added basic motion

jetracer/nvidia_racecar.py

@@ -7,6 +7,7 @@ class NvidiaRacecar(Racecar):
 
     i2c_address = traitlets.Integer(default_value=0x40)
     steering_gain = traitlets.Float(default_value=-0.65)
+    steering_offset = traitlets.Float(default_value=0)
     steering_channel = traitlets.Integer(default_value=0)
     throttle_gain = traitlets.Float(default_value=0.8)
     throttle_channel = traitlets.Integer(default_value=1)
@@ -19,8 +20,8 @@ def __init__(self, *args, **kwargs):
 
     @traitlets.observe('steering')
     def _on_steering(self, change):
-        self.steering_motor.throttle = change['new'] * self.steering_gain.value
+        self.steering_motor.throttle = change['new'] * self.steering_gain + self.steering_offset
 
     @traitlets.observe('throttle')
     def _on_throttle(self, change):
-        self.throttle_motor.throttle = change['new'] * self.throttle_gain.value
+        self.throttle_motor.throttle = change['new'] * self.throttle_gain

jetracer/racecar.py

@@ -2,5 +2,23 @@
 
 
 class Racecar(traitlets.HasTraits):
-    steering = traitlets.Float(min=-1.0, max=1.0)
-    throttle = traitlets.Float(min=-1.0, max=1.0)
+    steering = traitlets.Float()
+    throttle = traitlets.Float()
+
+    @traitlets.validate('steering')
+    def _clip_steering(self, proposal):
+        if proposal['value'] > 1.0:
+            return 1.0
+        elif proposal['value'] < -1.0:
+            return 1.0
+        else:
+            return proposal['value']
+
+    @traitlets.validate('throttle')
+    def _clip_throttle(self, proposal):
+        if proposal['value'] > 1.0:
+            return 1.0
+        elif proposal['value'] < -1.0:
+            return 1.0
+        else:
+            return proposal['value']

notebooks/basic_motion/basic_motion.ipynb

@@ -1,11 +1,154 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Execute the following block of code by selecting it and clicking ``ctrl + enter`` to create an ``NvidiaRacecar`` class.  "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from jetracer.nvidia_racecar import NvidiaRacecar\n",
+    "\n",
+    "car = NvidiaRacecar()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The ``NvidiaRacecar`` implements the ``Racecar`` class, so it has two attributes ``throttle`` and ``steering``. \n",
+    "\n",
+    "We can assign values in the range ``[-1, 1]`` to these attributes.  Execute the following to set the steering to 0.4.\n",
+    "\n",
+    "> If the car does not respond, it may still be in ``manual`` mode.  Flip the manual override switch on the RC transmitter."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "car.steering = 0.3"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The ``NvidiaRacecar`` class has two values ``steering_gain`` and ``steering_bias`` that can be used to calibrate the steering.\n",
+    "\n",
+    "We can view the default values by executing the cells below."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "print(car.steering_gain)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "print(car.steering_offset)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The final steering value is computed using the equation\n",
+    "\n",
+    "$y = a \\times x + b$\n",
+    "\n",
+    "Where,\n",
+    "\n",
+    "* $a$ is ``car.steering_gain``\n",
+    "* $b$ is ``car.steering_offset``\n",
+    "* $x$ is ``car.steering``\n",
+    "* $y$ is the value written to the motor driver\n",
+    "\n",
+    "You can adjust these values calibrate the car so that setting a value of ``0`` moves forward, and setting a value of ``1`` goes fully right, and ``-1`` fully left."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "To set the throttle of the car to ``0.2``, you can call the following.\n",
+    "\n",
+    "> Give JetRacer lots of space to move, and be ready on the manual override, JetRacer is *fast*"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "car.throttle = 0.0"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The throttle also has a gain value that could be used to control the speed response.  The throttle output is computed as\n",
+    "\n",
+    "$y = a \\times x$\n",
+    "\n",
+    "Where,\n",
+    "\n",
+    "* $a$ is ``car.throttle_gain``\n",
+    "* $x$ is ``car.throttle``\n",
+    "* $y$ is the value written to the speed controller\n",
+    "\n",
+    "Execute the following to print the default gain"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {},
    "outputs": [],
-   "source": []
+   "source": [
+    "print(car.throttle_gain)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Set the following to limit the throttle to half"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "car.throttle_gain = 0.5"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "That's it for this notebook!"
+   ]
   }
  ],
  "metadata": {
@@ -24,7 +167,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.2"
+   "version": "3.6.8"
   }
  },
  "nbformat": 4,

setup.py

@@ -6,5 +6,6 @@
     description='An easy to use AI racecar powered by NVIDIA Jetson Nano',
     packages=find_packages(),
     install_requires=[
+        'adafruit-circuitpython-servokit'
     ],
 )