Lines Matching +full:relative +full:- +full:axis
2 * is the definition of +/- values practical or counterintuitive?
13 that produce three-dimensional data in relation to the world where it is
23 relative to some specific device frame of reference.
29 screen and (z) being depth, the axis perpendicular to the screen.
36 A sensor can be mounted in any angle along the axes relative to the frame of
37 reference. This means that the sensor may be flipped upside-down, left-right,
38 or tilted at any angle relative to the frame of reference.
47 Device-to-world examples for some three-dimensional sensor types:
49 - Accelerometers have their world frame of reference toward the center of
52 device relative to the center of the planet, i.e. relative to its surface at
53 this point. Up and down in the world relative to the device frame of
55 9.81 m/s^2 upwards along the (z) axis, i.e. out of the screen when the device
57 as the gravity vector is projected 1:1 onto the sensors (z)-axis.
67 +--------+ +--------+
69 +--------+ +--------+
78 its top towards surface, you get a negative y axis.
80 (---------)
81 ! ! y: -g
85 ! ! x: +g <- z: +g -> x: -g
90 (---------)
93 - Magnetometers (compasses) have their world frame of reference relative to the
94 geomagnetic field. The system orientation vis-a-vis the world is defined with
97 perpendicular to the North axis and positive towards the East and (z) is
103 (---------)
113 (---------)
129 - Gyroscopes detects the movement relative the device itself. The angular
131 device on a flat surface and spin it around the z axis (such as rotating a
133 along the (z) axis if rotated clockwise, and a positive value if rotated
134 counter-clockwise according to the right-hand rule.
137 (---------) y > 0
138 ! ! v---\
141 ! ! <--\
143 ! 1 2 3 ! --/
147 (---------)
151 relative orientation of any given sensor of this type with respect to the
154 To achieve this, use the device tree property "mount-matrix" for the sensor.
157 to orient the senor axes relative to a desired point of reference. This means
159 multiplied by this matrix to give the proper vectors values in three-dimensional
160 space, relative to the device or world point of reference.
185 mount-matrix = "1", "0", "0",
189 The sensor is mounted 30 degrees (Pi/6 radians) tilted along the X axis, so we
190 compensate by performing a -30 degrees rotation around the X axis:
192 mount-matrix = "1", "0", "0",
194 "0", "-0.5", "0.866";
196 The sensor is flipped 180 degrees (Pi radians) around the Z axis, i.e. mounted
197 upside-down:
199 mount-matrix = "0.998", "0.054", "0",
200 "-0.054", "0.998", "0",
203 ???: this does not match "180 degrees" - factors indicate ca. 3 degrees compensation