Redundancy Resolution Integrated Model Predictive Control of CDPRs: Concept, Implementation and Experiments

Abstract

This paper introduces a Model Predictive Control (MPC) strategy for fully-constrained Cable-Driven Parallel Robots. The main advantage of the proposed scheme lies in its ability to explicitly handle cable tension limits. Indeed, the cable tension distribution is performed as an integral part of the main control architecture. This characteristic significantly improves the safety of the system. Experimental results demonstrate this advantage addressing a typical pick-and-place task with two different scenarios: nominal cable tension limits and reduced maximum tension. Satisfactory tracking errors were obtained in the first scenario. In the second scenario, the desired trajectory escapes from the workspace defined by the new set of tension limits. The proposed MPC scheme is able to minimize the tracking errors without violating the tension limits. Satisfying results were also obtained regarding robustness against uncertainties on the payload mass.

A Nonlinear Model Predictive Control for the Position Tracking of Cable-Driven Parallel Robots

“…To overcome this problem, a Model Predictive Control (MPC) strategy was introduced in our preliminary work [28]. As highlighted in [29], MPC is one of the few control strategies able to handle system constraints explicitly.…”

“…As highlighted in [29], MPC is one of the few control strategies able to handle system constraints explicitly. Thus, the Linear MPC (LMPC) introduced in [28] integrates the cable tension distribution calculation within its formulation. Experimental results showed that this MPC is not prone to the aforementioned feasibility issues since it can operate on the WFW boundary without failure.…”

A Simple and Efficient Non-model Based Cable Tension Control

“…(1) was implemented as part of a position tracking control strategy. More precisely, the Model Predictive Control (MPC) strategy proposed by the authors in [14] was implemented and used to perform the trajectory illustrated in Figure 10. The resulting measured cable tensions and cable tension tracking errors are shown in Figure 11.…”

Path Tracking in Cable Suspended Parallel Robots through Position- Dependent Model Predictive Control with Embedded Integrator

“…It should be noted that the proposed formulation of MPC with embedded integrator includes in the cost function the variation of the cable tensions through c N ΔT , rather than the value of the tensions. This aspect is particularly useful in real case scenarios, as discussed [12], because large variations of cable tensions are not physically feasible.…”

“…In the very last years, attention has been spent by a few researchers in the field of CDRs to apply the concepts of MPC ( [8], [9], [10], [11], [12]), also showing promising results. Different MPC architectures are proposed by these papers, with reference of fully constrained CDRs, and different approaches are proposed to deal with the nonlinear dynamic behavior of the system.…”