inertia in proportion to the square of the gear ratio . Moreover , modern control systems with advanced algorithms and high-resolution feedback devices can address inertia mismatch issues . However , the adverse effects of inertia mismatch , or a high load to motor inertia , can become worse by a lack of stiffness in the system , also known as load compliance . To minimise these issues , we can look to wider components of the application or machine to optimise rigidity .
Load compliance challenges are more common in indirect drive systems . Here , the motor is not directly coupled with the load but is connected through one or more power transmission elements such as a gear mechanism , pulley belt systems , chain drives , or ballscrews . To simplify an indirect system to increase stiffness , as well as
reduce further potential causes of inertia , it is useful to consider the effect of each connected component beyond the motor shaft .
Direct drive systems For demanding applications that would significantly benefit from a close motor-to-load inertia ratio , starting with the possibility of a direct drive system is advisable . This motion design approach will keep the number of power transmission elements to a minimum while optimising compliance .
With a direct drive , the motor is directly coupled to its load . This connection removes the inertia resulting from power transmission components , and the less inertia the motor needs to overcome , the less torque it requires to meet the desired acceleration rate . A direct drive system also minimises effects such as backlash , the play between mechanical components that can also impact power transfer and system reliability .
To minimise the overall inertia within an application or machine , as well as optimize the inertia balance between the motor and the load , a comprehensive review of all design aspects impacting the motion cycle is advisable . To effectively achieve this , involving motion engineers early in the overall design process is preferable .
Firstly , engineering input can help to improve the wider machine or application design and advise on the best motion solution approach . Secondly , early involvement of motion designers means that if customisation is required for the motor or transmission , the most effective results can be reached early in the process with no impact in time to market .
Portescap provides a ready supply of tools and motor data to help guide original equipment manufacturer ( OEM ) engineers in their specifications . Most importantly , the company ’ s motion specialists are available to discuss design and customisation needs across a range of applications .
For further information , please visit www . portescap . com
Issue 69 PECM 35