Danny's Mindstorms® JohnNXT 5 (number five)

This model is moved by 6 servo motors and can sense the world with 3 sensors (up to 8 sensors can be plugged).

Master NXT (the front one) controls treads motors and head; US sensor, line sensor and sound sensor are plugged here.

Slave NXT (the bottom one) controls torso raising motor, laser and arms ones.

The only sensor attached is the light sensor, that lights up laser tip.

Slave NXT runs a program that simply waits for Bluetooth commands coming from master NXT, actuating the motors; the state of every motor is saved in variables.

The triangular structure of the treads has been built after precise studies of real Johnny five photos: a pre-production CAD drawing helped this process. An early version of J5 base had the most perfect proportions achievable with Lego gears, using Technic large turntables: unfortunately, those turntables made links escape while treads were turning.

So, in the actual version, turntables has been replaced by 40z gears, that don't damage design too much and allow a very smooth motion.

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.

The only hope is to never see a gear shatter!

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.

Laser is moved by a serie of levers that don't simply rotate it:

from a rest position, it is lowered, rotated and aligned to the shoulder.

An earlier solution is shown here. 

Light sensor can be programmed to be on or off: it's easy to simulate a blinking laser!

G-language programs download

Show (master NXT) -  (559KB)

Show (slave NXT) - (453KB)

Line Follower - (128KB)

Hand Follower - (338KB)

Laser MyBlock - (259KB)

Torso MyBlock - (462KB)

These programs are to be opened with Mindstorms NXT Graphic language programming environment.

.rso sound resources download

Montage soundtrack - (32KB)

"Number five... is alive!" - (20KB)

"I am alive!" - (15KB)

"Hello, bozos!" - (14KB)

"Malfunction!" - (9KB)

"Need input!" - (8KB)

"Yeah! Johnny five. That's cool!" - (26KB)

To use these files, simply paste them into the NXT program sound folder (e.g.: C:\Program Files\LEGO Software\LEGO MINDSTORMS NXT\engine\Sounds\). Then select them among other sound files.

Videos

JohnNXT shows off its features - (5MB)

Line following - (3,08MB)

Hand following - (2,9MB)

Panoramic view - (1,33MB)

Head detail - (457KB)

Arms detail - (1,22MB)

Torso moving - (642KB)

Torso gears detail - (580KB)

Laser detail - (731KB)