应用领域：智能穿戴

方案类型：原型方案

主控芯片：STM32F411

方案概述

方案简介

基于STM32F411的步行者航迹推算技术(PDR)为一种辅助定位方式, 适用于中短程相对位置推测。

• 室外模式与GPS结合使用， 减少GPS开启时间，节约功耗

• 室内模式与WiFi、蓝牙结合使用，提高定位精度

• 高精度九轴融合算法，高准确率计步算法，机器学习获得最优参数

STM32F411

The STM32F411xC/xE devices are based on the high-performance ARM®Cortex® -M4 32-bit RISC core operating at a frequency of up to 100 MHz. The Cortex®-M4 core features a Floating point unit (FPU) single precision which supports all ARM single-precision data-processing instructions and data types. It also implements a full set of DSP instructions and a memory protection unit (MPU) which enhances application security.

The STM32F411xC/xE belongs to the STM32 Dynamic Efficiency™ product line (with products combining power efficiency, performance and integration) while adding a new innovative feature called Batch Acquisition Mode (BAM) allowing to save even more power consumption during data batching.

The STM32F411xC/xE incorporate high-speed embedded memories (up to 512 Kbytes of Flash memory, 128 Kbytes of SRAM), and an extensive range of enhanced I/Os and peripherals connected to two APB buses, two AHB bus and a 32-bit multi-AHB bus matrix.

All devices offer one 12-bit ADC, a low-power RTC, six general-purpose 16-bit timers including one PWM timer for motor control, two general-purpose 32-bit timers. They also feature standard and advanced communication interfaces.

Key Features

Dynamic Efficiency Line with BAM (Batch Acquisition Mode)

1.7 V to 3.6 V power supply

- 40°C to 85/105/125 °C temperature range

Core: ARM® 32-bit Cortex® -M4 CPU with FPU, Adaptive real-time accelerator (ART Accelerator™) allowing 0-wait state execution from Flash memory, frequency up to 100 MHz, memory protection unit, 125 DMIPS/1.25 DMIPS/MHz (Dhrystone 2.1), and DSP instructions

Memories

Up to 512 Kbytes of Flash memory

128 Kbytes of SRAM

Clock, reset and supply management

1.7 V to 3.6 V application supply and I/Os

POR, PDR, PVD and BOR

4-to-26 MHz crystal oscillator

Internal 16 MHz factory-trimmed RC

32 kHz oscillator for RTC with calibration

Internal 32 kHz RC with calibration

Power consumption

Run: 100 μA/MHz (peripheral off)

Stop (Flash in Stop mode, fast wakeup time): 42 μA Typ @ 25C; 65 μA max @25 °C

Stop (Flash in Deep power down mode, slow wakeup time): down to 9 μA @ 25 °C; 28 μA max @25 °C

Standby: 1.8 μA @25 °C / 1.7 V without RTC; 11 μA @85 °C @1.7 V

VBAT supply for RTC: 1 μA @25 °C

1×12-bit, 2.4 MSPS A/D converter: up to 16 channels

General-purpose DMA: 16-stream DMA controllers with FIFOs and burst support

Up to 11 timers: up to six 16-bit, two 32-bit timers up to 100 MHz, each with up to four IC/OC/PWM or pulse counter and quadrature (incremental) encoder input, two watchdog timers (independent and window) and a SysTick timer

Debug mode

Serial wire debug (SWD) & JTAG interfaces

Cortex® -M4 Embedded Trace Macrocell™

Up to 81 I/O ports with interrupt capability

Up to 78 fast I/Os up to 100 MHz

Up to 77 5 V-tolerant I/Os

Up to 13 communication interfaces

Up to 3 x I2 C interfaces (SMBus/PMBus)

Up to 3 USARTs (2 x 12.5 Mbit/s, 1 x 6.25 Mbit/s), ISO 7816 interface, LIN, IrDA, modem control)

Up to 5 SPI/I2Ss (up to 50 Mbit/s, SPI or I2S audio protocol), SPI2 and SPI3 with muxed full-duplex I2 S to achieve audio class accuracy via internal audio PLL or external clock

SDIO interface (SD/MMC/eMMC)

Advanced connectivity: USB 2.0 full-speed device/host/OTG controller with on-chip PHY

CRC calculation unit

96-bit unique ID

RTC: subsecond accuracy, hardware calendar

All packages (WLCSP49, LQFP64/100, UFQFPN48, UFBGA100) are ECOPACK® 2

CIRCUIT DIAGRAM

航迹推算

航迹推算是根据罗经和计程仪所指示的航向、航程，以及船舶操纵要素和风流要素等在不借助外界导航物标的条件下，求取航迹和船位的方法。

作用

航迹推算的作用是：

(1)驾驶员在任何情况下、任何时刻求取船位的基本方法;

(2)使驾驶员清晰地了解船舶在海上运动的连续轨迹，并且能够根据它推算出船舶在继续航行的前方是否存在航海危险;

(3)推算船位又是天文定位和无线电航仪定位的基础。

算法编辑

仅仅根据罗经和计程仪所提供的航向、航速和估计的风和流的影响，从

已知的起算点推算出有一定准确度的航迹和船位的航海作业。航迹推算从出航到目的地连续进行。在推算过程中应根据测定的船位适时更新起算点继续推算。航迹推算是航海者随时求取当前或未来的近似船位的基本方法，也是在无法得到观测船位时，确定船位的惟一方法。航迹推算是海图作业的基本内容，是天文定位(见天文航海)和无线电定位(见船舶无线电导航)的基础，也是预计接岸和到达目的地时间的依据。用机械方法或电子计算机方法记录航迹，可以不间断地显示出瞬时的推算船位。用惯性导航仪

求得的推算航迹已接近实际航迹。英、美等许多国家采用不计风和流的航迹推算作为海图作业的基础，所得船位称为积算船位;对风和流的影响加以修正后所得船位称为估算船位。航迹推算有求航迹和船位、求驾驶航向两类作业。

求航迹和船位

已知航向、航速、风和流求航迹和船位。一般有四种情况。①无风、流航行。船位可直接在航向线上

推算(图1) :由起算点画航向线,在线上按计程仪或主机转速量取航程,即得推算船位。②风中航行。风对在航船舶的影响同风速、风舷角、航速、船型和吃水等有关。因此，船舶一般都备有本船的风压差表，表中以风速和风舷角为引数列出不同航速与吃水的风压差角(ɑ)。风中航行推算船位(图2) :由航向线向下风按风压差角画出风中航迹线;在此线上按计程仪量取航程，即得推算船位(一般计程仪记录的对水航程已包括风的影响)③流中航行。船舶随流漂移，因此流中航迹推算要在对水航行矢量上加水流矢量才能求得推算船位(图3)。④风和流中航行。先求受风压影响的船位

，再由该点作水流矢量求得推算船位(图4)。

求驾驶航向

已知计划航迹向、航速、风和流，求驾驶航向。目的是使船舶能沿着计划航迹线航进。一般有三种情况。①风中航行。将风压差角向上风加于计划航迹向，即得驾驶航向。②流中航行。在计划航迹线上按流向、流速和航速作流压三角形，即可求得驾驶航向，以及实际航速和流压

差角 (β)(图5) 。③风流中航行。先作流压三角形，求出流中计划航迹线，再向上风加风压差角，即得风流中航行的驾驶航向。