Raspberry PI Spiderbot

Inspired by the Arduino Project below we'd like to create a Raspberry PI version as in https://github.com/yasaspeiris/aragog

Links

• Spider robot(quad robot, quadruped)-MG90 regishu 2017
• https://www.hackster.io/yasaspeiris/raspberry-pi-powered-quadruped-bbb68b
• https://github.com/yasaspeiris/aragog

Parts

#	picture	part	example sources	documents	~ price
1		Raspberry PI 3 B+	Raspberry PI 3 B+	en	35 €
2		microSD Card	SanDisk 16 GB		7 €
3		Raspberry PI Camera	1080 p Camera Module		23 €
4		DC/DC Converter 12 V-> 5V	12 V->5 V Converter Module		7 €
5		Micro USB Connector	Delock USB 2.0 Micro USB		6 €
6		3D Printed Parts: Coxa, Tibia, Femur, Hinge	parts from regishu's design
7		Adafruit PCA9685 16 channel PWM controller	PCA9685		6.5 €
8		set of small screws	set of small screws		8.5 €
9		12 x MG90S	12 x MG90s		42 €
				Total	~ 135 €
a		Breadbord Kit	MB102 Breadbord Kit		7 €
b		Ulrasound Sensor	5 x HC-SR04 + Cables		10 €

Printing

You might want to make sure that you print your parts with sufficient infill - I used 75%.

Example for broken part

This part was printed with Cura's default infill and broke off:

Assembly

• Legs and hinges are connected with 1.4x5mm screws
• Legs and servos are connected with 1.7x6mm screws

We use the raspberry base from https://github.com/yasaspeiris/aragog/blob/master/3d%20printed%20parts/base.STL

Leg Test

sudo python3 testadafruit.py 0 1 2 3  0

sudo python3 testadafruit.py 0 1 2 3  90

sudo python3 testadafruit.py 0 1 2 3  180

testadafruit.py

# Test Adafruit 
# WF 2019-07-09
import sys
import time
from adafruit_servokit import ServoKit
kit = ServoKit(channels=16)

# 
# set the given angle for the given servos
#
def setAngle(servos,angle):
  print (angle)
  for id in servos:
    kit.servo[id].angle=angle
  time.sleep(0.3)

# Test Servo Software
servos=[]
args=len(sys.argv)
fromangle=0
toangle=180
step=1
if args>1:
  for port in range(1,args-1,1):
    servos.append(int(sys.argv[port]))
  anglestr=sys.argv[args-1]
  if "-" in anglestr:
    parts=anglestr.split("-") 
    fromangle=int(parts[0])
    toangle=int(parts[1])
  else:
    fromangle=int(anglestr)
    toangle=fromangle
else:
  servos.append(0)
  servos.append(1)
  servos.append(2)

if fromangle!=toangle:
  try:
    while True:
      for setangle in range(fromangle,toangle+step,step):
        setAngle(servos,setangle)
  except KeyboardInterrupt:
    print("Keyboard interrupt")
else:
  setAngle(servos,fromangle)

Evolution of Base

Since we'd like to use a Raspberry PI we couldn't use the orignal Base by regishu. Trying the one from https://github.com/yasaspeiris/aragog also did not work since our raspberry PI case hat a different size. So incrementally a new design was created:

Legtest 2

The three parts of a leg have been connected to the ports 10,11 and 12 and then the test was started with:

sudo python3 testadafruit.py 10 11 12 60-120

What Links Here

• BITPlan Self Driving RC Car