Vision-based control for trajectory tracking of four-bar linkage

Abstract

It is well-known that mechanical sensors suffer failure in hostile environments. Therefore, in such applications, vision control is a suitable solution. In this paper, we propose a new approach for design and implementation of the control system for the speed of the coupler point in a four-bar linkage. To measure the coupler point position a computational vision system is implemented; the vision system sends the controller the precise position of the desired point for a wide range of crank rotational speeds. A proportional integral derivative control system is designed and implemented in a microprocessor. Stability analysis for the controlled system is performed via the Lyapunov stability theory. Performance of the system is validated experimentally in a prototype of a planar mechanism obtaining an average square error of measurement less than 0.03% and regulation of operating point less than 1% for different speed references.

Neural Network Based Control of Four-Bar Mechanism with Variable Input Velocity

“…To calculate this reference signal, we design the second control loop where we must consider the velocity tracking error, defined as e v = φ2 − φ2 * , where φ2 * is the reference velocity. Considering (30), the velocity error dynamics can be written as…”

“…This control scheme is defined as variable input velocity control. There are few reports of simulation studies on cases of trajectory tracking where the problem of variable input velocity control is addressed [2,3,6,15,[28][29][30]. In [6], a model reference adaptive controller for the velocity regulation of a four-bar mechanism is designed.…”

“…In [15], a robust backstepping controller is designed and tested in simulation for a four-bar linkage mechanism that is driven by a DC motor, without a priori knowledge of the model parameters where five cases were examined. In reference [29,30], the problem of trajectory tracking by controlling the angular velocity of the input link is investigated in a four-bar mechanism to fulfill moving the coupler point with a constant velocity. A vision controller for regulation of the velocity of the coupler point in a four-bar mechanism was implemented in [30], where the desired trajectory for the coupler point of the mechanism is achieved by controlling the angular velocity of the crank using a feedback linearization algorithm for the error dynamics and a PID controller.…”

Sabit Hız İle Yörünge Takibi Sağlayan Dört Çubuk Mekanizmasının Hız Kontrolü

“…Kısa bir süre önce de Bañuelos vd. [12], aynı problem için yaptıkları deneysel çalışmalarını sunmuşlardır. Bu çalışmalarında biyel noktasının hızı anlık kamera görüntüleri ile belirlenmiş ve PID kontrol algoritması kullanılmıştır.…”