Maybe it can be useful to look at difference between some EMA values and high/low values for some period of time.
I have a hi/low scanner. Most of it is chop but everday I find several stocks w clearly visible trends. It is easier in the afternoon. If the potential trade fits in with my rules, i take the trade!
The common measure for a stock's or ETF's volatility is its trailing 3-year standard deviation. For smoothness you want a low number.
The R^2 of the regression of the stock price vs. time is an estimate of trend smoothness. A stock rising or falling the same amount daily would have an R^2 of 1.