Patent GB-623547-A (GB)
Title: Improvements in or relating to dog-racing equipment
IPC: A63K1/02
Filed: 1946-03-07
Abstract: 623,547. Automatic control systems. MULLEY, A., WOOD, K. M., and LAURENCE, R. F. March 7, 1946, Nos. 7164 and 37527. [Class 38 (iv)] [Also in Group XL (b)] In a dog race, to maintain the hare at a prearranged though not necessarily constant distance in front of the leading dog, detector means such as photo-electric cells are provided around the track, the signals produced by the detectors being used to modify the hare speed for positional and velocity error. In the form shown, photo-cells a, b, c, d, &c. at fixed points around the track supply impulses to electromagnetic switches HS and DS of the type used in automatic telephony. Operation of cell a, Fig. 2, by the hare moves the wiper arm of the hare switch HS to contact 2 and the wiper of the dog switch DS to contact 7 which, however, is still connected to cell a. As a result. of this, HS is afterwards operated by the hare and DS by the leading dog. Speed error correction (Fig. 3).-Signals from the cells actuated by 'the dog are passed from the dog switch DS to the dog timer DT which supplies a signal proportional to the time taken by the dog to pass from one cell to the next to a dog velocity computer DVC which supplies a signal proportional to leading dog speed to the hare driving system which may be of the Ward-Leonard type. This velocity is compared with hare speed as measured on a tachometer TAC on the hare driving system and the resulting signal used to accelerate. or decelerate the hare. Position error correction (Fig. 3).-The tachometer output proportional to the speed of the hare is fed to a hare lead error measuring device HLEM which receives also the signals from the photo-cells through the hare and dog switches and measures the total tachometer output over the difference in time for the hare to pass one cell and the dog to pass an adjacent one. Should the cell spacing be equal to the required animal and dog spacing, the resulting signal will be directly proportional to the positional error. This signal is fed to a hare lead error corrector HLEC where the magnitude and sense of the position error is determined and then fed to the hare driving system to accelerate or decelerate the hare. Should the cell spacing not equal the required hare and dog spacing, the actual distance between the dog and hare may be found by adding or subtracting the actual cells spacing to the calculated animal spacing and comparing the result with the desired spacing. A further modification consists in measuring the difference in time for both animals to pass the same cell, measuring the total tachometer output during that time thus obtaining the animal spacing and comparing this result with the true distance to produce an error signal. Additional features of the invention are a hare lead modifier HLM connected to a certain switch contact to alter the speed of the hare at any pre-arranged point, e.g. a bend by altering the resistance of the hare driving system; a trap release TR also connected to a particular contact to open the traps when the hare passes a certain cell; automatic covering gear for the hare connected, say, to the last contact in the bank of the switch HS and resetting gear RG also operated from the last contact to brake the hare and reset the switchgear. Modifications.-Since dog speed is substantially constant the dog velocity computing circuit may be replaced by an artificial signal representing estimated average dog speed, the hare lead error corrector being relied on to maintain the correct spacing between the hare and leading dog. Further, since hare speed is substantially constant, instead of measuring the actual tachometer output and determining the positional error an artificial signal representing average hare speed may be measured. The first Provisional Specification describes a system in which a radiation beam projected from the hare is modified by the dogs or a light from a source carried on the hare driving band is reflected from mirrors on the flanks of the dogs to actuate photo-electrical cells. The second Provisional Specification describes a system in which the dog switch has a time delay fitted so that it is operated after actuation by the dog at the same time as the hare operates the hare switch HS. A discriminator circuit balanced when impulses arrive simultaneously is used to effect alteration of the hare speed. Specification 597,545, [Group XL], is referred to in the second Provisional Specification.