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-- Copyright (C) 2002 Morgan Kaufmann Publishers, Inc
-- This file is part of VESTs (Vhdl tESTs).
-- VESTs is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at
-- your option) any later version.
-- VESTs is distributed in the hope that it will be useful, but WITHOUT
-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
-- for more details.
-- You should have received a copy of the GNU General Public License
-- along with VESTs; if not, write to the Free Software Foundation,
-- Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
library ieee; use ieee.math_real.all;
entity pendulum is
end entity pendulum;
----------------------------------------------------------------
architecture constrained of pendulum is
constant mass : real := 10.0;
constant arm_length : real := 5.0;
constant pin_angle : real := 0.25 * math_pi;
constant pin_distance : real := 2.5;
constant damping : real := 1.0;
constant gravity : real := 9.81;
constant short_length : real := arm_length - pin_distance;
quantity phi : real := -0.5*math_pi;
quantity current_length : real := arm_length;
begin
if phi'above(pin_angle) use
current_length == short_length;
else
current_length == arm_length;
end use;
break phi'dot => phi'dot * arm_length/short_length
when phi'above(pin_angle);
break phi'dot => phi'dot * short_length/arm_length
when not phi'above(pin_angle);
mass * current_length * phi'dot'dot
== - mass * gravity * sin(phi) - damping * current_length * phi'dot;
end architecture constrained;
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