Page 742 - Mechatronics with Experiments

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, t
, t
where a, d are acceleration and deceleration values, v is the top speed, t acc dec run are
the time periods for acceleration, deceleration, and constant speed run phases of the index
motion (Figure 3.13). Let us assume that the index time period is equally divided between
acceleration, constant speed run, and deceleration time periods,
1
t acc = t run = t dec = ⋅ t index (10.6)
3
Let t = 3.0 s. The motor rotation to make the 1.0 in move is 1.0in ⋅ 5rev∕in = 5rev. It
index
can be shown that the total traveled distance is
1 1
x = ⋅ v ⋅ t acc + v ⋅ t run + ⋅ v ⋅ t dec (10.7)
2 2
( )
1 1 1 1 1
= ⋅ + + ⋅ ⋅ v ⋅ t index (10.8)
2 3 3 2 3
2
= ⋅ v ⋅ t index (10.9)
3
3 x
v = (10.10)
2 t index
3 1.0in
= (10.11)
2 3.0s
= 0.5in∕s (10.12)
The pseudo code to define these motion sequences may look as follows. The exact
syntax of the motion control software will depend on the particular motion controller.
% Assume we have two functions “MoveAt(...)” and “MoveFor
(....) ” to generate the desired motion.
% If these motion command (trajectory) generator functions
are defined in C/C++, they can be overloaded to accept
% different argument list.
%
%
% Calculate or set parameters
Home_Speed_1 = 2.5 % [rev/sec]
Home_Speed_2 = 0.25 % [rev/sec]
Home_Sensor = 1 % I/O channel number for the home
sensor
Jog_Speed = 1.0 % [rev/sec]
Jog_Stop = 2 % I/O channel to indicate to stop
motion.
Stop_Rate = 10.0 % [rev]/[secˆ2]
Index_Value = 5.0 % [rev]
t_acc = 1.0 % [sec]
t_run = 1.0 % [sec]
t_dec = 1.0 % [sec]

% Home motion
MoveAt (Home_Speed_1)
Wait until Home_Sensor = ON
MoveAt (Zero_Speed, Stop_Rate)
Wait for 1.0 sec
MoveFor(Index_Value)
Wait for 1.0 sec
MoveAt (Home_Speed_2)