From d0c13eed893ea8d50dd8f6471af5a19c625d7842 Mon Sep 17 00:00:00 2001
From: Erik Andresen <erik@vontaene.de>
Date: Sun, 8 Jul 2018 10:34:10 +0200
Subject: [PATCH] dwm1000: Ignore outdated distance values

---
 scripts/dwm1000.py | 105 ++++++++++++++++++++++++++++-----------------
 1 file changed, 65 insertions(+), 40 deletions(-)

diff --git a/scripts/dwm1000.py b/scripts/dwm1000.py
index d36a5d2..a1dac53 100755
--- a/scripts/dwm1000.py
+++ b/scripts/dwm1000.py
@@ -9,6 +9,7 @@ import rospy
 import tf
 import numpy as np
 from math import *
+from datetime import datetime
 from i2c import i2c
 from time import sleep
 from std_msgs.msg import Float32
@@ -48,6 +49,7 @@ class DW1000(threading.Thread):
 		self.offset = offset
 		self.addr = addr
 		self.name = name
+		self.last_update = datetime.min
 
 		self.pub = rospy.Publisher(name, Float32, queue_size=16)
 
@@ -62,6 +64,12 @@ class DW1000(threading.Thread):
 	def distance(self):
 		return self.dist
 
+	# Returns each distance only if current
+	def distance_valid(self):
+		if (datetime.now() - self.last_update).seconds < 1:
+			return self.dist
+		return None
+
 	def run(self):
 		last_val = 10
 		while True:
@@ -70,6 +78,7 @@ class DW1000(threading.Thread):
 				print "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()
 				self.pub.publish(self.distance())
 				last_val = val
 			sleep(0.1)
@@ -97,6 +106,10 @@ 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()
@@ -113,9 +126,13 @@ class Position:
 		self.filter_x.x_est = pos[0]
 		self.filter_y.x_est = pos[1]
 
-		# run kalman
-		x = self.filter_x.run(x)
-		y = self.filter_y.run(y)
+		# run kalman if new measurements are valid
+		if x != None and y != None:
+			x = self.filter_x.run(x)
+			y = self.filter_y.run(y)
+		else:
+			x = self.filter_x.x_est
+			y = self.filter_y.x_est
 
 		self.last_time = current_time
 		return x,y
@@ -123,49 +140,57 @@ class Position:
 
 if __name__ == "__main__":
 	rospy.init_node('DW1000')
-	dwleft  = DW1000("uwb_dist_left",  0xc2, +0.0)
-	dwright = DW1000("uwb_dist_right", 0xc0, -0.0)
+	dwleft  = DW1000("uwb_dist_left",  0xc2, +0.02)
+	dwright = DW1000("uwb_dist_right", 0xc0, -0.02)
 	dist_l_r = 0.285
 	rate = rospy.Rate(10)
 	pos = Position()
 	tf_broadcaster = tf.broadcaster.TransformBroadcaster()
 
 	while not rospy.is_shutdown() and dwleft.is_alive() and dwright.is_alive():
-		dist_left = dwleft.distance()
-		dist_right = dwright.distance()
-		dir = "left" if (dist_left < dist_right) else "right"
-
-		diff = abs(dist_left - dist_right)
-		if diff >= dist_l_r:
-			# difference to high, correct to maximum
-			off = diff - dist_l_r + 0.01
-			if dist_left > dist_right:
-				dist_left -= off/2
-				dist_right += off/2
+		dist_left = dwleft.distance_valid()
+		dist_right = dwright.distance_valid()
+		if dist_left == None or dist_right == None:
+			print "no valid sensor update"
+			# run kalman prediction only
+			pos.filter(None, None)
+		else:
+			dir = "left" if (dist_left < dist_right) else "right"
+
+			diff = abs(dist_left - dist_right)
+			if diff >= dist_l_r:
+				# difference to high, correct to maximum
+				off = diff - dist_l_r + 0.01
+				if dist_left > dist_right:
+					dist_left -= off/2
+					dist_right += off/2
+				else:
+					dist_left += off/2
+					dist_right -= off/2
+			print "%.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
+				# Rotate 90 deg
+				x, y = (y, -x)
+
+				x, y = pos.filter(x, y)
+				tf_broadcaster.sendTransform((x, y, 0.0), (0, 0, 0, 1), rospy.Time.now(), "uwb_beacon", "base_footprint")
+
+				if VISULAIZE:
+					circle_left = plt.Circle((-dist_l_r/2, 0), dwleft.distance, color='red', fill=False)
+					circle_right = plt.Circle((dist_l_r/2, 0), dwright.distance, color='green', fill=False)
+					plt.gca().add_patch(circle_left)
+					plt.gca().add_patch(circle_right)
+					plt.grid(True)
+					plt.axis('scaled')
+					plt.show()
 			else:
-				dist_left += off/2
-				dist_right -= off/2
-		print "%.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
-			# Rotate 90 deg
-			x, y = (y, -x)
-
-			x, y = pos.filter(x, y)
-			tf_broadcaster.sendTransform((x, y, 0.0), (0, 0, 0, 1), rospy.Time.now(), "uwb_beacon", "base_footprint")
-
-			if VISULAIZE:
-				circle_left = plt.Circle((-dist_l_r/2, 0), dwleft.distance, color='red', fill=False)
-				circle_right = plt.Circle((dist_l_r/2, 0), dwright.distance, color='green', fill=False)
-				plt.gca().add_patch(circle_left)
-				plt.gca().add_patch(circle_right)
-				plt.grid(True)
-				plt.axis('scaled')
-				plt.show()
+				# No current position, still need up update kalman prediction
+				pos.filter(None, None)
 
 		rate.sleep()
-- 
2.39.5