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Intelligent Robotics I: Servo Control

Intelligent Robotics I: Servo Control. Overview and example of robot control Jeff Allen. Robot Recipe. Sensors Artificial (sonar, cameras, temp, light, water,.......you get the point) Human (From a controller perceiving a worthy input) Intelligence

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Intelligent Robotics I: Servo Control

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  1. Intelligent Robotics I: Servo Control Overview and example of robot control Jeff Allen

  2. Robot Recipe • Sensors • Artificial (sonar, cameras, temp, light, water,.......you get the point) • Human (From a controller perceiving a worthy input) • Intelligence • Artificial (computational, search, genetic, NN, cellular automata, … too name a few) • Human (a controller intelligence varies in extremes, and is both time and subject variant) • Actuators • Artificial **(this is a requirement)

  3. Robotic SystemThe world and the boxes • Sensors • Can exist solely in either domain • Can exist in mix of both • Intelligence • Can exist solely in either domain • Can exist in mix • Robot State • Internal conditions used to represent actions • Actuators • The method the robot interacts, injects it’s will onto the real world Robo world Sensors Input Intelligence Robot HW/SW State Actuators Output Outside World : Part of your system feedback mechanism hopefully!?

  4. Robotic System: simplification • Input to Intelligence • Ignore all outside possibility as it is not in the system • Intelligence to Robot State to Output • Imply state as part of the connection Robo world Sensors Input Intelligence Robot HW/SW State Actuators Output Outside World : Part of your system feedback mechanism hopefully!?

  5. An Abridged Robotic SystemTransistions and related factors • Input to Intelligence • Complexity of sensor input • Must travel in robot world even if remote controlled. • Intelligence to Actuators • Must travel in robot world Robo world Sensors Input Intelligence Actuators Output Outside World : Part of your system feedback mechanism hopefully!?

  6. Sensor Information Complexity (Artificial) • Simple • Touch • Sonar • IR • Light • Temp • Engine and systems feedback • Radio signal • etc • Middle to Upper Complexity • Sonar Arrays/Radar Arrays • LIDAR • Camera(s) • GPS Positioning • Etc

  7. Consequences of increased sensor information complexity • Information size • Processing difficulty • Usefulness of data may require many different processes • Yet another etc…. • All ultimately lead in one way or another to increased requirements of therobot system. Which usually means $$$$!

  8. Information Traveling in the Robot World • Information and it’s communication must happen. If nothing is communicated how can it be a robot? • We all know how it is done. Electrical signals and representations sent to devices program to respond accordingly.

  9. Some robot system methodologies • Single autonomous unit • All onboard system intelligence is onboard. With remote communications generally limited to system reprogramming or goal adjustments. Not direct actuator control. • Remotely controlled units • The controlling unit, human or artificial, is located at another location controlling the unit. • Mixed units • Remotely controlled units with certain automated subsumbtive responses controlled directly. Example robotic overrides, like your brakes

  10. More about robot system methodologies • Single autonomous unit • Varying complexities based on onboard computational and sensing abilities as well as actuator device complexities. • Complexity increases are expensive and can create extremely difficult systems in situations where onboard requirements are stretched to limits • Excellent response times are possible • Remotely controlled units • Onboard equipment requirements are lessened with respect to computational devices. (less expensive) • Complexity increases due to sensors now increase bandwidth requirements, but are otherwise less expensive. • Natural lag in response related to communicated distance as well as bandwidth • Mixed units (see all above)

  11. PC remote controlled systemsToday’s example • Inexpensive. • PC (look at a Fry’s ad) • Servo controller board ($10 - $200 on average) • Potentially Powerful • Information communicated can be communicated along multiple channels: usb, serial, firewire, etc.. • Numerous programming languages to choose from. • Why do we use them? Look above

  12. Review: Traveling in the Robot World.what did we say? • Information and it’s communication must happen. If nothing is communicated how can it be a robot? • We all know how it is done. In theory. Practically?

  13. A communicating example:A PC controlled robot Communication Channel PC to Control: In this case RS232 Our development environment: Visual Studio VB 6.0 Input to PC: Predefined movement scripts / Sensors Actuator Control: ASC 16 Board

  14. Communication channel:PC to RS232 piece • MS Visual studio provides the MSComm object capable of: • Transmitting/ receiving / open / close to a comm port using rs232. The requirement is only that the data be presented in the format it is to be sent according to receiving device. • ASC 16 has specific commands for each servo device. • Each servo is capable of 180 degrees of movement with a precision of 180/4000 degrees/point, .045 Deg/point • The ASC16 is capable of simple position commands ,small loop programs as well as positional feedback (not in this example) • Commands are given in 1,2, and 3 byte packages

  15. Example goal • We need something to convert commands from the PC to appropriate ASC16 commands, a translator.

  16. Requirements • Each servo device will have a different range of motion and rarely will move all 180 degree. • Each device is a separate entity, interrelations can be calculated but otherwise do not exist

  17. ASC16 Commands • ac (81-96 DEC) (51-60 HEX) • Acceleration • am (250 DEC) (FA HEX) • Abort All Motion • at (249 DEC) (F9 HEX) • Abort Triggers • bt (124 DEC) (7C HEX) • Base Time • en (121 DEC) (79 HEX) • Enable Module • f+ (251 DEC) (FB HEX) • Freeze Motion • f- (252 DEC) (FC HEX) • Freeze Motion Off

  18. ASC16 Commands (cont.) • fp (21-36 DEC) (15-24 HEX) • Flyby Position • iv (112 DEC) (70 HEX) • Invert Servo Coordinates • la (242 DEC) (F2 HEX) • Load All • ld (123 DEC) (7B HEX) • Load Default Position • lm (253 DEC) (FD HEX) • Loop Marker • lp (254 DEC) (FE HEX) • Loop • mk (221-228 DEC) (DD-E4 HEX) • Marker

  19. ASC16 Commands (cont.) • mr (41-56 DEC) (29-38 HEX) • Move Relative • mk (221-228 DEC) (DD-E4 HEX) • Marker • mr (41-56 DEC) (29-38 HEX) • Move Relative • mv (1-16 DEC) (01-0F HEX) • Move servo absolute • no (0 DEC) (00 HEX) • No Operation • no no no (0,0,0 DEC) (00,00,00 HEX) • Terminate • nv (113 DEC) (71 HEX) • Non-invert Servo Positions

  20. ASC16 Commands (cont.) • op (110 DEC) (6E HEX) • Output • pg (120 DEC) (78 HEX) • Program Module address • ra (141-148 DEC) (8D-94 HEX) • Read Input as Analog • rd (179 DEC) (63 HEX) • Read Inputs as digital • rp (116 DEC) (74 HEX) • Report Position • rs (117 DEC) (75 HEX) • Report Speed • s+ (245 DEC) (F5 HEX) • Servos On

  21. ASC16 Commands (cont.) • s- (246 DEC) (F6 HEX) • Servos Off • sa (241 DEC) (F1 HEX) • Save All • sp (61-76 DEC) (3D-4C HEX) • Speed • st (151- 168 DEC) (97 - A8 HEX) • Stop • sv (122 DEC) (7A HEX) • Save Default Servo Position • tl (119 DEC) (77 HEX) • Trigger Level • tm (181-196 DEC) (65-C4 HEX) • Trigger on Motion Completion • tp (201-216 DEC) (C9-D8 HEX) • Trigger on Servo Position

  22. ASC16 Information:Command Set Example mv (1-16 DEC) (01-0F HEX) Move servo absolute Format: mv$ position mv$ = 1-16 for servo 1(mv1) to 16 (mv16) position = 0-4000 Description: Moves a servo to a new absolute position at the speed and acceleration rate set for the specified servo. Example: Mnemonic Numeric mv2 1500 Move servo 2 to position 1500 2, 5, 220 mv10 200 Move servo 10 to position 200 10, 0, 200

  23. Translator specs • Class (single instance for each servo) • Provides separate initialization data to exist within each object • Separate variable data such as position and rates are stored with each object • Functions compute output string based on object data - Normalized control

  24. Class local Variable 'local variable(s) to hold property value(s) Private mvarminRange As Integer 'local copy Private mvarmaxRange As Integer 'local copy Private mvarmultiplier As Single 'local copy Private mvarmark As Integer 'local copy Private mvarservo As Integer 'local copy Private mvarposition As Integer 'local copy Private mvarreverse As Boolean 'local copy Public outputstring As String Public value As Integer Private mvargood As Boolean 'local copy

  25. Why private? • Private can help guarantee values are within appropriate ranges. This helps make sure the system doesn’t get bad information. • Provides protection to data from outside. • It just means a function is must be called to write data.

  26. ASC16 Information:Command Set Example ac (81-96 DEC) (51-60 HEX) Acceleration Format: ac$ accel ac$ = 81-96 for servo 1 (ac1) to 16 (ac16) accel = 1-255 Example: mnemonic Numeric tl 2 ‘ set trigger level to suspend processing 119, 2 ac1 5 ‘set acceleration rate for servo 1 to 5cnts/20mS2 81, 0, 5

  27. Accel command for servo object Public Function Accel(ByVal rate As Integer) As String Dim locservo locservo = mvarservo + 80 Accel = Chr$(locserver) & Chr$(rate) End Function

  28. ASC16 Information:Command Set Example mv (1-16 DEC) (01-0F HEX) Move servo absolute Format: mv$ position mv$ = 1-16 for servo 1(mv1) to 16 (mv16) position = 0-4000 Description: Moves a servo to a new absolute position at the speed and acceleration rate set for the specified servo. Example: Mnemonic Numeric mv2 1500 Move servo 2 to position 1500 2, 5, 220 mv10 200 Move servo 10 to position 200 10, 0, 200

  29. Servo Movement as seen by PC • Movement are absolute otherwise: • Increased chance of leaving initialized range • Must poll often to stay up to date, therefore increasing communication

  30. Move command Public Function Move(ByVal pos As Integer) As String Dim bigmove As Integer Dim litmove As Integer Dim overall As Integer If pos >= 0 And pos <= 255 Then If mvargood Then If mvarreverse Then overall = mvarminRange - (pos * mvarmultiplier) litmove = (overall Mod 256) bigmove = ((overall - litmove) / 256) Else overall = mvarminRange + (pos * mvarmultiplier) litmove = overall Mod 256 bigmove = ((overall - (litmove)) / 256) End If mvarposition = pos Move = Chr$(mvarservo) & Chr$(bigmove) & Chr$(litmove) End If End If End Function

  31. Initialization function Public Sub makenew() 'this is surely ugly as but since cannot use new like .NET 'this will do. If (mvarservo >= 1) And (mvarservo <= 16) And (mvarmaxRange <= 4000) And (mvarminRange <= 4000) And _ (mvarmaxRange >= 0) And (mvarminRange >= 0) Then mvargood = True If mvarmaxRange > mvarminRange Then mvarreverse = False mvarmultiplier = (mvarmaxRange - mvarminRange) / 256 Else mvarreverse = True mvarmultiplier = (mvarminRange - mvarmaxRange) / 256 End If End If mvarposition = 127 End Sub

  32. Using objects • Create instantiate an object for each servo device Dim eyeLr As New asc16stringbuilder Dim eyeDu As New asc16stringbuilder Dim neckLR As New asc16stringbuilder Dim neckDU As New asc16stringbuilder Dim mouth As New asc16stringbuilder • Initialize eyeLr.servo = 1 eyeLr.minRange = 1390 eyeLr.maxRange = 2810 eyeLr.makenew • Use MSComm.Output = eyeLr.Move(value) ’value range 0 255

  33. A trivial use example • Random eye movement Public Sub LRAnimEye() Dim randomx As Integer randomx = Int(10 * Rnd) - 5 randomx = randomx * 15 MSComm.Output = eyeLr.Move(randomx + 127) End Sub

  34. Questions Discussion ??

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