If you have a braille display with a Perkins style keyboard, you can control your iOS device by entering certain key combinations. I will include a list of these braille keyboard commands. While some of them will work with iOS 10 as well, iOS 11 will allow you to assign keyboard commands where none currently exist, and also change existing keyboard commands.
To assign a keyboard command where none exists, or change an existing keyboard command, go to Settings\General\Accessibility\VoiceOver\Braille.
From there, select more info next to the braille display that you have paired to your device, and then select Braille Commands. Now you will see a list of buttons like Braille, Device, Interaction, Keyboard, ETC. Each one has a list of braille commands that you can see when you click on one. I have included the complete list below; to make it easier to find the command you are looking for.
Braille Keyboard Commands for iOS 11
Braille
Action Keyboard Command
Next Input Mode Dots 2, 3, 6 Plus Space bar
Next Output Mode Dots 1, 2, 4, 5 Plus Space bar
Pan Left Dot 2 Plus Space bar
Pan Right Dot 5 Plus Space bar
Toggle 8-Dot braille No Assigned Braille Keys
Toggle Announcement History Dots 1, 3, 4, 5 Plus Space bar
Toggle Contractions No Assigned Braille Keys
Toggle Braille Wrap No assigned Braille Keys
Translate Dots 4, 5 Plus Space bar
Device
Action Keyboard Command
Control Center Dots 2, 5 Plus Space bar
Home F2 or Dots 1, 2, 5 Plus Space bar
Notifications Dots 4, 6 Plus Space bar
Rotate Device Left No assigned Braille Keys
Rotate Device Right No assigned Braille Keys
Show or Hide Keyboard F4 or Dots 1, 4, 6 Plus Space bar
Siri No Assigned Braille Keys
Speak Screen No Assigned Braille Keys
Toggle Orientation Lock No assigned Braille Keys
Volume Down Dots 1,2 6 Plus Space bar
Volume Up Dots 3, 4, 5 Plus Space bar
Interaction
Action Keyboard Command
3D Touch Selected Item Dots 3, 5, 6 Plus Space bar
Double Tap No Assigned Braille Keys
Escape current Context Dots 1, 2 Plus Space bar
Label Selected Item Dots 1, 2, 3, 4, 6 Plus Space bar
Pause or Continue Speech Dots 1, 5, 6 Plus Space bar
Scroll Down Dots 1, 4, 5, 6, 8 Plus Space bar
Scroll Left Dots 2, 4, 6 Plus Space bar
Scroll Right Dots 1, 3,5 Plus Space bar
Scroll Up Dots 3, 4, 5, 6 Plus Space bar
Speak Page Number Dots 3, 4 Plus Space bar
Tap Dots 3, 6 Plus Space bar
Keyboard
Action Keyboard Command
Bottom of Document No Assigned braille Keys
Command Dots 1, 7 Plus Space bar
Control Dots 3, 7 Plus Space bar
Copy Dots 1, 4 Plus Space bar
Cut Dots 1, 3, 4, 6 Plus space bar
Delete Dot 7 or Dot 7 Plus Space bar or Dots 1, 4, 5 Plus Space bar
Down Arrow No Assigned Braille Keys
First Word No Assigned Braille Keys
FN Dots 5, 7 Plus Space bar
Last Word No Assigned Braille Keys
Left Arrow No Assigned Braille Keys
Next Keyboard No Assigned Braille Keys
Option Dots 2, 7 Plus Space bar
Paste Dots 1, 2, 3, 6 Plus Space bar
Redo Dots 2, 3, 4, 6 Plus Space bar
Return Dot 8 or Dot 8 Plus Space bar or Dots 1, 5 Plus Space bar
Right Arrow No Assigned Braille Keys
Select All Dots 2, 3, 5, 6 Plus Space bar
Select Left Dots 2, 3, 5 Plus Space bar
Select Right Dots 2, 5, 6 Plus Space bar
Shift Dots 4, 7 Plus Space bar
Shift-tab Dots 1, 2, 5, 6 Plus Space bar
Speak Link Address No Assigned Braille Keys
Speak Number of Lines No Assigned Braille Keys
Speak Selected Text No Assigned Braille Keys
Speak Text Style Dots 2, 3, 4, 5, 6 Plus Space bar
Tab Dots 2, 3, 4, 5 Plus Space bar
Toggle Command Dots 1, 8 Plus Space bar
Toggle Control Dots 3, 8 Plus Space bar
Toggle FN Dots 5, 8 Plus Space bar
Toggle Option Dots 2, 8 Plus Space bar
Toggle Shift Dots 4, 8 Plus Space bar
Top of Document No Assigned Braille Keys
Undo F3 or Dots 1, 3 5, 6 Plus Space bar
Up Arrow No Assigned Braille Keys
Navigation
Action Keyboard Command
First Item Dots 1, 2, 3 Plus Space bar
Hide Side App Switcher No Assigned Braille Keys
Last Item Dots 4, 5, 6 Plus Space bar
Move to Bottom of Container No Assigned Braille Keys
Move to Left app Dots 3, 5 Plus Space bar
Move to Right App Dots 2, 6 Plus Space bar
Move to Status Bar Dots 2, 3, 4 Plus Space bar
Move to Top of Container No Assigned Braille Keys
Next Character No Assigned Braille Keys
Next Container No Assigned Braille Keys
Next Item Dot 4 Plus Space bar
Next Line No Assigned Braille Keys
Next Paragraph No Assigned Braille Keys
Next Sentence No Assigned Braille Keys
Open Next App No Assigned Braille Keys
Open Previous App No Assigned Braille Keys
Previous Character No Assigned Braille Keys
Previous Container No Assigned Braille Keys
Previous Item Dot 1 Plus Space bar
Previous Line No Assigned Braille Keys
Previous Paragraph No Assigned Braille Keys
Previous Sentence No Assigned Braille Keys
Show Side App Switcher Dots 1, 6 Plus Space bar
Rotor
Action Keyboard Command
Next Rotor Option Dots 5, 6 Plus Space bar
Previous Rotor Option Dots 2, 3 Plus Space bar
Rotor Down Dot 6 Plus Space bar
Rotor Up Dot 3 Plus Space bar
Speak Current Rotor Option No Assigned Braille Keys
VoiceOver
Action Keyboard Command
Copy Speech No Assigned Braille Keys
Item Chooser Dots 2, 4 Plus Space bar
Next Search Result No Assigned Braille Keys
Open VoiceOver settings No Assigned Braille Keys
Previous Search Result No Assigned Braille Keys
Read All Dots 1, 2, 3, 5 Plus Space bar
Read from Top Dots 2, 4, 5, 6 Plus Space bar
Related Content No Assigned Braille Keys
Single Letter Search No Assigned Braille Keys
Speak Hint No Assigned Braille Keys
Text Search Dots 1, 2, 4 Plus Space bar
Toggle Mute Dots 1, 3, 4 Plus Space bar
Toggle QuickNav Dots 1, 2, 3, 4, 5 Plus Space bar
Toggle Screen Curtain Dots 1, 2, 3, 4, 5, 6 Plus Space bar
Toggle Single Letter QuickNav Dots 1, 2, 3, 4, 5, 7 Plus Space bar
Toggle Speech Dots 1, 2, 3, 4 Plus Space bar
VoiceOver Help Dots 1, 3, 7 Plus Space bar