Off the wall, first thing that comes to mind is can you send the serial command to start the motor but then put a " long" delay/sleep serial command ie 100uS then motor on then a short delay ie 80 uS etc until the motor is at your full desired speed!? Akin to PWM.....sometimes a crazy question can lead to a new perspective

Thanks Glen but it didn't work. I'm hitting dead end walls now with this issue. If I cant get it worked out I'll have to abandon the Kangaroo X2 and go back to having EZB ramp speed using progressing PWM commands. I cant put up with the jerky start up and stop. Now I'm even having problems with giving servo commands. I cant get ServoSpeed to work and servo position is resulting in jerky movement. Cant understand what happened. I had the servo commands working OK yesterday.

Tomorrow I'm going to do a factory reset on the Kangaroo and if that doesn't get things working again I'm moving on.

Dang! That's just weird confused.....Lumpy! where are you? and or other Kangaroo people

Well, I got my answer I needed from Dimension Engineering. They say Kangaroo X2 does not support speed ramping in Position Mode. Speed ramping only works in Velocity Mode. The only thing I can control in Position Mode is Speed and position. From what I can tell Velocity Mode seems to be best used with RC controllers. They seemed to say that the only way I can get my motor to stop exactly at certain spots in Velocity Mode is to write script in one of the supported languages (C+, C++, VB and others). With a script like that I could also set ramping, speed and stopping points and send that script through the serial port. Problem is that Velocity Mode is not very precise or exact where it stops. Image an RC car rolling to a stop when you bring the joy stick back to center. I guess you could reverse to stop quickly or break.

To tell the truth if I have to learn all that language and write all these scripts to get a gradual ramp up and down I'm really not gaining much using the Kangaroo X2. I need speed ramping in position mode to get my B9 joint movements to look natural. I can see where this Sabertooth / Kangaroo would be a great little combo for other people in other types of platforms. It does a great job converting RC Signals and magically controlling a DC motor and accepting servo commands. If you really don't mind your motor starting up and stopping fast then the coolness of sending servo commands to a DC motor is for you.

With that said I still have this Sabertooth / Kangaroo X2 combo installed and I did a lot of rewiring to get it installed and working with B9's waist and hip motors. I'm not one to give up and hoped to get this setup to work the way I want in my B9 robot and EZB. So.... I started to rethink Glen's (irobot58) suggestion of sending gradual increasing speeds through a EZB serial port to the Kangaroo. Thanks Glen! . After some trials and more then a few errors I got it to work! I've got a first draft of a nice speed ramp up and down. The trick that works is to send a very low speed setting like s050 with a very short Sleep delay like 0050 before I go to the next gradual speed increase of s100. I continue this (keeping the Sleep to a very short 0050) up to about s300 or s400 then jump to the speed I want. In my case the best natural speed in about s500 or s600. The trick is the timing at full speed so it starts to reverse the ramp code at the right time so it drops speed back down to s050 at the very end of rotation. The result is a nice start up and a very slow cost to a stop. So the code looks something like this:

#This is the Ramp up section
SendSerial(D0, 9600, "1,p2450 s050", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s100", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s150", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s200", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s250", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s300", 0x0d)
Sleep(0050)

#This is the full speed setting. The Sleep setting is adjusted to the amount of time of rotation before speed ramps down
SendSerial(D0, 9600, "1,p2450 s500", 0x0d)
Sleep(1500)

#This is the ramp down section. It needs to reach the last command just before the end of rotation
SendSerial(D0, 9600, "1,p2450 s300", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s250", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s200", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s150", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s100", 0x0d)
Sleep(0050)
SendSerial(D0, 9600, "1,p2450 s050", 0x0d)

#This section turns off and releases the motor control
Sleep(1500)
SendSerial(D0, 9600, "1,Powerdown", 0x0d)

Like I said this is a ruff script that ramps nicely. I still need to work on it to see if I really need all the speed commands and if I can cut the Sleep commands even shorter. I also would like to see If I can send this script using only one SendSerial command with the speed changes called as a script.

If there are any suggestions on refining or tuning this I would really appreciate it.

That's awesome Dave! Of course the script is cumbersome to build and not as elegant as we like....but...it will do what you want! I am doubly pleased today as I was able to help out .....and...am currently holding my day old, first grandchild, Oliver in my arms Perhaps a script that incorporates a variable that adds by certain increments and subtracts will fulfil the "elegant" quality! I have been helped so many times by the awesome people of this Forum its a pure pleasure and joy to assist someone in whatever way possible ....... Thanks for the accolade Dave

Hey, congratulations on the grandchild! I know you must be proud.

Writing scripts is not one of my strong points. I'm going to have to think about this and try a few things out. Variables may work if I can figure out how to implement them.

Some snippets of code which may help you out

Increase a variable by a set amount

$X2_Speed = $X2_Speed + 50

So to ramp up from 0 to 300;

$X2_Speed = 0
:loop
IF($X2Speed < 300)
  $X2_Speed = $X2_Speed + 50
Else
  Halt()
EndIF
Sleep(50)
Goto(loop)

So if you put the send serial command below the :loop label and above the IF it'll run the command, starting at 0 speed, increase by 50, loop back up, send the serial data again, increase by 50 and so on until it hits 300, when it hits 300 (after sending the speed 300) the IF will terminate the script with the halt command.

To add in the speed variable to the serial data, i.e. SendSerial(D0, 9600, "1,p2450 s300", 0x0d) you simply need to break the data at the s and add in the variable so it would be like SendSerial(D0, 9600, "1,p2450 s"+$X2_Speed, 0x0d)

The same could be done for position, but break it at the p like SendSerial(D0, 9600, "1,p"+$X2_Position+" s300", 0x0d)

Note: I haven't tested this, I am unable to as I don't have a sabertooth or a Kangaroo (yet)

Unfortunately I'm out of time, it's late and I need sleep, but hopefully that will have explained a few things and helped guide you in the right direction. If not feel free to ask about whatever you are stuck with and I'll try to explain better.

@Rich Your awesome! I wish I could give you half of Dave's accolade You have articulated my vague script suggestion very well. When Dave reads this I am sure he will be very pleased ...and anyone else who needs Kangaroo ramping

Thanks Rich for poppping in here with help on this code. It helps more then you know and is very welcomed. I dont think I would have ever thought of writing it this way. Very nice and just what I was needing. I can see how it will be much smoother. It will be fun to get this code to ramp up, go to the right spot and ramp down as the motor gets there.

I only have a few free hours over the next few days so it may be a while till I get this working. Please keep an eye on me over the next week as I may need a helping hand on this code if your still willing and available.

Dude, I keep an eye on everyone even if I don't always post Glad it helped.

@irobot58 I have enough praise, I can let a few slide

Rich,

I haven't had a chance to try this code but I've been looking at it a little. I do have a question or two;

Would I have to set this speed variable in the INT script when ARC starts up? I guess I would not have to keep the loop script running all the time waiting if I set it at start up and just call the script when I want to move the jount.

Also I have a feeling I'm going to have to change your commands from EZ Language to C++ or even VB. I'm not sure the Kanagroo will understand the EZ commands. If so I'm going to have to try to learn some of this code. I know the Kangraroo will understand code you would send from an Arduino. Any thoughts on this?

If it understands the Arduino it should understand the ARC commands too. I'll have to look and see if there's any kind of serial monitor I can use to look at exactly what the Kangaroo received from both the Arduino and EZ-B though. Initially though I don't think it would be a problem.

The $X2_Speed would need to be set to something prior to running the script. If you are ramping up, at the very start of the script simply set it to 0 $X2_Speed = 0. If ramping down set it to the fastest speed at the start.

The label for the loop would come after that.

Then the If to slowly increase the speed until a set speed

The the goto

Something like

# Set the speed to 0
$X2_Speed = 0

# Make a point to loop back to
:loop

# Send the serial command
SendSerial() # Im too lazy to fill in the serial command, copy from the last page.

# Check the speed and act accordingly
IF($X2_Speed < 300)
  $X2_Speed = $X2_Speed + 50
Else
  
  # If the speed is already at 300 end the script.
  Halt()
EndIf

# Go back to the loop
Goto(loop)

The code will only loop until max speed (300 in the example) is reached. Once it hits 300 the IF is not true so it runs the code after the Else, which is Halt() which will terminate that script.

Cool, thanks for the fast and thoughtful reply. This all makes sense. I can't wait to have some time this weekend and give this a try.

As far as a monitor, kangaroo does feedback codes and other info like speed and position to a microcontroller. It can be seen with a terminal program on the laptop. I have tried to hook one up to the kangaroo but although I can open a channel I can't understand how to run the several programs I've tried. This is just one more thing I need to tackle. Any suggestions on a good and easy terminal program I can try and that has good instructions?

As far as info feedback from Kangaroo on position and speed maybe the new V4 will be able to read this and let me control better with" Get" statements in scripts.

Holy cats Rich ! Your code works! I'm not surprised but completely amazed that it works so well. I've been struggling with this setup for a while now and had true fears I couldn't make it move to my expectations. I've overcome many challenges and ramping was about the last issue. If I couldn't get it to work I was going to give up. Your code makes the movement ramp up very smoothly and I'm able to easily adjust the acceleration.

Now that I've got the ramp up working I'll need to get the ramp down as the rotation nears the end of rotation. I'll be working on that on the next few days. I would think the code needs to be duplicated and placed between the end of your code (with maybe a delay) and the Halt() command. I've run out of time and energy today so I'll be working on this again in a day or so when I find more of each.

Anyway, Thanks very much Rich. I'm completely thrilled!

I've now got a working script. Thanks again to @Rich for pointing me in the right direction. This successfully ramps the Sabertooth / Kangaroo X2 up to any speed wanted, move to a exact point on a radius and then ramps down to a crawl near the stop point. With the proper timing of the Sleep() command the motor ramps down just before the end and adjusts into center.

It works pretty good but the timing with the Sleep($Sleep) variable and the sleep() pauses in the call script is vital or the ramping will miss and the motor will jerk to a stop at any speed. There has got to be a way to get the position read from Kangaroo into the script. Once I figure that out I can just use Kangaroo's GetP command to start ramping at an exact point instead of relying on timing. That's my next trick. In the mean time the sleep() is working OK and the ramping script is the key part anyway. I'm still looking for other ways to ramp but haven't really tried other commands in C++ that may work. In Kangaroo's Serial Packet reference manual I did find the following but I have no idea how to work it into the script or if it will work. It may only work with the Velocity command but I dont know yet:

public KangarooMonitor S(
	int velocity,
	int rampLimit = -1,
	KangarooMoveFlags flags = KangarooMoveFlags.Default

Any ideas? I wish I knew better how to write scripts in C++ but in the mean time:

This is the main movement script (pardon my mess) :

#The following are the variables that can be set in a call script or from within this script. 

# Sets top speed. This can be called from another script. 
#$Set_Max_Speed =0300

# sets the positon to stop at. This can be called from another script. 
#$Positon = 2550

#sets the sleep pause be set from the call script. This lets the motor turn to the proper spot to ramp speed down. This can be called from another script. Recommended. Easier to get timing right with multiple calls. 
Sleep($Sleep)

# sets the speed to 0 to start ramping up to speed. This should always be set from within this script. 
$X2_Low_Speed =0000

# Sets final speed. This should always beset from within this script
$Set_Final_Speed =0010

####################################################################

# Point to loop back to
:loop
# Send the serial command with wanted Kangaroo variables
SendSerial(1.D0, 9600, "1,p"+$Positon, "s"+$X2_Low_Speed, 0x0d)

# Starts at zero, Checks the speed and adds 00XX speed each time it loops till it gets to the top speed (play with it to find the smoothest ramp). Then it will to the the :Ramp Down section.
IF ($X2_Low_Speed < $Set_Max_Speed)
  $X2_Low_Speed = $X2_Low_Speed + 0010
  # Go back to the loop
  Goto(loop)
  
  # When the speed is at $Set_Max_Speed, sleep then ramp down.
  Goto(Ramp Down)
ENDIF 
  
:Ramp Down
SendSerial(1.D0, 9600, "1,p"+$Positon, "s"+$X2_Low_Speed, 0x0d)  #this command may not be needed. It worked with and without it. 

#sets the sleep pause variable that's set from the call script. This lets the motor turn to the proper spot to ramp speed down. 
Sleep($Sleep)

# 2nd Point to loop back to. This must be named different from the first loop!
:Loop2
# Sends the serial command with wanted Kangaroo variables. the $X2_Low_Speed variable is still set to the max speed by the first loop. This loop will take it down. 
SendSerial(1.D0, 9600, "1,p"+$Positon, "s"+$X2_Low_Speed, 0x0d)   
IF ($X2_Low_Speed > $Set_Final_Speed)
  $X2_Low_Speed = $X2_Low_Speed - 0010    #this number should be set to the same as the $Set_Final_Speed varible or the motor wont crawl into exact position after ramping completes.  
  
ELSE 
  # When the speed is at $X2_Low_Speed, end the script.
  Halt()
ENDIF 
 
#takes us back to Loop2 if needed. 
Goto(loop2)

Here's an example of the call script. I can make several scripts with different variables set depending on where I what to the motor to stop or how fast to go. It's important to adjust the Sleep() commands so the ramping happens at the right times or the ramping will happen too soon or too late. I only need one "Waist Movement" script that will keep being called:

# Sets Final speed
$Set_Max_Speed = 300

#sets the positon to stop at Left
$Positon = 3500

$Sleep = 2800

#calls the ARC EZ Script
ControlCommand("Waist Movment", ScriptStart)

Sleep(4000)

#sets the positon to stop at Center
$Positon = 2550

$Sleep = 2600
#calls the ARC EZ Script
ControlCommand("Waist Movment", ScriptStart)

Sleep(4250)

#sets the positon to stop at Right
$Positon = 1600

$Sleep = 2900

ControlCommand("Waist Movment", ScriptStart)

Sleep(4000)

#sets the positon to stop at Center
$Positon = 2550

$Sleep = 2700

#calls the ARC EZ Script
ControlCommand("Waist Movment", ScriptStart)

Sleep(8000)

#Shuts down the Sabertooth. The above sleep() keeps it from shutting down too soon and stopping the motor
ControlCommand("Start", ScriptStart)

As always I'm open to suggestions or criticism. Any help is welcomed.

Thanks Dave

I like these scripts. Couldn't they be incorporated into the movement panel? For instance a check box for ramp up and ramp down then if they are ticked, a box for the rate is enabled. A handy feature to be sure. I asked a similar question at one time on the servo control.

Humm, that's a cool idea. Maybe some day when the team get more time they could look into this. IMHO ramping is an area that really needs to be addressed not only with EZ Robots but with other companies that provide motion control boards. It seems like it's just an after thought or partially implemented. I may be wrong about all this but I haven't found much where this is a concern. With people now building larger and more human like robots I imaging the need to get them to move more naturally is going to be in demand. They all really should address this lack of support to stay ahead. The kangaroo does do adjustable ramping but only in Velocity Mode unless you do involved scripting that most people (like me) don't know how to do. Velocity Mode is good for RC controlled bots and cars that just drive forward, reverse and turn. I need position and speed control. DE says their Kangaroo doesn't do ramping in Position Mode unless you script. WHY?

The only way I was able to get ramping to work on my DC Motors with ARC was to send gradual increased or decreased PWM commands. That actually worked very nicely. That script looks like this:

PWM(1.D6,10)
$adcSpecified = 185
controlcommand("Move Waist", scriptstart)
Sleep(0250)
PWM(1.D6,20)
Sleep(0250)
PWM(1.D6,30)
Sleep(0250)
PWM(1.D6,50)
Sleep(2250)

To be honest I got smoother ramping with simpler EZ code (as seen above) then I am getting with the Kangaroo script I just made over serial. I'm still not really convinced my new setup using the Sabertooth/Kangaroo is better then what I had with a H-bridge and a pot attached to an ADC port on the EZB. The Sabertooth is more rugged and top quality and the Kangaroo does do all the work that EZB used to do. Added to that, I now only use one Digital port on the EZB and send all info with a serial command. Also, I can now use servo commands but I found if I mix servo commands and serial commands using the same Digital port on EZB everything will lock up and I need to reboot everything. So it's one or the other. With servo commands I have no ramping. It's all or nothing.

Dave, I do not use Sabertooth or Kangaroo controllers, so have little knowledge of them, but here are some thoughts.

I guess that your main problem is not getting the position feedback so the script does not know when to start ramping down as it approaches the target position. The lack of serial comms (read) on the V3 is a real problem sometimes, but it should be solved when the V4 arrives, as it has bi-directional comms. You really need a thing called analogue PID (proportional-integral-derivative) controller see

en.wikipedia.org/wiki/PID_controller

With a controller like this using PID the motor would move very smoothly from start position to (accurately) the target position thanks to the on board PID algorithm. I use the Motor Mind 3 controllers with great success on the EZ:1 robot using serial PID control, the robot accurately moves from one location to another. Serial mode uses encoders but the mode you need is analogue (using positional feedback resistor). Here is a link to the Motor Mind 3

www.solutions-cubed.com/content/Downloads/MotionMind3Docs/MOTM3DS_6.pdf

One thing to note, I found that PID is quite complicated and very difficult to set up properly, it may be worth waiting for the V4 as PID may be a steep learning curve for you. Once you get the V4 with bi-directional comms you could roll out a simple script like

1. Extract start position value from end position value = travel_v - [example if start_pos = 500 : end_pos = 2600 then travel_v = 2100]
2. If travel_v < (min position to ramp) then goto move - what this means is that if the travel_value is to small its does not need up/down ramping
3. Calculate (say 10%) of travel_v - [2100/100*10 = 210]
4. Add this value to start_pos = pos_2 - [500+210 = 710]
5. Slow ramp-up motor until current_pos = pos_2 [710] - slow ramp_up speed from start position to position 2 (end of ramp-up) 6} Calculate pos_3 (say 90%) of travel_v - [2100/100*90 = 1890]
6. Motor full speed until current_pos = pos_3 - set motor at full speed until reaching 10% before end position
7. Slow ramp-down motor until current_pos = end_pos - slow ramp_down for position 1890 to position 2100 (end position)
8. Target position attained

In the above example the first 10% of travel is slow ramp-up with the next 80% of travel being full speed and the last 10% being slow ramp-down. The ramp up/down percentage (10% in the example) may need to be changed to suit the particular motor setup that you have.

I hope I have interpreted your problem correctly and this has been of some help.

Tony

@Tony,

Thanks so much for sharing your thoughts here. You've confirmed what I thought the problem may be. I really have been hampered by not having two way serial communication between EZB and the Kangaroo. That and the lack of good documents or active Kangaroo community forums and my lack of C++ script writing knowledge has made this a true struggle with slow progress.

Also thanks for the tip and link to the PID board. I don't think I'm up for another steep learning curve just yet so I think I'll wait for my Pre-ordered V4 EZB. Hopefully it will be here in a matter of weeks. That sounds like the natural solution. Your outline of a script will help a lot when I get back to this point.

I the mean time I'll keep plugging away. Heck, even a blind squirrel finds an acorn once in a while.

I haven't had chance to check this topic for a while (and even now I've just quickly skimmed over it), glad the script got you going

On the servo commands and no ramping, you could use scripts to simulate ramping by moving the position step by step with sleep between... Something like;

Servo(D1, 10)
Sleep(10)
Servo(D1, 11)
Sleep(10)
Servo(D1, 12)
Sleep(10)
# and so on
Servo(D1, 20)
Sleep(5)
Servo(D1,25)
Sleep(5)
Servo(D1,30)
# and so on

Or if the ServoUp and ServoDown commands work with it;

$new_position = 90
$steps = 1

:loop
If(GetServo(D1) < $new_position)
  ServoUp(D1, $steps)
  Sleep(10)
Else
  Halt()
EndIf
Goto(loop)

The above would need more work, using Tony's algorithm and some error checking along with some code to make sure that moving the servo up by $steps wont push it over the $new_position - something like IF(GetServo(D1) + $steps > $new_position).

It may be simpler than that, I will admit I didn't put much thought in to this one but the concept is the point I am trying to get across and hopefully I have done so

@Rich, Your best guess without much thought is a whole lot better then my hours of slight progress. I did get ramping to work like this on other applications with PWM commands. I didn't think about trying it on servo commands. Thanks once again!

@Dave, with my algorithm I need to add the following, because of the lag time it takes for the EZ-B to read the position (back from the Kangaroo), it is likely that the actual position will "over shoot" when the equality checks (10% in the example) are being made, especially when the motor is on full speed (like when going to pos_3) etc. So the check should not be for equality, it should be ">" (more than), this will allow for any over shoot.

Dave, when the V4 is available, I will write this algorithm into an EZ-B script for you, if that will help.

Tony

Thanks Tony... that will help me as well. I just picked up a couple of kangaroo boards myself...

@Tony, Once more you've proved what a great guy you are. I couldnt get most of this stuff to work the way I want to without people like you offering help. I intend to learn this type of programing soon so I dont have to relay on good people like you so much. In the mean time I will gladly accept your offer of help. When the V4 arrives I'll contact you. Fit it in as your scheduel allows. Many thanks!

@Richard, When you start to install your Kanagroo please contact me if you like. I'll gladly share what I've learned so you dont have to struggle through what I have. It's a good PID board but documentation sucks and it seems to me that what they do have is geared towards the more advanced among us.

@Dave... sounds good Dave, thanks....

I just ordered C# for Dummies and C++ for Dummies off of Amazon. Free 2 day shipping so it should be here by the weekend. I really want to understand what I'm asking here and hopefully lend a hand. I know it's a complex language and will take some time to learn but at least this will give me a base and a start. Hopefully I'll be able to at least write a simple cammand to send over serial and know what I'm trying to do.

If you buckle down C shouldn't be too difficult... I use EasyC for my vex stuff, but it's not C... it does spit out C pseudo code so one can see how C works as a language... However, EasyC is really just a graphical language that has almost no C programming for the user. Robot C is another Vex controller (among others) language that is nearly full blown C... That I wouldn't mind learning... I do agree with you C is worth learning.. I would learn C for no other reason than to establish a serial connection between my EZB and the Vex controller .... Maybe I should I should learn it, then...

interesting and informative thread, Dave I need hep with this

Hey Reed, good to hear from you. I'll be glad to help as much as I can but I'm at work right now and have a busy evening ahead of me. I'll try to get back to you on this as soon as I can. This is all thread and lots has changed since then. Good news is that the kangaroo now has built-in ramping. You do have to access the controls through the software which means you need cables connected in the proper way to your computer. It's all a little confusing and frustrating at first but once you get the hang of it it's really an awesome and easy to adjust set up. Getting into the software and making adjustments is the best way to get the best results. You will also need a good feedback device attached to your kangaroo and your motor. Pots are okay but I really suggest encoders. Once you have a kangaroo properly tuned and your ramp settings adjusted the ez script to move your motor is very easy. Just a few lines and some sleep commands and you're good to go. By the way I connect my kangaroo 2 my EZB through the serial port. That's the only way you can get feedback to the kangaroo from your encoder. I can send you any commands you will need to put in your script. Good luck and have fun. I'll talk to you later.

David, at the beginning of this post, you mentioned: I had an issue where I was continually getting error codes at power up and would have to power cycle the unit to get it to respond to serial commands. However I found I had to make sure the Sabertooth/Kangaroo powered down completely when the robot and EZB was switched off and then powered up after the EZB was powered up. I seem to be having that issues as well.  How did you resolve it?  How did you get the Sabertooth/Kangaroo to power down completely, and how did you make sure the Sabertooth/Kangaroo powered up AFTER the EZB was powered up?

This was an issue to me because my robot had a battery attached in line that kept power feeding the even after the robot's main  power switch was turned off. At that time my robot pugged into the wall and was powered through a AC to DC converter. I used that battery only for a place to dump the regeneration power created by the Sabertooth. If not used the regen power would have kicked out and possibly damaged the power supply.

I solved that issue by placing a relay between the battery and the sabretooth that was controlled by the EZB and ARC. When the robot was powered up the relay would be in the NO position keeping the dump battery disconnected from the Sabertooth. ARC would then run a script that would close the relay and connect the two. When The robot was powered down the Relay would naturally open and disconnect the dump battery and let the Sabertooth/Roo power down.

A much better solution is to simply buy a Sabertooth 2x32 Sabertooth. the Sabertooth 2x32 can is shipped and configured to allow it's power outputs as a voltage clamp to operate from a power supply without a parallel battery. A much more elegant solution.

I guess my issue is something else then. I am just using batteries at this point. Have the EZ-B on a separate power line than the sabortooth/kangaroo. So what is happening is, after I got the kangaroo "trained" with the limits (used teach mode), I created EZ-B scripts to set the max/min for both motors, set the initial speed, and set the initial position (which is the end/home position). Then I created a script to shutdown the robot, moving motors to the start/home position. Then I powered off the EZ-B and sabortooth. Then I turned them back on, ran the startup script, did some moving of the arms, and then called the shutdown script. Then power off. And repeated. This all worked fine. Then I powered off once more, left it off of several minutes, then powered back on, ran the startup script. Then when I attempted to move the arms, nothing happened, and the LED on the Kangaroo now flashed 3 times. Don't understand why it worked a couple of times, and then quit working. When I re-power up, and run the startup script, all seems fine, no flashing LED, no errors from the script. But as soon as I try moving an arm, the LED starts flashing 3 times.

What device are you using for feedback? 3 flashes is a control error. From the manual:

Quote:

Control error, channel disabled. Check to make sure your feedback sources are working and the system matches how it was set up during the tune.

If you are sitting on a limit switch on start up you will have issues.

How are you sending your commands? Simple Serial through the Uart or servo commands? Some of my motors I have controlled by the Kangaroo I have attached to EZB's digital ports and control using servo commands. I have had issues with them nor responding if they are out of position on startup. However I don't get an error code so this is probably not your issue.

I am using a gear motor with encoder. Using EZB digital ports and servo commands to send commands. Now that you mention it, I believe it might be a homing issue. The motor does seem to start to move just a bit, then quit. I believe I saw a setting in Describe control software where you can set the Origin and homing positions. I’ll take a look at that tomorrow and see what I can set/try.

If you are using digital pins with servo commands I don't know of any way to home manually. When using servo commands I set the Min/Max settings and position and speed for these Sabertooth/Roo controlled DC motors in my INT script. It seems that the motor first moves on it's own to a limit switch the first time I send a servo command then moves to it's command position. Sometimes if the motor is in the center of it's travel it wont do it on it's own. I have to send a position manually then it will find a limit switch and then proceed to the position.

I think I finally got this figured out. When the Kangaroo is programmed using the Teach Mode of Auto-tune, it assumes that the start position is in the middle. So when it first powers up, it reads the PWM setting from the EZ-robot, then calculates how much/direction it needs to move the motor to get it to the PWM setting. In other words, if the PWM is at say 50 (of 1-180), it would be 40 units short of center, so the Kangaroo moves the motor 40 units backwards from center. If at power up, the motor is actually at PWM position 20, when the Kangaroo powers up, it again assumes it is at center, figures it needs to move 70 units backwards (to get from 90 to 20), and then the motor hits the limit of travel, and the Kangaroo errors. Turns out, there is a setting called Origin which can be set via the Describe software. That Origin is the line count of the encoder, and is set to 0 when you do the Teach Mode (line count goes from negative to positive, with zero being center of travel). Using the Describe software to set the Origin to the min or max line count (shown on the position tab of Describe), will make the Kangaroo assume the start position at power up is that min or max value of the Origin. In my case, the min line count was -1375, max was 1375. I set the Origin to be 1375, and updated Kangaroo with the new settings. Then I did a power off/on, and now everything works like I need it. I make sure my motor is at the start position (1375) on power up, and the PWM setting on EZ-robot is 1, and then there is no initial homing of the motor. Of course, I must make sure when powering down, the EZ-robot moves the motors back to the initial start positions, before I turn the power off, but that is something that has to be done anyway. Only issue will be if the power is ever cut off before returning to start positions, then everything gets out of sync. But that’s another problem, for another day.