Dev/dc motor transmission (#27)

* Add translated transmission class

* Add docs and unit tests

* Add function for calculating speed

* fixed

build.gradle

@@ -32,7 +32,7 @@ dependencies {
 }
 
 group = 'org.team5499'
-version = '2.2.0'
+version = '2.2.1'
 
 task sourcesJar(type: Jar) {
     from sourceSets.main.allJava

src/main/kotlin/org/team5499/monkeyLib/math/physics/DCMotorTransmission.kt

@@ -5,16 +5,25 @@ package org.team5499.monkeyLib.math.physics
  * and efficiency losses).  The motor is assumed to be symmetric forward/reverse.
  *
  * @property speedPerVolt kV, or rad/s per V (no load)
- * @property torquePerVolt N•m per V (stall)
+ * @property torquePerVolt N•m per Amp (stall)
  * @property frictionVoltage the voltage needed to overcome static
+ * @property stallAmperage the stall amperage at 12 volts
  */
 class DCMotorTransmission(
     val speedPerVolt: Double,
     val torquePerVolt: Double,
-    val frictionVoltage: Double
+    val frictionVoltage: Double,
+    val stallAmperage: Double
 ) {
     // TODO add electrical constants?  (e.g. current)
 
+    val torquePerAmp: Double
+    val internalResistance: Double
+
+    init {
+        torquePerAmp = torquePerVolt * 12.0 / stallAmperage
+        internalResistance = 12.0 / stallAmperage
+    }
     /**
      * Returns the idle speed of the motor at this voltage
      *
@@ -87,4 +96,16 @@ class DCMotorTransmission(
         }
         return torque / torquePerVolt + outputSpeed / speedPerVolt + modifiedFrictionVoltage
     }
+
+    /**
+     * Get the theoretical speed for voltage and amperage.
+     *
+     * @param voltage
+     * @param amperage
+     * @return speed rad/s
+     */
+    fun getSpeedForVoltageAndAmperage(voltage: Double, amperage: Double): Double {
+        var modifiedVoltage = voltage - frictionVoltage
+        return (modifiedVoltage - amperage * internalResistance) * speedPerVolt
+    }
 }

src/test/kotlin/tests/math/physics/DCMotorTransmissionTest.kt

@@ -6,7 +6,7 @@ import org.junit.Assert.assertEquals
 import org.team5499.monkeyLib.math.physics.DCMotorTransmission
 
 class DCMotorTransmissionTest {
-    val motor = DCMotorTransmission(1000.0, 0.5, 1.0)
+    val motor = DCMotorTransmission(1000.0, 0.5, 1.0, 120.0)
     val stallTorque = 5.5 // N•m
     val freeSpeed = 11000.0 // rad/s
     val epsilon = 0.1
@@ -31,4 +31,11 @@ class DCMotorTransmissionTest {
         assertEquals(0.5, motor.torquePerVolt, 0.0)
         assertEquals(1.0, motor.frictionVoltage, 0.0)
     }
+
+    @Test
+    fun speedForVoltageAndAmperageTest() {
+        val predictedSpeed = motor.getSpeedForVoltageAndAmperage(6.0, 24.0)
+        println(predictedSpeed)
+        assertEquals(2600.0, predictedSpeed, epsilon)
+    }
 }