Robotic Claws using Arduino

While we wait for the Replicator‘s delivery, courtesy of MakerBot Education, I have continued working with local groups using many of the same technologies that will be employed for SOLID Learning including the marvelous Arduino microprocessor and many things it can control.

My students have an older LEGO Mindstorms Robotics Invention System (RIS) that provides the RCX 2.0 controller, which has been configured as a tracked vehicle with two bumper sensors.

A LEGO robot using the old RCX 2.0 controller.

LEGO has since evolved their marvelous system from this humble beginning system into the much more flexible and powerful NXT robotics controller and ended support for the RCX sveral years back. The software, Lego’s ROBOLAB, and the USB tower controller can only be configured to run on an XP system or earlier – allowing many opportunities to discuss system upgrades and the progress of technology with students. The RCX has the ability to control up to three motors using +9V/-9V software reversible DC power connections, but only comes with two motors – which are currently driving the two tracks.

Boy Scouts Robotics Merit Badge created in 2011Girl Scouts FIRST Robotics Participation Patch created in 2008

The Boy Scouts Robotics Merit Badge and the Girl Scouts FIRST Robotics Participation Patch involve the creation of robots that can autonomously fulfill a task rather than simply constructing a complex radio controlled device requiring constant human control. Our local kids are working on adding an Arduino-controlled servo operated robotics claw to the LEGO robot using the third motor control to trigger the opening and closing movements.

Parts to construct a servo-actuated robotic claw.

The first experience for simple construction for many students will be the first time they take a tool in hand and attempt to bend parts to their will and fashion them into a completed whole. This is not a journey to be taken without planning, and dynamic DIYMaker Movement” interaction by the educator will often be required to make the not-quite-right fit into a functional form.

A completed servo-controlled mechanical robotic claw for capture of small objects.

This aluminum robot claw was obtained from Sparkfun for under $10 if you already have the servo. I am looking forward to testing it against a 3D-printable version like Kepler’s Robotic Claw over on Thingiverse (Thing:18339).

Kepler's 3D-Printable Robotic Claw on <strong>Thingiverse</strong>

I have been discussing half-wave and full-wave bridge rectifiers, opto-isolators and several types of transistors with my students as they perform experiments to transform the reversable bidirectional motor signal into open and close trigger signals the Arduino can respond to – this bridges other requirements for my Scouting kids, such as one of the Electronics Merit Badge options to design and construct a control circuit.

Once the kids decide how they want to control the servo for the claw, they will then have to find a way to connect it, the Arduino and the battery pack for the servo to the existing LEGO RCX system – and then how to properly respond to sensor input and trigger the appropriate action to use this claw to accomplish a task. Students will be exposed to many different aspects of critical thinking, structural analysis, and the ability to develop and build designs based on their own ideas and what they have available rather than simply buying a kit and following pre-printed instructions start to finish.

Once the Replicator becomes available, a version of this lesson design will be folded into the SOLID Learning model to let students build robots without even the 10+ year old LEGO device we are currently building around.

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