Following calculation of the torque requirement , the wheels ’ rotational speed can be determined , and appropriate selection of the motor and gearbox can then be made based on the output frequency . Typically , the higher the operating voltage , the higher the motor ’ s speed capability .
While sufficient packaging space must be provided for the encoder , brake , motor and gearing , an important factor if the motor stack is enclosed is operating temperature and avoidance of overheating . Motor capacity and heat dissipation techniques may need to be considered in such circumstances to ensure reliability when the robot is deployed in the field .
MOTION SOLUTION DEVELOPMENT FOR A WHEELED ROBOT
Portescap recently provided the motion solution for a four-wheel drive robot . With two pairs of powered wheels , each pair turns in the same direction . It ’ s vital that the motion system controls both pairs to run at the same speed , otherwise overall robot speed will be reduced and steering won ’ t be aligned . Unlike differential steering that uses separately driven wheels , this four-wheel drive solution has a differential steering mechanism that requires only a single motor , which reduces footprint , energy use and cost .
The solution was achieved using a Portescap Brushed DC 35 GLT motor and a planetary gearbox with a 99.8 total gearbox ratio . In a packaging of just 32 mm diameter and 115 mm in length , the gearbox output torque capacity reaches 8 Nm with an output speed of 80 rpm .
A major benefit of robots is their ability to complete tasks that may be difficult or hazardous for humans to perform .
With a life expectancy of 1,000 hours , the motion system can withstand temperatures up to 125 ° C . These results provide reliable , durable motion to a variety of wheeled robot applications .
SPECIALIST APPLICATION ENGINEERING
Terrain can be a challenge for wheeled robots , particularly among rocky environments , sharp declines , or areas with low friction . While technology such as tracks with a differential drive and skid steer four-wheel drive are increasingly used , techniques to optimise existing motion solutions can also be deployed to increase durability , efficiency , and reduce noise .
For example , needle roller bearings can be introduced to increase durability and efficiency by avoiding scuffing failures and providing smooth rotation of planet gears . Ensuring the gearbox has the optimum teeth combination with lower torsional forces can also reduce noise , which can be improved with an advanced acoustic simulation to predict noise emission .
To achieve the optimum motion system for a wheeled robot design , it ’ s crucial that it is specified according to analysis of the application requirements and the environment in which the robot will operate . Portescap ’ s engineers can provide a range of solutions for robotic motion , with engineers able to create customised designs for precise needs .
For further information , please visit Web : www . portescap . com
Issue 54 PECM 25