Module TeachMyAgent.environments.envs.bodies.walkers.ClassicBipedalBody

Classes

class ClassicBipedalBody (scale, motors_torque=80, nb_steps_under_water=600, reset_on_hull_critical_contact=False)

New version of the Bipedal walker implemented in https://gym.openai.com/envs/BipedalWalker-v2/.

In the initial version, the embodiment is created with an angle on legs, but position are not set according to this. This results in bodies with wrong positions that Box2D's solver has to reposition at the first step of the environment. This new version uses straight legs and fixed bad positions.

Creates a bipedal walker.

Args

scale

Scale value used in the environment (to adapt the embodiment to its environment)

motors_torque

Maximum torque the embodiment can use on its motors

nb_steps_under_water

How many consecutive steps the embodiment can survive under water

reset_on_hull_critical_contact

Whether a contact detected with the head should stop the episode

Expand source code

class ClassicBipedalBody(WalkerAbstractBody):
    '''
        New version of the Bipedal walker implemented in https://gym.openai.com/envs/BipedalWalker-v2/.

        In the initial version, the embodiment is created with an angle on legs, but position are not set according to this.
        This results in bodies with wrong positions that Box2D's solver has to reposition at the first step of the environment.
        This new version uses straight legs and fixed bad positions.
    '''
    def __init__(self, scale, motors_torque=80, nb_steps_under_water=600, reset_on_hull_critical_contact=False):
        '''
            Creates a bipedal walker.

            Args:
                scale: Scale value used in the environment (to adapt the embodiment to its environment)
                motors_torque: Maximum torque the embodiment can use on its motors
                nb_steps_under_water: How many consecutive steps the embodiment can survive under water
                reset_on_hull_critical_contact: Whether a contact detected with the head should stop the episode
        '''
        super(ClassicBipedalBody, self).__init__(scale, motors_torque, nb_steps_under_water)
        self.LEG_DOWN = 3 / self.SCALE # 0 = center of hull
        self.LEG_W, self.LEG_H = 8 / self.SCALE, 34 / self.SCALE
        self.TORQUE_PENALTY = 0.00035
        self.reset_on_hull_critical_contact = reset_on_hull_critical_contact

        self.AGENT_WIDTH = HULL_BOTTOM_WIDTH / self.SCALE
        self.AGENT_HEIGHT = 17 / self.SCALE + \
                            self.LEG_H * 2 - self.LEG_DOWN
        self.AGENT_CENTER_HEIGHT = self.LEG_H * 2 + self.LEG_DOWN

    def draw(self, world, init_x, init_y, force_to_center):
        HULL_FIXTURES = [
            fixtureDef(
                shape=polygonShape(vertices=[(x / self.SCALE, y / self.SCALE) for x, y in polygon]),
                density=5.0,
                friction=0.1,
                categoryBits=0x20,
                maskBits=0x000F)  # 0.99 bouncy
            for polygon in HULL_POLYGONS
        ]

        LEG_FD = fixtureDef(
            shape=polygonShape(box=(self.LEG_W / 2, self.LEG_H / 2)),
            density=1.0,
            restitution=0.0,
            categoryBits=0x20,
            maskBits=0x000F)

        LOWER_FD = fixtureDef(
            shape=polygonShape(box=(0.8 * self.LEG_W / 2, self.LEG_H / 2)),
            density=1.0,
            restitution=0.0,
            categoryBits=0x20,
            maskBits=0x000F)

        hull = world.CreateDynamicBody(
            position=(init_x, init_y),
            fixtures=HULL_FIXTURES
        )
        hull.color1 = (0.5, 0.4, 0.9)
        hull.color2 = (0.3, 0.3, 0.5)
        hull.ApplyForceToCenter((force_to_center, 0), True)

        hull.userData = CustomBodyUserData(True, is_contact_critical=self.reset_on_hull_critical_contact, name="hull")
        self.body_parts.append(hull)
        self.reference_head_object = hull

        for i in [-1, +1]:
            leg = world.CreateDynamicBody(
                position=(init_x, init_y - self.LEG_H / 2 - self.LEG_DOWN),
                #angle=(i * 0.05),#2°
                fixtures=LEG_FD
            )
            leg.color1 = (0.6 - i / 10., 0.3 - i / 10., 0.5 - i / 10.)
            leg.color2 = (0.4 - i / 10., 0.2 - i / 10., 0.3 - i / 10.)
            rjd = revoluteJointDef(
                bodyA=hull,
                bodyB=leg,
                anchor=(init_x, init_y - self.LEG_DOWN),
                enableMotor=True,
                enableLimit=True,
                maxMotorTorque=self.MOTORS_TORQUE,
                motorSpeed=i,
                lowerAngle=-0.8,
                upperAngle=1.1,
            )

            leg.userData = CustomBodyUserData(False, name="leg")
            self.body_parts.append(leg)

            joint_motor = world.CreateJoint(rjd)
            joint_motor.userData = CustomMotorUserData(SPEED_HIP, False)
            self.motors.append(joint_motor)

            lower = world.CreateDynamicBody(
                position=(init_x, init_y - self.LEG_H * 3 / 2 - self.LEG_DOWN),
                #angle=(i * 0.05), #2°
                fixtures=LOWER_FD
            )
            lower.color1 = (0.6 - i / 10., 0.3 - i / 10., 0.5 - i / 10.)
            lower.color2 = (0.4 - i / 10., 0.2 - i / 10., 0.3 - i / 10.)
            rjd = revoluteJointDef(
                bodyA=leg,
                bodyB=lower,
                anchor=(init_x, init_y - self.LEG_DOWN - self.LEG_H),
                enableMotor=True,
                enableLimit=True,
                maxMotorTorque=self.MOTORS_TORQUE,
                motorSpeed=1,
                lowerAngle=-1.6,
                upperAngle=-0.1,
            )

            lower.userData = CustomBodyUserData(True, name="lower")
            self.body_parts.append(lower)

            joint_motor = world.CreateJoint(rjd)
            joint_motor.userData = CustomMotorUserData(
                SPEED_KNEE,
                True,
                contact_body=lower,
                angle_correction=1.0)
            self.motors.append(joint_motor)

Ancestors

• WalkerAbstractBody
• AbstractBody

Inherited members

• WalkerAbstractBody:
  • activate_motors
  • draw
  • get_action_size
  • get_elements_to_render
  • get_motors_state
  • get_state_size