EDITOR ’ S CHOICE MINIATURE MOTORS
PORTESCAP
Top motor trends in the continuing evolution of robots
Robots depend on miniature motors for their motion , so evolution within robotics relies on technological advances in motor design . Dave Beckstoffer of Portescap highlights the key trends in miniature motor development for robots .
The use of robots proliferates in applications which span from surgical suites to the battlefield . While robots become more specialised , a commonality is the corresponding development of miniature motors on which robots depend for their motion . Advances in the development of robots therefore must be matched by advances in the motors which drive them , so let ’ s look at the key trends in miniature motor technology .
MOBILITY AND FOOTPRINT
Robot design , particularly for cobots , has to enable mobility and compactness . To effectively match the capability of a human hand , the motors that power them require high power density in a small , lightweight package . A higher power density in a smaller and lighter motor details the advantage of brushless DC motors ( BLDC ) compared to conventional DC designs . Slotless BLDC motors , combined with efficient planetary gearboxes , achieve this combination and can be integrated into typical robot formats to suit the footprint constraint .
Key capabilities of robots involved in tasks such as manufacturing automation are speed and precision . In a pick and place robotic application , coreless DC motors and disc magnet stepper motors are well suited as a result of their extremely low inertia , enabling repeated and rapid changes in acceleration and deceleration . Similarly , applications requiring dynamic yet smooth control , such as camera systems , benefit from the elimination of cogging or detent torque , making slotless BLDC an excellent motor choice .
The mobility of many robotic applications depends on battery power , which makes energy efficiency a critical factor .
The mobility of many robotic applications depends on battery power , which makes energy efficiency a critical factor . Ironless brush DC motors can achieve up to 90 % efficiency and are selected where long robotic running time is required . For high torque-low speed applications , it is also key to ensure that the gearbox is efficient and matched to the motor .
ROBUSTNESS AND EXTENDED LIFE
A significant advantage of robots is that they can be used in environments and under conditions which humans cannot , or ideally would not , sustain . Surveillance and patrol of industrial pipelines , high voltage electrical networks or even theatres of war mean that robots are put into motion by miniature motors protected against the most arduous conditions to ensure ongoing operation .
Protection against extremes of temperature and pressure are required for robotic applications such as surgical robots undergoing autoclave sterilisation . The robot ’ s motor depends on a high degree of resilience ; setting components within a thermoset epoxy maximises robustness and extends its lifecycle .
Robots used in surgical applications demand close coordination so multiple axis control is required .
24 PECM Issue 48