bcar 0.2.1

BCar is a Rust library with basic bicycle car computations.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149

//! Basic properties of bicycle car.

/// Structure to hold car motion.
#[derive(Copy, Clone, PartialEq, Debug)]
pub struct Motion {
    pub speed: f64,
    pub steer: f64,
}

impl Motion {
    pub fn new(speed: f64, steer: f64) -> Motion {
        Motion {speed, steer}
    }

    /// Return default motion.
    ///
    ///
    /// Examples
    /// ========
    ///
    /// ```
    /// let m = bcar::Motion::default();
    /// assert_eq!(m, bcar::Motion::new(0.0, 0.0));
    /// ```
    pub fn default() -> Motion {
        Motion {speed: 0.0, steer: 0.0}
    }
}

/// Structure to hold car dimensions.
#[derive(Copy, Clone, PartialEq, Debug)]
pub struct Size {
    pub curb_to_curb: f64,
    pub width: f64, // width
    pub wheelbase: f64, // wheelbase
    pub distance_to_front: f64, // from the rear axle center
    pub length: f64,
}

impl Size {
    pub fn new(
        curb_to_curb: f64,
        width: f64,
        wheelbase: f64,
        distance_to_front: f64,
        length: f64,
    ) -> Size {
        Size {
            curb_to_curb,
            width,
            wheelbase,
            distance_to_front,
            length,
        }
    }

    /// Return default size of Porsche car.
    ///
    /// Default size is based on [Porsche Panamera 971 dimensions](https://www.porsche.com/international/models/panamera/panamera-turbo-models/panamera-turbo/featuresandspecs/).
    ///
    ///
    /// Examples
    /// ========
    ///
    /// ```
    /// let s = bcar::Size::default_porsche();
    /// assert_eq!(s, bcar::Size::new(11.8872, 2.165, 2.950, 3.9865, 5.049));
    /// ```
    pub fn default_porsche() -> Size {
        Size {
            curb_to_curb: 11.8872,
            width: 2.165,
            wheelbase: 2.950,
            distance_to_front: 3.9865,
            length: 5.049,
        }
    }

    /// Return default size of Fiat car.
    ///
    /// Default size is based on [Fiat Punto](https://en.wikipedia.org/wiki/Fiat_Punto).
    ///
    ///
    /// Examples
    /// ========
    ///
    /// ```
    /// let s = bcar::Size::default_fiat();
    /// assert_eq!(s, bcar::Size::new(10.820, 1.625, 2.450, 3.105, 3.760));
    /// ```
    pub fn default_fiat() -> Size {
        Size {
            curb_to_curb: 10.820,
            width: 1.625,
            wheelbase: 2.450,
            distance_to_front: 3.105,
            length: 3.760,
        }
    }
    pub fn default() -> Size {
        Size::default_fiat()
    }

    pub fn diagonal_length(&self) -> f64 {
        (self.width.powi(2) + self.length.powi(2)).sqrt()
    }

    /// Return maximum steering angle for the car properties.
    ///
    /// Examples
    /// ========
    ///
    ///     let s = bcar::Size::default_fiat();
    ///     assert!((s.max_steer() - 0.5483439469279819).abs() < 1e-10);
    ///     let s = bcar::Size::default_porsche();
    ///     assert!((s.max_steer() - 0.6263322191718842).abs() < 1e-10);
    pub fn max_steer(&self) -> f64 {
        // atan of wb / mtr, where mtr = ((ctc/2)^2 - wb^2)^0.5 - w/2
        self.wheelbase.atan2((
            (self.curb_to_curb/2.0).powi(2)
            - self.wheelbase.powi(2)
        ).sqrt() - self.width/2.0)
    }

    /// Return the length of the perfect parking slot.
    ///
    /// The width of the slot is the same as the width of the car.
    ///
    /// References
    /// ----------
    ///
    /// - Simon R. Blackburn *The Geometry of Perfect Parking*
    /// - https://www.ma.rhul.ac.uk/SRBparking
    pub fn perfect_parking_slot_length(&self) -> f64 {
        let r = self.curb_to_curb / 2.0;
        let l = self.wheelbase;
        let k = self.distance_to_front - self.wheelbase;
        let w = self.width;

        self.length
        + (
            (r * r - l * l)
            + (l + k).powi(2)
            - ((r * r - l * l).sqrt() - w).powi(2)
        ).sqrt()
        - l
        - k
    }
}