Speed control of a HSR-2645CR Continuous Rotation Servo

Help & Support Robot Parts
1

Hi There,

I’m using Hitec HSR-2645CR servos as wheel motors on a robot that I’m building at the moment, but I’m having difficulty getting any speed control with them. I’ve tried driving them with an RC receiver as well as an Adafruit servo hat on a raspberry pi. In both cases the servos are either stopped or turning CW / CCW at full speed. As soon as the controller leaves the dead-band the servo is suddenly going full whack!

Has anyone else had this problem with these servos? I was expecting them to operate the same as other continuous servos with smooth speed adjustment as the duty cycle is changed. Do I need to get a servo programmer to configure them to do this?

Thanks in advance,

Pete

2

Hi Pete,

The HSR-2645CR should have a linear speed control. It will rotate at a specific speed based on that signal it receives.
Its speed should be proportional meaning that the further the signal deviates from the center (1500usec), the faster the servo will rotate.
What is the PWM signal you send from your RC transmitter ?
If you have an Arduino board, can you try to control the servo with it ?

Regards,

3

Hi Brahim,

Thanks for your reply, however the problem turned out to be with the servos themselves in this case! And I’d like to put this out there as a warning to the robotics community as a whole.

I purchased my HSR-2645CR servos from an online retailer in Europe since we’re based in the UK. According to the official EU Hitec distributor the HSR-2645CR servos sold by them in Europe don’t have any speed control. I personally find this beyond ridiculous, and I’m currently trying to get them replaced for servo’s that behave as advertised. But if anyone else is wanting to use these servos and you’re in Europe either buy them from the US or get your retailer to directly guarantee you that you will be getting the version which has full PWM range speed control.