You can use Tasker plus you have to use the addon Secure Settings. You must be rooted. You could create a task that disables your pattern lock while connected to your home Wi-Fi. Create another for when your connected to power.
I want to warn you if your looking for a simple app this is not it. This is a powerful app that can allow you to control many aspects of your phone. Be prepared to be confused. Read the online documentation , read through some of the "tasks". If your somewhat technically inclined you will pick it up and controlling automating things with your phone!

My personal favorite is the task that check to see if I'm moving faster than 5 mph assumes I'm driving texts that not only am I driving but how fast I'm going!