I did a project similar to this and had to account for something blocking door travel. I ended up with .1 ohm, I think, in series with the motor to monitor load by measuring the voltage across the resistor to determine current flow.

If motor is free running then current will be high initially but should be lower once friction and inertia are overcome. But if it's blocked/hampered/whatever the stall current will stay relatively high. I think I set it up to try to open and if blocked wait some time and then try again. Another ADC input if you've got a free port. Just a thought.