scripts/move_base.py

   1 #!/usr/bin/env python
   2 # -*- coding: iso-8859-15 -*-
   3
   4 import rospy
   5 import tf
   6 import struct
   7 from i2c import *
   8 from math import *
   9 from geometry_msgs.msg import Twist
  10 from nav_msgs.msg import Odometry
  11 from diagnostic_msgs.msg import DiagnosticArray, DiagnosticStatus, KeyValue
  12
  13 WHEEL_DIST = 0.248
  14
  15 class MoveBase:
  16         def __init__(self):
  17                 rospy.init_node('wild_thumper_move_base')
  18                 rospy.Subscriber("cmd_vel", Twist, self.cmdVelReceived)
  19                 self.tf_broadcaster = tf.broadcaster.TransformBroadcaster()
  20                 self.pub_odom = rospy.Publisher("odom", Odometry, queue_size=16)
  21                 self.pub_diag = rospy.Publisher("diagnostics", DiagnosticArray, queue_size=16)
  22                 self.set_speed(0, 0)
  23                 rospy.loginfo("Init done")
  24                 i2c_write_reg(0x50, 0x90, struct.pack("BB", 1, 1)) # switch direction
  25                 self.run()
  26
  27         def run(self):
  28                 rate = rospy.Rate(20.0)
  29                 while not rospy.is_shutdown():
  30                         self.get_tle_err()
  31                         #self.get_odom()
  32                         #self.get_dist_forward()
  33                         #self.get_dist_backward()
  34                         #self.get_dist_left()
  35                         #self.get_dist_right()
  36                         rate.sleep()
  37
  38         def get_tle_err(self):
  39                 err = struct.unpack(">B", i2c_read_reg(0x50, 0x94, 1))[0]
  40
  41                 msg = DiagnosticArray()
  42                 msg.header.stamp = rospy.Time.now()
  43                 stat = DiagnosticStatus()
  44                 stat.name = "Motor: Error Status"
  45                 stat.level = DiagnosticStatus.OK if not err else DiagnosticStatus.ERROR
  46                 stat.message = "OK" if not err else "Error"
  47
  48                 stat.values.append(KeyValue("Motor 1", str(bool(err & (1 << 0)))))
  49                 stat.values.append(KeyValue("Motor 2", str(bool(err & (1 << 1)))))
  50                 stat.values.append(KeyValue("Motor 3", str(bool(err & (1 << 2)))))
  51                 stat.values.append(KeyValue("Motor 4", str(bool(err & (1 << 3)))))
  52
  53                 msg.status.append(stat)
  54                 self.pub_diag.publish(msg)
  55
  56
  57         def get_odom(self):
  58                 posx, posy, angle = struct.unpack(">fff", i2c_read_reg(0x50, 0x40, 12))
  59                 speed_trans, speed_rot = struct.unpack(">ff", i2c_read_reg(0x50, 0x38, 8))
  60                 current_time = rospy.Time.now()
  61
  62                 # since all odometry is 6DOF we'll need a quaternion created from yaw
  63                 odom_quat = tf.transformations.quaternion_from_euler(0, 0, angle)
  64
  65                 # first, we'll publish the transform over tf
  66                 self.tf_broadcaster.sendTransform((posx, posy, 0.0), odom_quat, current_time, "base_link", "odom")
  67
  68                 # next, we'll publish the odometry message over ROS
  69                 odom = Odometry()
  70                 odom.header.stamp = current_time
  71                 odom.header.frame_id = "/odom"
  72
  73                 # set the position
  74                 odom.pose.pose.position.x = posx
  75                 odom.pose.pose.position.y = posy
  76                 odom.pose.pose.position.z = 0.0
  77                 odom.pose.pose.orientation.x = odom_quat[0]
  78                 odom.pose.pose.orientation.y = odom_quat[1]
  79                 odom.pose.pose.orientation.z = odom_quat[2]
  80                 odom.pose.pose.orientation.w = odom_quat[3]
  81
  82                 # set the velocity
  83                 odom.child_frame_id = "base_link"
  84                 odom.twist.twist.linear.x = speed_trans
  85                 odom.twist.twist.linear.y = 0.0
  86                 odom.twist.twist.angular.z = speed_rot
  87
  88                 # publish the message
  89                 self.pub_odom.publish(odom)
  90
  91
  92         def set_speed(self, trans, rot):
  93                 i2c_write_reg(0x50, 0x50, struct.pack(">ff", trans, rot))
  94
  95         def cmdVelReceived(self, msg):
  96                 trans = msg.linear.x
  97                 rot = msg.angular.z # rad/s
  98                 self.set_speed(trans, rot)
  99
 100         # http://rn-wissen.de/wiki/index.php/Sensorarten#Sharp_GP2D12
 101         def get_dist_ir(self, num):
 102                 dev = i2c(0x52)
 103                 s = struct.pack("B", num)
 104                 dev.write(s)
 105                 dev.close()
 106
 107                 sleep(2e-6)
 108
 109                 dev = i2c(0x52)
 110                 s = dev.read(2)
 111                 dev.close()
 112
 113                 val = struct.unpack(">H", s)[0]
 114                 return 15221/(val - -276.42)/100;
 115
 116         def get_dist_srf(self, num):
 117                 dev = i2c(0x52)
 118                 s = struct.pack("B", num)
 119                 dev.write(s)
 120                 dev.close()
 121
 122                 sleep(50e-3)
 123
 124                 dev = i2c(0x52)
 125                 s = dev.read(2)
 126                 dev.close()
 127
 128                 return struct.unpack(">H", s)[0]/1000.0
 129
 130         def get_dist_left(self):
 131                 dist = self.get_dist_ir(0x1)
 132
 133         def get_dist_right(self):
 134                  dist = self.get_dist_ir(0x3)
 135
 136         def get_dist_forward(self):
 137                 dist = self.get_dist_srf(0x5)
 138
 139         def get_dist_backward(self):
 140                 dist = self.get_dist_srf(0x7)
 141
 142
 143 if __name__ == "__main__":
 144         MoveBase()