Crossing starting bar: speed/torque

My team has been debating over whether we need speed or torque on our drivetrain in order to drive over the starting bar. Can someone please help us clear up our misunderstanding?

why not both? :wink:
so in my experience, i found that its a mix of both, there are a lot of factors to consider, the weight of your bot, ground clearance of your chassis, wheel grip etc. personally, I have a 6 turbo drivetrain, compared to the most common drivetrain, 4 High speed’s, I have more speed and torque. obviously, this isn’t always feasible. if your robot is on the heavier side and is planted to the ground, I would focus on torque. if your robot bounces off the starting bar and is generally lighweight, speed might be a better option. the only problem with speed on a heavier chassis that one, it might not be able to bounce off the starting bar as well, and more importantly, it might not have enough space to gain the speed required to get over it as you reverse. if you want to specify your specific scenario, I would be more than happy to tell you what I think would be better.

Like what @Manitha has mentioned - there are many other factors that will affect whether the robot can cross the bar. Eg. The clearance of the chassis, type of wheels, and even the CG of the robot will affect to certain extent.

The torque required depends a lot on the total weight of your robot + mobile goal (?) + cones (?) .

In my experience, crossing the 10 point bar is not a torque problem. If your wheels have enough grip, and you base has enough clearance, crossing the bar is not a problem. However, when adding in the weight of the mogo and any potential cones you are seeing an increase of almost 7 to 8 pounds. This is why few teams that I have seen are going with a 4 motor drive. While a torque configuration will have enough torque, it will not be very slow. The best configuration that I have seen is a 6 motor HS, which is faster than a torque drive and has more torque than a 4 motor drive.

To answer your question, either drive will work, if you have enough clearance. If not, even a torque configuration will be prone to get caught on the bar and will be too slow to “jump” over it, as I have seen some teams do.

Honestly, it’s really easy with whatever drivetrain you have. I’ve been in competitions with all kinds of robots, and I can say they all got over the starting bar.

Our robot is a multi-purpose robot, with a priority on scoring mobiles, but it can also stack on mobiles and stationary. We have a double reverse four bar, which makes our robot pretty heavy (I haven’t measured it though). Right now we are unable to cross the starting bar with our two motor torque drive (1:1), but we are going to add two more motors to our drive. We were wondering if we should use high-speed motors, or torque motors, or even an external torque ratio.

We use omni wheels if that helps.

Posting a video to show the problem might make it easier for us to give a solution

Our robot has four speed motors and we haven’t had any issues going over the bar, we have a pretty big scissor lift and we can make it over just fine with a goal and 11 cones. We have four Omni wheels although I’d imagine that traction wheels would help more. Only two thirds of our robot actually cross the bar

You need a good medium of both. Drives that are too fast (ex. a six motor 3:1 drive; yes, they exist) don’t get over the pipe and drives with too much torque (like the four motor grip wheel drive we made and stuck on torque) just sit and push back the pipe instead of get over it. I think 4 motor high speed or 6 motor turbo is your best shot.