Mike Binnard's PhD Research

I want to develop a system that makes it easier to design robots.

I spent seven years working at the MIT Mobile Robotics Lab. While there, I was frustrated by the inadequacies of the robots we built. Even though the component technologies (sensors, actuators, and electronics) are well understood, the robots had reliability and performance limitations. We believe that with better design tools and more attention to the design process, we can build complex robots quickly and reliably. Several factors make designing robots a difficult and unreliable process:
  • Complexity: Interesting robots are complex machines. This complexity hampers reliability, as well as making the design process cumbersome.
  • Components: Off the shelf components are never exactly what you want for a certain design; they tend to be general-purpose compromises.
  • Manfacturing: It is difficult to keep track of manufacturing constraints and capabilities while designing complex electro-mechanical machines.
  • Prototypes: Building prototypes for testing is too slow and expensive.

At the same time, there are new tools and techniques which could mitigate these problems:
  • Simulation: New software allows fast and accurate simulation of complex dynamic systems.
  • Manufacturing Processes: New processes allow faster prototype cycles.
  • Embedded Components: Electronics, sensors, and actuator elements can be embedded in structural parts.
  • Multi-material Parts: New processes allow parts made from multiple materials.

I believe it is possible to develop a CAD environment which will enable us to build new robotic devices in less time, for less money, and with greater flexibility, performance, and reliability.
    The proposed system will work by embedding design rules in the CAD software. The CAD software will continually monitor compliance with the rules during the design process. Some of the rules will ensure that the device is manufacturable. By monitoring compliance with initial assumptionsother rules will guarantee that the mechanism will function properly. An important quality of these rules is that they are intimately related to geometry.

    A Linear Motor

    A 3-phase, linear DC motor.

Electric motors use magnetic forces to produce mechanical motion. The forces are created by the interactions of electric currents and permanent magnets. Based on the geometry of the design (see the picture below), it is possible to calculate the force produced by the motor with equations like these:
    It is important to remember, however, that the analysis which produced these equations makes several assumptions about the device. For example, the magnetic analysis is only valid if the ratio of magnet thickness to airgap is greater than 10.

    Assumptions about the design are also made by the manufacturing process. These assumptions impose constraints, such as minimum wall thicknesses and corner radii. For example, if the stator shown was machined, the stator slots would be filleted at each corner, reducing the area available for the coils.