Montreal Team Has Winning Habit at SAE “Walking Machine” Competition
F or the second consecutive year, a robot designed by a team of students from Ecole de Technologie Superieure (ETS), a part of the University of Quebec, won the Society of Automotive Engineers ‘Walking Machine Decathlon’ competition in 1999.
‘We’re fortunate to have a great deal of expertise on our team-mechanical engineering, electrical engineering, computer science, and automated production engineering,’ says this year’s team leader, Michel Gendron, a third year mechanical engineering student. ‘It gives us a running start in the competition.’
Nonetheless, the team begins working together a full year before each year’s competition. Early in the cycle, team members may stop at the dedicated shop and work on the project once or twice a week. By spring, some are devoting 80 hours a week to the Walking Machine. It’s a true team effort, and an invaluable adjunct to classroom education.
The Walking Machine Decathlon is one of eight student design competitions sponsored annually by the Society of Automotive Engineers (SAE). Teams from 15 different universities in Canada, Mexico, and the United States competed in the most recent three-day event. The ETS robot, Hydraumas III, used hydraulics to propel itself and accomplish various tasks. It outperformed 14 other robots in a variety of predefined activities including a dash, load retrieval, grand tour, object retrieval, object avoidance, object seeking, hill climb and obstacle course. The ETS robot won eight of the 10 Decathlon events.
Hydraumas III was the third iteration of a basic hydraulic design pioneered by the ETS team in 1997. But for the year 2000 competition, the ETS team is starting from scratch with a new approach. Named Heimlich, for the caterpillar in the animated movie A Bug’s Life , the new walking machine moves in an entirely different way. It features a number of small, legged tractors connected by an articulated spine. A computer animation of the design in action shows why it was named for a caterpillar; as one tractor moves forward, the spine stretches out; then the next tractor moves forward, and that section of the spine contracts.
Team members say past competitions have taught them that small robots can move faster, but bigger robots have greater strength and agility. Heimlich combines the best of both worlds.
To accelerate the design process, the ETS team is divided into sub-teams specializing in different aspects of the design: a tractor group, a backbone group, and a control group. ‘Everyone has different backgrounds, and this way, we take advantage of what strengths everyone has to offer,’ Mr. Gendron explains.
For his part, Mr. Gendron has headed the mechanical design effort using a new tool-SolidDesigner solid modeling software from CoCreate Software Inc. The team recruited sponsorship from RCS CAD Systems (Montreal, Quebec and Toronto, Ontario, Canada), CoCreate Software, and Hewlett-Packard to provide the software and HP Visualize C3000 UNIX workstation for mechanical design. The Hydraumas series was mechanically drafted using older, two-dimensional CAD tools. But Heimlich is being designed from the ground up in a solid modeling package, which makes an enormous difference.
‘We’ve probably saved years of design time already,’ claims Mr. Gendron. Working in 2-D means having to create three separate views. Then each view has to be redrawn each time the team changes its robot design. A solid modeler, on the other hand, allows the team to develop a single model, which can then be rotated on any axis for instant 3-D viewing.
But that difference is true of any 3-D program. Mr. Gendron specifically sought out SolidDesigner software because of what he learned while using it during an internship. Other programs use parametric modeling, which builds constraints into the model at the very outset of the design process. You can’t change a design in a way that violates the constraints. So a substantial design change often means starting over-from scratch.
SolidDesigner employs dynamic modeling. It doesn’t impose constraints on the model. So a designer can think ‘outside the lines’ without having to start over. He just changes the design and tries a new approach to solving a design challenge. The designer always has the option of adding constraints that define relationships between features and surfaces of the design. But they’re not imposed on the design by the software.
‘With other solid modeling programs, you must know exactly what you will draw, and how you will draw it, from the beginning. If you want to move something, it’s sometimes faster to scrap a whole drawing and recreate it. In the parametric world, half the time you’re programming, and half the time you’re designing,’ the team leader explains. ‘I can work at least twice as fast using SolidDesigner.’
The Walking Machine competition rewards competitors for various things: speed, agility, sturdiness and, perhaps most of all, autonomy. Autonomy means the robot carries out a task on its own without one of the team members exerting manual control (through a remote control device). Few teams achieve autonomy in many of the Decathlon events. At ETS, it has become a primary goal.
‘Completing two events autonomously will probably get a team first or second place,’ Mr. Gendron says. The competition awards 1000 points for the best mechanical design, but up to 2500 points for autonomous operation. In last year’s competition, ETS won the first event not because its robot was fastest, but because it maneuvered the course autonomously.
This year, the team hopes to achieve a second autonomous event. And some members of the team are already planning ahead, to the 2001 competition. This year’s model will use a crude sonar to locate objects (including balls that must be picked up). Next year, the team plans to refine the sonar and possibly add a video camera and a GPS-inspired positioning system. The goal is to enable Heimlich to autonomously locate, pick up and return a ball using just the camera, sonar and positioning system. That will give the team a bonus factor of five for the event.
Mr. Gendron and several of his teammates will be alumni of ETS and off the team next year. Younger students will take their place. That points out another advantage of the SolidDesigner software being used to design Heimlich this year. It doesn’t generate a history tree. So next year, the mechanical engineering student who steps into Mr. Gendron’s shoes can open up the solid model and immediately begin incorporating the 2001 upgrades-without ever having seen the CAD model before.
‘That’s an important advantage for a design that people use and improve on over a period of months or years,’ explains Denis Raymond, a principal in RCS CAD Systems, who has taken a personal interest in the team’s success. ‘A second designer can step in without knowing the history of the project-that is, how the model was created. He can make changes and improvements just based on what he sees. Other solid modeling programs don’t provide that kind of freedom.’
Will Heimlich be able to continue the ETS team’s winning tradition in his maiden competition? Only time will tell. Long hours of development, production and testing lie ahead for the team. So do plenty of sleepless nights. But win or lose, every team member from ETS will have gained immeasurably from the experience.
‘This project forces us to integrate and apply everything we learn in our courses and design exercises,’ says Mr. Gendron. ‘And it gives us experience in project management. We learn engineering in school but we don’t manage it. This is where we apply all the theory.’