cannot perform command after remote logging in via ssh

I'm trying to use my Linux VM to ssh to a Drone (running Linux 16.4) and perform command roscore to start the Drone. The command is:

So I do, for example, ssh drone@192.168.1.1 'roscore', and I actually got:

ngocdp@ngocdp-VirtualBox:~$ ssh drone@192.168.1.1 'uptime;bash'
drone@192.168.1.1's password:
bash: roscore: command not found

If I just run ssh on my Terminal ssh drone@192.168.1.1 and then manually run roscore, I can start it successfully:

ngocdp@ngocdp-VirtualBox:~$ ssh drone@192.168.1.1
drone@192.168.1.1's password:
Welcome to Ubuntu 16.04.6 LTS (GNU/Linux 4.15.0-45-generic x86_64) * Documentation: * Management: * Support:
211 packages can be updated.
136 updates are security updates.
Last login: Sun Jul 7 17:04:59 2019 from 192.168.1.100
drone@drone-Drone:~$ roscore
WARNING: unable to configure logging. No log files will be generated
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

I would expect the command ssh drone@192.168.1.1 'roscore' would get into the root directory drone@drone-Drone:~$ first, then execute the command roscore.

When I try pwd, by ssh drone@192.168.1.1 'pwd', it give home\drone, which is the root directory. But I don't know why I cannot execute the command.

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