Optimal Paint Gun Orientation in Spray Paint Applications—Experimental Results

Abstract

In this paper, we present the experimental results of a new spray paint algorithm presented in previous publications. Both theory and simulations indicate that the proposed method allows a robotic manipulator to paint a given surface using substantially lower joint torques than with conventional approaches. In this paper, we confirm this by implementing the algorithm on an ABB robot and we find that the joint torques needed to follow the trajectory are substantially lower than for the conventional approach.The approach presented is based on the observation that a small error in the orientation of the end effector does not affect the quality of the paint job. It is far more important to maintain constant velocity for the entire trajectory. We thus propose to allow a small error in the specification of the end-effector orientation, and we show how this allows us to obtain a higher constant speed throughout the trajectory. In addition, to improve the uniformity of the paint coating we are also able perform the paint job in less time. Note to Practitioners-This paper presents several experiments that verify previously obtained theoretical results. For a large class of taskswhere the robot is to hold a pointing device, such as a painting gun or a heating device, we show through experiments on a real robot, that we can increase the speed at which the robot tool traverses the surface. In spray painting it is for example far more important to keep a constant speed than to hold the paint gun orthogonal to the surface. The method proposed is to implement a slightly different planning algorithm in turns by allowing a small orientation error. The trajectory planner will then use the freedom obtained by allowing this orientation error to follow the trajectory with a higher constant velocity. The experiments presented in this paper show that we are able to reduce the energy needed to paint a surface with about 50% or increase the speed at which the paint gun traverses the surface with more than 50%.

Set-Based Control for Autonomous Spray Painting

“…if a is True then 8q q q des = f f f 1 ; 9 else 10q q q des = f f f 2 ; 11 end Algorithm 2: One iteration in the control system. The choice of θ = 20 • is the same as in [27]. Since the function h(x, y) is a constant, the spray surface is flat, and the desired distance between the nozzle and the point of intersection p p p i is 0.3 m. Note that in these experiments, no paint has actually been applied to a surface.…”

“…This is exploited in [20], where the nonlinear orientation constraints are transformed into positive definiteness constraints imposed on certain symmetric matrices to find the desired orientation every time-step. It is shown that this approach allows the end effector to maintain a higher constant velocity throughout the trajectory guaranteeing uniform paint coating and substantially reducing the time needed to paint the object, something that is experimentally validated in [27].…”

Trajectory Optimization of Electrostatic Spray Painting Robots on Curved Surface

“…In this process, it is necessary to transform between the spatial coordinate system of the workpiece and the base coordinate system of the robot (also called workpiece calibration). The transformission between the coordinate system of the end effector and the base coordinate system of the robot is also necessary (also called tool calibration) [21][22][23][24].…”

Trajectory Optimization of Spray Painting Robot for Complex Curved Surface Based on Exponential Mean Bézier Method

“…Therefore, it is of vital importance to find the new basis functions of Bézier curves. In this section, Bézier curves are evenly combined with exponential mean, and the definition of exponential mean Bézier curves with parameter is put forward [14,15]. The three basic properties of this kind of curves are given, such as the elevation, de Casteljau algorithm, and segmentation theorem which are applied to the method for generating the painting path in complicated surface.…”