Realistic Robot Simulation (RRS)

The RRS-1 project was initiated by leading automotive companies in order to enable a precise simulation of robot motion behavior. As a solution, major robot and simulator manufacturers designed the Robot Controller Simulation (RCS) Interface during 1992 and 1993. This interface enables a standardized integration of motion software for robot controllers with simulators. Hence, the motion software of any robot manufacturer can be integrated into any simulation system. Today the RCS-Interface is the world-wide de-facto standard for precise simulation of robot motion behavior.

After the success of the RRS-1 project, the RRS-2 project was started with the following goals:

• to cover all controller software relevant for simulation and
• to support the over-all data flow during development and maintenance of manufacturing systems.

The resulting Virtual Robot Controller (VRC) Interface was developed during 1998 and 2001 by a consortium extended for line builders and measurement system manufacturers. The VRC-Interface is intended as a long-term replacement for the RCS-Interface.

The interface specifications are maintained by the RRS-Interface Maintenance Group that meets in regular intervals. At the meetings the specifications are continuously improved and adapted to latest developments, while related activities are coordinated.

Further projects for extending the developed technology to other areas are in preparation, e.g. Programmable Logic Controllers (PLCs) and process simulation.

Until the early 1990s, the motion behavior of robot simulation often strongly deviated from real behavior (see figure 1). It turned out that the only technically and economically reasonable solution for improvement is a standard interface for integrating the motion controller software of any robot controller into any simulation system (see figure 2).

The RCS-Interface provides the original motion control software as a call library. The principal calls are INITIALIZE for creating an instance of a robot controller, SET_INITIAL_POSITION for giving it a start pose, SET_NEXT_TARGET for passing motion targets, GET_NEXT_STEP for scanning the interpolated positions and TERMINATE for ending the existence of an instance (see figure 3). Further calls are provided for the following groups

The VRC-Interface Specification aims at integrating robot controller software almost completely into simulators. Furthermore it supports the over-all data flow during the development and maintenance of installations with robots and automates several technical integration aspects.

The VRC-Interface Specification defines six categories of services for running real controller software in simulation (see figure 1). Three categories model the interfaces of real controllers:

• I/O: Transfer of binary, analog and serial communication lines
• File System: Transfer of single files and complete file systems
• User Interface: Generic functions like start/stop and handling of controller specific (native) user interfaces

Three categories are required for running VRCs in simulation:

• Base Commands: Creation, management and deletion of VRC Instances
• Time Management: Control of simulation progress in virtual time
• Simulator Support: Provision of controller internal algorithms and events

The VRC-Interface defines a user activity model and functionality for supporting the over-all data flow during development, commissioning and maintenance of manufacturing systems (see figure 2).

• For mechanical design, the simple means for programming on a geometric level are provided.
• From there Code Generation enables an automatic transition to detailed programming in controller specific 'native' languages.
• Native language programs can be down-loaded to the real line with the file system functionality.
• Programs from the shop-floor can be up-loaded into VRCs for maintenance purposes.
• Data Consistency Mechanisms enable to shift shop-floor maintenance also back to the geometric level