Table of Contents

Satellite Communications

Tele-Robotics, Tele-Medicine and Time Delay

Description of Activity

This activity simulates the adverse effect of time delay, as it is associated with telecommunications, when dealing with action-at-a-distance topics of tele-medicine, tele-robotics and planetary exploration.

Purpose

The purpose of this activity is to have students appreciate the effects of time delay in tele-medicine and space exploration. The activity simulates the interaction-at-a-distance, in particular time-delay, that takes place during a tele-medicine or tele-robotic activity.

Preparation Time

Time needed to prepare students and to have them work through their communications strategies - 30 minutes

Activity Time

Using 5 minutes as a reasonable time for each team - and with 15 teams - approximately 90 minutes.

Materials

• Large room such as a gymnasium, auditorium or an isolated hallway
• 2 Remote control cars - one using 27 MHz the other using 40 MHz (specification usually is written on the controllers for the cars. These may have to be borrowed from willing students or their families)
• Batteries for the cars
• Blindfold
• Stopwatch
• Masking tape
• Chairs (2)
• Pylons, books or other items that may be used as a hazard.

Procedure

1. Obtain 2 remote control cars one at each of the two characteristic radio frequencies used by these toys (about 28 MHz and 40 MHz) - these frequencies are usually printed on the packaging and on the vehicle itself - you can work with one but it will double your activity time. Vehicles working at the same frequency will interfere with each other. If these vehicles have more than one speed setting, it is suggested that one use a high setting while the other a low setting.
   
   
2. Set up a course using the pylons in one portion of the room and set two chairs at one end of the course. The chairs may face the course. Place a strip of masking tape about a meter from the chairs across the front of the course. Place pylons such that the course is a box or a figure of eight or something simple.
   
   
3. Students work in teams of two. One student is the pilot and is required to operate the controls of the car. The second student is the navigator and is responsible for giving the pilot instructions on how to drive the car (forward / back / stop / etc.) To ensure that there is no interference in the navigator's commands, the pilot should be blindfolded.
   
   
4. Note that two cars will be on the course at the same time and collisions should be avoided. It speaks to the skills of the navigators as to how well they avoid the collisions. To assist with the collision avoidance, have one team begin at one end of the course (say Blue Team) while the other begins at the other end (Red Team). On simple courses, collision zones can be reduced. On more complex courses the whole course could be a collision zone.
   
   
   
   
5. It is recommended that the teams have a few minutes each to become accustomed to how the cars work, before starting the simulation. It is also recommended that the teacher selects both the team members and which teams are on the course at the same time.
   
   
6. Starting with two groups of two and a stopwatch, have two teams take their positions with the blindfolded pilots seated. With the two remote control cars behind the masking tape start line, and with a "3-2-1-Go" command allow the two teams to proceed through the course.
   
   
7. Set a maximum time on the course for each team - say 3 to 5 minutes. Time the students and record the complete times. Accidental collision can earn a penalty time of, for example 15 seconds (added to both teams). Intentional ramming of one of the cars by the other could result in the elimination of the ramming team.
   
   
8. Run through each team recording the time to complete the course and the speed setting on the cars.

What you can expect when teams have little or no practice.

• Students with fast cars will be all over the course and will have difficulty finishing in a reasonable time.
• Students with slower cars may actually finish the course.
• Students will want to steer the cars so that the front always goes first (this is not a requirement to finish the course).

If the teams have time to practice on the course then:

• Fast cars may not finish - slow cars will probably finish.
• Students may work out that short bursts of movement followed by an assessment of the position of the car on the course will help complete the task (both speeds of vehicle).
• Students with fast cars may want to slow them down.
• Students may realize that backing up their car works better in the right circumstances.

NOTE: The time delay aspects of this simulation come from the need for the navigator to assess where the pilot is driving the car and to feedback this information through verbal commands. Although this simulation appears straightforward, the time delayed caused by the need to collaborate may cause frustration with team members (usually the navigator).