Project based activities are a good way to expose secondary school students to more science and math at earlier grades. In the last few years has been a decrease of enrolment for engineering programs in Spain. For this reason, the University of Girona (UdG), the Social Council of UdG and the Catalan Government started initiatives, with the aim of increasing the interest of students for technology and promote engineering skills, capabilities and values. These institutions support and promote scientific and technological activities of recreational nature that are attractive for students.
The advantages of such an activity are numerous. Working directly with experts at their laboratories makes really a difference in terms of student motivation and eagerness to learn. Our research group has conditioned a fully equipped experimentation lab where secondary school students and senior researchers cohabitate for some time in a learning experience. Through creating this atmosphere that makes the students feel determined to learn, engineering questions are better answered if the student directly puts his hands into the problem.
Workshops to Build Remotely Operated Underwater Robots (ROVs)
The activity is inspired on the ideas of MIT SeaPearch, has been designed for students from 14- to 16-year-old. The ractivity presented here shows the results of a workshop to build a remotely-operated underwater robot. The robot is fully built by a team of 5-6 secondary school students during a 2½-day workshop, which ends with the students showing their ability to teleoperate it and to execute underwater challenging operations that are realistic approaches to real missions developed by the real Remotely Operated Underwater Robots (ROVs). These operations consist in collecting metallic parts from the bottom of the pool and placing them into a cargo (cleaning operations), launching and releasing objects using different techniques (as if they were scientific instrumentation moored on the seabed to collect data), etc . Some of these missions can only be accomplished by following collaborative strategies using more than one vehicle.
The robot prototype is built using low-cost materials, with a total cost not exceeding 60 €. Another important purpose of this activity is to introduce the students into the correct and safe utilization of standard tools.
The workshop starts with three short presentations. In the first one, the professors welcome the students and introduce themselves. Some instructions are given and the group starts familiarizing with the environment and the tools. In most cases, this will be the first contact of secondary school students with the university and, therefore, kindness and closeness are a must to minimize their fears while keeping the appropriate levels of respect. Professors try to encourage motivation and provide positive feedback to the students to create a positive atmosphere, which always helps when starting to work with an unknown group of pupils.
A multimedia presentation is given next, accompanied with individual documentation of the whole activity. An accurate temporization of the workshop and the planning strategy are described, showing the different parts of the submarine and the tools used to build them. Safety advices about tools and their correct utilization receive a special attention during all the presentation. The students are going to start a serious project, and for that purpose they need real, professional tools. It is important to remark that the safety elements (protective goggles, gloves, aprons, etc.) are as important as the tools. Moreover, students are also instructed to follow adequate security protocols and behave accordingly.
On the other hand, and as stated at the beginning of this section, the students are divided into groups of 6 pupils. In order to build a balanced teamwork, the students are accurately grouped. For this purpose, an individual questionnaire is filled in by every student . This questionnaire describes their working profiles and capabilities, providing the basis to group balanced working teams and, thus, avoiding conflicting members within the same team. The first duty of the new groups is to choose a name for the team. This name will identify them and their work along the whole workshop development.
The last presentation aims to promote the research done at the Computer Vision and Robotics Group (VICOROB). The objective is to awake the student's interest in the engineering field. The numerous industrial applications around underwater technology, such as environmental monitoring, oceanographic research or maintenance/monitoring of underwater structures are presented to the pupils.
The first task of the students is to build the teleoperation unit. The console is made out of wood. Students must assemble the spare parts using wood glue and nails. While the pupils wait for the glue to dry, they can start constructing the vehicle's chassis. The structure is made of PVC pipes of different lengths linked together by means of T’s, 90º and 45º elbows. Students measure and cut all the pipes using the appropriate tools. The chassis, once finished, is used as a starting point to explain and understand the dynamics and force-torque vectors acting on an underwater vehicle.
The next step would be to start with the electrical connections. Before introducing the pupils to soldering and connectivity issues, they expend some time learning and training some electrical principles. To do so, they build a couple of “test wires”. This simple tool will be used during all the electrical design and construction phases of the robot to check connections, polarities and switches. By this time, the wooded console is ready to be polished and painted. The students can feel free to decorate and customize their teleoperation units as they like, since design skills and artistic creativity are 100% compatible with engineering.
Once the electric issues are clear, the pupils complete the first day task plan by mounting all the connection wires that will be needed for the console. The students must attach fast-on connectors to each cable edge, leaving the wire set ready for the next day. In order to level the progression of the teams, the most advanced groups can help the delayed ones with the wiring.
The second day starts wiring the console up. With all the right wires prepared from the previous day, the students must assemble three DC motor polarity inversion circuits. The correct interpretation of the circuit schematics is crucial to succeed. This phase is closely guided by the teachers, since the students initiate themselves experiencing with electric components. In order to understand that a motor can rotate clockwise or counter clockwise depending on how we polarize it, the student uses the test wires to connect the DC motor to a power supply and makes it rotate in both senses. As soon as the circuit schematics have been empirically derived, the next step is to transfer the assembly to the teleoperation console. Each motor circuit is verified independently. With the installation of the push-buttons and the joystick, the teleoperation unit is finally completed.
In order to prepare the motors to be submerged, the next step is to seal them with standard wax to make them watertight. For that purpose, the delicate parts of the motors are first covered with electric tape and thermal adhesive. Also, the motor shaft and the frontal plane of the motor are generously covered with petroleum jelly to prevent water coming inside the motor through the shaft. Then, the motor is introduced into a photo roll plastic case. Students have to drill a small hole at the bottom of the case for the motor shaft. Subsequently, the case is filled with melted wax. After a short period of time, when the wax hardens, we obtain a solid sealed motor with only a shaft and 2 wires coming out.
The final task of the second day is to fix the sealed motors to the chassis of the vehicle and connect them -by means of an umbilical tether- to the teleoperation console. With all the connections between the robot and the console established, every team must verify the correct operation of the robot. To do so, pupils must connect the console to the power supply and test the response of the vehicle’s motors to the different commands given by the teleoperation console. If everything is correctly working, the vehicle is ready to face the final assembly phases to be carried out along the last day of this workshop.
On the last day of the proposed activity, students only have until noon to finish their vehicles and test them in the water test tank. The adjustment of the robot’s buoyancy is the last step prior to real experimentation. To be efficient, the stability and density of the vehicle is a key factor. The robot’s stability and density are the result of an accurate distribution of the heavier elements at the lower part of the chassis combined with the effect of technical foam placed in the top, which should provide a slightly positive buoyancy to the robot, assuring that it will surface automatically in case of motor failure. For these reasons, the students must adjust the buoyancy and the stability by combining technical foam located at the top of the robot and small weights strategically placed at the bottom of the chassis. At this point, the robot is ready to begin the final experiments at the CIRS water tank. If all the previous steps have been accomplished with no delays, pupils should have around 2 hours to test, play and enjoy with their robots. At this stage, different obstacles are artificially introduced in the pool to make the students test their skills and fully experiment the performance capabilities of their robots. While playing, the robot goes through various stages of testing and final adjustments. The vehicles can also be equipped with a small watertight camera which allows them to watch the underwater scene and experience navigation as professional pilots do. Finally, students are requested to complete an assessment survey questionnaire which is used to evaluate the workshop.
Since 2008 we performed more than 20 editions of this workshop. We built more than 80 underwater ROVs for more than 350 students coming from 18 Secondary Education Schools.