single_transform.py
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32 
33 import numpy
34 from numpy import matrix, vsplit, sin, cos, reshape, zeros, pi
35 import rospy
36 
37 import PyKDL
38 import yaml, math
39 
40 # This represents the transform for a single joint in the URDF
41 # parameters are x,y,z and rotation as angle-axis
42 
43 param_names = ['x','y','z','a','b','c']
44 
46  def __init__(self, config = [0, 0, 0, 0, 0, 0], name=""):
47  self._name = name
48  eval_config = [eval(str(x)) for x in config]
49  self._config = reshape(matrix(eval_config, float), (-1,1))
50 
51  rospy.logdebug("Initializing single transform %s with params [%s]", name, ", ".join(["% 2.4f" % x for x in eval_config]))
52  self.inflate(self._config)
53 
54  def calc_free(self, free_config):
55  return [x == 1 for x in free_config]
56 
57  def params_to_config(self, param_vec):
58  return param_vec.T.tolist()[0]
59 
60  # Convert column vector of params into config
61  def inflate(self, p):
62  self._config = p.copy() # Once we can back compute p from T, we don't need _config
63 
64  # Init output matrix
65  T = matrix( zeros((4,4,), float))
66  T[3,3] = 1.0
67 
68  # Copy position into matrix
69  T[0:3,3] = p[0:3,0]
70 
71  # Renormalize the rotation axis to be unit length
72  U,S,Vt = numpy.linalg.svd(p[3:6,0])
73  a = U[:,0]
74  rot_angle = S[0]*Vt[0,0]
75 
76  # Build rotation matrix
77  c = cos(rot_angle)
78  s = sin(rot_angle)
79  R = matrix( [ [ a[0,0]**2+(1-a[0,0]**2)*c, a[0,0]*a[1,0]*(1-c)-a[2,0]*s, a[0,0]*a[2,0]*(1-c)+a[1,0]*s],
80  [a[0,0]*a[1,0]*(1-c)+a[2,0]*s, a[1,0]**2+(1-a[1,0]**2)*c, a[1,0]*a[2,0]*(1-c)-a[0,0]*s],
81  [a[0,0]*a[2,0]*(1-c)-a[1,0]*s, a[1,0]*a[2,0]*(1-c)+a[0,0]*s, a[2,0]**2+(1-a[2,0]**2)*c] ] )
82 
83  T[0:3,0:3] = R
84  self.transform = T
85 
86  # Take transform, and convert into 6 param vector
87  def deflate(self):
88  # todo: This currently a hacky stub. To be correct, this should infer the parameter vector from the 4x4 transform
89  return self._config
90 
91  # Returns # of params needed for inflation & deflation
92  def get_length(self):
93  return len(param_names)
94 
95 
96 # Convert from rotation-axis-with-angle-as-magnitude representation to Euler RPY
98  angle = math.sqrt(sum([vec[i]**2 for i in range(3)]))
99  hsa = math.sin(angle/2.)
100  if epsEq(angle, 0):
101  return (0.,0.,0.)
102  quat = [vec[0]/angle*hsa, vec[1]/angle*hsa, vec[2]/angle*hsa, math.cos(angle/2.)]
103  rpy = quat_to_rpy(quat)
104  return rpy
105 
106 # Convert from Euler RPY to rotation-axis-with-angle-as-magnitude
108  if epsEq(vec[0], 0) and epsEq(vec[1], 0) and epsEq(vec[2], 0):
109  return [0.0, 0.0, 0.0]
110  quat = rpy_to_quat(vec)
111  angle = math.acos(quat[3])*2.0
112  hsa = math.sin(angle/2.)
113  axis = [quat[0]/hsa*angle, quat[1]/hsa*angle, quat[2]/hsa*angle]
114  return axis
115 
116 def rpy_to_quat(rpy):
117  return PyKDL.Rotation.RPY(rpy[0], rpy[1], rpy[2]).GetQuaternion()
118 
119 def quat_to_rpy(q):
120  return PyKDL.Rotation.Quaternion(q[0], q[1], q[2], q[3]).GetRPY()
121 
122 #return 1 if value1 and value2 are within eps of each other, 0 otherwise
123 def epsEq(value1, value2, eps = 1e-10):
124  if math.fabs(value1-value2) <= eps:
125  return 1
126  return 0
127 
def epsEq(value1, value2, eps=1e-10)


calibration_estimation
Author(s): Vijay Pradeep, Michael Ferguson
autogenerated on Fri Apr 2 2021 02:12:53