Polynomials and VEX Drive Motor Control

VEX Robots can be more competitive when they have addressed several drive motor control challenges:

  1. Stopping a motor completely when the joystick is released. Joysticks often do not output a value of  “zero” when released, which can cause motors to continue turning slowly instead of stopping.
  2. Starting to move gradually, not suddenly, after being stopped. When a robot is carrying game objects more than 12 inches or so above the playing field, a sudden start can cause the robot to tip over.
  3. Having motor speeds be less sensitive to small joystick movements at slow speeds. Divers seeking to position the robot precisely during competition need “finer” control over slow motor speeds than fast motor speeds.

These challenges can be solved using one or more “if” statements in the code controlling the robot, however using a single polynomial function can often solve all of these challenges in one step. A graph can help illustrate the challenges and their solution:

Continue reading Polynomials and VEX Drive Motor Control

Linear Equation Activity Ideas

Once a set of learning objectives have been settled on for an activity, problem, or project, what should the problem’s context be? Since linear equations model situations where there is a constant rate of change, common contexts for linear equation projects often include the following:

  • Steepness, height, angle
    Examples: road grade, hillside, roof, skateboard park element, tide height over the two weeks before (or after) a full moon, sun angle at noon over a six month period
  • Estimating time to complete a task (setup plus completion)
    Examples: mowing a lawn, painting a wall, writing a research paper
  • Purchase and delivery costs of bulk materials
    Examples: mulch, gravel, lumber
  • Purchasing a service that charges by consumption
    Examples: cell phone, electricity, water, movie rental, etc.
  • Total earnings over time from differing wage and bonus plan structures
    Examples: hiring bonuses, longevity bonuses
  • Energy use over time
    Examples: calories burned, electricity, heating oil, gasoline
  • Game points accumulated over time
    Examples: by a professional athlete, a team, a video game player
  • Pollutant levels over time Continue reading Linear Equation Activity Ideas