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机器人往前方移动的速度为Vx,往左方平移的速度为Vy,逆时针旋转的角速度为ω。

同理,如果需要机器人向后移动,那么Vx为负值,顺时针旋转,则ω为负值。同理,如果需要机器人向后移动,那么Vx为负值;向右移动,Vy为负值;顺时针旋转,则ω为负值。

这些速度和角速度的计量单位均为公制单位,即分别为米每秒,和弧度每秒。

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Code Block
languagecpp
linenumberstrue
base_set_velocity_request_t req;


float vx = req.velocity_x_q16 / 65536.f;
float vy = req.velocity_y_q16 / 65536.f;
float omega = req.angular_velocity_q16 / 65536.f;

而这个指令的响应报文如下:(由于历史原因,响应报文中dx ,dy的单位是mm, dtheta的单位是度)

Code Block
languagecpp
firstline137
titlebase_deadreckon_response_t
linenumberstrue
typedef struct _base_deadreckon_response
{
    _s32 base_dx_mm_q16;
    _s32 base_dy_mm_q16;
    _s32 base_dtheta_degree_q16;
    _u8  status_bitmap;
} __attribute__((packed)) base_deadreckon_response_t;

...

Code Block
languagecpp
linenumberstrue
// 假设机器人是布局a

#ifndef PIf
#	define PIf 3.14159265f
#endif

#define COS30f	0.86602540f
#define SIN32fSIN30f  0.5f
#define R		0.18f  // robot radius: 18cm

static float wheel_odometer[3];

static void on_set_v_and_get_deadreckon(const base_set_velocity_request_t& req, base_deadreckon_response_t& resp)
{
    // calculate response
    float current_wheel_odometer[3];
    motion_get_wheel_odometer(current_wheel_odometer);

    float da = current_wheel_odometer[0] - wheel_odometer[0];
    float db = current_wheel_odometer[1] - wheel_odometer[1];
    float dc = current_wheel_odometer[2] - wheel_odometer[2];

	memcpy(wheel_odometer, current_wheel_odometer, sizeof(current_wheel_odometer));

    float dx = (db / COS30f - dc / COS30f) / 2
	float dy = (-da + db / SIN32fSIN30f + dc / SIN30f) / 3
	float dtheta = (da + db + dc) / 3

	resp.base_dx_mm_q16 = (_s32)(dx * 1000 * 65536);
	resp.base_dy_mm_q16 = (_s32)(dy * 1000 * 65536);
	resp.base_dtheta_degree_q16 = (_s32)(dtheta * 180 / PIf * 65536);
	resp.status_bitmap = 0; // 这个字段用以报告轮组的异常状态,请务必都填0

	// calculate wheel speed
	float vx = req.velocity_x_q16 / 65536.f;
	float vy = req.velocity_y_q16 / 65536.f;
	float omega = req.angular_velocity_q16 / 65536.f;

	float va = vy + R * omega;
	float vb = - vx * COS30f - vy * SIN30f + R * omega;
	float vc = vx * COS30f - vy * SIN30f + R * omega;

	motion_set_whellwheel_speed(va, vb, vc);
}