Motion design for high speed machines.
The dynamic performance of a programmable manipulator depends on both
the motion profile to be followed and the feedback control method used.
To improve this performance the manipulator trajectory requires planning at
an advanced level and an efficient control method has to be used.
The purpose of this study is to investigate high-level trajectory planning and
trajectory tracing problems. It is shown that conventional trajectory planning
methods where the motion curves are generated using standard mathematical
functions are ineffective for general application especially when velocity and
acceleration conditions are included. Polynomial functions are shown to be
the most versatile for these applications but these can give curves with
unexpected oscillations, commonly called meandering. In this study, a new
method using polynomials is developed to overcome this disadvantage.
A general motion design computer program (MOTDES) is developed which
enables the user to produce motion curves for general body motion in a
plane. The program is fully interactive and operates within a graphics
A planar manipulator is designed and 'constructed to investigate the practical
problems of trajectory control particularly when operating at high speeds.
Different trajectories are planned using MOTDES and implemented to the
The precise tracing of a trajectory requires the use of advanced control
methods such as adaptive control or learning. In learning control, the inputs
of the current cycle are calculated using the experience of the previous
crcle. The main advantage of learning control over adaptive control is its
stmplicity. It can be applied more easily in real time for high-speed systems.
However, learning algorithms may cause saturation of the driving servo
motors after a few learning cycles due to discontinuities being introduced
into the command curve. To prevent this saturation problem a new approach
involving the ftltering of the input command is developed and tested.