Lines Matching +full:in +full:- +full:and +full:- +full:around
2 * is the definition of +/- values practical or counterintuitive?
3 * are the definitions unambiguous and easy to follow?
13 that produce three-dimensional data in relation to the world where it is
18 defined in linear algebra.
22 and thus implying that the component should be mounted in a certain orientation
29 screen and (z) being depth, the axis perpendicular to the screen.
33 and (z) depth to be negative under the screen and positive in front of it,
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,
43 to this world. When using the mounting matrix, the sensor and device orientation
44 becomes identical and we can focus on the data as it relates to the surrounding
47 Device-to-world examples for some three-dimensional sensor types:
49 - Accelerometers have their world frame of reference toward the center of
53 this point. Up and down in the world relative to the device frame of
54 reference can thus be determined. and users would likely expect a value of
56 is held with its screen flat on the planets surface and 0 on the other axes,
57 as the gravity vector is projected 1:1 onto the sensors (z)-axis.
67 +--------+ +--------+
69 +--------+ +--------+
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
95 respect to the local earth geomagnetic reference frame where (y) is in the
96 ground plane and positive towards magnetic North, (x) is in the ground plane,
97 perpendicular to the North axis and positive towards the East and (z) is
98 perpendicular to the ground plane and positive upwards.
103 (---------)
113 (---------)
118 Sensors and driver can not and should not take care of this because there
119 are complex calculations and empirical data to be taken care of. We leave
124 If the device is placed at the equator and the top is pointing north, the
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 (---------)
154 To achieve this, use the device tree property "mount-matrix" for the sensor.
156 This supplies a 3x3 rotation matrix in the strict linear algebraic sense,
159 multiplied by this matrix to give the proper vectors values in three-dimensional
183 mechanically mounted in an ideal way and we need no transformation):
185 mount-matrix = "1", "0", "0",
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