Exploring the Role of Motors and Mechanics in Robotics

By Stu Grove on Jan 23, 2015

A well-rounded understanding of robotics begins with the exploration of four essential characteristics inherent in the design and engineering stages of this exciting scientific field. Movement, power, sensor driven input, and artificial intelligence are all components to be investigated throughout such a course of study. This activity specifically focuses on movement and power, demonstrating how electrical energy may be converted into mechanical energy, thus allowing the robot to complete a certain task, in this case transportation. By building a simple electrical circuit, comprised of a power source and a small motor, and affixing it to a body built from Lego® parts, students gain exposure to these concepts whilst participating in a design project that encourages creative thinking and problem solving strategies. Students with visual impairments tactually and auditorily explore how the vibrations caused by the unbalanced motorized ‘propeller’ create the movement of the robot, and its smooth metallic feet enable it to glide across many different surfaces.   

                                                                                                                  three views of the lego robot

Key Terms:

Actuator - A mechanical device that takes energy, such as electrical energy, and converts it into motion.

Kinetic Energy - Energy an object possesses because of its motion.

Mechanical Energy - Energy associated with the motion and position of an object.

(Forced) Vibrational Motion - When a force applied to an object causes the object to be put into a vibrational, or back and forth, motion.

This activity is adapted to allow students with visual impairments to manipulate electronic components with greater ease, and requires relatively simple adaptations to commonly available materials prior to the building procedure. While we suggest certain materials, such as pennies, cardboard cutouts, and paper cups, we invite students to propose other materials that may be effective, as well as alternative designs that may be used when constructing the body.

Preparation:

It is common for beginner electronics enthusiasts to struggle with the minute size of the components being utilized, and in attaching them to other components within a circuit. We have chosen to use a hot-glue gun to attach small Lego® pieces to the bottom of the motor and battery case so that may easily be attached wherever the student sees fit.  Additionally, we make sure that the wiring is short in length, and that alligator clips are in place at the end of each wire so as to make connecting and disconnecting the circuit easier for the students. Textured tape, or other material, is placed on either the red or black wire, in order to make its polarity distinguishable for a student with a visual impairment. An evaluation of student’s skills using tools, or building with Legos®, prior to the activity may help inform how much of the preparation and procedure is completed by the instructor versus the student.

Prior to the activity, discuss the key terms with the students. Demonstrate and discuss examples of vibrational movement. Have the students explore how objects such as a tuning fork or a speaker, produce vibrations when energy is applied to them. Point out that the ‘propeller’ is, in this case, acting more as an affixed object acting to create a slight offset to the balance of weight put upon the motor. This in turn causes more or less vibration, depending on the shape and size of the object. Demo a completed robot and ask the students to brainstorm different designs.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

3 images:  hot glue gun

Materials

  • Lego® Blocks of various shape and size
  • Small electronic motor with plastic cap/platform (with wiring)
  • Double A battery and case (with wiring)
  • Velcro stick-on dots
  • 4 pennies
  • Paper cup
  • Cardboard cutouts or other materials for propeller

Procedure

 

1. Locate two long, flat platform pieces. Take one of the pieces and flip it upside down. Stick a Velcro dot to each of the four corners of the piece. Stick a Velcro dot to each of the four pennies and attach them to your base.

 

Lego platform with pennies and velcro dots

2. Flip it over and attach the battery case (with glued-on Lego® attachment) to the end of the base horizontally with the battery inserted. At the other end place three blocks on top of each other (approximate height of the battery case & battery). Attach the second flat platform piece so that one end snaps into the Lego® blocks and the other rests on the battery. This will create a distinct ‘flapping’ sound when the motor causes the vibration.

 

lego platform with battery attached

3. Attach the motor (with glued-on Legos® piece) to any number of Lego® blocks, creating a small platform. This will prevent the propeller from coming into contact with the ground. Attach the plastic cap on the motor shaft, and place a Velcro dot in the middle of the cap.

4. Stick a Velcro dot to the underside of a paper cup and stick it to the motor platform.

3 images of the steps in adding the Velcro dot and other components

5. Students will locate the positive lead, which has been wrapped in textured paper to indicate its polarity, and attach it to one of the wires coming from the motor using the alligator clips. They will then do the same with the negative lead from the battery, attaching it to the remaining wire from the motor.

6. Place robot on smooth surface and observe as the vibrations caused by the motor cause it to slide across the table. The force of friction is reduced as a result of its metallic ‘feet’.

Variations

           

Two images of adding thin pieces of cardboard

Using thin sheets of cardboard have the students cut out different shapes of varying size to use as an alternative to the paper cup. This can be adapted to make cutting out the shapes manageable, by applying a line of hot glue or puff paint to designate the line of the shape. Have the students alter the location and orientation of the motor and observe the effect this has on the movement of the robot. The students may each demonstrate their designs and compare the results of each modification, ultimately deciding upon an optimal design.        

3 images of the motor being activated to turn on a light

NGSS Standards:

Standards:

MS-ETS1-2. Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.

MS-ETS1-4. Develop a model to generate data for iterative testing and modification of a proposed object, tool, process such that an optimal design can be achieved.

collage of robotics