Cheapest direct drive wheel almost ready for purchase
Just noticed the update on SimXperience. AccuForce will be "available for purchase at year end 2014". The base package would be $1749 or $1449 depending on whether you go DIY or pre-built.
Might be a good time to get rid of CSWs and such if this works out well.
so basically u pay a lot more, for a lot less?!
as i read it its just a motor, inside a casing, with a wheel attached to it.
and what in the world is so expensive in this?
There are no gears or belts or anything. The FFB is direct from the motor to your hands. This means the FFB is more direct. I've used a Leo Bodnar Simsteering wheel, and it's in a complete different league. This wheel is basically a toned-down version of that, so I imagine that it's the same idea.
The motor in a wheel like this isn't anything like in other wheels. I'm not 100% sure what kind of engine they use in the Accuforce (most likely something cheap (relatively)), but the good direct drive wheels use a Servomotor/Stepper motor. This means that they can set theirself to a certain position, and keep at that position. The normal motors just turn quickly left or right. This means that these wheel also can have a very good and strong 'soft-lock' to limit the rotation of the wheel. Again, not sure about this wheel, but that Leo Bodnar wheel has virtually no limit of rotation because it's just tracked by the software, and you can limit it at anything you want.
Also the speed of which it can change its position is a lot faster than a regular engine, and its resolution is a lot higher, which means it's more precise. So you do pay a lot more for 'less', but the when the motor is good enough, it's a lot better. There is no sound if the motor is of good quality, and there virtually shouldn't be any wear and tear.
Good to see another SimSteering user here. Great wheel.
The concept that DD wheels use servo motors seems to be quite popular. DD wheels tend to use "servo motors" just because many high quality motor products that fit the purpose happened to be designed (or advertised) with servo application in mind. Using a motor in a servo feedback loop requires a position target being sent to the hardware, which is not possible given the existing FFB game controller interface. The sim software could do it by itself, but that has nothing to do with what kind of motor is running in the physical device. In a DD wheel product, even if the motor has built-in servo control logic it can not be used. Actually I'm not aware of any DD wheel that has a servo motor assembly with the stock servo controller left in place. It's always just one stand-alone motor. An external controller programmed with FFB function in mind would control the current through the motor so the hardware can aim at the given torque target. There's no position target non PID loop.
It's the same for the AccuForce. The hardware has unlimited rotation with only soft lock. The driver appears to limit it to 4500deg, which is more than enough anyway.
On top of that, DD wheels are expected to deliver completely linear and angular-velocity-independent response within the range of torque and angular-velocity meaningful for the application. Its torque response does not die out as the wheels rotates faster. This is why much more powerful motors are used. Non-DD consumer wheels use drive ratio bigger than 1 to amplify the torque. But you can't amplify power that way, so actual torque dies out quickly as you get close to what the motor or controller can handle. To make matters worse, low range wheels don't aim at a target current at all. They simply control duty ratio on the power supply and hope for the best, which doesn't work very well. There's no feedback/modulation/compensation whatsoever and even when you're far from the power limit of the hardware the response linearity is bad.
So assuming the product lives up to its expectations you do get accurate force (torque) with an AccuForce.
BTW, the double markers on LFS's steering gauge used to trick me into thinking it has steering column spring/damper simulation linked to steering geometry that doesn't teleport, which is technically a PID servo loop if the FFB is calculated accordingly. Unfortunately I tested further and it seems to be the effect of input filtering.
my accuforce pro doesnt ship till april or may :/ CSW v2 was supposed to ship today, but there's some sort of Delay caused by a dispute at the shipping ports
the accuforce produces about 14nm of sustained torque according to reviewers, and Leo bodnar does 16 (peak? or sustained?). Is the leo more linear/responsive? Also, the Simcommander 4 software is something I'm looking forward to trying.
According to Leo's shop page it's "up to 16Nm of torque" with default Kollmorgen motor. Sounds like peak to me.
This is very likely a matter of wording though. A typical oversimplified model of DC motors looks like below:
At stall the highest torque can be expected. However too much current going through the system could lead to overheating and other problems. So a more realistic model looks like below:
To create a sustained maximum torque load condition you have to stall the motor. But that's not what makes a DD wheel interesting. What a regular non-DD consumer wheel can't do is shown at the middle and right area of the graph where angular velocity is high and mechanical power output is bumped up. Within this range there's not much difference between peak and continuous.
Technically only providing a peak/continuous torque rating is not very helpful as we don't know in what angular velocity range the FFB product can achieve such a torque.
According to a post on rF forum the AccuForce has torque artificially limited to 13Nm for safety concerns. The hardware can do better (within some unknown angular velocity range) but you have to sign a waiver.
