Tips on prevention of stall?

VEX V5 General Discussion General Forum
1

Hi all,

Ever since the Skyrise season I have been experiencing stalls on my reverse double 4 bar lift with a capacity of 3 cubes. For weeks I have been searching for ways to reduce and minimalise these amounts of stall but none of them helped. It was only until 1 day into World Vex when I applied a considerable amount of lubricant to the joints and axles to ensure that my lift does not stall on the second day. I do know of some tips and tricks of reducing these stalls such as decreasing the amount of friction points, and load weight.

I also went through multiple tests for the Nothing but Net season but ended up using an extensive number of motors for my flywheel mechanism to ensure that it could last for the entire match without stalling.

Before I build the second version of my robot, I was hoping to use few number of motors for a flywheel and a speed base that could afford 4-5 bumps that would not cause it to stall. Could I get some solutions to how to reduce stalls, and are there tricks and different configurations that make things stall less?

Cheers

2

Ahh yes, the dreaded PTC trip… You’re not the first to be hit by this.

You already seem to know tip #1 - reduce the torque needs of the motors. You did that by lubricating things as friction is a tricky widget to overcome. That same friction is the thing to avoid in the flywheel.

Lots of threads here on the forums for motor speed torque curves and tripping PTC’s.
https://vexforum.com/t/motor-torque-speed-curves/21602/1

Tip #2 is reduce the weight of the robot - especially for drive motors. Aluminum and generally less metal is the way to go there.

Tip #3 - don’t jam the motors full of current at once. There’s a trick called slew rate that steps up the power over a period of time to avoid sudden spikes in current. It is not a catch all, but it helps.
Big thread that has this : https://vexforum.com/t/robotc-programming-tips/19718/1
Post you want: https://vexforum.com/showpost.php?p=225727&postcount=25

Tip #4 - let the smart motor library stop you from doing too much current. This may lead to frustration in that the calculations say you are using too much power. But it stops the PTC trips. (Go back to tip 1 at that point to reduce torque needs)
[https://vexforum.com/t/smart-motor-library/22282/1

Tip #5 - you can use 12 motors this year! Use em.

Power expanders can help mildly but are no panacea if torque, weight, and friction are the real problems.](https://vexforum.com/t/smart-motor-library/22282/1)

3

+1 for this. Study the smart motor library and master it. It is a very good thing dealing with motor power/PTC issues.

4

Tip #2 is reduce the weight of the robot - especially for drive motors. Aluminum and generally less metal is the way to go there.

Tip #3 - don’t jam the motors full of current at once. There’s a trick called slew rate that steps up the power over a period of time to avoid sudden spikes in current. It is not a catch all, but it helps.
Big thread that has this : https://vexforum.com/t/robotc-programming-tips/19718/1
Post you want: https://vexforum.com/showpost.php?p=225727&postcount=25

Tip #4 - let the smart motor library stop you from doing too much current. This may lead to frustration in that the calculations say you are using too much power. But it stops the PTC trips. (Go back to tip 1 at that point to reduce torque needs)
[Smart Motor Library - Technical Discussion - VEX Forum

Tip #5 - you can use 12 motors this year! Use em.

Power expanders can help mildly but are no panacea if torque, weight, and friction are the real problems.](Smart Motor Library - Technical Discussion - VEX Forum)

Thanks a lot! Will try it out when I start on work on my new robot.