Technical Article on Electric Steering Engineering and Why it Actually Sucks
02-08-2017, 01:02 PM
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Technical Article on Electric Steering Engineering and Why it Actually Sucks
There is a very interesting technical article in Car and Driver that interviews one of BMW's chief engineers about steering feel and electric power steering. Basically what he says is:
1. 99% of customers want a car without steering feel, and this is where the money is (even in the M line), so we are giving them this for sales reasons.
2. EPS is actually engineered specifically to reduce steering feel, even on M cars. For instance, they program it to reduce road vibration and even lane drift due to grooves in pavement, even on M cars. This cannot be done with hydraulic systems due to the slow control system response time.
What this tells me is that EPS sucks because car makers design it to suck. Its not because EPS is inherently worse than hydraulic. I'm sure Porsche is also doing this to some extent on all but the GT3 lines. The engineer creatively refers to steering feel as "bad feedback". Either way, this is proof that even the M line purposefully has artificial steering feel programmed in.
http://blog.caranddriver.com/steer-m...steering-feel/
1. 99% of customers want a car without steering feel, and this is where the money is (even in the M line), so we are giving them this for sales reasons.
2. EPS is actually engineered specifically to reduce steering feel, even on M cars. For instance, they program it to reduce road vibration and even lane drift due to grooves in pavement, even on M cars. This cannot be done with hydraulic systems due to the slow control system response time.
What this tells me is that EPS sucks because car makers design it to suck. Its not because EPS is inherently worse than hydraulic. I'm sure Porsche is also doing this to some extent on all but the GT3 lines. The engineer creatively refers to steering feel as "bad feedback". Either way, this is proof that even the M line purposefully has artificial steering feel programmed in.
http://blog.caranddriver.com/steer-m...steering-feel/
Asked to cite an example of bad information, Kistler explained: “Lines in the road with an orientation parallel to the car’s path cause what we call ‘pull drift.’ The tires try to follow the lines instead of the direction selected by the driver through the steering wheel. While that’s difficult to address with hydraulic power steering, with EPS we can install what we call pull-drift compensation to help keep the car locked on a straight path instead of following longitudinal grooves.
...
Attempting to shift the focus from steering effort to the feedback routed from the pavement to the driver’s hands, I asked if any EPS strides had been made in that specific area. Kistler responded: “We surveyed both current BMW 5-series customers and owners of competitive models, asking, ‘What are your wishes?’ We have two million customers around the globe who’ve purchased the 5-series during the past five years, which results in a broad spread of demands. Our job is to fulfill those mainstream needs. “There was a clear request for less steering effort. No one wants bad feedback—such as a steering wheel that vibrates in response to bumps in the road.”
...
Attempting to shift the focus from steering effort to the feedback routed from the pavement to the driver’s hands, I asked if any EPS strides had been made in that specific area. Kistler responded: “We surveyed both current BMW 5-series customers and owners of competitive models, asking, ‘What are your wishes?’ We have two million customers around the globe who’ve purchased the 5-series during the past five years, which results in a broad spread of demands. Our job is to fulfill those mainstream needs. “There was a clear request for less steering effort. No one wants bad feedback—such as a steering wheel that vibrates in response to bumps in the road.”
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