Here is a nice sized sentry robot for your distant future needs. It's been fitted with massive tasers to drop intruders without killing them. Powered by the same power core that Senior Chief uses in the field. So this could work side by side with the spidermech providing security anyplace, anytime. This robot in 1/87 scale stands 4 and a half foot tall. So it's still smaller than a person, allowing the robot to get into places a human guard couldn't get into.