectifiers (44, 45) of opposite polarity to one control line, and a single contact (41) on the other side connected directly to the other control line. A vehicle for use on the track comprises a battery powered electric motor 55, Fig. 4, driving through the gearing shown to rear wheels 51, 52, and a steering unit 57 connected to front wheels 53. The steering unit 57 contains a permanent magnet rotated to turn the front wheels and located between two coils to be positioned in dependence on the ratio of the current in these coils. In another form of vehicle, two separate electric motors (120, 121), Fig. 8 (not shown), are independently powered to drive individual rear wheels and the front wheel (125) is a castor wheel. A circuit for controlling a motor M, Fig. 5, includes contacts 61, &c. as in Fig. 1, in circuit with transistors 73, 77; 76, 82 and a diode 74. Coils 81, 83 actuate the steering of the vehicle. On increasing the sensed potential gradient across the track at the contacts 61, &c. from zero, a value is reached rendering the transistors 73, 77 conducting; these transistors saturate, so that the speed of the motor M remains constant. The voltage drop of the diode 74 is so selected that at this value of potential gradient, it does not conduct. Thus potential is applied only to the steering control coil 81, and not to the steering coil 83. On further increase in the potential gradient sensed by the contacts 61, &c., the diode 74 conducts, the transistors 76, 82 conduct, and the second steering coil 83 is energized. Thus the vehicle steering is moved, e.g. from full left lock to full right lock. If a second vehicle is also to operate on the track, it may be arranged to respond to a potential gradient of opposite polarity by connecting the contacts 61, 62 through rectifiers (90, 91) Fig. 6 (not shown), of reversed polarity to the line 70, similarly the contacts 63, 64 through rectifiers (92, 93) of reversed polarity to the line 67. To obtain simultaneous control of both the vehicles on the track 10, an A.C. potential from a mains supply 100, Fig. 7, may be applied through a transformer 101 and lines 103, 104 to the conducting strips 11, 12 along the edges of the track. Rectifiers 105, 109 separate alternate half-waves. Press-buttons 106, 110 act as on-off switches for the individual vehicles, and variable resistors 108, 112 control the two potential gradients. Alternatively, control of two vehicles on the track may be effected by arranging that one responds only to a potential gradient within one specified range, and the other to a different, non-overlapping range. Alternative potential variations which may be used include changes in polarity, amplitude, frequency, phase of mark-to-space ratio, &c.