Robot Drifting in rviz

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Hello I have my custom made robot URDF which I a using to simulate the robot in rviz, I am publishing the odo data over TF for simulation.

But When I give velocity (fake) as vx =1, vy = -1 and angular velocity as 0, then robot actually drifts, ie. the robot is not moving as expected, it moves in a straight line with at an angle of 45 deg from the origin and even the orientation or heading of the robot doesn't match with the direction of the moment of the robot.

The urdf for my robot is as below:

  <link name="base_link">
  <inertial>
    <mass value="1"/>
    <inertia ixx="100" ixy="0" ixz="0" iyy="100" iyz="0" izz="100" />
    <origin/>
  </inertial>
    <visual>
      <geometry>
        <box size="0.6 0.35 0.15"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="white">
        <color rgba="0.2 1 0.3 1"/>
      </material>
    </visual>
  </link>

 <link name="lwheel">
    <visual>
      <geometry>
        <cylinder length="0.04" radius="0.1"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="black">
        <color rgba="0 0 0 1"/>
      </material>
    </visual>
  </link>

  <joint name="base_to_lwheel" type="fixed">
    <parent link="base_link"/>
    <child link="lwheel"/>
    <origin xyz="-0.1 -0.2 -0.025" rpy="1.5708 0 0"/>
    <axis xyz="-0.1 -0.2 -0.025 " />
  </joint>

 <link name="rwheel">
    <visual>
      <geometry>
        <cylinder length="0.04" radius="0.1"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="black">
        <color rgba="0 0 0 1"/>
      </material>
    </visual>
  </link>

  <joint name="base_to_rwheel" type="fixed">
    <parent link="base_link"/>
    <child link="rwheel"/>
    <origin xyz="-0.1 0.2 -0.025" rpy="-1.5708 0 0"/>
  </joint>

  <link name="fwheel_left">
    <visual>
      <geometry>
        <cylinder length="0.05" radius="0.03"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="black">
        <color rgba="0 0 0 1"/>
      </material>
    </visual>
  </link>

  <joint name="base_to_fwheel_left" type="fixed">
    <parent link="base_link"/>
    <child link="fwheel_left"/>
    <origin xyz="0.22 -0.1 -0.095" rpy="1.5708 0 0"/>
  </joint>

  <link name="fwheel_right">
    <visual>
      <geometry>
        <cylinder length="0.05" radius="0.03"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="black">
        <color rgba="0 0 0 1"/>
      </material>
    </visual>
  </link>

  <joint name="base_to_fwheel_right" type="fixed">
    <parent link="base_link"/>
    <child link="fwheel_right"/>
    <origin xyz="0.22 0.1 -0.095" rpy="-1.5708 0 0"/>
  </joint>

   <link name="scanner">
    <visual>
      <geometry>
        <box size="0.28 0.065 0.04"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="black">
        <color rgba="0 0 0 1"/>
      </material>
    </visual>
  </link>

   <link name="scan_support">
    <visual>
      <geometry>
        <cylinder length="0.4" radius="0.015"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="black">
        <color rgba="1 0.2 0.1 1"/>
      </material>
    </visual>
  </link>

  <joint name="base_to_scan_support" type="fixed">
    <parent link="base_link"/>
    <child link="scan_support"/>
    <origin xyz="0.15 0 0.25" rpy="0 0 0"/>
 </joint>

  <joint name="base_to_scanner" type="fixed ...