Question about PEP

Lynxmotion Legged Robots
1

Hi.
First of all I’m a beginner so I might lack informations. :blush:
I have a phoenix hexapod and a couple of questions.

  1. All my coxa servos are running in the opposite direction when I connect to PEP. (the femur and the tibia are ok). How can I reverse the calculation in PEP?

  2. I don’t have the Visual Sequencer (SEQ) and I want to write the EEPROM myself. How can I get the PWM result from PEP? (I know it is possible because the PEP can send that data to SSC32.

I tried to find the same issues on the forum with no results. If someone can give me a link it will also be ok. :slight_smile:

Thank you.
Sorin Petrila

2

The PEP was made graciously by Zenta (thank you again Zenta!), so he would be in the best position to answer these questions.

3

Hi,

It’s been years since I did anything with PEP so I’m a bit rusty here.

  1. Do I understand you correctly that you have connected PEP to a working Phoenix hexapod with a SSC-32? You say the coxa servo turn to the opposite direction, just to be sure you are not mixing the direction of the robot front/rear?. What PEP version are you using? What kind of servos are you using (brand)? What pins are the servos connected to?

  2. Take a look at the VB code in the Excel sheet. Open the SSC32com module and look for the CalculateAllPWM() sub. Here are the pwm values calculated, you can easily turn the direction by reversing the pwm value. Reversed pwm value = 3000- Old pwmvalue.

4

  1. Yes, I connected the SSC32 to PEP. Only on the coxa I have the modelcraft RS-2. (the femur and the tibia are towardpro MG996R). I use PEP ver 2.02LMbeta. The coxa are on 0,4,8, 16,20,24. I know that the front of the model in excel is oriented to the floor . For example: when I move the rear left on the X-axis , the leg make moves on the Z-axis. The same for all coxa servo. The femur and tibia are ok. I made an excel sheet that converts degree in PWM and GP Sequencer format. There I multiply all coxa with (-1) …but I haven’t tested yet.

  2. Thank you Zenta :slight_smile:

5

Did you test what direction the RS-2 turn vs the TowerPro. Say moving from 1000->2000 pwm, does both servos turn CW or CCW?

Btw: do you have a picture of your hex?

6

Hi Zenta,
For a rising PWM the RS-2 is CCW and Towerpro CW. I manage to reverse the calculation in your PEP excel. Thanks again. I’m working on calculation of PWM and code for EEPROM. It’s working :smiley: . I have some issues with the calibration but I hope I will solve it.

http://i1187.photobucket.com/albums/z394/sorinpetrila/Hexapod%20Phoenix/IMG_0914_zps6c37e079.jpg
This is the project for my master degree thesis from next year. It will involve image processing and commands in LabView.

Thank you.
Sorin Petrila

7

To confirm - the brackets are Lynxmotion but the servos are TowerPro? Any issues with assembly?
Unfortunately we cannot test all servos in these robots, so it’s good to know if you have found one which is compatible with the SES brackets.

8

Yes, the servos are the TowerPro MG996R. No problem with the assembly.

9

Appreciated :slight_smile:

10

Your Phoenix looks great. I hope you’ll post more about your project one time.

11

One of my servos has died, and I had to buy another. The surprise was to see that it moves in opposite direction than the other servos. I realized that the new one is a normal servo for PEP. So to save time I reversed the direction of rotation vs pwm just by reversing the wire inside the servo. I hope someone will need this information sometime and I hope to find it here :smiley:
http://i1187.photobucket.com/albums/z394/sorinpetrila/Hexapod%20Phoenix/bf814c7a-5319-489c-8fc9-5b9ac45d5b3e_zps86330ae8.jpg

ps:hope my english is good enough :blush:

12

Nice idea to post the pix on reversing the servo!

I see the two motor wires swapped, and the two outside pot wires swapped.

Good job!

Alan KM6VV