Legs curling up when executing complex movements

Hexy Questions, Problems and Suggestions
#1

Firstly, thanks so much for Hexy! Such a fantastic project and really well executed.

After building Hexy and powering it up I have some questions about particular ‘leg curl’ behaviour. I’m running Hexy off a lab power supply set to 6 volts, which can supply up to 15 Amps. Hexy moves forward, backwards and turns well. However, when more complex actions are performed, such as ‘dance’ in PoMoCo, Hexy will drop to the ground and the legs will curl up (just like a dead spider). What triggers the curl up? Is that low voltage in the logic circuit?

I’ve tried powering the logic circuit off its own battery pack and Hexy has been plugged into USB when the curl occurs. I’m interested to know what triggers the ‘curl’ behaviour so I can work out a way to prevent it.

#2

Hi Brendan, did you ever come across a reason for this? I finished building my Hexy tonight but I can’t even get it to stand up, several of the legs just ‘curl’. I wonder if what you’ve found out might give me some clues in troubleshooting my problem?

They seemed to be fine when I was centering them when attaching the legs, though one of the hip servos I’m concerned about. My Servotor arrived with v1.2 installed, so I updated to v1.7 and tried various commands from PoMoCo - but I just get the leg spasms/curling. They are not even curling in the direction you’d expect from the movement pattern I select. I double checked the wiring matches from the Make tutorial (the only question I have is that i assumed the servo connections on the right hand side are plugged in that the brown wire is closest to the Servotor edge on the right, whereas on the left hand side all the servo connections are connected with the brown wire to the left). I’m using four fresh Duracel Plus AA 1.5v Alkaline batteries as the power source, I’m going to replace these with 5 NiMH once the stores open after New Year.

Is there anything else I could be checking in the meantime?

#3

Hi kojacker,

Regarding the wiring of the servos: on mine I’ve got all the brown wires (ground) towards the edge of the Servotor and the yellow signal wires towards the centre.

In the end the curling was related to a number of things, primarily the power supply and the older versions of Servotor32 and PoMoCo (I think). I had set my old power supply to 6V but in fact a multimeter said it was only providing around 4.5-5.5V depended on the load. I’m using a new external power supply that provides a constant 6V, along with Servotor32 v1.7 and PoMoCo 1.0, and it is working really well.

I had also tried a LiPo battery (2180 mAh, 11.1V) with a 6V 5A SBEC (Turnigy SBEC 26V), which didn’t work well when using Servotor32 v1.6 and the older PoMoCo. Having just upgraded both, Hexy is working with the LiPo battery setup. However, the BEC overheats and shuts down after a while and Hexy curls up, which indicates it proberly can’t quite handle the load (two in parallel should work better but I havn’t tested this yet).