A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems <s> Optimized Sharing <s> A method for the regenerative energy saving in multi-axis servo-motor-drives is presented in this paper. This energy management is achieved through a proper time-coordination between the speed commands of multi-axis drives. Moreover, the proposed approach significantly limits the peak value of the ac input current in these systems. It is mathematically proved that a time-delay can significantly increase the amount of utilized regenerative energy and consequently decreases the amount of dissipated energy. In this paper, a set of closed-form formulas is developed, where the motor losses are neglected. The findings of this investigation were experimentally verified using a two-axis permanent-magnet (PM) motor-drive system, and the results are presented in this paper. The experimental results are in remarkable agreement with the developed closed-form formulas. <s> BIB001 </s> A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems <s> Optimized Sharing <s> This paper proposes a novel cost function formulation for minimization of the energy consumption of industrial robots by trajectory optimization. Besides the dynamics of the robot including friction losses, the model especially takes into account the losses of servo drives and inverters. Furthermore, the ability of energy exchange between the robot axes via the coupled DC-bus is included, since the servo drives support generator mode during deceleration. The utilized energy-based robot model is applicable to different manipulator types. For the energy-efficient motion planning, point-to-point trajectories are defined by B-spline functions. The given nonlinear optimization problem is solved using gradient-based methods, considering kinematic and dynamic constraints. Several simulation results are presented, demonstrating the intense effect of energy exchange in the robot controller's power electronics. Furthermore, a comparative study is given showing that the proposed method is able to outperform existing torque-based approaches. <s> BIB002 </s> A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems <s> Optimized Sharing <s> The improvement of energy efficiency in automation and robotic systems still has high significance in engineering research. This paper presents experimental results of minimum energy trajectory optimization for multi-axis manipulators using electrical energy exchange via the shared inverter DC link. Thus, existing simulation findings demonstrating the potential of the proposed minimum energy optimization approach are validated. In this context, a global optimization method is applied utilizing an advanced cost function formulation that is based on an energy flow model including all servo drive components. After the validation of the utilized system model, increased efficiency improvements are proven and compared to established methods. The presented approach as well as the experimental results are fully transferable to any kind of multi-axis system comprising DC link energy supply. <s> BIB003 </s> A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems <s> Optimized Sharing <s> The energy demand of applications using in- verter controlled electrical servo drives is considerably de- pendent on the applied trajectory profiles. In this paper, the improvement potential in supply energy consumption is an- alyzed with respect to the standard servo controller func- tionality. The optimal choice of trajectory profiles and ex- ecution times for point-to-point movements offers distinct energy savings. From the presented results, a number of general trajectory parametrization advices of even roughly known system characteristics can be derived. Even with lit- tle effort and without knowledge of exact system parameters, considerable energy savings are achievable. <s> BIB004 </s> A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems <s> Optimized Sharing <s> Positioning tasks of multi-axis servo drive mechanisms typically lead to high energy demands, especially if lossy operating points are applied and/or recuperated break energy, e. g. during deceleration phases, is not effectively reused. A trajectory optimization approach based on the particle swarm algorithm is presented for the adaption of multi-axis positioning tasks during system run-time. Established path planning methods (including the possibility of minimum time motion) are applied, that are adapted by only two parameters per axis and positioning task. In this manner, idle-times that often exist between the motion cycles and/or energy exchange via coupled inverter DC-links are utilized to reduce energy demands and improve system efficiency. In contrast to existing offline trajectory optimization procedures, the method is able to adapt changing motion tasks during system run-time within only few movement cycles. Experimental results prove that, depending on the use case and the chosen optimization constraints, energy losses are effectively reduced, brake chopper dissipation often is even completely avoidable and, hence, total energy demands are distinctly reduced. The approach is applicable to different multi-axis configurations and enables to considerable energy savings without additional hardware invest. <s> BIB005
The addition of energy-sharing devices to mechatronic and robotic systems allows for exploiting the available kinetic energy that instead would be wasted and in addition, for opening new scenarios for motion planning optimization. This is valid both when different systems are cooperating in a robotic cell as well as in multi-degrees-of-freedom mechanisms. Even if not many works have been published, some interesting applications and results can be found. Indeed, the concept of the cooperation between a trajectory planner and energy recovery and sharing devices has been considered BIB002 BIB003  BIB004 . However, most of these works rely only on the concept that the braking energy can be fully recovered and is then essentially subtracted from the total energy requested BIB002 BIB003  BIB004 . On the contrary, in BIB001 , a study of the optimal trajectory also considering the energy recoverable as the result of an optimization of the energy that could be shared between two axes working together is carried out. The results show how a proper coordination of the axes, that is, shifting and overlapping of the two trapezoidal-velocity profiles, allows for increasing the amount of utilized regenerative energy and thus the reduction of energy consumption. In a similar manner, Hansen et al. BIB005 consider an optimization method of multi-axis servo-drive mechanisms able to work while the system performs its task. This method exploits the idle times that exist between the motion cycles and the energy exchange via coupled inverter DC links. Thus, the standard double-S velocity profile is stretched and delays on the starting of the motions are inserted in order to reduce the consumed energy.