gear studies megathread

ev3 31313 and 45544 sets

stop at 50sec

Lego Freewheel & rachet Mechanism

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one output to two :

seems to use friction.

bullet points learned from book : the lego mindstorms EV3 laboratory by daniel benedettelli:

ceil (truncating)

wall following bot formula :
steering = - distanceInput(constDistanceThresHold(50)-measurementTolerance(2))

getting gears to mesh together : the sum of the gear radius should to an integer
(cause assembled on a studless beam with integer size) for example :
8z 0.5 with 40z 2.5 gears

biped robot wieght shifting :
the projection of the center of mass must be within the support area of the foot that
is still on the ground

formula : computing the degrees parameter to steer precisely :
(T*L)/R
T = degrees to turn robot (rov3r model for example)
L = the distance from the tire center to the bot center
R = radius of the wheel

turn the motor 208 degrees to turn rov3r 90 degress : (90*50)/21.6

rear wheel electric differential formula :
Vr = V(1+.017D*a/H) // outer wheel
Vl = V(1-.017D*a/H)// inner wheel
v = speed
a = turn angle
D = half dist between 2 rear wheels
H = dist rear to front wheel
.017=degrees by radians (pie/180)

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gyro

https://frobotme.wordpress.com/2014/04/29/algorithm-for-self-balancing-robot/

void loop() {
 float expectedTilt = 0;
 float currentTilt = getCurrentTilt(); // From accelerometer
 float currentTiltRate = getCurrentTiltRate(); // From gyro
 float thrust = pid(currentTilt - expectedTilt, 0, currentTilt + currentTiltRate, 0.25, 0, 0.75);

 // Apply thrust to each motor
}

Proportional – present error
The present error is the amount of tilt that the robot has. It is supposed to have a tilt of 0°.
If it is tiled by 10°, the error is -10.

terry griffin wrote:

progressively reduce kp by .05 and increase ki by.01 for thrust x till stable

float pid(error, integral, derivative, Kp, Ki, Kd) {
 return -(error * Kp + integral * Ki + derivative * Kd);
}

iris shutter mechanism

lego part 4612100 the actuator may appear defective or stuck, because it doesn't move when you spin it. but the knob needs to be still direction wize while spinning the axel for it to move