Method for preventing a collision between a part movable along an axis and an obstacle

• US 8,577,591 B2
• Filed: 09/14/2005
• Issued: 11/05/2013
• Est. Priority Date: 09/15/2004
• Status: Active Grant

• Current Assignee: WFL Millturn Technologies GmbH & Co. KG (Helmut Rothenberger, PhD)
• Original Assignee: WFL Millturn Technologies GmbH & Co. KG (Helmut Rothenberger, PhD)
• Inventors: Schinerl, Christoph
• Primary Examiner(s): Black, Thomas
• Assistant Examiner(s): Kong, Sze-Hon
• Application Number:
  US11/662,566
• Publication Number:
  US 20080243387A1
• Time in Patent Office: 2,974 Days
• Field of Search: 700/245, 700/250, 700/255, 700/258, 700/259, 700/260, 700/261, 700/247, 701/23, 701/26, 701/27, 701/70, 701/300, 701/301, 701/302
• US Class Current: 701/301
• CPC Class Codes: B25J 9/1666 Avoiding collision or forbidden zones
• CPC Class Codes: B25J 9/1676 Avoiding collision or forbidden zones
• CPC Class Codes: G05B 19/4061 Avoiding collision or forbidden zones
• CPC Class Codes: G05B 2219/39098 Estimate stop, brake distance in predef time, then verify if in safe distance
• CPC Class Codes: G05B 2219/49141 Detect near collision and slow, stop, inhibit movement tool

Abstract

A method for preventing the collision of an obstacle and a part movable along at least two axes, which axes each have a feeder drive, includes the steps of a minimum stopping distance being determined repeatedly at predetermined time intervals from the relative location and speed data of the moving part as a function of the machine and part data required for this purpose and taking the minimum stopping distance as the basis for the collision calculation. The collision calculation is based on at least one component, from the components of the stopping distance that are related to the individual axes, which component is determined from the speed data retrieved in the individual time intervals and varied by a maximum acceleration of the associated feeder drive at least during the retrieval time interval.

Claims

1. A method for preventing the collision of an obstacle by a part movable along at least two axes of a machine, each axis of the at least two axes having a feeder drive, the method comprising steps of:

retrieving speed data of the part at a moment of retrieval during an individual predetermined time interval to obtain retrieved speed data,

varying the retrieved speed data via a maximum acceleration of the associated feeder drive at least during the individual predetermined time interval to obtain varied speed data,

repeatedly determining a minimum stopping distance at individual predetermined time intervals using relative location data and the speed data of the part as a function of the machine and of part data, the minimum stopping distance having components related to an individual axis,

wherein at least one component of the components of the minimum stopping distance is determined from the varied speed data instead of from the retrieved speed data, and

performing a collision calculation using the minimum stopping distance.

2. The method for preventing a collision as claimed in claim 1, wherein the collision calculation establishes a stopping region formed by possible minimum stopping distances of the part for each axis on the basis of two components,

wherein the first component of the two components takes braking into account and is increased by a maximum positive acceleration of the associated feeder drive at least during the individual predetermined time interval where the speed data is retrieved, and

wherein the second component of the two components takes braking into account and is reduced by a maximum negative acceleration of the associated feeder drive at least during the individual predetermined time interval where the speed data is retrieved.

3. The method for preventing a collision as claimed in claim 1, wherein for reducing a stopping region, at least location data associated with a time interval following the individual predetermined time interval where the speed data is retrieved is used and the collision calculation is based on the location data associated with the time interval following the individual predetermined time interval.

4. The method for preventing a collision as claimed in claim 1, wherein the at least one component has a value additionally changed by a safety factor.

5. The method for preventing a collision as claimed in claim 1, wherein the braking of the part is initiated at a start of a time interval following the individual predetermined time interval where the speed data is retrieved if either a collision scenario is determined or the collision calculation has not been completed by the start of the time interval following the individual predetermined time interval where the speed data is retrieved.

6. The method for preventing a collision as claimed in claim 5, wherein after the initiation of the braking, the repeated determination of the components of the stopping distance is continued and is taken as the basis for the collision monitoring, and

wherein a brake is released with a freedom from collision determined by the repeated determination.