I have been tinkering for a while with Arduino, building an obstacle avoidance robot and some other projects where I was more copying then inventing something.
After gaining some experience, I started a new project from scratch. I wanted to do an anatomically accurate robotic arm, taking my right arm as reference.
I wanted to do this robot with whatever materials I could find at home, so the choice of the materials is somehow eclectic.
Step 1: Building the Frame
The hand and arm are made out of brass wire, soldered with tin. The springs are made with piano wire, and the “tendons” are made out of dental floss.
I started by making the palm of the hand, that is basically a wire square that I have doubled for the back of the hand. The fingers consist of linked trapezoids. I build all the pieces first and the assembled them, taking the ones that better matched and had the right length. The fingers stay in open position thanks to little spring that I did by hand. I took 0.5 mm piano wire and rolled it around a thin screwdriver. It took several trials till I made a decent spring. In the pictures you can see different spring trials that did not work
Step 2: Assembling the Hand
Once all fingers are attached, I added the servos in the arm and the ultrasonic distance sensor in the palm.
It took a bit of time to adjust the tension of all the finger springs to give a natural movement to to the hand.
I had to add a piece of wire to the servo heads because they did not have enough lever.
Step 3: Wiring
Depending on the sketch you load, the hand acts differently.
One sketch measure the distance of the object in front of the hand and opens the fingers accordingly to the distance.
Another sketch performs a different routine depending on the distance of the object.