Method and apparatus for moving a shaft into a predetermined angular position

Claim 3

The method as defined in claim 1, wherein said braking of said shaft is fully applied initially and is applied partially thereafter for bringing said shaft to a stopped position at said predetermined angular position.

Claim 4

The method as defined in claim 2, wherein the braking interval during which braking is fully applied is expressed as w f1(n), the interval during which partial braking is applied being expressed by w f2(n), wherein w is the angular shaft position relative to said predetermined angular position and n is said instantaneous angular speed of said shaft, the instant of changing from fully applied braking to partial braking corresponding to the intersection of f1(n) and f2(n).

Claim 5

The method as defined in claim 1, wherein saId instantaneous angular speed of said shaft is derived from the instantaneous angular position of said shaft.

Claim 6

The method as defined in claim 1, wherein the instantaneous angular position of said shaft is derived from said instantaneous angular speed of said shaft, said instantaneous angular speed of said shaft being defined by a sequence of pulses, said instantaneous angular position of said shaft being defined by a summation of said pulses.

Claim 7

The method as defined in claim 1, including the step of removing said braking from said shaft when said shaft has attained said predetermined angular position.

Claim 8

An arrangement for carrying out the method of claim 1 for moving a shaft to a predetermined angular position, comprising, in combination, a source of rotational motion for rotating said shaft at an angular speed corresponding to the speed of said source; coupling means between said source and said shaft; braking means connectable to said shaft for braking said shaft and decreasing the speed of said shaft, said braking means being applied to said shaft when said shaft is decoupled from said source; speed measuring means connected to said shaft for measuring the instantaneous speed of said shaft; first comparator means connected to said speed measuring means for comparing said instantaneous speed with a desired input speed of said shaft; computing means connected to said speed measuring meas for computing a braking angle function; second comparator means connected to said computing means for comparing a braking angle function with said predetermined angular function; and regulating means connected to said comparator means for regulating said braking means in dependency on said braking angle function, whereby said shaft is braked so that said shaft is stopped at said predetermined angular position.

Claim 9

The arrangement as defined in claim 7, wherein the output of said second comparator means is connected to one input of said first comparator means.

Claim 10

The arrangement as defined in claim 8, including signal gating means connected in series with the output of said second comparator means; gate control means connected to said gating means and said speed measuring means for controlling the transmission of said gating means so that the output of said second comparator means is not transmitted to said first comparator means when said instantaneous speed of said shaft exceeds a predetemined value.

Claim 11

The arrangement as defined in claim 8, including speed input means for applying a desired input speed to said first comparator means; signal gating means connected in series with the output of said second comparator means, said gating means being controlled by said input speed means so that the output of said second comparator means is not transmitted to said first comparator means when the input speed applied by said input speed means is different from zero.

Claim 12

The arrangement as defined in claim 7, including gating means connected in series with the input to said regulating means for disconnecting said coupling means and said braking means from said shaft in dependency on the arrival of said shaft at said predetermined angular position.

Claim 13

The arrangement as defined in claim 7, including a hall generator for measuring the instantaneous position of said shaft, said hall generator having a magnetic disc coupled to said shaft, said magnetic disc having a varying radius from a predetermined minimum radius to a predetermined maximum radius, the transition between said minimum radius and said maximum radius being a step function.

Claim 14

The arrangement as defined in claim 7, wherein said speed measuring means comprises speed computing means for computing the instantaneous speed of said shaft from the angular position of said shaft.

Claim 15

The arrangement as defined in claim 13, wherein said speed computing means for computing said instantaneous speed of said shaft comprises two operational amplifiers connected in series, one of said operationaL amplifiers being a summing amplifier and the other one of said amplifiers being an integrating amplifier, said two amplifiers being further connected so that when applying an input signal of the form x(t) to said summing amplifier the output signal of said summing amplifier is of the form of y(t) x + by - Integral y dt.

Claim 16

The arrangement as defined in claim 7, wherein said computing means comprises an operational amplifier with feedback network interconnected to said operational amplifier so that upon applying an input signal of the form of x(t) to the input of said operational amplifier, an output signal from said amplifier is obtained in the form of y(t) ex + C.

Claim 17

The arrangement as defined in claim 7, wherein said second comparator means comprises an operational amplifier with feedback network whereby said operational amplifier functions as a summing amplifier.

Claim 18

The arrangement as defined in claim 7, wherein said first comparator means comprises an operational amplifier with feedback network interconnected to said operational amplifier, whereby said operational amplifier functions as a summing amplifier.

Claim 19

The arrangement as defined in claim 7, including angular position sensing means for sensing the instantaneous angular position of said shaft; control means connected to said angular position sensing means and to said regulating means for moving said shaft to a second predetermined angular position after having attained said first mentioned predetermined angular shaft position.

Claim 20

The arrangement as defined in claim 18, including gating means connected to said control means and output of said second comparator means for alternatingly blocking and transmitting the signal outputs of said control means and said second comparator means.

Claim 21

The arrangement as defined in claim 19, including programming means connected to said gating means for controlling said gating means so that the positioning of said shaft to a second predetermined angular position is always preceded by braking said shaft to said first-mentioned predetermined angular position.

Claim 22

The arrangement as defined in claim 18, including input speed applying means for applying said desired input speed of said shaft, the signal output from said input speed applying means signalling also the transition from said first mentioned predetermined angular to a second predetermined angular position.

Claim 23

The arrangement as defined in claim 21, including gating means connected between said input speed applying means and said regulating means for inhibiting the transmission of the output signal from said input speed applying means to said regulating means during the interval when said shaft moves from said first-mentioned predetermined angular position to said second predetermined angular position.

Claim 24

The arrangement as defined in claim 12, including a source of reference voltages for comparing the minimum and maximum output voltage values from said hall generator means; and auxiliary regulating means connected to said hall generator means for regulating said minimum and maximum output voltages from said hall generator means in dependence on said reference voltages.

Claim 25

The method as defined in claim 1, including the step of applying a braking torque to said shaft while braking said shaft, said braking torque being below the maximum braking torque applicable to said shaft when braking said shaft in dependence on said braking angle.

Claim 26

The arrangement as defined in claim 7, wherein said source of rotational motion is an electrically driven motor.

Claim 27

The arrangement as defined in claim 7, wherein said coupling means comprises an electromagnetic coupling having an actuating winding energized by said regulating means.

Claim 28

The arrangement as defined in claim 7, wherein said braking means comprises an electromagnetic brake having a winding energized by said regulatIng means.