Hi there,

The Tiva C used for this project didn't work out for me. My boards were defective and I got fed up with them so I used an Arduino instead. I ported your Tiva C code to Arduino C.

Would you like me to create a Pull Request for this repository with my ported code?

Thanks for the book,

Peter Chau

subscribing to 'cmd_vel' did not work for us.
In our case, your previous commit 'cmd_vel_mux/input/teleop' worked fine.

After creating Pyaiml package as instructed with:

catkin_create_pkg ros_aiml rospy std_msgs sound_play

I copied the files from chapter 9 into ros_aiml package file.

I ran catkin_make and sourced the /devel/setup.bash

I then changed launch files to:

For some reason the error below constantly appears. Scripts folder does contain
the python scripts. Not sure whats happening.

ERROR: cannot launch node of type [ros_aiml/aiml_server.py]: can't locate node [aiml_server.py] in package [ros_aiml]
process[soundplay_node-2]: started with pid [7720]
ERROR: cannot launch node of type [ros_aiml/aiml_tts_client.py]: can't locate node [aiml_tts_client.py] in package [ros_aiml]
ERROR: cannot launch node of type [ros_aiml/aiml_speech_recog_client.py]: can't locate node [aiml_speech_recog_client.py] in package [ros_aiml]

Hello:
your diff_tf.cpp has ros::spinOnce() so I know how to call Odometry_calc::leftencoderCb() and Odometry_calc::rightcoderCb().

      But I found your diff_tf.py and pid_velocity.py don't rospy.spinOnce().I wonder how to call callback function?

      Looking forward to your reply.Thank you.

Hello

I have the Chefbot successfully setup. Instead of using the tiva launch pad board. I am using the arduin mega and a pololu MD25 motor controller with integrated encoders. http://www.robot-electronics.co.uk/htm/md25i2c.htm. The arduino-mega talks to the MD25 by sending the the range of -128 (full reverse) 0 (Stop) 127 (full forward). What edits should be made on the pid_velocity.py or other scripts to accommodate this? For example what to do when dealing with theshold value or min-out and min-out.

Hope you can help.

Cheers.

Hello.

I have been trying to run cv_bridge_demo.py using the Intel real sense camera. The error below constantly keeps appearing . Some forums say its to do with the depth camera mismatch.

Not sure ! hope you can help. its on chapter 7.

cv_bridge_demo.py:96: ComplexWarning: Casting complex values to real discards the imaginary part depth_array = np.array(depth_image, dtype=np.float32)

Do you answer questions on here, not directly about your robot but about differential drive and how you used it?

I have trouble viewing color images from R200 realsense camera using the python-opencv interface.
The window is blank when I run this script.
When I comment out'cv2.namedWindow("Image window", 1)', it shows the first image.

-P

import roslib
import sys
import rospy
import cv2
from std_msgs.msg import String
from geometry_msgs.msg import Twist
from sensor_msgs.msg import Image
from rospy.numpy_msg import numpy_msg
#from rospy_tutorials.msg import Floats
from cv_bridge import CvBridge, CvBridgeError
import numpy as np
import math;
import cv2;
#import matplotlib.pyplot as plt;
import sys;
#import caffe;
import socket;
#from sklearn import datasets;
import subprocess;

import message_filters
from rospy.numpy_msg import numpy_msg
import time
#####################

import os.path

class image_converter:

Initializing variables, publishers and subscribers

def init(self):
print 'show window'
cv2.namedWindow("Image window", 1)

print 'start bridge and subscribe'

self.bridge = CvBridge()

self.image_sub = rospy.Subscriber("/camera/rgb/image_color", Image, self.callback)

The main callback that processes the color and depth data.

def callback(self,color):

start = time.time()
# acquiring color and depth data (from ROS-python tutorial)
try:
  
  frame = self.bridge.imgmsg_to_cv2(color, "bgr8")
except CvBridgeError, e:
  print e
  
frame = np.array(frame, dtype=np.uint8)

cv2.imshow("Image window", frame)
print 'test'
cv2.waitKey(0)

def main(args):
ic = image_converter()
rospy.init_node('image_converter', anonymous=True)
try:
rospy.spin()
except KeyboardInterrupt:
print "Shutting down"
cv2.destroyAllWindows()

if name == 'main':
main(sys.argv)

thanks for your excellent book.

in
chefbot_bringup/scripts/pid_velocity.py

        self.Kp = rospy.get_param('~Kp',10)
        self.Ki = rospy.get_param('~Ki',10)
        self.Kd = rospy.get_param('~Kd',0.001)

however, in the book and the launch file
chefbot_bringup/launch/robot_standalone.launch

      <rosparam param="Kp">400</rosparam>
      <rosparam param="Ki">100</rosparam>
      <rosparam param="Kd">0</rosparam>

There is a significant difference between the defaults values in the python pid code and what you finally used. I am also guessing that the parameter ticks_meter (which depends on hardware encoder resolution * gear reduction) might influence the final Kp/Ki/Kd.
You must have somehow tuned your PID controller. But -- unless i missed it -- it says nothing about the procedure you used to tune it. I'm complete noob about PID.
Wikipedia does mention a manual procedure, but i could not implement it successfully with my own hard (in particular my ticks_meters value (that i did calibrate following its specific section in the book), is much lower.

Bottom line : how did you tune the Ki/Kp/Kd values of your pid controller?