From 721db3c859a69179a9f956a53ae7e40cf0ca655b Mon Sep 17 00:00:00 2001
From: Erik Andresen <erik@vontaene.de>
Date: Sun, 15 Jul 2018 11:32:35 +0200
Subject: [PATCH] dwm1000: variance dependant on distance

---
 scripts/dwm1000.py | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/scripts/dwm1000.py b/scripts/dwm1000.py
index bf58657..15c4025 100755
--- a/scripts/dwm1000.py
+++ b/scripts/dwm1000.py
@@ -73,10 +73,10 @@ class DW1000(threading.Thread):
 
 	def run(self):
 		last_val = 10
-		while True:
+		while not rospy.is_shutdown():
 			val = self.get_value()
 			if abs(val - last_val)  > 10:
-				print "Ignoring values too far apart %s: %.2f - %.2f" % (self.name, val, last_val)
+				rospy.logwarn("Ignoring values too far apart %s: %.2f - %.2f", self.name, val, last_val)
 			elif not isnan(val):
 				self.dist = val + self.offset
 				self.last_update = datetime.now()
@@ -107,10 +107,6 @@ class Position:
 		self.speed_y = msg.twist.twist.linear.y
 		self.speed_z = msg.twist.twist.angular.z
 
-	"""
-	TODO:
-	- variance of kalman should be dependant on distance
-	"""
 	def filter(self, x, y):
 		# Correct estimation with speed
 		current_time = rospy.Time.now()
@@ -129,8 +125,14 @@ class Position:
 
 		# run kalman if new measurements are valid
 		if x != None and y != None:
+			print "Var", self.filter_x.R, self.filter_y.R
 			x = self.filter_x.run(x)
 			y = self.filter_y.run(y)
+
+			# Update covariance
+			dist = np.linalg.norm([x, y])
+			self.filter_x.R = np.polyval([0.017795,  -0.021832, 0.010968], dist)
+			self.filter_y.R = np.polyval([0.0060314, -0.013387, 0.0065049], dist)
 		else:
 			x = self.filter_x.x_est
 			y = self.filter_y.x_est
@@ -143,14 +145,14 @@ def handle_center_call(req):
 	diff = dwleft.distance_valid() - dwright.distance_valid()
 	dwleft.offset -= diff/2
 	dwright.offset += diff/2
-	print "Centering to %.2f %.2f" % (dwleft.offset, dwright.offset)
+	rospy.loginfo("Centering to %.2f %.2f", dwleft.offset, dwright.offset)
 	return DWM1000CenterResponse()
 
 if __name__ == "__main__":
-	rospy.init_node('DWM1000')
-	dwleft  = DW1000("uwb_dist_left",  0xc2, +0.02)
-	dwright = DW1000("uwb_dist_right", 0xc0, -0.02)
-	dist_l_r = 0.285
+	rospy.init_node('DWM1000', log_level=rospy.DEBUG)
+	dwleft  = DW1000("uwb_dist_left",  0xc2, +0.00)
+	dwright = DW1000("uwb_dist_right", 0xc0, -0.00)
+	dist_l_r = 0.285 # Distance between both DWM1000
 	rate = rospy.Rate(10)
 	pos = Position()
 	tf_broadcaster = tf.broadcaster.TransformBroadcaster()
@@ -160,7 +162,7 @@ if __name__ == "__main__":
 		dist_left = dwleft.distance_valid()
 		dist_right = dwright.distance_valid()
 		if dist_left == None or dist_right == None:
-			print "no valid sensor update"
+			rospy.logerr("no valid sensor update")
 			# run kalman prediction only
 			pos.filter(None, None)
 		else:
@@ -176,14 +178,14 @@ if __name__ == "__main__":
 				else:
 					dist_left += off/2
 					dist_right -= off/2
-			print "%.2f %.2f %.2f %.2f %s" % (dwleft.distance(), dwright.distance(), dist_left, dist_right, dir)
+			rospy.logdebug("%.2f %.2f %.2f %.2f %s", dwleft.distance(), dwright.distance(), dist_left, dist_right, dir)
 
 			a_r = (-dist_right**2 + dist_left**2 - dist_l_r**2) / (-2*dist_l_r)
 			x = dist_l_r/2 - a_r
 			t = dist_right**2 - a_r**2
 			if t >= 0:
 				y = sqrt(t)
-				print x,y
+				rospy.logdebug("x=%.2f, y=%.2f", x, y)
 				# Rotate 90 deg
 				x, y = (y, -x)
 
-- 
2.39.5