Create imu.py

test/imu.py

@@ -0,0 +1,69 @@
+# taken from https://github.com/pms67/Attitude-Estimation/blob/master/imu.py
+import smbus
+import math
+from time import sleep
+
+class IMU:
+        
+    def __init__(self):
+        
+        self.power_mgmt_1 = 0x6b
+        self.power_mgmt_2 = 0x6c
+        self.addr = 0x68
+        
+        self.bus = smbus.SMBus(1)
+        self.bus.write_byte_data(self.addr, self.power_mgmt_1, 0)
+        
+        print("[IMU] Initialised.")
+    
+    # rad/s
+    def get_gyro_bias(self, N=100):
+        bx = 0.0
+        by = 0.0
+        bz = 0.0
+        
+        for i in range(N):
+            [gx, gy, gz] = self.get_gyro()
+            bx += gx
+            by += gy
+            bz += gz
+            sleep(0.01)
+            
+        return [bx / float(N), by / float(N), bz / float(N)]            
+        
+    # rad/s
+    def get_gyro(self):
+        gx = self.read_word_2c(0x43) * math.pi / (180.0 * 131.0)
+        gy = self.read_word_2c(0x45) * math.pi / (180.0 * 131.0)
+        gz = self.read_word_2c(0x47) * math.pi / (180.0 * 131.0)
+        return [gx, gy, gz]        
+        
+    # m/s^2
+    def get_acc(self):
+        ax = self.read_word_2c(0x3b) / 16384.0
+        ay = self.read_word_2c(0x3d) / 16384.0
+        az = self.read_word_2c(0x3f) / 16384.0
+        return [ax, ay, az]
+    
+    # rad
+    def get_acc_angles(self):
+        [ax, ay, az] = self.get_acc()
+        phi = math.atan2(ay, math.sqrt(ax ** 2.0 + az ** 2.0))
+        theta = math.atan2(-ax, math.sqrt(ay ** 2.0 + az ** 2.0))
+        return [phi, theta]
+      
+    def read_byte(self, reg_adr):
+        return self.bus.read_byte_data(self.addr, reg_adr)
+    
+    def read_word(self, reg_adr):
+        high = self.bus.read_byte_data(self.addr, reg_adr)
+        low = self.bus.read_byte_data(self.addr, reg_adr + 1)
+        val = (high << 8) + low
+        return val
+    
+    def read_word_2c(self, reg_adr):
+        val = self.read_word(reg_adr)
+        if (val >= 0x8000):
+            return -((65535 - val) + 1)
+        else:
+            return val