text: import gym
  from gym import spaces
  from gym.utils import seeding
  import numpy as np
  from os import path
  
  from servorobots.components.dc_motor import GearedDcMotor
  from servorobots.components.dc_motor import TimestampInput
  
  import servorobots.tools.utils as utils
  
  class PendulumEnv(gym.Env):
      metadata = {
          'render.modes' : ['human', 'rgb_array'],
          'video.frames_per_second' : 30
      }
  
      def __init__(self, g=10.0, latency=0):
  
  
          self.max_speed = 8
          self.max_torque = utils.ParamRandomizer(2.0, 0.5)
          self.dt=.05
          self.time = 0
          self.g = g
          self.m = 1.
          self.l = 1.
          self.viewer = None
          self.motor = GearedDcMotor(R=4, Kv=5, K_viscous=0.0006, K_load=3, timestep=self.dt, latency=latency, V_max=1000)
  
          high = np.array([1., 1., self.max_speed])
          self.action_space = spaces.Box(low=-1, high=1, shape=(1,), dtype=np.float32)
          self.observation_space = spaces.Box(low=-high, high=high, dtype=np.float32)
  
          self.seed()
  
      def seed(self, seed=None):
          self.np_random, seed = seeding.np_random(seed)
          return [seed]
  
      def step(self,u):
          th, thdot = self.state # th := theta
  
          g = self.g
          m = self.m
          l = self.l
          dt = self.dt
          u = np.clip(u, -self.max_torque.value, self.max_torque.value)[0]
  
          torque, current = self.motor.torque_from_voltage(
                                          TimestampInput(u * 85, self.time), thdot)
          # print("Torque, U")
          # print(torque)
          # print(u)
          u = torque
  
          self.last_u = u # for rendering
          costs = angle_normalize(th)**2 + .1*thdot**2 + .001*(u**2)
  
          newthdot = thdot + (-3*g/(2*l) * np.sin(th + np.pi) + 3./(m*l**2)*u) * dt
          newth = th + newthdot*dt
          newthdot = np.clip(newthdot, -self.max_speed, self.max_speed) #pylint: disable=E1111
  
          self.state = np.array([newth, newthdot])
          self.time = self.time + dt
          return self._get_obs(), -costs, False, {}
  
      def reset(self):
  
  
          self.max_torque.randomize(1)
  
          # print(self.max_torque.value)
          high = np.array([np.pi, 1])
          self.state = self.np_random.uniform(low=-high, high=high)
          self.last_u = None
          return self._get_obs()
  
      def _get_obs(self):
          theta, thetadot = self.state
          return np.array([np.cos(theta), np.sin(theta), thetadot])
  
      def render(self, mode='human'):
  
          if self.viewer is None:
              from gym.envs.classic_control import rendering
              self.viewer = rendering.Viewer(500,500)
              self.viewer.set_bounds(-2.2,2.2,-2.2,2.2)
              rod = rendering.make_capsule(1, .2)
              rod.set_color(.8, .3, .3)
              self.pole_transform = rendering.Transform()
              rod.add_attr(self.pole_transform)
              self.viewer.add_geom(rod)
              axle = rendering.make_circle(.05)
              axle.set_color(0,0,0)
              self.viewer.add_geom(axle)
              fname = path.join(path.dirname(__file__), "assets/clockwise.png")
              self.img = rendering.Image(fname, 1., 1.)
              self.imgtrans = rendering.Transform()
              self.img.add_attr(self.imgtrans)
  
          self.viewer.add_onetime(self.img)
          self.pole_transform.set_rotation(self.state[0] + np.pi/2)
          if self.last_u:
              self.imgtrans.scale = (-self.last_u/2, np.abs(self.last_u)/2)
  
          return self.viewer.render(return_rgb_array = mode=='rgb_array')
  
      def close(self):
          if self.viewer:
              self.viewer.close()
              self.viewer = None
  
  def angle_normalize(x):
      return (((x+np.pi) % (2*np.pi)) - np.pi)