US 6,476,574 B1Granted

Method and device for controlling the movement of a movable part

AssigneeDeLaval Holding AB

InventorsMats Nilsson, Bohao Liao

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Abstract

A method and device (1) for controlling the movement of a movable part such as a robot arm (3) in a milking robot (1). A control (7) controls the movement of the arm (3) from an actual position (Pxa, Pya, Pza) to a desired position (Pxd, Pyd, Pzd) A detector (45, 47, 49) detects the actual position of the robot arm (3) and transmits signals corresponding to the actual position to the control (7). The predicted position (Pxp, Pyp, PyP), that the robot arm (3) will pass through as it moves from the actual position to the desired position our model (S). The control (7) makes a comparison (S) of the actual positions of the arm (3) against to the predicted positions, and the movement of the robot arm (3) is modified if its actual position at any time differs by more than a predetermined amount from the predicted position at the same time.

Claims17

Dependent claims

A method for controlling the movement of a movable part such as a robot arm (3) in a milking robot (1) comprising control means (7) for controlling the movement of said robot arm (3) from a position from which it starts, to a desired final position (Pxd, Pyd, Pzd), robot arm position detecting means (45, 47, 49) which detect the actual position of said robot arm (3) and which transmits signals corresponding to said actual position (Pxa, Pya, Pza) to said control means (7), characterised by the steps of:

a) checking if the actual position (Pxa, Pya, Pza) differs from the desired final position (Pxd, Pyd, Pzd) by a distance which is greater than a predetermined distance,
b) if the actual position (Pxa, Pya, Pza) differs from the desired final position (Pxd, Pyd, Pzd) by a distance which is greater than a predetermined distance, calculating a predicted position (Pxp, Pyp, Pzp), in which the robot arm (3) should be after a selected time interval, as it moves from said actual position (Pxa, Pya, Pza) towards said desired final position (Pxd, Pyd, Pzd),
c) after said time interval comparing said predicted position (Pxp, Pyp, Pzp) with the actual position (Pxa, Pya, Pza), and
d) if the actual position (Pxa, Pya, Pza) of said robot arm (3) differs from said predicted position (Pxp, Pyp, Pzp) by a distance which is less than a predetermined allowed error distance, repeating step a) above and the steps following upon it.

1 more element

A device for controlling the movement of a movable part such as a robot arm (3) in a milking robot (1) comprising control means (7) for controlling the movement of said robot arm (3) from a position from which it starts, to a desired final position (Pxd, Pyd, Pzd), robot arm position detecting means (45, 47, 49) which detect the actual position of said robot arm (3) and which transmits signals corresponding to said actual position (Pxa, Pya, Pza) to said control means (7), characterised in that it further comprises:

a) means for checking if the actual position (Pxa, Pya, Pza) differs from the desired final position (Pxd, Pyd, Pzd) by a distance which is greater than a predetermined distance,
b) means for calculating a predicted position (Pxp, Pyp, Pzp), in which the robot arm (3) should be after a selected time interval, as it moves from said actual position (Pxa, Pya, Pza) towards said desired final position (Pxd, Pyd, Pzd), if the actual position (Pxa, Pya, Pza) differs from the desired final position (Pxd, Pyd, Pzd) by a distance which is greater than a predetermined distance,
c) means for comparing said predicted position (Pxp, Pyp, Pzp) with the actual position (Pxa, Pya, Pza) after said time interval, and
d) means for repeating the check, the calculation and the comparison executed by the means in a)-c) above, if the actual position (Pxa, Pya, Pza) of said robot arm (3) differs from said predicted position (Pxp, Pyp, Pzp) by a distance which is less than a predetermined allowed error distance.

1 more element

Dependencies are inferred from the claim text.