A Minimal Touch Approach for Optimizing Energy Efficiency inPick-and-Place Manipulators

The interest in novel engineering methods andtools for optimizing the energy consumption in robotic systemsis currently increasing. In particular, from an industry pointof view, it is desirable to develop energy saving strategiesapplicable also to established manufacturing systems, beingliable of small possibilities for adjustments.Within this scenario,an engineering method is reported for reducing the totalenergy consumption of pick-and-place manipulators for givenend-effector trajectory. Firstly, an electromechanical model ofparallel/serial manipulators is derived. Then, an energy-optimaltrajectory is calculated, by means of time scaling, starting froma pre-scheduled trajectory performed at maximum speed (i.e.compatible with actuators limitations). A simulation case studyfinally shows the effectiveness of the proposed procedure

A Simulation Tool for Computing Energy Optimal Motion Parameters of Industrial Robots

This paper presents a novel robot simulation tool, fully interfaced with a common Robot Offline Programming software (i.e. Delmia Robotics), which allows to automatically compute energy-optimal motion parameters, for a given end-effector path, by tuning the joint speed/acceleration during point-to-point motions whenever allowed by the manufacturing constraints. The main advantage of this method, as compared to other optimization routines that are not conceived for a seamless integration with commercial industrial manipulators, is that the computed parameters are the same required by the robot controls, so that the results can generate ready-to-use energy-optimal robot code

Optimal Design Methods for Increasing Power Performance of Multiactuator Robotic Limbs

abstract: In order for assistive mobile robots to operate in the same environment as humans, they must be able to navigate the same obstacles as humans do. Many elements are required to do this: a powerful controller which can understand the obstacle, and power-dense actuators which will be able to achieve the necessary limb accelerations and output energies. Rapid growth in information technology has made complex controllers, and the devices which run them considerably light and cheap. The energy density of batteries, motors, and engines has not grown nearly as fast. This is problematic because biological systems are more agile, and more efficient than robotic systems. This dissertation introduces design methods which may be used optimize a multiactuator robotic limb's natural dynamics in an effort to reduce energy waste. These energy savings decrease the robot's cost of transport, and the weight of the required fuel storage system. To achieve this, an optimal design method, which allows the specialization of robot geometry, is introduced. In addition to optimal geometry design, a gearing optimization is presented which selects a gear ratio which minimizes the electrical power at the motor while considering the constraints of the motor. Furthermore, an efficient algorithm for the optimization of parallel stiffness elements in the robot is introduced. In addition to the optimal design tools introduced, the KiTy SP robotic limb structure is also presented. Which is a novel hybrid parallel-serial actuation method. This novel leg structure has many desirable attributes such as: three dimensional end-effector positioning, low mobile mass, compact form-factor, and a large workspace. We also show that the KiTy SP structure outperforms the classical, biologically-inspired serial limb structure.Dissertation/ThesisDoctoral Dissertation Mechanical Engineering 201

Control of electric drive by means of inverse dynamics

This paper presents a method for positioning an electric drive with an elastic mechanical part by applying the inverse problem of dynamics. The presented assumptions take into account technological requirements and limitations of dynamic variables. The desired trajectory of the mechanical part of the electromechanical system has also been determined. On this basis, an algorithm for determining the control voltage waveform is proposed

Dynamic Optimization of a Rimless Wheel with an Actuated Pendulum

As the demand for mobile robots that work alongside humans increases, the amount of energy that these co-robots consume will become a critical limiting factor in their deployment. This need is clearly captured in one of the fifteen main goals of the 2009 Roadmap for US Robotics which is to create a robot that can walk with half the energy consumption of a human being. At this point, the most energy-efficient walking robot is about as energy efficient as a human. Energy efficient bipedal motion is an active area of research. It has been proven that it is theoretically possible to design a robot with intermittent support, one of the most fundamental attributes of legged locomotion, to have a zero-energy cost collisionless gait. Optimal control has been used by a number of researchers to study the generation of periodic gaits for walking robots. However little research exists demonstrating walkers with energy efficient collisionless motion. The research that does exist demonstrates that a significant amount of the energy lost to the system when walking is from losses due to step collisions. In this work energy efficient locomotion of a prototype actuated rimless wheel on level ground is explored using numerical optimal control. The actuated rimless wheel has an internal pendulum driven by a DC motor. The locomotion problem is posed as an optimal control problem. Different cost functions and initial configurations are investigated and the corresponding gait trajectories analyzed and assessed based on their use of energy and the potential for collisionless motion

Design and Energetic Evaluation of a Mobile Photovoltaic Roof for Cars

Abstract Hybrid electric vehicles, associated with photovoltaic panels, are gaining interest mainly for two reasons: the increasing attention on the recourse of green transports and the production of electricity by a gratis and largely diffused source of energy, the solar one. Previously a considerable gain of solar energy for tracking system instead of fixed horizontal photovoltaic ones has been demonstrated and validated by historical data taken from an online calculator PvWATTS. Otherwise, there is a difference between solar tracking systems for fixed pants and for mobile applications. In this paper a prototype of a tracking solar system for vehicles and the energetic analysis has been presented. After the presentation of the system adopted, geometric optimization, it has been presented the energy evaluation: there is the computation between energy solar gain, mechanical energy spent to move the roof and energy losses, computed with a MATLAB® tool named SimMechanics™

Energy-oriented Modeling And Control of Robotic Systems

This research focuses on the energy-oriented control of robotic systems using an ultracapacitor as the energy source. The primary objective is to simultaneously achieve the motion task objective and to increase energy efficiency through energy regeneration. To achieve this objective, three aims have been introduced and studied: brushless DC motors (BLDC) control by achieving optimum current in the motor, such that the motion task is achieved, and the energy consumption is minimized. A proof-ofconcept study to design a BLDC motor driver which has superiority compare to an off-the-shelf driver in terms of energy regeneration, and finally, the third aim is to develop a framework to study energy-oriented control in cooperative robots. The first aim is achieved by introducing an analytical solution which finds the optimal currents based on the desired torque generated by a virtual. Furthermore, it is shown that the well-known choice of a zero direct current component in the direct-quadrature frame is sub-optimal relative to our energy optimization objective. The second aim is achieved by introducing a novel BLDC motor driver, composed of three independent regenerative drives. To run the motor, the control law is obtained by specifying an outer-loop torque controller followed by minimization of power consumption via online constrained quadratic optimization. An experiment is conducted to assess the performance of the proposed concept against an off-the-shelf driver. It is shown that, in terms of energy regeneration and consumption, the developed driver has better performance, and a reduction of 15% energy consumption is achieved. v For the third aim, an impedance-based control scheme is introduced for cooperative manipulators grasping a rigid object. The position and orientation of the payload are to be maintained close to a desired trajectory, trading off tracking accuracy by low energy consumption and maintaining stability. To this end, an optimization problem is formulated using energy balance equations. The optimization finds the damping and stiffness gains of the impedance relation such that the energy consumption is minimized. Furthermore, L2 stability techniques are used to allow for time-varying damping and stiffness in the desired impedance. A numerical example is provided to demonstrate the results

An analysis of the effect of gravitational load on the energy consumption of industrial robots

The gravitational load has a great impact on industrial robots’ torque. Much research has gone into investigating this parameter in order to find an effective solution for achieving high performance of the robot systems. However, the existing investigations are still limited to analyze the influence of the gravitational load on the robot torque behavior. An analysis of the direct influence of gravitational load on electrical energy consumption has not yet been explored. This paper provides a model based approach for analyzing the effect of the gravitational load to the energy consumption. A mechatronic simulation tool is used for analyzing robot energy consumption. The results show that the gravitational load has an influence on the energy consumption of high-mass industrial robots, especially during upward movement