Tools for Simulating Mechatronics

Though mechatronics promises more efficient machines at alower cost, following the mechatronics' approach of integrated designhas been challenging for most machine builders. The premise ofmechatronics is based on the ability of mechanical, electrical, controldesign and embedded programming engineers to collaborate their designefforts. However, collaboration requires them to share and validatedesign ideas and effectively sharing ideas requires design toolintegration. This dilemma has kept most machine builders away fromfollowing the mechatronics' design approach.

Fortunately, design tool vendors are now helping to overcome thisdilemma by providing integration between their software packages. Thisis allowing machine builders to follow the mechatronics' approach whilecontinuing to use the best-in-class design software for differentdesign disciplines. An example of design tool integration that isenabling mechatronics is the pioneer interfaces National Instruments and SolidWorks jointly developed to integrate their control design andmechanical design software packages.

The NI LabVIEW-SolidWorksinterface, which is in its pioneer stage, enables quick development ofcomplex multi-axis motion profiles and allows designers to simulatethem on a 3-D CAD model of the machine. The leading machine builderswho have tried the toolkit benefited from lowered design risk and cost.The LabVIEW-SolidWorks interface enabled them to virtually plan motiontrajectories, detect collisions, estimate machine cycle time and sizemotors, drives and mechanical transmissions.

"As a custom design house, our machines have to be right the first timewe build them. Any design changes late in the design process can mean atransition from profit to loss. Using the LabVIEW-SolidWorks interfacesignificantly reduced this risk for us by streamlining the designprocess," says Mark Ganninger, president, Design and Assembly Concepts.

Using the LabVIEW-SolidWorks interface allows machine designers to:

• Virtually plan motion trajectories. LabVIEWenables the virtual design of complex motion profiles containing aseries of sequential or concurrent move operations composed of 2-Dstraight-line moves, contoured moves and arc moves. For each movemachine designers can specify trapezoidal or S-curve profiles and applyvelocity, acceleration, deceleration and jerk constraints. Each axis ofmotion in LabVIEW can then be mapped to a joint of the 3-D CAD model ofthe machine designed in SolidWorks. Finally, the motion profiledesigned in LabVIEW can be simulated on the CAD model.
By animating their 3-D machine models designers can quickly evaluatethe feasibility of the overall conceptual design for the machine veryearly in the machine design process. This fosters better communicationwith customers and between design team members and helps to close theloop on the design requirements, must-have features and engineeringtrade-offs. Visualization can also be used as a pre-sales tool whenbidding on a project, since it enables machine designers to show aworking simulation of the machine to potential customers beforebuilding a physical prototype.

• Virtually detect collisions. The collisiondetection feature in SolidWorks enables validation of the motionprofiles on a 3-D CAD model before implementing them on the realmachine. Machine designers can check for interferences, evaluate theneed for interlock control logic to prevent collisions, optimize motionprofiles to minimize unnecessary dead time and safely test new controlsystem logic without the risk of damaging the physical machine. Afterthe machine has been designed, prototyped and deployed to the field,collision detection can also be used to validate new motion profilesbefore downloading them to machines operating at a customer site;reducing the risk of unplanned downtime due to programming mistakes.

• Perform throughput time studies. By validatingmotion system design using a simulation that includes the actual motionprofile constraints and the mechanical dynamics of the machine such asmass and friction, designers can better estimate the cycle timethroughput of their machines. LabVIEW indicates the profile duration,in seconds, for the motion profile at the end of the simulation.

• Size motors, drives and transmissions. Motortorque and velocity requirements depend on the accelerationcharacteristics of your motion profile and the mechanical dynamics ofthe payload and transmission components such as lead screws. Using theLabVIEW-SolidWorks interface, machine designers can calculate therequired motor torque and velocity charts for their motion profiles.SolidWorks simulations account for mechanical dynamic effects such aspayload mass, friction and gravity; enabling designers to validate thefeasibility of their motion profile velocity and accelerationconstraints and make more prudent design trade-offs when selectingcoupled electrical and mechanical components.

By using integrated machine design tools, designers can follow themechatronics design methodology of sharing and validating ideas earlyin the machine design process, which lowers the cost and of machinedesign.