Bioinspired Wall Climbing Robot (Without Electronics, Not Finished)

This DIY tells you how to build a bioinspired wall climbing robot by using digital production techniques like laser cutting and 3D Printing. With some patience, everybody can build a wall climbing robot.

The robot consists out of a body with 4 legs, a head and a tail.
Each leg has 2 degrees of freedom that are controllable by 2 servo's (up and down movement and forward and backward movement)
A small and simple spring system is used in each leg to make sure the body can move while the legs are sticking to a surface. A lot of smart design choises were made after testing with early prototypes to ensure that the robot is very solid. In the middle of the body, space is left free to place the electronics, if needed.

Gecko tape is placed on the tips of each leg, this tape sticks on very smooth surfaces like glass, this makes it possible to walk on glass or very smooth walls.

By downloading the PDF file (for lasercutting), STL-files (for 3D printing) and following the instructions, a robot can be made like shown in the pictures.

Note that the electronics to control the robot aren't included in this DIY. The servo's are build in and are ready to be controlled by an Arduino (or PCB) and some basic electronics. By following other DIY's to control servo's, this can be achieved. Further testing need to be done to achieve a working robot!

Step 1: What Do You Need?

MATERIALS:

Light plywood, 5mm thick (about 350mm*600mm, see included PDF)
3D Printing Filament (about 335g) (210g for legs only)
4 servo's: HS-485HB and
4 servo's: FS5103B
(The wooden parts need to be adjusted when using different servo's with other dimensions)
(8 equal servo's is also perfect! We had to work with the servo's that were available)
Servo accessories (see picture for quantity)
Gecko Tape (To be able to walk on walls)
8 little springs (diameter about 4mm and length about 3cm)
(In our robot, we used ballpoint springs)
Bolts and nuts:
32 M4x12mm screws
16 M4 nuts
24 M3x24mm screws
11 M3x16mm screws
20 M3x12mm screws
55 M3 nuts
Wood glue (optional)

TOOLS:

Lasercutter (you can use manuel machines or a fretsaw as well but in this instructable, we used a lasercutter
3D Printer (In this DIY, we used a Robox 3D Printer)
Flat screwdriver
Cross screwdriver
flat plier

Step 2: 3D Printing the Plastic Parts

The included STL-files need to be 3D Printed.
Parts needed:
1x

Head1
Head2
Tail1
Tail2
Tail3
Tail4
Tail5
Tail6

Head3
Leg5
Leg6

Shoulder1
Shoulder3
Shoulder4
Leg1
Leg2
Leg4

Shoulder2
Leg3

3D Printing in this DIY is done by a Robox 3D Printer.
We choose for PLA Filament, which is the easiest filament to work with.
A layer height of 0.2mm has been used, this can be chosen freely.

We used 2 colours to add some contrast to the robot.
Grey filament to give it a robot look.
Green filament to give it a natural look.
Filament colours can ofcourse be chosen freely.

Important:
Every 3D Printer has a different finish and accuracy.
With some sandpaper or a precision cutter, you can easily remove excess material.

3D print parts.zip
Download

Step 3: Laser Cutting the Wooden Parts

The included PDF-file is the printing file for the lasercutter.
Laser cutting needs to be done with a freely chosen material (we use plywood) of 5mm thick.
Traditional wood cutting techniques can be used if no laser cutter is available, however this will be a difficult task!

Important:
Every 3D Printer has a different accuracy.
Perfect dimensions have been used for all the parts (In the PDF-file). Unfortunately, a laser cutter can't print perfectly, the beam has a thickness.
In photoshop or free variants, the dimensions can be adjusted to match the margin of error of the laser cutter.
This ensures that all pieces fit securely in to each other.

When the PDF-file isn't adjusted, wood glue is needed to put everything together.

lasercutter file.pdf
Download

Step 4: Assembling the Main Body

Assembling the body needs to be done like the included pictures.
2 exploded views and 2 finished views are shown.

If the laser cutted parts are a bit loose, use wood glue to fix them or use different margins for the laser cutter files.
Tip: Only use glue when you have complety put together the robot and you are sure everything fits!

The 4 servo's can be secured with 16 M4 screws and nuts. Use pliers and screw drivers to fix them firmly.
Make sure the moving part of the servo lies on the outside of the body like in the pictures.

Place the 4 included accessories on the servo tips (see picture).

Step 5: Assembling the Legs

The pictures included are instructions for 1 leg (The front-left leg).
The other 3 legs are almost exactly a copy of that one leg.

Parts needed for 1 leg:
1x

Shoulder1
Shoulder3
Shoulder4
Leg1
Leg2
Leg4
Leg5 or Leg6

Shoulder2
Leg3
Screw M3 16mm
Springs

Screw M3 24mm

Screw M4 12mm
Screw M3 12mm
Nuts M4

Nuts M3

How to assemble?
Start by placing the accessories on the tip of the servo's (see picture).
Mount Leg2, 2x Leg3, 2x Shoulder2 and Shoulder3 to the base part (Shoulder1) by using one M3 24mm screw, two M3 12mm screws and three M3 nuts. After that, mount the servo in the base part by using four M4 12mm screws and nuts.

Mount Leg1 on to the servo's tip and tighten it with a screw that comes with the servo.

Mount Leg4 and Leg5 together by using two M3 12mm screws and nuts.

Mount the last part on the first part by using two M3 24mm screws and nuts. While doing this, make sure one end of the springs is attached to the screws.

Finally attach the two M3 16mm screws and nuts on the legs. While doing this, make sure the other end of the springs is attached to the screws. (See picture).

Step 6: Assembling Everything

The most difficult parts are the legs, the other parts of the robot are easy to mount by just looking at the pictures.

The head (2parts) is mounted on to the body by using two M3 24mm screws and nuts.
The eyes can be clicked in to the upper part of the head.

The tail is build simply by connecting the pieces together with M3 screws and nuts.

And last but not least: the legs are mounted on the body by pushing them against the servo's on the body, while fixing the legs by 2 M3 24mm screws and nuts that goes true Shoulder4 and the wooden parts.

Tip:
Guide the wires of the servo's true the spine of the robot to make sure the wires don't get tangled with the legs.

Step 7: Attaching the Gecko Tape

Cut pieces of Gecko tape in the shape of the tips of each leg.
Use double-sided tape if the Gecko tape doesn't stick very well on the plastic legs.

Tips:
Gecko tape doens't work if it's dirty or covered with dust.
Clean the tape by placing masking tape on the Gecko tape. This will remove the tape.
Don't use water to clean it, Gecko tape doesn't work if it's wet.

Gecko tape works best on very smooth and clean surfaces like glass.