1. Model of robot system Óbuda University
John von Neumann Faculty of Informatics
Institute of Applied Mathematics
Master in Engineering Informatics and Applied Mathematics
Course System Level Modeling for Cyber-Physical Engineering Structures in the Cloud
Lecture and laboratory No. 11
Model of robot system
Dr. László Horváth

2. László Horváth UÓ-JNFI-IAM http://users.nik.uni-obuda.hu/lhorvath/
This presentation is intellectual property. It is available only for students in my courses.
The screen shots in this presentation were made in the CATIA V5 and the V6 PLM systems as well as the 3DEXPERIENCE platform at the Laboratory of Intelligent Engineering systems, in the course of active modeling process.
The CATIA V5 és V6 PLM systems as well as the 3DEXPERIENCE platform are operated at the above laboratory with the support of Dassult Systémes Inc. and CAD-Terv Ltd.
László Horváth UÓ-JNFI-IAM

3. László Horváth UÓ-JNFI-IAM http://users.nik.uni-obuda.hu/lhorvath/
Contents
Lecture
Model of robot system
Representation of robot mechanical system
Representation of control system
Robot motion profile
Robot motion planning
Generic inverse kinematics at robots
Robot task design
Laboratory task
Slm_CS_11 model: Role based modeling capabilities
László Horváth UÓ-JNFI-IAM

4. Model of robot system
Integrated modeling of robot system is explained.
Industrial robots are considered
Robot basics are supposed to know
Robot is a mechanical system which serves well defined application process.
Motion controller is applied for a resource reference (mechanism) with inverse kinematics.
Main units to represent: robot, control device, tool device.
Mechanical connections of robot to tool and environment are defined
Generic robot models are considered which are available for instancing by appropriate parameterization.
Relevant shape modeling methodologies apply and supposed to know (see previous lectures in this course).
Modeling of dynamic behavior is essential (see lecture 10).
László Horváth UÓ-JNFI-IAM

5. Representation of robot mechanical system
System resources
Robotic tools as end-effectors, grippers
Industrial robot consisting of rigid bodies (parts) and articulated joints
Control device
Inverse kinematic is driven in Cartesian tool point coordinates. Some robot like modeled solutions may include forward kinematic that is driven in joint coordinates.
Robot resource includes mechanical ports:
A base port, to indicate that the robot can be attached by another resource (in production or other system)
A mount port, to indicate where any tooling (like a weld gun) should be mounted
Workspace envelope
Defines a volume within which all the points are reachable in case of a tool profile.
László Horváth UÓ-JNFI-IAM

6. Representation of robot mechanical system
Joint is modeled as combination of mechanical (rotation about a fixed axis) and geometric constraints (following the surface of a part).
Joints are referenced by a mechanism
Joints are solved during simulation execution.
Predefined set of engineering connections (joints) determine how the components move with respect to each other.
The DOF value is modified when angle driven or length driven command is added to a joint.
A mechanism can be simulated when the DOF=0.
Directly manipulation of joints or manipulate Cartesian tool point coordinates for resulting configuration.
László Horváth UÓ-JNFI-IAM

7. Representation of robot control system
Jogging is applied to check if the robot can reach all the demanded positions.
Manipulates commands between the minimum and maximum travel limits.
Control of DOF is checked
Linear and angular step sizes are used in increment and decrement functions
Jogging by direct manipulation (dragging joints) or home position (move a mechanism to one of its home positions) .
László Horváth UÓ-JNFI-IAM

8. Representation of robot control system
Control device is created on a robot or tool reference or instance resource.
Multiple resources are often to be programmed within the context of an organizational resource (for example a workstation).
The controller for the resource instance copies the controller data from the controller for the resource reference.
Controller data
Robot profiles
Home positions
Travel Limits
Speeds and accelerations
László Horváth UÓ-JNFI-IAM

9. Representation of robot control system
Robot controller properties
Motion Controller
Singularity Tolerance: it is the zone in degrees around the wrist singular position that is considered unreachable by the inverse kinematics.
Joint Interpolation Mode.
Time Compensation
Response Delay: amount of time between the activation of the motion command and the actual motion of the robot.
Settle Time: This value is an estimated time required for settling of manipulator vibrations after reaching the point.
Acceleration:
Constant: The value of velocity is scaled in order to extend the motion time to the desired value.
Variable: The value of acceleration is scaled in order to extend the motion time to the desired value.
Speed limits:
Are taken into account when performing motion.
Acceleration Mode
Variable Time: Acceleration constrained by joint max acceleration rate
Constant Time: Acceleration constrained by joint acceleration time.
László Horváth UÓ-JNFI-IAM

10. Representation of robot control system
Robot data profiles
Part of robot controller data
Aspects of the robot profile: tool, accuracy, motion, and object frame.
Tool profile
The tool profile defines tool data such as the weight of the tool and its tool center point (TCP) offset.
Robot positioning is defined in relation to TCP
Tool is fixed or moves with the robot.
Port for the device defined as the tool point.
Accuracy profile
The accuracy profile defines data about how accurate the robot's path should be. Two algorithms are applied:
Distance: The accuracy value represents the radius of a virtual sphere with center position to which the TCP is being moved. Purposeful motion is started when the robot's TCP reaches any point on this virtual sphere. Robot's TCP will never reach the programmed position at non zero distance value.
Speed: accuracy value is a percentage of the deceleration speed at which operation should begin.
Motion profile
The motion profile defines speed and acceleration as motion parameters.
Object frame profile
The object profile usually defines a reference for the product in the work station.
László Horváth UÓ-JNFI-IAM

11. Representation of robot control system
Home positions of robot
Predefined positions and a timetable about moving between them.
One or more standard configurations (or home positions) for a mechanism.
Each home position is characterized by a set of command values.
Home positions are typically used to define the desired states of a mechanism (for example, the open and closed configurations of a gripper).
László Horváth UÓ-JNFI-IAM

12. László Horváth UÓ-JNFI-IAM http://users.nik.uni-obuda.hu/lhorvath/
Robot motion profile
Motion controller has motion profiles to specify speed and acceleration values as motion parameters for the robot.
Each profile defines characteristics of different aspects of the controller.
Profile types set speed and acceleration parameters which
appropriate to a particular kind of move (e.g., moving to weld point) or
appropriate to a different kind of move (e.g., a via point).
The standard velocity vs. time profile
For a move is modeled as a trapezoid, with equal magnitudes assumed for acceleration and deceleration.
If the initial and final velocities are equal, this will result in equal acceleration and deceleration times.
Based on the distance between points and the specified TCP speed, the velocity/time profile may be a triangle, the maximum speed may never be attained.
László Horváth UÓ-JNFI-IAM

13. László Horváth UÓ-JNFI-IAM http://users.nik.uni-obuda.hu/lhorvath/
Robot motion planning
Stages of motion planning are planning, interpolation, and timing.
Planning
The purpose of the planning stage is to calculate the amount of time required for each degree of freedom to reach its target value. Once all motion times are calculated, the longest motion time becomes a reference motion time. Velocities or accelerations of all non-reference motion times are scaled down in order to provide for the same amount of motion time.
Interpolation
Robot controller sampling rate at which the interpolation calculations are made.
Sample rate represents time steps at which motion interpolation takes place.
The sample rate is a rate at which the controller samples its own internal state.
Total amount of travel time is Tmove
Definition motion between two points in terms of motion time
Calculated Motion Time. The user sets velocity, acceleration and distance and motion planning algorithms calculate the amount of time needed for such move.
User-Defined Motion Time. System sets appropriate parameter values.
László Horváth UÓ-JNFI-IAM

14. Generic inverse kinematics at robots
Inverse kinematics calculates joint parameters to specified configuration.
Generic robot model has initial configuration joints for generic robot kinematic classes. Generic kinematic classes are defined for devices.
Instance robot model is defined by setting actual parameter values.
Parameters
DOF functions and joint types for each joint.
Device mounting plate.
Actuator space map.
When instance has fewer DOF than generic one, present and absent joints are selected.
Solvers (as available at DELMIA V6 )
Numeric Inverse
Generic Inverse
Device Specific Inverse
User Inverse
László Horváth UÓ-JNFI-IAM

15. László Horváth UÓ-JNFI-IAM http://users.nik.uni-obuda.hu/lhorvath/
Robot task design
Modeling at the work cell level.
Product and manufacturing resource models are integrated for the definition of robotic processes.
Robotic feasibility studies.
Robot reach and access in a complex manufacturing work cell.
Robot tasks and tag definitions for robot motion.
Task
It is resource-oriented process for given robot programming.
It is a linear sequence of activities called as operations.
Operation contains motion activity and a set of actions.
Tags added to tasks or can create tags in free space for clearance moves.
Reachability
Reachability targets defined in the robot task, tag group, or work trajectory.
Robot on rail.
Possible locations for placing a robot that must reach specific points
Programming (not topic of this lecture)
Translating robot tasks into robot controller-specific programming languages.
Converted programs written in robot controller-specific languages into robot tasks.
László Horváth UÓ-JNFI-IAM

16. Slm_CS_11 model: Role based modeling capabilities
Understanding issues below using active modeling environment with industrially proven capabilities.
Issues
Role based organization of modeling capabilities on the example of the 3DEXPERIENCE platform.
Understanding work on dashboard.
Participant related issues on the example of 3DEXPERIENCE platform.
Definition of complex shape as surface. Topology in surface representation.
Surface based solid features.
László Horváth UÓ-JNFI-IAM

17. Slm_CS_11 model: Role based modeling capabilities
Source: Dassault Systémes
László Horváth UÓ-JNFI-IAM

18. Slm_CS_11 model: Role based modeling capabilities
Source: Dassault Systémes
László Horváth UÓ-JNFI-IAM

19. Slm_CS_11 model: Role based modeling capabilities
Source: Dassault Systémes
László Horváth UÓ-JNFI-IAM

20. Slm_CS_11 model: Role based modeling capabilities
Source: Dassault Systémes
László Horváth UÓ-JNFI-IAM

21. Slm_CS_11 model: Role based modeling capabilities
Source: Dassault Systémes
László Horváth UÓ-JNFI-IAM