kinematics and storing foot location

i want use joystick drive foot of leg around x,y axis.

i can map joystick inputs multiplier, , use multiplier add or subract current x or y axis. ,,

i can set constraints on possible x,y locations, can manage first phase of experiment,,, how able know foot is? can serial print foot location phase one,, want first move 1 leg, next leg, etc. .,, can use operator collect ,,, last cycle of function 1 leg,, how multiple legs?? variables store in way,

is possible know servo angles function, , program forward kinematics equation reads servos, , figures location once leg selected??

well, didn't joysticks can watch happen , feel about. however, did manage use 2 10k potentiometers mapped x,y coordinates , move foot around x,y axis.

there things experiment. using buggy servos randomly go haywire no reason other minor voltage change caused unknown power variation,, , interesting thing noticed. although code should not change value of both analog inputs when 1 pot turned,, both potentiometers hooked same power rail, , ground. suppose there way add fixed resistors circuit affect stability of voltage, not know happen analogread results. 1 potentiometer affected other being turned,, i'm sure reason both values changing because 1 potentiometer gained or lost resistance, altered amount of current flowed through other potentiometer, them being wired in parallel. (although center taps going 2 seperate, similar pins, paths ground parallel, , paths voltage parallel, amount of available power affected. matters driving servos arduino 5v, there's 2 of them , they're small,, suppose drawing enough current when move potentiometers, when try move, combined activity causes change in voltage present @ pin potentiomter not changing.

anyway, experiment have 1 success, , code facilitate changing position of foot x,y coordinates.

code: [select]

//servo leg experiment. 2 servos moving on 2 dimensional x,y coordinate plane. hip servo @ 0,0
//hip servo oriented such 0 degrees straight downward, , 180 straight upward
//knee servo oriented 0 directly toward femur, , 180 directly away tibia (so 180 extends leg)
//my model backward, leg extending left, input negative values , seems want work
//there still problems code, solutions may pick may not within range of motion of servos.
//all measurements in milimeters.
//open serial monitor see angle b angle a, b hip angle printed first

#include <servo.h>
#include <math.h>

servo hip;
servo knee;

int femur = 100;
int tibia = 90;


void setup() {
  // put setup code here, run once:
hip.attach(9);
knee.attach(10);
serial.begin(9600);

}

void loop() {
  // put main code here, run repeatedly:
int joyx = analogread(a0);
int joyy = analogread(a1);
int x = map(joyx, 0, 1023, -180, 0);
int y = map(joyy, 0, 1023, -150, 150);
serial.print (x);
serial.print ("    ");
serial.println (y);
//assuming servo hip oriented, 0 straight down, 180 straight up, y inverted, -y above x axis
 float l = sqrt((x*x)+(y*y));
 float = acos(((femur*femur)+(tibia*tibia)-(l*l))/(2*femur*tibia));//outputs number in radians a
 float b = acos(((femur*femur)+(l*l)-(tibia*tibia))/(2*femur*l))+acos(((l*l)+(y*y)-(x*x))/(2*l*y));//outputs number in radians b
serial.print(degrees(b));//converts radians degrees
serial.print("    ");
serial.print(degrees(a));//converts radians degrees
serial.println ("----------------------");
hip.write(degrees(b));//converts radians degrees
knee.write(degrees(a));//converts radians degrees
delay(1000);
}

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