Question about wheelchair motor brakes when system is powered off

Hi everyone,

I am currently building a 2-DOF full motion simulator using 24V wheelchair motors, but I cannot see any brake systems on the motors commonly used in these builds.

How do you keep the rig stable and prevent it from tilting or collapsing when the system is powered off or during normal gaming?

My wheelchair motors have a manual engagement/clutch lever for the electromagnetic brakes. I plan to manually engage these levers to lock the rig when the system is off, and disengage them when the motion is active. Would this approach work well, or is there a better way to handle this?

Thanks in advance for your help!

With a 2DOF rig with no heave I wouldn't worry too much. It can't really collapse unless the U-joiunt would break. If the tilting range is large enough and the motors powerful enough that you fear being thrown off the chair in the case of a malfunction I'd simply put on seatbelts. And install an E-stop button in reach.

For 6DOF rigs or 3/4DOF with heave and large linear stroke actuators this really can become a serious problem, though. After a power failure the rig could almost free-fall to the ground. Motor brakes that automatically engage after power failure are handy in this case.

Thank you so much for the helpful answers! This was actually my biggest concern regarding a 2-motor simulation setup. Because of this, I have decided to change my project plans; instead of using wiper motors, I will be going with 24V wheelchair motors. The fact that they have a manual engagement/brake lever is a huge advantage for me.

Additionally, even though I will be positioning the universal joint (U-joint) perfectly at the center of gravity, I am still considering adding two 28.5 cm spring dampers (shocks) to the front section just to be safe and reduce the load on the motors when the system is active.

Do you think adding these shocks is overkill or unnecessary? Or does it make good sense to support the wheelchair motors this way? I would love to hear your thoughts.

For wheel chair motors, the brake is engaged when they are not powered.

There is an electromagnet in the brake housing. When the brake is powered, the electromagnet lifts away from the motor housing releasing the motor armature to freely spin.

Here's the reasoning, a person is in a wheel chair riding down an incline and the batteries die. The electromagnets are no longer powered as the battery is dead so now the brakes engage and the chair stops.

I had the same thought you did initially and it would work. But decided to pull the brakes off my build.

Yes, my rig droops when not powered on. Usually the rig will go to the center position when initially powered on. Sometimes it does not, so I just open SCM3 and power it up to get it back in the center position, then turn SCM3 off and run SimTools and whatever game.

Gas struts may or may not be needed. Depends on the build and weight distribution. Our designs are all a bit different.

2 DoF does not have true heave/surge but can be approximated, I use heave/surge in my assignments. It's not "true" heave/surge because in a 2DoF they are also on the Pitch axis. Some people use a ball screw under the seat/frame in a 3 DoF for real heave/surge effect.

hi, I build some on this motors, only think You need to focus is: after turn off -sensors need to be in working range, use only hall sensors, if You going to use ibt2 - than use 2 on 1 motor have a nice day

Thank you so much for the kind words! I will definitely keep updating the thread as the project moves forward.

Regarding the components, I have a quick question about the feedback sensors. It turns out I mistakenly bought multi-turn (infinite rotation) potentiometers. I've read on some forums that multi-turn potentiometers can cause positioning or scaling issues within the SMC3 software. Currently, I'm not planning to modify my pot setup just yet, but I wanted to ask the community: Which specific sensors or potentiometers did you use for your setups to get the most stable results?

Also, as a quick update on the electronics: I have purchased two separate BTS7960 (IBT-2) drivers, one for each motor.

I would appreciate your recommendations on the sensors. Thanks!"

Positioning the U-joint below the center of gravity or using springs to compensate for any imbalance is good. The motors have to work less if the rig is well balanced.

Shock absorbers do dampen the impact at the end stops are not neccessary, though. If you use rotary actuators (with crank arms) and the rig happens to fall to one side, either the top or bottom dead point of the actuator, the movemtnt automatically slows down smoothly.

I have separated the triple monitor mount from the cockpit chassis. My goal was to reduce the overall weight so it wouldn't overload the motors and cause the IBT-2 drivers to strain or overheat.

By lightening the rig this way, I’m planning to place a universal joint (u-joint) under the seat, and install two 50cc scooter shock absorbers—either at the rear or the front—to manage the balance and movement."

Read this https://www.xsimulator.net/communit...-200w-adjustable-rig-done-and-runing-d.16667/
I spend realy much time to answer any questions by build this threat,
Long story short- witch pot and one ibt2 -You will burn it at beginning as walk all of us that patch