JohnNXT

Differential Drive

Rotating Head

Raising Torso

Moving Laser

Grabbing & Lifting Hands

Hand Following

Line Following

Speech and music directly from the movie

Double NXT system

Full remote control

This model is moved by 6 servo motors and can sense the world with 3 sensors (up to 8 sensors can be plugged). The two NXTs communicate with each other using the serial link on port 4.

The triangular structure of the treads has been built after precise studies of real Johnny five photos.

Motors drive 40z gears by a couple of 24z gears, so that J5 can go at a max speed of 10cm/s.

The motor that turns the head is fitted inside J5 torso. The only mechanical bond to the rest of the frame is the axle that moves head gears.

The complete geartrain is 16:16 x 16:8 x 1:8 = 1/4. The wormgear brings motion from horizontal to vertical axle.

The most stressed motor is the torso raising one!

A powerful geartrain is needed to lift the upper frame, including 3 motors, head, arms ecc...

The ratio is 8:24 x 8:40 = 1/15 so that the motor torque is powered by a 15 factor.

In such cases symmetry is very important: otherwise gears could slip under this huge load.

Gear ratio of arms mechanism is 12:20 x 8:24 = 1/5.

Universal joints allow arms bending inwards and outwards.

So placed, the motor resembles J5 toolkit box.

The arms position is a bit affected when torso is lifted:

this is due to axle sharing between multiple mechanisms.

This is a minor defect of the complex parallel kinematic structure

that mantains shoulders correctly aligned to the ground, both when J5's torso is raised or lowered.

A chain brings motion to the elbow. Here you can see the sphere joint lever that opens and closes the hand, and rotates the wrist.

A rubber band is necessary to let the arm come down before the hand is opened.

Rubber pieces (savagely cut) on finger tips add a little grip while grasping objects.

Here is the old Lego RCX Johnny five.

Check out my smaller Johnny five version.