Tools for Simulating Mechatronics

Though mechatronics promises more efficient machines at a lower cost, following the mechatronics' approach of integrated design has been challenging for most machine builders. The premise of mechatronics is based on the ability of mechanical, electrical, control design and embedded programming engineers to collaborate their design efforts. However, collaboration requires them to share and validate design ideas and effectively sharing ideas requires design tool integration. This dilemma has kept most machine builders away from following the mechatronics' design approach.

Fortunately, design tool vendors are now helping to overcome this dilemma by providing integration between their software packages. This is allowing machine builders to follow the mechatronics' approach while continuing to use the best-in-class design software for different design disciplines. An example of design tool integration that is enabling mechatronics is the pioneer interfaces National Instruments  and SolidWorks jointly developed to integrate their control design and mechanical design software packages.

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

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

Using the LabVIEW-SolidWorks interface allows machine designers to:

• Virtually plan motion trajectories. LabVIEW enables the virtual design of complex motion profiles containing a series of sequential or concurrent move operations composed of 2-D straight-line moves, contoured moves and arc moves. For each move machine designers can specify trapezoidal or S-curve profiles and apply velocity, acceleration, deceleration and jerk constraints. Each axis of motion in LabVIEW can then be mapped to a joint of the 3-D CAD model of the machine designed in SolidWorks. Finally, the motion profile designed in LabVIEW can be simulated on the CAD model.
By animating their 3-D machine models designers can quickly evaluate the feasibility of the overall conceptual design for the machine very early in the machine design process. This fosters better communication with customers and between design team members and helps to close the loop on the design requirements, must-have features and engineering trade-offs. Visualization can also be used as a pre-sales tool when bidding on a project, since it enables machine designers to show a working simulation of the machine to potential customers before building a physical prototype.

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

• Perform throughput time studies. By validating motion system design using a simulation that includes the actual motion profile constraints and the mechanical dynamics of the machine such as mass and friction, designers can better estimate the cycle time throughput 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. Motor torque and velocity requirements depend on the acceleration characteristics of your motion profile and the mechanical dynamics of the payload and transmission components such as lead screws. Using the LabVIEW-SolidWorks interface, machine designers can calculate the required motor torque and velocity charts for their motion profiles. SolidWorks simulations account for mechanical dynamic effects such as payload mass, friction and gravity; enabling designers to validate the feasibility of their motion profile velocity and acceleration constraints and make more prudent design trade-offs when selecting coupled electrical and mechanical components.

By using integrated machine design tools, designers can follow the mechatronics design methodology of sharing and validating ideas early in the machine design process, which lowers the cost and of machine design.