A Trapezoidal Velocity Profile Generator for Position Control Using a Feedback Strategy

Abstract

Position control is usually achieved using a position controller and a profile generator. The profile generator produces a desired position trajectory from a position reference and predefined profiles. The position controller forces the actual position to trace the generated position trajectory. A time-based profile generator is the most famous profile generator due to its capability of generating various profiles. However, time base difference in analysis and implementation causes a steady-state error. In order to remove the steady-state error, this paper proposes a novel profile generator for a trapezoidal velocity profile generation. The proposed generator is based on a cascaded P-PI position controller which is designed to trace the position reference. A dynamic range limiter is adopted to provide the acceleration and velocity restrictions which are basic functions for generating the trapezoidal profile. In spite of these restrictions, it cannot make a desired velocity profile only using the limiter because deceleration point is inaccurate. To adjust the deceleration point, a feedback compensator is designed which requires the velocity of the deceleration point. The velocity of the deceleration point is estimated from the initial position error. The compensator moves the deceleration point to the appropriate point which can generate the desired velocity profile. The proposed profile generator can remove the steady-state error, and the position response can be easily adjusted to be either overdamped or underdamped by selecting the two gains appropriately. Several experimental results are presented to verify the usefulness of the proposed generator.

A New Seven-Segment Profile Algorithm for an Open Source Architecture in a Hybrid Electronic Platform

“…A value of acceleration and jerk have to be calculated to use Equations (6)- (8),. The velocity obtained by the desired position can be computed using (11).…”

“…On the other hand, the parabolic velocity profile presents a smoother velocity curve than the triangular, making the jerk value less than triangular profile but neither of them maintain a velocity constant phase [9,10], it means that they accelerate and decelerate the actuator immediately. The trapezoidal velocity profile consists of three phases: acceleration, constant velocity and deceleration phase [10,11]. A constant velocity phase offers less wear on the actuator extending its life period, since, the change in acceleration occurs after a period and not abruptly after to reach the desired velocity [12,13].…”

A New Methodology for a Retrofitted Self-tuned Controller with Open-Source FPGA

“…On the other hand, the trapezoidal velocity profile is a second-degree polynomial that consists of an acceleration and deceleration phase; here, the velocity increase its magnitude considerably; a constant velocity stage is present in the middle of the acceleration-deceleration phases. The computational cost is suitable for simple structure and fast response [28]. That is the main reason for which the trapezoidal profile is one of the most used speed profiles in commercial controllers [11].…”

“…The maximum angular velocity ω max and the desired angular position θ d of the motor spur are proposed and, with this, the total duration T of the movement and the acceleration a are calculated, as follows [28]:…”

A PID-Type Fuzzy Logic Controller-Based Approach for Motion Control Applications

“…Motion control is a sub-field of automation that involves controlling mechanical movements of load and it is applied directly to the actuator to manage physical variables, such as torque, acceleration, velocity and position of an axis or axes, depending of the degree of freedom (DoF) of the system [ 2 ]. Motion control is applied to avoid the stress that is produced by a fast movement and to reduce the vibrations that are caused by the high rate of change in acceleration; also, trajectories are created to reach a desired position that the actuators must achieve [ 3 , 4 ]. Most commercial motion controllers that are available for industrial processes are based on classic controllers, such as Proportional-Integral-Derivative (PID) controller, and they are of closed architecture [ 5 ].…”