MatteoAlbi / tpa-homework1

Generate machines SVG drawings using C language. The main scope is to practice C programming and GIT utilization.

Homework 1: Incredible Machines

Piston

This is a piston like device, to convert a rotation motion into a translation one

Device definition

Parameters:

• dShaft: shaft's diameter .
• stroke: distance covered by the movement of the piston.
• lRod: connecting rod's lenght.
• wRod: connecting rod's width.
• hPiston: piston's hight.
• dPiston: piston's diameter.
• angle: crank's rotation angle.

Definizione corpi e vincoli dei parametri:

• SHAFT: connection element to the rotation motion, defined by its diameter (dShaft).

• CRANK: connects the crank to the connecting rod

  • Half the piston stroke (stroke) is defined as the crank's lenght. It's the distance between the shaft's axis and crank-connecting rod joint's axis.
  • The crank-connecting rod joint's diameter is equal to the connecting wRod.
  • The total crank's lenght depends on: stroke, dShaft, wRod. It's equal their sum plus two addition coupling terms for the joints with the shaft and the connecting rod.
  • The additional term for the connecting rod's joint is 1/5 wRod.
  • The additional term for the shaft's joint is 1/5 the dShaft.

  CONSTRAINTS:

  • The crank's lenght must be greater the sums of the two joints' radius.

• CONNECTING ROD: Connects crank and piston.

  • The connecting rod's lenght (lRod) is the distance between the axis of the crank and the piston joint.
  • The piston-connecting rod's joint is inside the piston, with an additional coupling term equal to 1/5 wRod.

  CONSTRAINTS:

  • lRod must avoid interference between crank and piston in the lower dead point (angle equal to 180°).
  • wRod can't be lower than 1/6 lRod.
  • wRod can't be greater than dShaft.

• PISTON: connection element to the translation motion.

  CONSTRAINTS:

  • Piston's diameter and lenght (dPiston e hPiston) must ensure the additional coupling term for the connecting rod joint, so they cant be lower than 7/5 wRod.

• ANGLE: crank's rotation angle (angle) in degrees.

P.S. The coupling term is an additional portion of material around the whole joint edge.

Example image:

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Motor

The objective is to implement a simple representation of a motor.

Machine definition

The motor is made by multiple structs called cylinder. Each cylinder is made by one piston and two camValve.

Cylinder struct:

• piston: pointer to piston (LBAMTTdevice).
• valveSx: pointer to camValve, it's the left valve.
• valveDx: pointer to camValve, it's the right valve.

Motor struct:

• n: number of cylinders.
• cylinders: array of pointers to cylinders.
• angle: motor shaft's angle.
• offset: array of double, angle offset of each cylinder with respect to the motor's shaft

Parameters:

Using these parameters, multiple Cylinders are intialized and stored into the array of the struct motor:

• n: number of cylinders of the motor.
• bore: cylinder's bore.
• displacement: motor's total displacement.
• angle: motor shaft's angle. Depending on n, the array offset is created with different values.

Constraints:

• n: can't be grater than four (to define offset easier)

• bore: It's equal the dPiston. Considering a car's motor, the bore /stroke ratio must be between 0.7 and 2.4 (Stroke ratio); this set a limit to the stroke. The lower bound for the bore is set to 60.

  Depending on n, there is a cap on the bore value to allow the image to fit in the bounds. The caps are:

n	cap
1	384
2	384
3	200
4	150

• displacement: from the displacement is possible to get the stroke of the single piston knowing that:

    displacement = PI * (bore/2)^2 * stroke * n
  

  To assure that the image fits in the bounds, the maximum value of the stroke is 140, turning into a cap on the displacement.

Offset and valve angle

Depending on n, the offset are set as follow:

n	offset	link
1	0
2	0-360	Straight-twin engine
3	0-240-480	Straight-three engine
4	0-180-540-360	Straight-four engine

The cylinder's angle is defined from 0 to 720 degrees for a four-stroke engine. The camshafts moving the valves rotate half the speed of the motor's shaft, so their angle is defined from 0 to 360 degrees and the rotation speed is halved also. The cycle is defined as follow:

• pistonAngle = 0 -> start compression: both valve closed (color yellow)
• pistonAngle = 180 -> explosion: both valve closed (color red)
• pistonAngle = 360 -> start expelling: valve Dx open, valve Sx closed (color blue)
• pistonAngle = 540 -> start aspiration: valve Sx open, valve Dx closed (color green)

To follow this scheme, the left valve has an offset of PI*3/4 between the piston (starting to close) and the right valve has an additional offset of PI/4, so it starts to open earlier.

Quotes

When quoting the motor, only the main parameters like bore, stroke, displacement, angle and n are displayed. The single devices aren't quoted to avoid confusion.

The quoted angle has range between 0-360° (angles grater than 360 are normalized in the range).

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Command line parameters

-h: show the helper as follow:

Command format: ./mainentry -"struct" -i importPath -e/-eq/-ea cxShaft cyShaft exportPath -p {params}

• "struct" must be device or motor: define wich one is used"

• -i import a struct from the file with path importPath.

• -e export a struct on the file with path exportPath. The struct is taken from:

  • an imported file called with the option -i (prioritized action).
  • the one crated with the params passed after the option -p (ignoerd if -i is called);

  cxShaft, cyShaft are the coordinates of the shaft's center on the SVG draw, needed only with struct device.

  ATT: passing cxShaft, cyShaft with struct motor will raise an error.

• -eq export a struct with quotes on the file with path exportPath (options as before).

• -ea export a struct animated on the file with path exportPath (options as before).

• -p followed by the params of the struct to be exported (can't be called if -e or -eq isn't called before).

  Params :  dShaft stroke lRod wRod hPiston dPiston angle   for device (for details see README);

                n bore displacement angle   for motor (for details see README).

More following params will be ignored

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Animation

The animations are created adding to the SVG the rappresentation of the device/motor of every frame. Than is added an animation option that change the color of each figure from transparent to the original color the instant the frame must appear, and than reset the color to transparent fir the next frame to be displayed.

Animation struct

• index: animation frame index.
• n: number of frame of the animation.
• T: duration of the animation.

n/T ratio define the fps of the animation.

Constraints: n and T must be greater that zero.

ATT: given the unefficient method with wich the animation is created, to avoid lags don't set a too higher value of n (suggested 720).

Examples animations: