1. Create the following servo_control.py script:

#!/usr/bin/env python3 
#servo_control.py 
import curses 
import os 
#HARDWARE SETUP 
# GPIO    
# 2[=VX==2=======]26[=======]40 
# 1[===013=======]25[=======]39 
# V=5V X=Gnd 
# Servo 0=Turn 1=Shoulder 2=Elbow 3=Claw 
name=["Turn","Shoulder","Elbow","Claw"] 
CAL=[90,90,90,90] 
MIN=[0,60,40,60]; MAX=[180,165,180,180] 
POS=list(CAL) 
KEY_CMD=[ord('c'),ord('x')] 
#Keys to rotate counter-clockwise 
KEY_LESS={ord('d'):0,ord('s'):1,ord('j'):2,ord('k'):3} 
#Keys to rotate clockwise 
KEY_MORE={ord('a'):0,ord('w'):1,ord('l'):2,ord('i'):3} 
 
STEP=5; LESS=-STEP; MORE=STEP #Define control steps 
DEG2MS=1.5/180.0; OFFSET=1 #mseconds 
IDLE=2000 #Timeout servo after command 
SERVOD="/home/pi/PiBits-mater/ServoBlaster/user/servod" #Location of servod 
DEBUG=True 
text="Use a-d, w-s, j-l and i-k to control the MeArm. c=Cal x=eXit" 
 
def initialize(): 
  cmd=("sudo %s --idle-timeout=%s"%(SERVOD, IDLE)) 
  os.system(cmd) 
 
def limitServo(servo,value): 
  global text 
  if value > MAX[servo]: 
    text=("Max %s position %s:%s"%(name[servo],servo,POS[servo])) 
    return MAX[servo] 
  elif value < MIN[servo]: 
    text=("Min %s position %s:%s"%(name[servo],servo,POS[servo])) 
    return MIN[servo] 
  else: 
    return value 
 
def updateServo(servo,change): 
  global text 
  POS[servo]=limitServo(servo,POS[servo]+change) 
  setServo(servo,POS[servo]) 
  text=str(POS) 
 
def setServo(servo,position): 
  ms=OFFSET+(position*DEG2MS) 
  os.system("echo %d=%dus > /dev/servoblaster" %(servo, ms/1000)) 
 
def calibrate(): 
  global text 
  text="Calibrate 90deg" 
  for i,value in enumerate(CAL): 
    POS[i]=value 
    setServo(i,value) 
 
def main(term): 
  term.nodelay(1) 
  term.addstr(text) 
  term.refresh() 
  while True: 
    term.move(1,0) 
    c = term.getch() 
    if c != -1: 
      if c in KEY_MORE: 
        updateServo(KEY_MORE[c],MORE) 
      elif c in KEY_LESS: 
        updateServo(KEY_LESS[c],LESS) 
      elif c in KEY_CMD: 
        if c == ord('c'): 
          calibrate() 
        elif c == ord('x'): 
          exit() 
      if DEBUG:term.addstr(text+"   ") 
 
if __name__=='__main__': 
  initialize() 
  curses.wrapper(main) 
#End 

2. Run the script:

python3 servo_control.py
  

3. You can control the servos fitted to the MeArm (or whatever you are using) as prompted:

Use a-d, w-s, j-l and i-k to control the MeArm. c=Cal x=eXit