Siemens Aktiengesellschaft

Steffen Mihatsch

Jochen Bretschneider

Jörg Handeck

Curd Weber

Steffen Schmauder

Peter Schiffer

Stephen Graham

Martin Sturm

A numerical controller uses specifications to control position-controlled axes of a production machine and determines a current group of position setpoint values and groups of position setpoint values expected for a forecast horizon. The numerical controller checks for the risk of a collision between at least one element moved by the position-controlled axes and at least one other element. The numerical controller carries out the same check for the expected groups. If there is no risk of collision, it stores the expected groups in a braking path memory and uses the current group. If there is the risk of a collision, it changes the axes along a path to a standstill defined by the braking path memory and braking is effected along a path which has been previously checked for the risk of a collision and for which no risk of a collision has been detected.

Stopping a production machine on a collision-free path

A control device of a production machine receives a present path and a movement command from an operator during manual operation of the production machine. An element of the production machine should be moved along the present path by means of position-controlled axes. Based on the movement command, a series of position setpoint values having a setpoint velocity is determined for the axes. The control device determines from the position setpoint values and corresponding position actual values control commands for the drives driving the axes and controls the drives accordingly. The determined control commands limit a contact force (F), which the at least one element exerts on its environment, to a force limit value (F) specified to the control device. The control device monitors a following error of the drives and suppresses further movement of the element when the following error reaches a maximum value.

Force-limited movement of at least one element of a production machine in manual operation

A numerical controller executes a system program. While executing the system program, the numerical controller executes a sub-program. On the basis of the execution of the sub-program, the numerical controller controls position-controlled shafts of a machine tool controlled by the numerical controller. The sub-program contains instruction sets which are retrieved sequentially one after the other by the numerical controller. The numerical controller only executes the retrieved instruction sets when the instruction sets comply with permitted boundary conditions. Otherwise, the instruction sets are not executed. Before executing the sub-program and while executing the system program, the numerical controller receives information defining the permitted boundary conditions via an interface protected from unauthorized access.

Numerical controller which can be parametrised by the machine manufacturer

A numerical control system determines iteratively a group of position setpoint values for axes of a production machine based on presets. When no risk of a collision of one moved element with another element exists, the group of position setpoint values is stored in a buffer store. Another already stored group of position setpoint values is read from the buffer store which then controls the axes and moves the element along a path defined by the sequence of the groups of position setpoint values. This process continues for as long as no risk of a collision exists. If a risk of a collision exists, the numerical control system brings the axes to a standstill. Previously unknown real time events are considered only in the determination of the groups of position setpoint values not yet stored in the buffer store. The groups of already stored position setpoint values are not altered.

Numerical control system with buffering of position setpoint values

Movable elements of a machine are moved by a control device of the machine by controlling drives of the machine. To monitor the movement of the movable elements for collision with each other or with a stationary element, two monitoring devices check, independently from each other, using a computer program, whether there is a risk of collision in the working space. Depending on whether the monitoring devices detect a risk of collision or not, they intervene, independently from each other, in a corrective manner, in the control of the drives or not, and/or independently emit an alarm message or not. The two computer programs are designed in a diverse manner. The two monitoring devices differ from one another. One monitoring device is identical to the control device, while the other monitoring device is embodied as an industrial PC with a data link to the control device.

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Renningen, Germany

Steffen Mihatsch